query: what is an attack where every possible password is attempted using a random or logical algorithm

pos: Brute-force attack common) password is tested against multiple usernames or encrypted files. The process may be repeated for a select few passwords. In such a strategy, the attacker is generally not targeting a specific user. Brute-force attack In cryptography, a brute-force attack consists of an attacker submitting many passwords or passphrases with the hope of eventually guessing correctly. The attacker systematically checks all possible passwords and passphrases until the correct one is found. Alternatively, the attacker can attempt to guess the key which is typically created from the password using a key derivation function. This is known as an exhaustive key search.

pos: Challenge–response authentication the integer "N". In other variations, a hash function operates on a password and a random challenge value to create a response value. Such encrypted or hashed exchanges do not directly reveal the password to an eavesdropper. However, they may supply enough information to allow an eavesdropper to deduce what the password is, using a dictionary attack or brute-force attack. The use of information which is randomly generated on each exchange (and where the response is different from the challenge) guards against the possibility of a replay attack, where a malicious intermediary simply records the exchanged data and retransmits it

pos: Master Password backups of potential password databases. The algorithm involves the following parameters: The master key is a global 64-byte secret key generated from the user's secret master password and salted by their full name. The salt is used to avoid attacks based on rainbow tables. The scrypt algorithm, an intentionally slow key derivation function, is used for generating the master key to make a brute-force attack infeasible. The template seed is a site-specific secret in binary form, generated from the master key, the site name and the counter using the HMAC-SHA256 algorithm. It is later converted to a character string using

pos: Password manager mitigated with the use of a multi-factor verification device. Some password managers include a password generator. Generated passwords may be guessable if the password manager uses a weak random number generator instead of a cryptographically secure one. A strong password manager will include a limited number of false authentication entries allowed before the password manager is locked down and requires IT services to re-activate. This is the best way to protect against the brute-force attack. Password managers that do not prevent swapping their memory to hard drive make it possible to extract unencrypted passwords from the computer’s hard drive. Turning

pos: Key derivation function from secret passwords or passphrases, which typically do not have the desired properties to be used directly as cryptographic keys. In such applications, it is generally recommended that the key derivation function be made deliberately slow so as to frustrate brute-force attack or dictionary attack on the password or passphrase input value. Such use may be expressed as , where is the derived key, is the key derivation function, is the original key or password, is a random number which acts as cryptographic salt, and refers to the number of iterations of a sub-function. The derived key is used instead

pos: Honey encryption Honey encryption Honey encryption is a type of data encryption that "produces a ciphertext, which, when decrypted with an incorrect key as guessed by the attacker, presents a plausible-looking yet incorrect plaintext password or encryption key." Ari Juels and Thomas Ristenpart of the University of Wisconsin, the developers of the encryption system, presented a paper on honey encryption at the 2014 Eurocrypt cryptography conference. A brute-force attack involves repeated decryption with random keys; this is equivalent to picking random plaintexts from the space of all possible plaintexts with a uniform distribution. This is effective because even though the attacker is

pos: Brute-force attack to recognize when the code has been cracked or by making the attacker do more work to test each guess. One of the measures of the strength of an encryption system is how long it would theoretically take an attacker to mount a successful brute-force attack against it. Brute-force attacks are an application of brute-force search, the general problem-solving technique of enumerating all candidates and checking each one. Brute-force attacks work by calculating every possible combination that could make up a password and testing it to see if it is the correct password. As the password's length increases, the amount

pos: Password cracking functionality. Most of these packages employ a mixture of cracking strategies, algorithm with brute force and dictionary attacks proving to be the most productive. The increased availability of computing power and beginner friendly automated password cracking software for a number of protection schemes has allowed the activity to be taken up by script kiddies. Password cracking In cryptanalysis and computer security, password cracking is the process of recovering passwords from data that have been stored in or transmitted by a computer system. A common approach (brute-force attack) is to try guesses repeatedly for the password and check them against an

pos: Brute-force attack Brute-force attack In cryptography, a brute-force attack consists of an attacker submitting many passwords or passphrases with the hope of eventually guessing correctly. The attacker systematically checks all possible passwords and passphrases until the correct one is found. Alternatively, the attacker can attempt to guess the key which is typically created from the password using a key derivation function. This is known as an exhaustive key search. A brute-force attack is a cryptanalytic attack that can, in theory, be used to attempt to decrypt any encrypted data (except for data encrypted in an information-theoretically secure manner). Such an attack might

pos: Password strength at risk. Passwords are created either automatically (using randomizing equipment) or by a human; the latter case is more common. While the strength of randomly chosen passwords against a brute-force attack can be calculated with precision, determining the strength of human-generated passwords is challenging. Typically, humans are asked to choose a password, sometimes guided by suggestions or restricted by a set of rules, when creating a new account for a computer system or Internet Web site. Only rough estimates of strength are possible, since humans tend to follow patterns in such tasks, and those patterns can usually assist an attacker.

pos: Microsoft Office password protection form ABABABABABAx where the first 11 chars are either A or B and the last is an ASCII character. There are a number of attacks that can be employed to find a password or remove password protection from Excel and Word documents. Password removal can be done with the help of precomputation tables or a guaranteed decryption attack. Attacks that target the original password set in Microsoft Excel and Word include dictionary attack, rule-based attack, brute-force attack, mask attack and statistics-based attack. The efficiency of attacks can be considerably enhanced if one of the following means is applied: multiple CPUs

pos: Brute-force attack truly random sequence of key bits. A 140 character one-time-pad-encoded string subjected to a brute-force attack would eventually reveal every 140 character string possible, including the correct answer – but of all the answers given, there would be no way of knowing which was the correct one. Defeating such a system, as was done by the Venona project, generally relies not on pure cryptography, but upon mistakes in its implementation: the key pads not being truly random, intercepted keypads, operators making mistakes – or other errors. In case of an offline attack where the attacker has access to the encrypted

pos: Microsoft Excel can choose any encryption algorithm that is available in the system (see Cryptographic Service Provider). Due to the CSP, an "Excel" file can't be decrypted, and thus the "password to open" can't be removed, though the brute-force attack speed remains quite high. Nevertheless, the older "Excel 97/2000" algorithm is set by the default. Therefore, users who did not changed the default settings lack reliable protection of their documents. The situation changed fundamentally in "Excel 2007", where the modern AES algorithm with a key of 128 bits started being used for decryption, and a 50,000-fold use of the hash function SHA1

neg: Random password generator Random password generator A random password generator is software program or hardware device that takes input from a random or pseudo-random number generator and automatically generates a password. Random passwords can be generated manually, using simple sources of randomness such as dice or coins, or they can be generated using a computer. While there are many examples of "random" password generator programs available on the Internet, generating randomness can be tricky and many programs do not generate random characters in a way that ensures strong security. A common recommendation is to use open source security tools where possible, since they

neg: Password strength allowing very rapid recovery of the password once its hash is obtained. Very long lists of pre-computed password hashes can be efficiently stored using rainbow tables. This method of attack can be foiled by storing a random value, called a cryptographic salt, along with the hash. The salt is combined with the password when computing the hash, so an attacker precomputing a rainbow table would have to store for each password its hash with every possible salt value. This becomes infeasible if the salt has a big enough range, say a 32-bit number. Unfortunately, many authentication systems in common use

neg: Password strength entropy is just the base-2 logarithm or log of the number of possible passwords, assuming each symbol in the password is produced independently. Thus a random password's information entropy, "H", is given by the formula where "N" is the number of possible symbols and "L" is the number of symbols in the password. "H" is measured in bits. In the last expression, "log" can be to any base. A binary byte is usually expressed using two hexadecimal characters. To find the length, "L," needed to achieve a desired strength "H," with a password drawn randomly from a set of "N"

neg: Password can operate by brute force (i.e. trying every possible combination of characters) or by hashing every word from a list; large lists of possible passwords in many languages are widely available on the Internet. The existence of password cracking tools allows attackers to easily recover poorly chosen passwords. In particular, attackers can quickly recover passwords that are short, dictionary words, simple variations on dictionary words or that use easily guessable patterns. A modified version of the DES algorithm was used as the basis for the password hashing algorithm in early Unix systems. The crypt algorithm used a 12-bit salt value

neg: Random password generator and probably most importantly, transmitting candidate passwords over the Internet raises obvious security concerns, particularly if the connection to the password generation site's program is not properly secured or if the site is compromised in some way. Without a secure channel, it is not possible to prevent eavesdropping, especially over public networks such as the Internet. A possible solution to this issue is to generate the password using a client-side programming language such as JavaScript. The advantage of this approach is that the generated password stays in the client computer and is not transmitted to or from an external server.

neg: One-time password OTP codes will be used in the "future." For example, an OTP password-generator that is pseudo-random rather than truly random might or might not be able to be compromised, because pseudo-random numbers are often predictable once one has the "past" OTP codes. An OTP system can only use truly random OTPs if the OTP is generated by the authenticator and transmitted (presumably out-of-band) to the user; otherwise, the OTP must be independently generated by each party, necessitating a repeatable, and therefore merely pseudo-random, algorithm. Although OTPs are in some ways more secure than a static memorized password, users of OTP

neg: War dialing in public places to advertise the availability of wireless networks. The term is also used today by analogy for various sorts of exhaustive brute force attack against an authentication mechanism, such as a password. While a dictionary attack might involve trying each word in a dictionary as the password, "wardialing the password" would involve trying every possible password. Password protection systems are usually designed to make this impractical, by making the process slow and/or locking out an account for minutes or hours after some low number of wrong password entries. War dialing War dialing or wardialing, a.k.a. "janning", is a

neg: Master Password Master Password Master Password is an algorithm designed by Maarten Billemont for creating unique passwords in a reproducible manner. It differs from traditional password managers in that the passwords are not stored on disk or in the cloud, but are recreated every time by using information entered by the user; most importantly, their full name, a master password, and a unique name for the service the password is intended for. By not storing the passwords anywhere, this approach tries to make it harder for attackers to steal or intercept them. It also removes the need for synchronization between devices, and

neg: Quicknet Opera 9+, Safari 3+ and Google Chrome 1+ . Quicknet is an AJAX framework that aims to protect users’ passwords with specially designed algorithm. This is achieved by using the same Cryptographic hash function in JavaScript code on the client-side, as well as PHP code on the server-side, to generate and compare hash results based on users’ passwords and some random data. However, no cleartext password would be sent over the network or stored in the server. It is believed that it is impossible to steal a session or discover the user’s original password, even if the data sent over

neg: Rainbow table this attack infeasible. Rainbow tables were invented by Philippe Oechslin as an application of an earlier, simpler algorithm by Martin Hellman. Any computer system that requires password authentication must contain a database of passwords, either hashed or in plaintext, and various methods of password storage exist. Because the tables are vulnerable to theft, storing the plaintext password is dangerous. Most databases, therefore, store a cryptographic hash of a users password in the database. In such a system, no one – including the authentication system – can determine what a users password is by merely looking at the value stored in

neg: Random password generator allow independent checks on the quality of the methods used. Note that simply generating a password at random does not ensure the password is a strong password, because it is possible, although highly unlikely, to generate an easily guessed or cracked password. In fact there is no need at all for a password to have been produced by a perfectly random process: it just needs to be sufficiently difficult to guess. A password generator can be part of a password manager. When a password policy enforces complex rules, it can be easier to use a password generator based on that

neg:
Anyplace Control traffic encryption
 All transferred data is encrypted with the RC4 algorithm with 128 bit random key for encryption.
 2. Double password protection
 For connection to the remote computer via Internet the knowledge of at least two passwords is required: Account Password and remote PC Access Password.
 3. No open ports in the Firewall
 No need to open additional ports in the firewall when connecting using Account Connection service. The product is shareware available for private and corporate usage. Licenses are provided on a per Host or Admin module basis. Anyplace Control Anyplace Control is a

neg: Elliptic Curve Digital Signature Algorithm for the PlayStation 3 game console. However, this attack only worked because Sony did not properly implement the algorithm, because formula_24 was static instead of random. As pointed out in the Signature generation algorithm section above, this makes formula_13 solvable and the entire algorithm useless. On March 29, 2011, two researchers published an IACR paper demonstrating that it is possible to retrieve a TLS private key of a server using OpenSSL that authenticates with Elliptic Curves DSA over a binary field via a timing attack. The vulnerability was fixed in OpenSSL 1.0.0e. In August 2013, it was revealed that bugs

neg: Random testing algorithm in a much more complex way for better performance. For example, to test an implementation of the Schönhage–Strassen algorithm, the standard "*" operation on integers can be used: int getRandomInput() { void testFastMultiplication(int n) { While this example is limited to simple types (for which a simple random generator can be used), tools targeting object-oriented languages typically explore the program to test and find generators (constructors or methods returning objects of that type) and call them using random inputs (either themselves generated the same way or generated using a pseudo-random generator if possible). Such approaches then maintain a pool

neg: Randomized algorithm time without this ability; this is the question of whether P = BPP. However, in other contexts, there are specific examples of problems where randomization yields strict improvements. Randomized algorithm A randomized algorithm is an algorithm that employs a degree of randomness as part of its logic. The algorithm typically uses uniformly random bits as an auxiliary input to guide its behavior, in the hope of achieving good performance in the "average case" over all possible choices of random bits. Formally, the algorithm's performance will be a random variable determined by the random bits; thus either the running time, or

neg: Password cracking to the attacker, this number can be in the billions or trillions per second, since an "offline attack" is possible. If not, the rate depends on whether the authentication software limits how often a password can be tried, either by time delays, CAPTCHAs, or forced lockouts after some number of failed attempts. Another situation where quick guessing is possible is when the password is used to form a cryptographic key. In such cases, an attacker can quickly check to see if a guessed password successfully decodes encrypted data. For some kinds of password hash, ordinary desktop computers can test over

neg: Password Safe through the command-line interface. The software features a built-in password generator that generates random passwords. The user may also designate parameters for password generation (length, character set, etc.), creating a "Named Password Policy" by which different passwords can be created. The original Password Safe was built on Bruce Schneier's Blowfish encryption algorithm. Rony Shapiro implemented Twofish encryption along with other improvements to the 3.xx series of Password Safe. The keys are derived using an equivalent of PBKDF2 with SHA-256 and a configurable number of iterations, currently set at 2048. Reviewers have highlighted the program's simplicity as its best feature. Password

neg: Forward secrecy Station-to-Station protocol. Forward secrecy has also been used to describe the analogous property of password-authenticated key agreement protocols where the long-term secret is a (shared) password. In 2000 the IEEE first ratified IEEE 1363, which establishes the related one-party and two-party forward secrecy properties of various standard key agreement schemes. A public-key system has the property of forward secrecy if it generates one random secret key per session to complete a key agreement, without using a deterministic algorithm. This means that the compromise of one session cannot compromise others as well, and there is no one secret value whose acquisition

neg: Random number generator attack these remaining weak keys, but researchers continue to find weak key implementations. In December 2010, a group calling itself "fail0verflow" announced recovery of the elliptic curve digital signature algorithm (ECDSA) private key used by Sony to sign software for the PlayStation 3 game console. The attack was made possible because Sony failed to generate a new random nonce for each signature. An analysis comparing millions of RSA public keys gathered from the Internet was announced in 2012 by Lenstra, Hughes, Augier, Bos, Kleinjung, and Wachter. They were able to factor 0.2% of the keys using only Euclid's algorithm. They exploited

neg: Password strength toss. Put another way, a password with 42 bits of strength would require 2 (4,398,046,511,104) attempts to exhaust all possibilities during a brute force search. Thus, adding one bit of entropy to a password doubles the number of guesses required, which makes an attacker's task twice as difficult. On average, an attacker will have to try half of the possible passwords before finding the correct one. Random passwords consist of a string of symbols of specified length taken from some set of symbols using a random selection process in which each symbol is equally likely to be selected. The symbols

neg: ElcomSoft password recovery In 2009 ElcomSoft released a tool that takes WPA/WPA2 Hash Codes and uses brute-force methods to guess the password associated with a wireless network. The brute force attack is carried out by testing passwords with a known SSID of a network of which the WPA/WPA2 Hash Code has been captured. The passwords that are tested are generated from a dictionary using various mutation (genetic algorithm) methods, including case mutation (password, PASSWORD, PassWOrD, etc.), year mutation (password, password1992, password67, etc.), and many other mutations to try to guess the correct password. The advantages of using such methods over the

neg: Monte Carlo localization Monte Carlo localization Monte Carlo localization (MCL), also known as particle filter localization, is an algorithm for robots to localize using a particle filter. Given a map of the environment, the algorithm estimates the position and orientation of a robot as it moves and senses the environment. The algorithm uses a particle filter to represent the distribution of likely states, with each particle representing a possible state, i.e., a hypothesis of where the robot is. The algorithm typically starts with a uniform random distribution of particles over the configuration space, meaning the robot has no information about where it is

neg: Randomized algorithm Randomized algorithm A randomized algorithm is an algorithm that employs a degree of randomness as part of its logic. The algorithm typically uses uniformly random bits as an auxiliary input to guide its behavior, in the hope of achieving good performance in the "average case" over all possible choices of random bits. Formally, the algorithm's performance will be a random variable determined by the random bits; thus either the running time, or the output (or both) are random variables. One has to distinguish between algorithms that use the random input so that they always terminate with the correct answer, but

neg: PBKDF2 is computed as follows (with codice_1 marking string concatenation): The function "F" is the xor (^) of "c" iterations of chained PRFs. The first iteration of PRF uses "Password" as the PRF key and "Salt" concatenated with "i" encoded as a big-endian 32-bit integer. (Note that "i" is a 1-based index.) Subsequent iterations of PRF use "Password" as the PRF key and the output of the previous PRF computation as the salt: where: For example, WPA2 uses: PBKDF2 has an interesting property when using HMAC as its pseudo-random function. It is possible to trivially construct any number of resulting collisions

neg: Password dictionary attack, all words in one or more dictionaries are tested. Lists of common passwords are also typically tested. Password strength is the likelihood that a password cannot be guessed or discovered, and varies with the attack algorithm used. Cryptologists and computer scientists often refer to the strength or 'hardness' in terms of entropy. Passwords easily discovered are termed "weak" or "vulnerable"; passwords very difficult or impossible to discover are considered "strong". There are several programs available for password attack (or even auditing and recovery by systems personnel) such as L0phtCrack, John the Ripper, and Cain; some of which use

neg: F-Zero GX level chosen are given to players before starting a cup. Players get an additional spare machine for every five contenders he or she eliminates, and each eliminated contender recovers a portion of the player's energy meter. Competitors can be damaged and eliminated by means of a spin or side attack. The Vs. Battle is the multiplayer mode where two to four players can compete simultaneously. Time Attack lets the player choose any track and complete it in the shortest time possible. An Internet ranking system was established where players enter a password on the official F-Zero website and get ranked

neg: SQRL SQRL SQRL (pronounced "squirrel") or Secure, Quick, Reliable Login (formerly Secure QR Login) is a draft open standard for secure website login and authentication. The software solution typically uses a link of the scheme sqrl:// or optionally a QR code, where a user identifies via a pseudonymous zero-knowledge proof rather than providing a user ID and password. This method is thought to be impervious to a brute force password attack or data breach. It shifts the burden of security away from the party requesting the authentication and closer to the operating system implementation of what is possible on the hardware,

neg: RC4 algorithm is: The value "w", is relatively prime to the size of the S array. So after 256 iterations of this inner loop, the value "i" (incremented by w every iteration) has taken on all possible values 0...255, and every byte in the S array has been swapped at least once. Like other sponge functions, Spritz can be used to build a cryptographic hash function, a deterministic random bit generator (DRBG), an encryption algorithm that supports authenticated encryption with associated data (AEAD), etc. Spritz was broken by Banik and Isobe. Where a protocol is marked with "(optionally)", RC4 is one

neg: Password strength can be individual characters from a character set (e.g., the ASCII character set), syllables designed to form pronounceable passwords, or even words from a word list (thus forming a passphrase). The strength of random passwords depends on the actual entropy of the underlying number generator; however, these are often not truly random, but pseudo random. Many publicly available password generators use random number generators found in programming libraries that offer limited entropy. However most modern operating systems offer cryptographically strong random number generators that are suitable for password generation. It is also possible to use ordinary dice to generate random

neg: Password length parameter Password length parameter In telecommunication, a password length parameter is a basic parameter the value of which affects password strength against brute force attack and so is a contributor to computer security. One use of the password length parameters is in the expression formula_1, where formula_2 is the probability that a password can be guessed in its lifetime, formula_3 is the maximum lifetime a password can be used to log into a system, formula_4 is the number of guesses per unit of time, and formula_5 is the number of unique algorithm-generated passwords (the 'password space'). The degree of password security

neg: Microsoft Office password protection key and decrypt the password-protected document instantly. In Excel and Word 97 and 2000 the key length was increased to 40 bits. This protection algorithm is also currently considered to be weak and presents no difficulties to hacking software. The default protection in Office XP and 2003 was not changed, but an opportunity to use a custom protection algorithm was added. Choosing a non-standard Cryptographic Service Provider allows increasing a key length so that a key which is used to encrypt a document can’t be found. However, password-cracking programs can enter multiple random passwords with the same speed, so use

neg: Random encounter their distribution. Random encounters in rapid succession are considered undesirable as they lead to the player's perception of getting "bogged down", but with the simple algorithm, it is possible to have an encounter from taking only one step after an encounter. The early games in the "Dragon Quest" series, for example, allow random encounters to occur one step after the other. A more elaborate random encounter algorithm (and similar to those used in many games) would be the following: This ensures that, in any terrain, the player will not experience more than one random encounter every eight steps. A game

neg: Google Authenticator named OTP Authenticator is also available on Google Play. Google Authenticator Google Authenticator is a software token that implements two-step verification services using the Time-based One-time Password Algorithm (TOTP) and HMAC-based One-time Password algorithm (HOTP), for authenticating users of mobile applications by Google. The service implements algorithms specified in RFC 6238 and RFC 4226, respectively. Authenticator provides a six- to eight-digit one-time password which users must provide in addition to their username and password to log into Google services or other sites. The Authenticator can also generate codes for third-party applications, such as password managers or file hosting services. Previous

neg: Random password generator it is based on one. Thus a password generated using a 32-bit generator is limited to 32 bits entropy, regardless of the number of characters the password contains. Note, however, that a different type of attack might succeed against a password evaluated as 'very strong' by the above calculation. A large number of password generator programs and websites are available on the Internet. Their quality varies and can be hard to assess if there is no clear description of the source of randomness that is used, and if source code is not provided to allow claims to be checked. Furthermore,

neg: Lyapunov optimization of the probabilities of the random network events (such as random job arrivals or channel realizations). Choosing formula_47 reduces to minimizing a bound on the drift every slot and, for routing in multi-hop queueing networks, reduces to the backpressure routing algorithm developed by Tassiulas and Ephremides. Using formula_48 and defining formula_37 as the network power use on slot formula_3 leads to the drift-plus-penalty algorithm for minimizing average power subject to network stability developed by Neely. Using formula_48 and using formula_37 as the negative of an admission control utility metric leads to the drift-plus-penalty algorithm for joint flow control and network

neg: Salt (cryptography) for every hashed password. While this will make current rainbow tables useless (if the salt is properly chosen), if the salt is hard-coded into a popular product that salt can be extracted and a new rainbow table can be generated using that salt. Using a single fixed salt also means that every user who inputs the same password will have the same hash (unless the password hash is also dependent on the username). This makes it easier to attack multiple users by cracking only one hash. Short salt If a salt is too short, it will be easy for an

neg: Baum–Welch algorithm formula_5 for state formula_13 is given by Taking into account all the possible values of formula_9 and formula_1, we obtain the formula_17 matrix formula_18 where formula_19 belongs to all the possible states and formula_11 belongs to all the observations. An observation sequence is given by formula_21. Thus we can describe a hidden Markov chain by formula_22. The Baum–Welch algorithm finds a local maximum for formula_23 (i.e. the HMM parameters formula_24 that maximise the probability of the observation). Set formula_25 with random initial conditions. They can also be set using prior information about the parameters if it is available; this can

neg: Password strength passwords. "See stronger methods." Random password programs often have the ability to ensure that the resulting password complies with a local password policy; for instance, by always producing a mix of letters, numbers and special characters. For passwords generated by a process that randomly selects a string of symbols of length, "L", from a set of "N" possible symbols, the number of possible passwords can be found by raising the number of symbols to the power "L", i.e. "N". Increasing either "L" or "N" will strengthen the generated password. The strength of a random password as measured by the information

neg: Password-authenticated key agreement user of the method to remember any secret or public data other than the password. Password authenticated key exchange (PAKE) is where two or more parties, based only on their knowledge of a password, establish a cryptographic key using an exchange of messages, such that an unauthorized party (one who controls the communication channel but does not possess the password) cannot participate in the method and is constrained as much as possible from brute force guessing the password. (The optimal case yields exactly one guess per run exchange.) Two forms of PAKE are Balanced and Augmented methods. Balanced PAKE allows

neg: Approximate counting algorithm the current value of the counter), and using the logical AND function on all of those bits. The result is a zero if any of those pseudo-random bits are zero, and a one if they are all ones. Simply add the result to the counter. This procedure is executed each time the request is made to increment the counter. The algorithm is useful in examining large data streams for patterns. This is particularly useful in applications of data compression, sight and sound recognition, and other artificial intelligence applications. Approximate counting algorithm The approximate counting algorithm allows the counting of a

neg: Distinguishing attack may reveal information of M. Two systems S and T are said to be indistinguishable if there exists no algorithm D, connected to either S or T, able to decide whether it is connected to S or T. A distinguishing attack is given by such an algorithm D. It is broadly an attack in which the attacker is given a black box containing either an instance of the system under attack with an unknown key, or a random object in the domain that the system aims to emulate, then if the algorithm is able to tell whether the system or

neg: Google Authenticator Google Authenticator Google Authenticator is a software token that implements two-step verification services using the Time-based One-time Password Algorithm (TOTP) and HMAC-based One-time Password algorithm (HOTP), for authenticating users of mobile applications by Google. The service implements algorithms specified in RFC 6238 and RFC 4226, respectively. Authenticator provides a six- to eight-digit one-time password which users must provide in addition to their username and password to log into Google services or other sites. The Authenticator can also generate codes for third-party applications, such as password managers or file hosting services. Previous versions of the software were open-sourced but subsequent releases

neg: Microsoft Office password protection to enter a correct password to the field which appears after an attempt to open a password-protected document, viewing and editing the document will not be possible. Due to the encryption of a document protected by a password to open it, a hacker needs to decrypt the document to get access to its contents. To provide improved security, Microsoft has been consistently enhancing the Office encryption algorithm strength. In Excel and Word 95 and prior editions a weak protection algorithm is used that converts a password to a 16-bit key. Hacking software is now readily available to find a 16-bit

neg: Password access to the system, while validation of user access attempts remains possible. The most secure don't store passwords at all, but a one-way derivation, such as a polynomial, modulus, or an advanced hash function. Roger Needham invented the now common approach of storing only a "hashed" form of the plaintext password. When a user types in a password on such a system, the password handling software runs through a cryptographic hash algorithm, and if the hash value generated from the user's entry matches the hash stored in the password database, the user is permitted access. The hash value is created

neg: John the Ripper cracked before), encrypting it in the same format as the password being examined (including both the encryption algorithm and key), and comparing the output to the encrypted string. It can also perform a variety of alterations to the dictionary words and try these. Many of these alterations are also used in John's single attack mode, which modifies an associated plaintext (such as a username with an encrypted password) and checks the variations against the hashes. John also offers a brute force mode. In this type of attack, the program goes through all the possible plaintexts, hashing each one and then

neg: Birthday attack himself by making some random, inoffensive changes to the document before signing it, and by keeping a copy of the contract he signed in his own possession, so that he can at least demonstrate in court that his signature matches that contract, not just the fraudulent one. Pollard's rho algorithm for logarithms is an example for an algorithm using a birthday attack for the computation of discrete logarithms. Birthday attack A birthday attack is a type of cryptographic attack that exploits the mathematics behind the birthday problem in probability theory. This attack can be used to abuse communication between two

neg: Encryption Encryption In cryptography, encryption is the process of encoding a message or information in such a way that only authorized parties can access it and those who are not authorized cannot. Encryption does not itself prevent interference, but denies the intelligible content to a would-be interceptor. In an encryption scheme, the intended information or message, referred to as plaintext, is encrypted using an encryption algorithm – a cipher – generating ciphertext that can be read only if decrypted. For technical reasons, an encryption scheme usually uses a pseudo-random encryption key generated by an algorithm. It is in principle possible to

neg: WANK (computer worm) Florida. The worm propagated through the network pseudo-randomly from one system to the other by using an algorithm which converted the victim machine's system time into a candidate target node address (composed of a DECnet Area and Node number) and subsequently attempted to exploit weakly secured accounts such as SYSTEM and DECNET that had password identical to the usernames. The worm did not attack computers within DECnet area 48, which was New Zealand. A comment inside the worm source code at the point of this branch logic indicated that New Zealand was a nuclear free zone. New Zealand had recently

neg: HMAC-based One-time Password algorithm HMAC-based One-time Password algorithm HMAC-based One-time Password algorithm (HOTP) is a one-time password (OTP) algorithm based on HMAC "(hash-based message authentication code)". It is a cornerstone of the Initiative for Open Authentication (OATH). HOTP was published as an informational IETF RFC 4226 in December 2005, documenting the algorithm along with a Java implementation. Since then, the algorithm has been adopted by many companies worldwide (see below). The HOTP algorithm is a freely available open standard. The HOTP algorithm provides a method of authentication by symmetric generation of human-readable passwords, or "values", each used for only one authentication attempt. The one-time

neg: Multiple-try Metropolis dimension is not formula_22 but instead is formula_23. As this step size is much smaller than the "true" scale of the probability distribution (assuming that formula_22 is somehow known a priori, which is the best possible case), the algorithm executes a random walk along every parameter. Suppose formula_25 is an arbitrary proposal function. We require that formula_26 only if formula_27. Additionally, formula_28 is the likelihood function. Define formula_29 where formula_30 is a non-negative symmetric function in formula_31 and formula_32 that can be chosen by the user. Now suppose the current state is formula_31. The MTM algorithm is as follows: 1)

neg: Ziggurat algorithm "y" as close to "f"(0) as possible. Alternatively, look for the value which makes the area of the topmost layer, "x"("f"(0) − "y"), as close to the desired value "A" as possible. This saves one evaluation of "f"("x") and is actually the condition of greatest interest. Ziggurat algorithm The ziggurat algorithm is an algorithm for pseudo-random number sampling. Belonging to the class of rejection sampling algorithms, it relies on an underlying source of uniformly-distributed random numbers, typically from a pseudo-random number generator, as well as precomputed tables. The algorithm is used to generate values from a monotone decreasing probability distribution.

neg: Password cracking More common methods of password cracking, such as dictionary attacks, pattern checking, word list substitution, etc. attempt to reduce the number of trials required and will usually be attempted before brute force. Higher password bit strength exponentially increases the number of candidate passwords that must be checked, on average, to recover the password and reduces the likelihood that the password will be found in any cracking dictionary. The ability to crack passwords using computer programs is also a function of the number of possible passwords per second which can be checked. If a hash of the target password is available

neg: Password manager off swap can prevent this risk. Web-based password managers, which run inside the browser of the user, are particularly fraught with pitfalls. A detailed study using several password managers uncovered the following possible flaws inside web-based password managers: Furthermore, password managers have the disadvantage that any potential hacker or malware just need to know one password to gain access to all of a user's passwords and that such managers have standardized locations and ways of storing passwords which can be exploited by malware. Various high-profile websites have attempted to block password managers, often backing down when publicly challenged. Reasons cited

neg: Salted Challenge Response Authentication Mechanism like bcrypt, scrypt or PBKDF2, and salt them as he wants. However, then Bob and Alice would still face the problems described above. To solve this problem, they use SCRAM, where Bob can store his password in a salted format, using PBKDF2. During login, Bob sends Alice his salt and the iteration count of the PBKDF2 algorithm, and then Alice uses these to calculate the hashed password that Bob has in his database. All further calculations in SCRAM base on this value which both know. Although all clients and servers have to support the SHA-1 hashing algorithm, SCRAM is, unlike

neg: Probabilistic encryption and compare each result to the target ciphertext. To combat this attack, public key encryption schemes must incorporate an element of randomness, ensuring that each plaintext maps into one of a large number of possible ciphertexts. An intuitive approach to converting a deterministic encryption scheme into a probabilistic one is to simply pad the plaintext with a random string before encrypting with the deterministic algorithm. Conversely, decryption involves applying a deterministic algorithm and ignoring the random padding. However, early schemes which applied this naive approach were broken due to limitations in some deterministic encryption schemes. Techniques such as Optimal Asymmetric

neg: Digital Signature Algorithm twice (even while keeping "k" secret), using a predictable value, or leaking even a few bits of "k" in each of several signatures, is enough to reveal the private key "x". This issue affects both DSA and ECDSA – in December 2010, a group calling itself "fail0verflow" announced recovery of the ECDSA private key used by Sony to sign software for the PlayStation 3 game console. The attack was made possible because Sony failed to generate a new random "k" for each signature. This issue can be prevented by deriving "k" deterministically from the private key and the message hash,

neg: Security token years before having to be replaced – so there is additional cost. Another type of one-time password uses a complex mathematical algorithm, such as a hash chain, to generate a series of one-time passwords from a secret shared key. Each password is unguessable, even when previous passwords are known. The open source OAuth algorithm is standardized; other algorithms are covered by US patents. Each password is observably unpredictable and independent of previous ones, wherefore an adversary would be unable to guess what the next password may be, even with knowledge of all previous passwords. Tokens can contain chips with functions

neg: Random number generator attack backdoor for the NSA. Due to these concerns, in 2014, NIST withdrew Dual EC DRBG from its draft guidance on random number generators, recommending "current users of Dual_EC_DRBG transition to one of the three remaining approved algorithms as quickly as possible." Crypto-1 is a cryptosystem developed by NXP for use on MIFARE chips. The system is proprietary and originally the algorithm has not been published. Upon reverse engineering of the chip, researchers from the University of Virginia and the Chaos Computer Club found an attack on Crypto-1 exploiting a poorly initialized random number generator. In May 2008, security researcher Luciano

neg: Password synchronization an administrator) and/or by the user initiating the change centrally through the software, perhaps through a web interface. Some password synchronization systems may copy password hashes from one system to another, where the hashing algorithm is the same. In general, this is not the case and access to a plaintext password is required. Two processes which yields synchronized passwords are shown in the following animations, hosted by software vendor Hitachi ID Systems: 1 Password synchronization Password synchronization is a process, usually supported by software such as password managers, through which a user maintains a single password across multiple IT systems.

neg: Reservoir sampling Efraimidis and Spirakis that uses interpretation 1: ReservoirSample(S[1..?], R[1..k]) This algorithm is identical to the algorithm given in Reservoir Sampling with Random Sort except for the line how we generate the key using random number generator. The algorithm is equivalent to assigning each item a key formula_41 where is the random number and then sort items using these keys and finally select top k items for the sample. Following algorithm was given by M. T. Chao uses interpretation 2: WeightedReservoir-Chao(S[1..n], R[1..k]) For each item, its relative weight is calculated and used to randomly decide if the item will be added

neg: One-time password token itself. To avoid duplicates, an additional counter is usually involved, so if one happens to get the same challenge twice, this still results in different one-time passwords. However, the computation does not usually involve the previous one-time password; that is, usually this or another algorithm is used, rather than using both algorithms. The methods of delivering the OTP which are "token-based" may use either of these types of algorithm instead of time-synchronization. A common technology used for the delivery of OTPs is text messaging. Because text messaging is a ubiquitous communication channel, being directly available in nearly all mobile

neg: Password management to retrieve some information. These inter-application connections normally require a login ID and password and this password. A privileged password management system secures privileged passwords by: A privileged password management system requires extensive infrastructure: Password management There are several forms of software used to help users or organizations better manage passwords: Privileged password management is a type of password management used to secure the passwords for login IDs that have elevated security privileges. This is most often done by periodically changing every such password to a new, random value. Since users and automated software processes need these passwords to function,

neg: Logical security time. Two-Way Authentication involves both the user and system or network convincing each other that they know the shared password without transmitting this password over any communication channel. This is done by using the password as the encryption key to transmit a randomly generated piece of information, or “the challenge.” The other side must then return a similarly encrypted value which is some predetermined function of the originally offered information, his/her “response,” which proves that he/she was able to decrypt the challenge. Kerberos (a computer network authentication protocol) is a good example of this, as it sends an encrypted integer

neg: SPEKE for public key cryptography, including elliptic-curve cryptography. However, when SPEKE is realized by using Elliptic-curve cryptography, the protocol is essentially changed by requiring an additional primitive that must securely map a password onto a random point on the designated elliptic curve. (This primitive is called the IOP or Integer-to-Point function in IEEE P1363.2 and ISO/IEC 11770-4.) SPEKE is one of the older and well-known protocols in the relatively new field of password-authenticated key exchange. It was first described by David Jablon in 1996. In this publication Jablon also suggested a variant where, in step 2 of the protocol, "g" is

neg: Passwd names are shown when the user lists the contents of a folder), while only the root user can write to it. Without password shadowing, this means that an attacker with unprivileged access to the system can obtain the hashed form of every user's password. Those values can be used to mount a brute force attack offline, testing possible passwords against the hashed passwords relatively quickly without alerting system security arrangements designed to detect an abnormal number of failed login attempts. Especially when the hash is not salted it is also possible to look up these hashed passwords in rainbow tables,

neg: Password (video gaming) large variables. The less the algorithm encrypts, the more easily players may notice patterns, such as an increment by one every level. They can then exploit these patterns to cheat or even beat the game. With a little luck, even a long password can be discovered by chance, as was the case for the infamous JUSTIN BAILEY code from "Metroid". While any save information is convertible into password form, it is practical only for game progress consisting of fewer or smaller variables. Overlong passwords needed by games such as RPGs with many large variables eventually cancels out the usability benefits

neg: One-time password to see a one-time password may have access for one time period or login, but it becomes useless once that period expires. The S/KEY one-time password system and its derivative OTP are based on Lamport's scheme. In some mathematical algorithm schemes, it is possible for the user to provide the server with a static key for use as an encryption key, by only sending a one-time password. The use of challenge-response one-time passwords requires a user to provide a response to a challenge. For example, this can be done by inputting the value that the token has generated into the

neg: Password management Password management There are several forms of software used to help users or organizations better manage passwords: Privileged password management is a type of password management used to secure the passwords for login IDs that have elevated security privileges. This is most often done by periodically changing every such password to a new, random value. Since users and automated software processes need these passwords to function, privileged password management systems must also store these passwords and provide various mechanisms to disclose these passwords in a secure and appropriate manner. Privileged password management is related to privileged identity management. There are

neg: History of the Church–Turing thesis a "calculational procedure" that consists of (1) a set of axioms and (2) a logical conclusion written in first-order logic, that is—written in what Davis calls "Frege's rules of deduction" (or the modern equivalent of Boolean logic). Gödel’s doctoral dissertation proved that Frege's rules were "complete" "... in the sense that every valid formula is provable". Given that encouraging fact, could there be a generalized "calculational procedure" that would tell us whether a conclusion can be derived from its premises? Davis calls such calculational procedures "algorithms". The Entscheidungsproblem would be an algorithm as well. "In principle, an algorithm for [the]

neg: One-time password has been synchronized with the clock on the proprietary authentication server. On these OTP systems, time is an important part of the password algorithm, since the generation of new passwords is based on the current time rather than, or in addition to, the previous password or a secret key. This token may be a proprietary device, or a mobile phone or similar mobile device which runs software that is proprietary, freeware, or open-source. An example of time-synchronized OTP standard is Time-based One-time Password Algorithm (TOTP). All of the methods of "delivering" the OTP below may use time-synchronization instead of algorithms.

neg: Statistical data type simple data types, associated distributions, permissible operations, etc. Regardless of the logical possible values, all of these data types are generally coded using real numbers, because the theory of random variables often explicitly assumes that they hold real numbers. Data that cannot be described using a single number are often shoehorned into random vectors of real-valued random variables, although there is an increasing tendency to treat them on their own. Some examples: These concepts originate in various scientific fields and frequently overlap in usage. As a result, it is very often the case that multiple concepts could potentially be applied

neg: Timing attack a proxy) in a way that reduces or eliminates data dependent timing information: consider an implementation in which every call to a subroutine always returns in exactly x seconds, where x is the maximum time it ever takes to execute that routine on every possible authorised input. In such an implementation, the timing of the algorithm leaks no information about the data supplied to that invocation. The downside of this approach is that the time used for all executions becomes that of the worst-case performance of the function. Timing attacks are practical in many cases: The execution time for the

neg: Key size Logjam attack revealed additional dangers in using Diffie-Helman key exchange when only one or a few common 1024-bit or smaller prime moduli are in use. This common practice allows large amounts of communications to be compromised at the expense of attacking a small number of primes. Even if a symmetric cipher is currently unbreakable by exploiting structural weaknesses in its algorithm, it is possible to run through the entire space of keys in what is known as a "brute force attack". Since longer symmetric keys require exponentially more work to brute force search, a sufficiently long symmetric key makes this

neg: Salt (cryptography) component of overall web application security. Some additional references for using a salt to secure password hashes in specific languages (PHP, .NET, etc.) can be found in the external links section below. Salt (cryptography) In cryptography, a salt is random data that is used as an additional input to a one-way function that "hashes" data, a password or passphrase. Salts are used to safeguard passwords in storage. Historically a password was stored in plaintext on a system, but over time additional safeguards developed to protect a user's password against being read from the system. A salt is one of those

neg: Pass the hash cleartext password (as it was required before this technique was published). The attack exploits an implementation weakness in the authentication protocol, where password hash remain static from session to session until the password is next changed. This technique can be performed against any server or service accepting LM or NTLM authentication, whether it runs on a machine with Windows, Unix, or any other operating system. On systems or services using NTLM authentication, users' passwords are never sent in cleartext over the wire. Instead, they are provided to the requesting system, like a domain controller, as a hash in a response

neg: Pass the hash designed to reduce the effectiveness of the attack. Pass the hash In cryptanalysis and computer security, pass the hash is a hacking technique that allows an attacker to authenticate to a remote server or service by using the underlying NTLM or LanMan hash of a user's password, instead of requiring the associated plaintext password as is normally the case. After an attacker obtains valid user name and user password hash values (somehow, using different methods and tools), they are then able to use that information to authenticate to a remote server or service using LM or NTLM authentication without the

neg: Randomization function time. The uniformity requirements for a randomizing function are usually much weaker than those of hash functions and pseudo-random generators. The minimum requirement is that it maps any input of the deterministic algorithm into a "good" input with a sufficiently high probability. (However, analysis is usually simpler if the randomizing function implements each possible mapping with uniform probability.) Randomization function In computer science, a randomization function or randomizing function is an algorithm or procedure that implements a randomly chosen function between two specific sets, suitable for use in a randomized algorithm. Randomizing functions are related to random number generators and

neg: Brooks–Iyengar algorithm input either real values with inherent inaccuracy or noise (which can be unknown), or a real value with apriori defined uncertainty, or an interval. The output of the algorithm is a real value with an explicitly specified accuracy. The algorithm runs in O("N"log"N") where "N" is the number of PEs: see Big O notation. It is possible to modify this algorithm to correspond to Crusader’s Convergence Algorithm (CCA), however, the bandwidth requirement will also increase. The algorithm has applications in distributed control, software reliability, High-performance computing, etc. The Brooks–Iyengar algorithm is executed in every processing element (PE) of a distributed

neg: Yarrow algorithm Yarrow algorithm The Yarrow algorithm is a family of cryptographic pseudorandom number generators (PRNG) devised by John Kelsey, Bruce Schneier, and Niels Ferguson. The Yarrow algorithm is explicitly unpatented, royalty-free, and open source; no license is required to use it. Yarrow is incorporated in iOS and macOS for their /dev/random devices, and was in FreeBSD (where it is superseded by Fortuna). An improved design from Ferguson and Schneier, Fortuna, is described in their book, "Practical Cryptography", and FreeBSD has now moved to using this. The name "Yarrow" alludes to the use of the yarrow plant in the random generating process

neg: Intuitive Password user's cellphone or Google Authenticator. It has configurable options to email users for every log in or to block different countries from logging in. Very confidential information can be protected by a second master password. Intuitive Password permits users to safely share authentication details with others who are using it. For logging in to public computers, users can generate a single-use password for authentication. In a 2013 Softpedia review, Gabriela Vatu said Intuitive Password was "an easy-to-use app, with a clean interface and what looks like strong security in place to protect user data". In a 2013 "PC Magazine" review,

neg: Group testing the simplest noisy case, where there is a constant probability, formula_5, that a group test will have an erroneous result, one considers a random binary vector, formula_93, where each entry has a probability formula_5 of being formula_75, and is formula_79 otherwise. The vector that is returned is then formula_97, with the usual addition on formula_98 (equivalently this is the element-wise XOR operation). A noisy algorithm must estimate formula_37 using formula_100 (that is, without direct knowledge of formula_89). The matrix representation makes it possible to prove some bounds on non-adaptive group testing. The approach mirrors that of many deterministic designs, where

neg: Algorithm characterizations is a proponent of strong artificial intelligence: the idea that the logical structure of an algorithm is sufficient to explain mind. John Searle, the creator of the Chinese room thought experiment, claims that "syntax [that is, logical structure] is by itself not sufficient for semantic content [that is, meaning]" . In other words, the "meaning" of symbols is relative to the mind that is using them; an algorithm—a logical construct—by itself is insufficient for a mind. Searle cautions those who claim that algorithmic (computational) processes are intrinsic to nature (for example, cosmologists, physicists, chemists, etc.): An example in Boolos-Burgess-Jeffrey (2002)

neg: Generalized assignment problem as an integer program: The generalized assignment problem is NP-hard, and it is even APX-hard to approximate it. Recently it was shown that an extension of it is formula_14 hard to approximate for every formula_15. Using any formula_16-approximation algorithm ALG for the knapsack problem, it is possible to construct a (formula_17)-approximation for the generalized assignment problem in a greedy manner using a residual profit concept. The algorithm constructs a schedule in iterations, where during iteration formula_18 a tentative selection of items to bin formula_19 is selected. The selection for bin formula_19 might change as items might be reselected in a

neg: Group testing be tackled with a group-testing approach. In a simple version of the problem, there is some unknown function, formula_172 where formula_173, and formula_174 (using logical arithmetic: addition is logical OR and multiplication is logical AND). Here formula_175 is 'formula_4 sparse', which means that at most formula_177 of its entries are formula_75. The aim is to construct an approximation to formula_179 using formula_60 point evaluations, where formula_60 is as small as possible. (Exactly recovering formula_179 corresponds to zero-error algorithms, whereas formula_179 is approximated by algorithms that have a non-zero probability of error.) In this problem, recovering formula_179 is equivalent to finding

neg: Randomization function presented in random order, but is very slow when they are presented in certain unfavorable orders. A randomizing function from the integers 1 to "n" to the integers 1 to "n" can be used to rerrange the "n" input items in "random" order, before calling that algorithm. This modified (randomized) algorithm will have small expected running time, whatever the input order. In theory, randomization functions are assumed to be truly random, and yield an unpredictably different function every time the algorithm is executed. The randomization technique would not work if, at every execution of the algorithm, the randomization function always

neg: Random dungeon Random dungeon A random dungeon is a dungeon in a role-playing video game which is procedurally generated by the computer using an algorithm, such that the dungeon is laid out differently every time the player enters it, and a player often never plays through quite the same dungeon twice, as there are innumerable possibilities for how they generate. Random dungeons are usually found in the Action RPG genre of games. Programs are also available that generate random dungeons for tabletop role-playing games. Random dungeons first appeared in the ASCII adventure game "Rogue", then in other "roguelikes", combining the kinds of