passwd is a tool on most Unix
Unix and Unix-like
Unix-like operating systems used to change a user's password. The password entered by the user is run through a key derivation function to create a hashed version of the new password, which is saved. Only the hashed version is stored; the entered password is not saved for security reasons. When the user logs on, the password entered by the user during the log on process is run through the same key derivation function and the resulting hashed version is compared with the saved version. If the hashes are identical, the entered password is considered to be correct, and the user is authenticated. In theory, it is possible for two different passwords to produce the same hash
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In computing, a shell is a user interface for access to an operating system's services. In general, operating system shells use either a command-line interface (CLI) or graphical user interface (GUI), depending on a computer's role and particular operation. It is named a shell because it is the outermost layer around the operating system kernel.[1][2] The design of a shell is guided by cognitive ergonomics and the goal is to achieve the best workflow possible for the intended tasks; the design can be constricted by the available computing power (for example, of the CPU) or the available amount of graphics memory
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A 2013 attack by Xie Tao, Fanbao Liu, and Dengguo Feng breaks MD5 collision resistance in 218 time. This attack runs in less than a second on a regular computer.[2] MD5
MD5 is prone to length extension attacks.The MD5
MD5 algorithm is a widely used hash function producing a 128-bit hash value. Although MD5
MD5 was initially designed to be used as a cryptographic hash function, it has been found to suffer from extensive vulnerabilities. It can still be used as a checksum to verify data integrity, but only against unintentional corruption. Like most hash functions, MD5
MD5 is neither encryption nor encoding
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Unix
Unix (/ˈjuːnɪks/; trademarked as UNIX) is a family of multitasking, multiuser computer operating systems that derive from the original AT&T Unix, development starting in the 1970s at the Bell Labs research center by Ken Thompson, Dennis Ritchie, and others.[3] Initially intended for use inside the Bell System, AT&T licensed Unix
Unix to outside parties in the late 1970s, leading to a variety of both academic and commercial Unix
Unix variants from vendors like the University of California, Berkeley
University of California, Berkeley (BSD), Microsoft
Microsoft (Xenix), IBM (AIX), and Sun Microsystems
Sun Microsystems (Solaris)
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Berkeley Software Distribution
Berkeley Software Distribution (BSD) was a Unix
Unix operating system derivative developed and distributed by the Computer Systems Research Group (CSRG) of the University of California, Berkeley, from 1977 to 1995. Today, the term "BSD" is often used non-specifically to refer to any of the BSD descendants which form a branch of the family of Unix-like
Unix-like operating systems. Operating systems derived from the original Berkeley source code, such as FreeBSD
FreeBSD and OpenBSD, remain actively developed and widely used. BSD was initially called Berkeley Unix
Unix because it shared the same source code with AT&T Research Unix
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In cryptography, plaintext or cleartext is unencrypted information, as opposed to information encrypted for storage or transmission. Plaintext usually means unencrypted information pending input into cryptographic algorithms, usually encryption algorithms. Cleartext usually refers to data that is transmitted or stored unencrypted ('in the clear').Contents1 Overview 2 Secure handling of plaintext2.1 Web browser saved password security controversy3 See also 4 ReferencesOverview[edit] With the advent of computing, the term plaintext expanded beyond human-readable documents to mean any data, including binary files, in a form that can be viewed or used without requiring a key or other decryption device. Information—a message, document, file, etc.—if to be communicated or stored in encrypted form is referred to as plaintext. Plaintext is used as input to an encryption algorithm; the output is usually termed ciphertext, particularly when the algorithm is a cipher
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Telnet is a protocol used on the Internet
Internet or local area networks to provide a bidirectional interactive text-oriented communication facility using a virtual terminal connection. User data is interspersed in-band with Telnet control information in an 8-bit byte oriented data connection over the Transmission Control Protocol
Transmission Control Protocol (TCP). Telnet was developed in 1969 beginning with RFC 15, extended in RFC 854, and standardized as Internet
Internet Engineering Task Force (IETF) Internet
Internet Standard STD 8, one of the first Internet
Internet standards
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In computing, ls is a command to list files in Unix
Unix and Unix-like operating systems. ls is specified by POSIX and the Single UNIX Specification. When invoked without any arguments, ls lists the files in the current working directory.Contents1 History 2 Behavior 3 Sample usage 4 See also 5 Notes 6 External linksHistory[edit] An ls utility appeared in the original version of AT&T UNIX, the name inherited from a similar command in Multics
Multics also named 'ls', short for the word "list".[1][2][3] Today, the two popular versions of ls are the one provided with the GNU
GNU coreutils package, and that released by various BSD variants
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In cryptography, a brute-force attack consists of an attacker trying 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[1] (except for data encrypted in an information-theoretically secure manner)
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In computer security, logging in (or logging on or signing in or signing on) is the process by which an individual gains access to a computer system by identifying and authenticating themselves. The user credentials are typically some form of "username" and a matching "password",[1] and these credentials themselves are sometimes referred to as a login, (or a logon or a sign-in or a sign-on).[2][1] In practice, modern secure systems also often require a second factor for extra security. When access is no longer needed, the user can log out (log off, sign out or sign off).Contents1 Procedure 2 History and etymology 3 See also 4 ReferencesProcedureFinger print login, a recent banking security application.Logging in is usually used to enter a specific page, which trespassers cannot see
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A rainbow table is a precomputed table for reversing cryptographic hash functions, usually for cracking password hashes. Tables are usually used in recovering a password (or credit card numbers, etc.) up to a certain length consisting of a limited set of characters. It is a practical example of a space–time tradeoff, using less computer processing time and more storage than a brute-force attack which calculates a hash on every attempt, but more processing time and less storage than a simple lookup table with one entry per hash
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Blowfish is a symmetric-key block cipher, designed in 1993 by Bruce Schneier and included in a large number of cipher suites and encryption products. Blowfish provides a good encryption rate in software and no effective cryptanalysis of it has been found to date. However, the Advanced Encryption Standard
Advanced Encryption Standard (AES) now receives more attention, and Schneier recommends Twofish
Twofish for modern applications.[2] Schneier designed Blowfish as a general-purpose algorithm, intended as an alternative to the aging DES and free of the problems and constraints associated with other algorithms. At the time Blowfish was released, many other designs were proprietary, encumbered by patents or were commercial or government secrets. Schneier has stated that, "Blowfish is unpatented, and will remain so in all countries
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In software engineering, the terms front end and back end refer to the separation of concerns between the presentation layer (front end), and the data access layer (back end) of a piece of software, or the physical infrastructure or hardware. In the client–server model, the client is usually considered the front end and the server is usually considered the back end, even when some presentation work is actually done on the server.Contents1 Introduction 2 Software
Software definitions2.1 Web development as an example2.1.1 Both 2.1.2 Front-end focused 2.1.3 Back-end focused3 Hardware definitions 4 See also 5 ReferencesIntroduction[edit] In software architecture, there may be many layers between the hardware and end user. Each can be spoken of as having a front end and a back end
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A 2011 attack breaks preimage resistance for 57 out of 80 rounds of SHA-512, and 52 out of 64 rounds for SHA-256.[1] Pseudo-collision attack against up to 46 rounds of SHA-256.[2] SHA-256 and SHA-512 are prone to length extension attacks. By guessing the hidden part of the state, length extension attacks on SHA-224 and SHA-384 succeed with probability 2−(256−224) = 2−32 > 2−224 and 2−(512−384) = 2−128 > 2−384 respectively. SHA-2
SHA-2 (Secure Hash Algorithm 2) is a set of cryptographic hash functions designed by the United States
United States National Security Agency (NSA).[3]
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A 2011 attack breaks preimage resistance for 57 out of 80 rounds of SHA-512, and 52 out of 64 rounds for SHA-256.[1] Pseudo-collision attack against up to 46 rounds of SHA-256.[2] SHA-256 and SHA-512 are prone to length extension attacks. By guessing the hidden part of the state, length extension attacks on SHA-224 and SHA-384 succeed with probability 2−(256−224) = 2−32 > 2−224 and 2−(512−384) = 2−128 > 2−384 respectively. SHA-2
SHA-2 (Secure Hash Algorithm 2) is a set of cryptographic hash functions designed by the United States
United States National Security Agency (NSA).[3]
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In cryptography, key stretching techniques are used to make a possibly weak key, typically a password or passphrase, more secure against a brute-force attack by increasing the time it takes to test each possible key. Passwords or passphrases created by humans are often short or predictable enough to allow password cracking. Key stretching makes such attacks more difficult. Key stretching techniques generally work as follows. The initial key is fed into an algorithm that outputs an enhanced key. The enhanced key should be of sufficient size to make it infeasible to break by brute force (e.g. at least 128 bits)
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