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Algorithms

Algorithm software standards are published by ISO and IEC. They cover random-bit generation, prime number generation, asymmetric ciphers, block ciphers, and stream ciphers.

ISO/IEC 18031:2011

Information technology - Security techniques - Random bit generation

ISO/IEC 18031:2011 specifies a conceptual model for a random bit generator for cryptographic purposes, together with the elements of this model. ISO/IEC 18031:2011 specifies the characteristics of the main elements required for a non-deterministic random bit generator, specifies the characteristics of the main elements required for a deterministic random bit generator, establishes the security requirements for both the non-deterministic and the deterministic random bit generator. Where there is a requirement to produce sequences of random numbers from random bit strings, ISO/IEC 18031:2011 gives guidelines on how this can be performed. Techniques for statistical testing of random bit generators for the purposes of independent verification or validation, and detailed designs for such generators, are outside the scope of ISO/IEC 18031:2011.

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ISO/IEC 18031:2011/Cor1:2014

Corrigendum

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ISO/IEC 18032:2020

Information security - Prime number generation

This document specifies methods for generating and testing prime numbers as required in cryptographic protocols and algorithms. Firstly, this document specifies methods for testing whether a given number is prime. The testing methods included in this document are divided into two groups: probabilistic primality tests, which have a small error probability. All probabilistic tests described here can declare a composite to be a prime; deterministic methods, which are guaranteed to give the right verdict. These methods use so-called primality certificates. Secondly, this document specifies methods to generate prime numbers. Again, both probabilistic and deterministic methods are presented. NOTE It is possible that readers with a background in algorithm theory have already had previous encounters with probabilistic and deterministic algorithms. The deterministic methods in this document internally still make use of random bits (to be generated via methods described in ISO/IEC 18031), and deterministic only refers to the fact that the output is correct with probability one. Annex A provides error probabilities that are utilized by the Miller-Rabin primality test. Annex B describes variants of the methods for generating primes so that particular cryptographic requirements can be met. Annex C defines primitives utilized by the prime generation and verification methods.

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ISO/IEC 18033-1:2021

Information security - Encryption algorithms - Part 1: General

This document is general in nature and provides definitions that apply in subsequent parts of the ISO/IEC 18033 series. It introduces the nature of encryption and describes certain general aspects of its use and properties.

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ISO/IEC 18033-2:2006

Information technology - Security techniques - Encryption algorithms - Part 2: Asymmetric ciphers

ISO/IEC 18033-2:2006 specifies encryption systems (ciphers) for the purpose of data confidentiality. The primary purpose of encryption (or encipherment ) techniques is to protect the confidentiality of stored or transmitted data. An encryption algorithm is applied to data (often called plaintext or cleartext ) to yield encrypted data (or ciphertext ); this process is known as encryption . The encryption algorithm should be designed so that the ciphertext yields no information about the plaintext except, perhaps, its length. Associated with every encryption algorithm is a corresponding decryption algorithm , which transforms ciphertext back into its original plaintext. An asymmetric, i.e. public-key, encryption scheme allows a sender to use a recipient's public key to transmit an encryption of a message to the receiver, who can use his secret key to decrypt the given ciphertext, thereby obtaining the original message. Such a scheme should be secure in the sense that no information about the message should be leaked to a (resource-bounded) attacker, even if that attacker mounts a so-called 'chosen ciphertext' attack, in which he may obtain decryptions of other ciphertexts. This is the strongest type of attack that has been proposed for a public-key encryption scheme. ISO/IEC 18033-2:2006 specifies the functional interface of such a scheme, and in addition specifies a number of particular schemes that appear to be secure against chosen ciphertext attack. The different schemes offer different trade-offs between security properties and efficiency.

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ISO/IEC 18033-3:2010

Information technology - Security techniques - Encryption algorithms - Part 3: Block ciphers

ISO/IEC 18033 specifies encryption systems (ciphers) for the purpose of data confidentiality. ISO/IEC 18033-3:2010 specifies block ciphers. A block cipher is a symmetric encipherment system with the property that the encryption algorithm operates on a block of plaintext, i.e. a string of bits of a defined length, to yield a block of ciphertext. ISO/IEC 18033-3:2010 specifies following algorithms: 64-bit block ciphers: TDEA, MISTY1, CAST-128, HIGHT; 128-bit block ciphers: AES, Camellia, SEED. NOTE The primary purpose of encryption (or encipherment) techniques is to protect the confidentiality of stored or transmitted data. An encryption algorithm is applied to data (often called plaintext or cleartext) to yield encrypted data (or ciphertext); this process is known as encryption. The encryption algorithm needs to be designed so that the ciphertext yields no information about the plaintext except, perhaps, its length. Associated with every encryption algorithm is a corresponding decryption algorithm, which transforms ciphertext back into its original plaintext.

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ISO/IEC 18033-4:2011

Information technology - Security techniques - Encryption algorithms - Part 4: Stream ciphers

ISO/IEC 18033-4:2011 specifies output functions to combine a keystream with plaintext, keystream generators for producing keystream, and object identifiers assigned to dedicated keystream generators in accordance with ISO/IEC 9834.

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