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Ccrypt
ccrypt is a utility for the secure encryption and decryption of files and streams. It was designed as a replacement for the standard UNIX crypt utility, which is notorious for using a very weak encryption algorithm. ccrypt is based on the Rijndael cypher, the same cipher used in the AES standard. However, in the AES standard a 128-bit block size is used, whereas ccrypt uses a 256-bit block size. ccrypt commonly uses the .cpt file extension for encrypted files. ccrypt does not provide an authenticated encryption scheme and therefore does not protect the integrity of encrypted data. See also * bcrypt * crypt (Unix) * mcrypt * scrypt In cryptography, scrypt (pronounced "ess crypt") is a password-based key derivation function created by Colin Percival in March 2009, originally for the Tarsnap online backup service. The algorithm was specifically designed to make it costly ... References External links ccrypt homepage Cryptographic software {{crypto-stub ...
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Crypt (Unix)
In Unix computing, crypt or enigma is a utility program used for encryption. Due to the ease of breaking it, it is considered to be obsolete. The program is usually used as a filter, and it has traditionally been implemented using a "rotor machine" algorithm based on the Enigma machine. It is considered to be cryptographically Cryptography, or cryptology (from grc, , translit=kryptós "hidden, secret"; and ''graphein'', "to write", or '' -logia'', "study", respectively), is the practice and study of techniques for secure communication in the presence of adv ... far too weak to provide any security against brute-force attacks by modern, commodity personal computers. Some versions of Unix shipped with an even weaker version of the ''crypt(1)'' command in order to comply with Export of cryptography from the United States, contemporaneous laws and regulations that limited the exportation of cryptographic software. Some of these were simply implementations of the Ca ...
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Mcrypt
mcrypt is a replacement for the popular Unix crypt command. crypt was a file encryption tool that used an algorithm very close to the World War II Enigma cipher. Mcrypt provides the same functionality but uses several modern algorithms such as AES. Libmcrypt, Mcrypt's companion, is a library of code that contains the actual encryption functions and provides an easy method for use. The last update to libmcrypt was in 2007, despite years of unmerged patches. These facts have led security experts to declare mcrypt abandonware and discourage its use in new development. Maintained alternatives include ccrypt, libressl, and others. Examples of mcrypt usage in a Linux command-line environment: mcrypt --list # See available encryption algorithms. mcrypt -a blowfish myfilename # Encrypts myfilename to myfilename.nc # using the Blowfish encryption algorithm. ...
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CPT (file Format)
.cpt is a filename extension denoting one of several different kinds of files: * A graphics file format used by some versions of Corel Photo Paint. It is also possible to open CPT version 6 files with IrfanView, but not with Paint Shop Pro (although it is from Corel). CPT version 6 is an almost identical copy of the TIFF format, whereas since Corel Photo-Paint 7.0 (released in 1997), this was deprecated for a new proprietary format (known as CPT7), however the user can still export the older TIFF-based CPT6 files. Chasys Draw IES can open CPT7 files as well as CPT8 and the latest CPT9; this support is available as from Chasys Draw IES version 4.58.0 Corel Photo Paint is not released as a standalone program. It is part of the Corel Draw Graphics Suite, available only for Windows. * The .cpt extension is used for files encrypted using ccrypt. * .cpt is used for screen captures in the video game Tekken Tag Tournament (PlayStation 2), which are saved to the Memory Card. * .cpt was ...
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Bcrypt
bcrypt is a password-hashing function designed by Niels Provos and David Mazières, based on the Blowfish cipher and presented at USENIX in 1999. Besides incorporating a salt to protect against rainbow table attacks, bcrypt is an adaptive function: over time, the iteration count can be increased to make it slower, so it remains resistant to brute-force search attacks even with increasing computation power. The bcrypt function is the default password hash algorithm for OpenBSD and was the default for some Linux distributions such as SUSE Linux. There are implementations of bcrypt in C, C++, C#, Embarcadero Delphi, Elixir, Go, Java, JavaScript, Perl, PHP, Python, Ruby, and other languages. Background Blowfish is notable among block ciphers for its expensive key setup phase. It starts off with subkeys in a standard state, then uses this state to perform a block encryption using part of the key, and uses the result of that encryption (which is more accurate at hashing) to ...
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Scrypt
In cryptography, scrypt (pronounced "ess crypt") is a password-based key derivation function created by Colin Percival in March 2009, originally for the Tarsnap online backup service. The algorithm was specifically designed to make it costly to perform large-scale custom hardware attacks by requiring large amounts of memory. In 2016, the scrypt algorithm was published by IETF as RFC 7914. A simplified version of scrypt is used as a proof-of-work scheme by a number of cryptocurrencies, first implemented by an anonymous programmer called ArtForz in Tenebrix and followed by Fairbrix and Litecoin soon after. Introduction A password-based key derivation function (password-based KDF) is generally designed to be computationally intensive, so that it takes a relatively long time to compute (say on the order of several hundred milliseconds). Legitimate users only need to perform the function once per operation (e.g., authentication), and so the time required is negligible. However ...
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Encryption
In cryptography, encryption is the process of encoding information. This process converts the original representation of the information, known as plaintext, into an alternative form known as ciphertext. Ideally, only authorized parties can decipher a ciphertext back to plaintext and access the original information. Encryption does not itself prevent interference but denies the intelligible content to a would-be interceptor. For technical reasons, an encryption scheme usually uses a pseudo-random encryption key generated by an algorithm. It is possible to decrypt the message without possessing the key but, for a well-designed encryption scheme, considerable computational resources and skills are required. An authorized recipient can easily decrypt the message with the key provided by the originator to recipients but not to unauthorized users. Historically, various forms of encryption have been used to aid in cryptography. Early encryption techniques were often used in military ...
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File (computing)
A computer file is a computer resource for recording data in a computer storage device, primarily identified by its file name. Just as words can be written to paper, so can data be written to a computer file. Files can be shared with and transferred between computers and mobile devices via removable media, networks, or the Internet. Different types of computer files are designed for different purposes. A file may be designed to store an Image, a written message, a video, a computer program, or any wide variety of other kinds of data. Certain files can store multiple data types at once. By using computer programs, a person can open, read, change, save, and close a computer file. Computer files may be reopened, modified, and copied an arbitrary number of times. Files are typically organized in a file system, which tracks file locations on the disk and enables user access. Etymology The word "file" derives from the Latin ''filum'' ("a thread"). "File" was used in the co ...
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Stream (computing)
In computer science, a stream is a sequence of data elements made available over time. A stream can be thought of as items on a conveyor belt being processed one at a time rather than in large batches. Streams are processed differently from batch data – normal functions cannot operate on streams as a whole, as they have potentially unlimited data, and formally, streams are '' codata'' (potentially unlimited), not data (which is finite). Functions that operate on a stream, producing another stream, are known as filters, and can be connected in pipelines, analogously to function composition. Filters may operate on one item of a stream at a time, or may base an item of output on multiple items of input, such as a moving average. Examples The term "stream" is used in a number of similar ways: * "Stream editing", as with sed, awk, and perl. Stream editing processes a file or files, in-place, without having to load the file(s) into a user interface. One example of such use is to ...
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UNIX
Unix (; trademarked as UNIX) is a family of multitasking, multiuser computer operating systems that derive from the original AT&T Unix, whose development started in 1969 at the Bell Labs research center by Ken Thompson, Dennis Ritchie, and others. Initially intended for use inside the Bell System, AT&T licensed Unix to outside parties in the late 1970s, leading to a variety of both academic and commercial Unix variants from vendors including University of California, Berkeley (Berkeley Software Distribution, BSD), Microsoft (Xenix), Sun Microsystems (SunOS/Solaris (operating system), Solaris), Hewlett-Packard, HP/Hewlett Packard Enterprise, HPE (HP-UX), and IBM (IBM AIX, AIX). In the early 1990s, AT&T sold its rights in Unix to Novell, which then sold the UNIX trademark to The Open Group, an industry consortium founded in 1996. The Open Group allows the use of the mark for certified operating systems that comply with the Single UNIX Specification (SUS). Unix systems are chara ...
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Algorithm
In mathematics and computer science, an algorithm () is a finite sequence of rigorous instructions, typically used to solve a class of specific Computational problem, problems or to perform a computation. Algorithms are used as specifications for performing calculations and data processing. More advanced algorithms can perform automated deductions (referred to as automated reasoning) and use mathematical and logical tests to divert the code execution through various routes (referred to as automated decision-making). Using human characteristics as descriptors of machines in metaphorical ways was already practiced by Alan Turing with terms such as "memory", "search" and "stimulus". In contrast, a Heuristic (computer science), heuristic is an approach to problem solving that may not be fully specified or may not guarantee correct or optimal results, especially in problem domains where there is no well-defined correct or optimal result. As an effective method, an algorithm ca ...
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Cipher
In cryptography, a cipher (or cypher) is an algorithm for performing encryption or decryption—a series of well-defined steps that can be followed as a procedure. An alternative, less common term is ''encipherment''. To encipher or encode is to convert information into cipher or code. In common parlance, "cipher" is synonymous with "code", as they are both a set of steps that encrypt a message; however, the concepts are distinct in cryptography, especially classical cryptography. Codes generally substitute different length strings of characters in the output, while ciphers generally substitute the same number of characters as are input. There are exceptions and some cipher systems may use slightly more, or fewer, characters when output versus the number that were input. Codes operated by substituting according to a large codebook which linked a random string of characters or numbers to a word or phrase. For example, "UQJHSE" could be the code for "Proceed to the following ...
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