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Padding (cryptography)
In cryptography, padding is any of a number of distinct practices which all include adding data to the beginning, middle, or end of a message prior to encryption. In classical cryptography, padding may include adding nonsense phrases to a message to obscure the fact that many messages end in predictable ways, e.g. ''sincerely yours''. Classical cryptography Official messages often start and end in predictable ways: ''My dear ambassador, Weather report, Sincerely yours'', etc. The primary use of padding with classical ciphers is to prevent the cryptanalyst from using that predictability to find known plaintext that aids in breaking the encryption. Random length padding also prevents an attacker from knowing the exact length of the plaintext message. A famous example of classical padding which caused a great misunderstanding is " the world wonders" incident, which nearly caused an Allied loss at the World War II Battle off Samar, part of the larger Battle of Leyte Gulf. In that e ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Cryptography
Cryptography, or cryptology (from "hidden, secret"; and ''graphein'', "to write", or ''-logy, -logia'', "study", respectively), is the practice and study of techniques for secure communication in the presence of Adversary (cryptography), adversarial behavior. More generally, cryptography is about constructing and analyzing Communication protocol, protocols that prevent third parties or the public from reading private messages. Modern cryptography exists at the intersection of the disciplines of mathematics, computer science, information security, electrical engineering, digital signal processing, physics, and others. Core concepts related to information security (confidentiality, data confidentiality, data integrity, authentication, and non-repudiation) are also central to cryptography. Practical applications of cryptography include electronic commerce, Smart card#EMV, chip-based payment cards, digital currencies, password, computer passwords, and military communications. ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Block Cipher Mode Of Operation
In cryptography, a block cipher mode of operation is an algorithm that uses a block cipher to provide information security such as confidentiality or authenticity. A block cipher by itself is only suitable for the secure cryptographic transformation (encryption or decryption) of one fixed-length group of bits called a block. A mode of operation describes how to repeatedly apply a cipher's single-block operation to securely transform amounts of data larger than a block. Most modes require a unique binary sequence, often called an initialization vector (IV), for each encryption operation. The IV must be non-repeating, and for some modes must also be random. The initialization vector is used to ensure that distinct ciphertexts are produced even when the same plaintext is encrypted multiple times independently with the same key. Block ciphers may be capable of operating on more than one block size, but during transformation the block size is always fixed. Block cipher modes ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Out-of-band Data
In computer networking, out-of-band data is the data transferred through a stream that is independent from the main ''in-band'' data stream. An out-of-band data mechanism provides a conceptually independent channel, which allows any data sent via that mechanism to be kept separate from in-band data. The out-of-band data mechanism should be provided as an inherent characteristic of the data channel and transmission protocol, rather than requiring a separate channel and endpoints to be established. The term "out-of-band data" probably derives from out-of-band signaling, as used in the telecommunications industry. Example case Consider a networking application that tunnels data from a remote data source to a remote destination. The data being tunneled may consist of any bit patterns. The sending end of the tunnel may at times have conditions that it needs to notify the receiving end about. However, it cannot simply insert a message to the receiving end because that end will not b ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
ISO/IEC 7816
ISO/IEC 7816 is an international standard related to electronic identification cards with contacts, especially smart cards, and more recently, contactless mobile devices, managed jointly by the International Organization for Standardization (ISO) and the International Electrotechnical Commission (IEC). It is developed by ISO/IEC JTC 1 (Joint Technical Committee 1) / SC 17 (Subcommittee 17). The following describes the different parts of this standard. : ''Note: abstracts and dates, when present, are mere quotations from the ISO website, and are neither guaranteed at the time of edition nor in the future''. Parts * ISO/IEC 7816-1:2011 ''Part 1: Cards with contacts—Physical characteristics'' * ISO/IEC 7816-2:2007 ''Part 2: Cards with contacts—Dimensions and location of the contacts'' * ISO/IEC 7816-3:2006 ''Part 3: Cards with contacts—Electrical interface and transmission protocols'' * ISO/IEC 7816-4:2013 ''Part 4: Organization, security and commands for interchange'' * IS ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
PKCS
Public Key Cryptography Standards (PKCS) are a group of public-key cryptography standards devised and published by RSA Security LLC, starting in the early 1990s. The company published the standards to promote the use of the cryptography techniques for which they had patents, such as the RSA algorithm, the Schnorr signature algorithm and several others. Though not industry standards (because the company retained control over them), some of the standards have begun to move into the " standards track" processes of relevant standards organizations in recent years, such as the IETF The Internet Engineering Task Force (IETF) is a standards organization for the Internet standard, Internet and is responsible for the technical standards that make up the Internet protocol suite (TCP/IP). It has no formal membership roster ... and the PKIX working group. Key Updates (2023–2024): * Integration of PKCS #7 and PKCS #12 into broader standards like S/MIME and TLS. * Evolu ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Byte
The byte is a unit of digital information that most commonly consists of eight bits. Historically, the byte was the number of bits used to encode a single character of text in a computer and for this reason it is the smallest addressable unit of memory in many computer architectures. To disambiguate arbitrarily sized bytes from the common 8-bit definition, network protocol documents such as the Internet Protocol () refer to an 8-bit byte as an octet. Those bits in an octet are usually counted with numbering from 0 to 7 or 7 to 0 depending on the bit endianness. The size of the byte has historically been hardware-dependent and no definitive standards existed that mandated the size. Sizes from 1 to 48 bits have been used. The six-bit character code was an often-used implementation in early encoding systems, and computers using six-bit and nine-bit bytes were common in the 1960s. These systems often had memory words of 12, 18, 24, 30, 36, 48, or 60 bits, corresponding t ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
ISO/IEC 9797-1
ISO/IEC 9797-1 ''Information technology – Security techniques – Message Authentication Codes (MACs) – Part 1: Mechanisms using a block cipher'' is an international standard that defines methods for calculating a message authentication code (MAC) over data. Rather than defining one specific algorithm, the standard defines a general model from which a variety of specific algorithms can be constructed. The model is based on a block cipher with a secret symmetric key. Because the standard describes a model rather than a specific algorithm, users of the standard must specify all of the particular options and parameter to be used, to ensure unambiguous MAC calculation. Model The model for MAC generation comprises six steps: # ''Padding'' of the data to a multiple of the cipher block size # ''Splitting'' of the data into blocks # ''Initial transformation'' of the first block of data # ''Iteration'' through the remaining blocks of data # ''Output transformation'' of the result ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Secure Hash Algorithm (other)
The Secure Hash Algorithms are a family of cryptographic hash functions published by the National Institute of Standards and Technology (NIST) as a U.S. Federal Information Processing Standard (FIPS), including: *SHA-0: A retronym applied to the original version of the 160-bit hash function published in 1993 under the name "SHA". It was withdrawn shortly after publication due to an undisclosed "significant flaw" and replaced by the slightly revised version SHA-1. *SHA-1: A 160-bit hash function which resembles the earlier MD5 algorithm. This was designed by the National Security Agency (NSA) to be part of the Digital Signature Algorithm. Cryptographic weaknesses were discovered in SHA-1, and the standard was no longer approved for most cryptographic uses after 2010. *SHA-2: A family of two similar hash functions, with different block sizes, known as ''SHA-256'' and ''SHA-512''. They differ in the word size; SHA-256 uses 32-bit words where SHA-512 uses 64-bit words. There are also t ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Hash Functions
A hash function is any function that can be used to map data of arbitrary size to fixed-size values, though there are some hash functions that support variable-length output. The values returned by a hash function are called ''hash values'', ''hash codes'', (''hash/message'') ''digests'', or simply ''hashes''. The values are usually used to index a fixed-size table called a ''hash table''. Use of a hash function to index a hash table is called ''hashing'' or ''scatter-storage addressing''. Hash functions and their associated hash tables are used in data storage and retrieval applications to access data in a small and nearly constant time per retrieval. They require an amount of storage space only fractionally greater than the total space required for the data or records themselves. Hashing is a computationally- and storage-space-efficient form of data access that avoids the non-constant access time of ordered and unordered lists and structured trees, and the often-exponentia ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Message Authentication Code
In cryptography, a message authentication code (MAC), sometimes known as an authentication tag, is a short piece of information used for authentication, authenticating and Data integrity, integrity-checking a message. In other words, it is used to confirm that the message came from the stated sender (its authenticity) and has not been changed (its integrity). The MAC value allows verifiers (who also possess a secret key) to detect any changes to the message content. Terminology The term message integrity code (MIC) is frequently substituted for the term ''MAC'', especially in communications to distinguish it from the use of the latter as ''media access control address'' (''MAC address''). However, some authors use MIC to refer to a message digest, which aims only to uniquely but opaquely identify a single message. RFC 4949 recommends avoiding the term ''message integrity code'' (MIC), and instead using ''checksum'', ''error detection code'', ''hash function, hash'', ''keyed hash'' ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Padding Oracle Attack
In cryptography, a padding oracle attack is an attack which uses the padding validation of a cryptographic message to decrypt the ciphertext. In cryptography, variable-length plaintext messages often have to be padded (expanded) to be compatible with the underlying cryptographic primitive. The attack relies on having a "padding oracle" who freely responds to queries about whether a message is correctly padded or not. The information could be directly given, or leaked through a side-channel. The earliest well-known attack that uses a padding oracle is Bleichenbacher's attack of 1998, which attacks RSA with PKCS #1 v1.5 padding. The term "padding oracle" appeared in literature in 2002, after Serge Vaudenay's attack on the CBC mode decryption used within symmetric block ciphers. Variants of both attacks continue to find success more than one decade after their original publication. Asymmetric cryptography In 1998, Daniel Bleichenbacher published a seminal paper on what became ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
