PKI

https://en.wikipedia.org/wiki/Public_key_infrastructure

A public key infrastructure (PKI) is a set of roles, policies, hardware, software and procedures needed

to create, manage, distribute, use, store and revoke digital certificates and manage public-key

encryption. The purpose of a PKI is to facilitate the secure electronic transfer of information for a

range of network activities such as e-commerce, internet banking and confidential email. It is

required for activities where simple passwords are an inadequate authentication method and more

rigorous proof is required to confirm the identity of the parties involved in the communication and to

validate the information being transferred.

Incorrect answers:

PIKE - stream cipher was invented by Ross Anderson to be a "leaner and meaner" version of FISH

after he broke FISH in 1994. Its name is supposed to be a humorous allusion to the pike fish.

GOST - hash function, defined in the standards GOST R 34.11-94 and GOST 34.311-95 is a 256-bit

cryptographic hash function. It was initially defined in the Russian national standard GOST R 34.11-94

Information Technology – Cryptographic Information Security – Hash Function. The equivalent

standard used by other member-states of the CIS is GOST 34.311-95.

CA - certificate authority or certification authority (CA) is an entity that issues digital certificates. A

digital certificate certifies the ownership of a public key by the named subject of the certificate. This

allows others (relying parties) to rely upon signatures or on assertions made about the private key

that corresponds to the certified public key. A CA acts as a trusted third party—trusted both by the

subject (owner) of the certificate and by the party relying upon the certificate. The format of these

certificates is specified by the X.509 or EMV standard.

Integral Cryptanalysis

https://en.wikipedia.org/wiki/Integral_cryptanalysis

Integral cryptanalysis is a cryptanalytic attack that is particularly applicable to block ciphers based on

substitution-permutation networks. It was originally designed by Lars Knudsen as a dedicated attack

against Square, so it is commonly known as the Square attack. It was also extended to a few other

ciphers related to Square: CRYPTON, Rijndael, and SHARK. Stefan Lucks generalized the attack to

what he called a saturation attack and used it to attack Twofish, which is not at all similar to Square,

having a radically different Feistel network structure. Forms of integral cryptanalysis have since been

applied to a variety of ciphers, including Hierocrypt, IDEA, Camellia, Skipjack, MISTY1, MISTY2,

SAFER++, KHAZAD, and FOX (now called IDEA NXT).

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Chosen Plaintext Attack - is an attack model for cryptanalysis which presumes that the attacker can

obtain the ciphertexts for arbitrary plaintexts. The goal of the attack is to gain information that

reduces the security of the encryption scheme.

Linear Cryptanalysis - is a general form of cryptanalysis based on finding affine approximations to the

action of a cipher. Attacks have been developed for block ciphers and stream ciphers. Linear

cryptanalysis is one of the two most widely used attacks on block ciphers.

Differential Cryptanalysis - is a general form of cryptanalysis applicable primarily to block ciphers, but

also to stream ciphers and cryptographic hash functions. In the broadest sense, it is the study of how

differences in information input can affect the resultant difference at the output. In the case of a

block cipher, it refers to a set of techniques for tracing differences through the network of

transformation, discovering where the cipher exhibits non-random behavior, and exploiting such

properties to recover the secret key (cryptography key).

DESX

https://en.wikipedia.org/wiki/DES-X

In cryptography, DES-X (or DESX) is a variant on the DES (Data Encryption Standard) symmetric-key

block cipher intended to increase the complexity of a brute-force attack using a technique called key

whitening.

Lehmer Random Number Generator https://en.wikipedia.org/wiki/Lehmer_random_number_generator The Lehmer random number generator (named after D. H. Lehmer), sometimes also referred to as the Park–Miller random number generator (after Stephen K. Park and Keith W. Miller), is a type of linear congruential generator (LCG) that operates in multiplicative group of integers modulo n. The general formula is: where the modulus m is a prime number or a power of a prime number, the multiplier a is an element of high multiplicative order modulo m (e.g., a primitive root modulo n), and the seed X0 is coprime to m. Other names are multiplicative linear congruential generator (MLCG) and multiplicative congruential generator (MCG).

IDEA

https://en.wikipedia.org/wiki/International_Data_Encryption_Algorithm

In cryptography, the International Data Encryption Algorithm (IDEA), originally called Improved

Proposed Encryption Standard (IPES), is a symmetric-key block cipher designed by James Massey of

ETH Zurich and Xuejia Lai and was first described in 1991. The algorithm was intended as a

replacement for the Data Encryption Standard (DES). IDEA is a minor revision of an earlier cipher

Proposed Encryption Standard (PES).

The cipher was designed under a research contract with the Hasler Foundation, which became part

of Ascom-Tech AG. The cipher was patented in a number of countries but was freely available for

non-commercial use. The name "IDEA" is also a trademark. The last patents expired in 2012, and

IDEA is now patent-free and thus completely free for all uses.

IDEA was used in Pretty Good Privacy (PGP) v2.0 and was incorporated after the original cipher used

in v1.0, BassOmatic, was found to be insecure. IDEA is an optional algorithm in the OpenPGP

standard.

Incorrect answers:

CAST - symmetric algorithm. Created in 1996 by Carlisle Adams and Stafford Tavares. Operates on 64

bit blocks and has a key size of 40-128 bits. Typically used in GPG and PGP. Encryption is either 12 or

16 rounds.

DES - The Data Encryption Standard is a symmetric-key algorithm for the encryption of digital data.

Although its short key length of 56 bits makes it too insecure for applications, it has been highly

influential in the advancement of cryptography.

RSA - a public-key cryptosystem that is widely used for secure data transmission. It is also one of the

oldest. The acronym RSA comes from the surnames of Ron Rivest, Adi Shamir, and Leonard Adleman,

who publicly described the algorithm in 1977

Blowfish

https://en.wikipedia.org/wiki/Blowfish_(cipher)

Blowfish is a symmetric-key block cipher, designed in 1993 by Bruce Schneier and included in many

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

(AES) now receives more attention, and Schneier recommends Twofish for modern applications.

Blowfish has a 64-bit block size and a variable key length from 32 bits up to 448 bits. It is a 16-round

Feistel cipher and uses large key-dependent S-boxes.

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Skipjack - symmetric algorithm. Designed by NSA for the clipper chip - a chip with built in encryption.

The decryption key was kept in key escrow in case law enforcement needed to decrypt data without

the owner's cooperation, making it highly controversial. Uses an 80 bit key to encrypt/decrypt 64 bit

data blocks. It is an unbalanced Feistel network with 32 rounds.

Serpent - symmetric algorithm. Designed by Ross Anderson, Eli Biham, and Lars Knudsen. Has a block

size of 128 bits. Key size is 128, 192, or 256 bits. Uses a substitution-permutation network instead of

Feistel cipher. Uses 32 rounds working with a block of four 32-bit words. Each round applies one of

eight 4-bit to 4-bit S-boxes 32 times in parallel. Designed so all operations can be done in parallel.

MD5 - hash function. Created by Ronald Rivest. Replaced MD4. 128 bit output size, 512 bit block size,

32 bit word size, 64 rounds. Infamously compromised by Flame malware in 2012.

RSA

https://en.wikipedia.org/wiki/RSA_(cryptosystem)

RSA (Rivest–Shamir–Adleman) is a public-key cryptosystem that is widely used for secure data

transmission. It is also one of the oldest. The acronym RSA comes from the surnames of Ron Rivest,

Adi Shamir, and Leonard Adleman, who publicly described the algorithm in 1977. An equivalent

system was developed secretly, in 1973 at GCHQ (the British signals intelligence agency), by the

English mathematician Clifford Cocks. That system was declassified in 1997.

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Diffie-Helmann - The first publicly described asymmetric algorithm. A cryptographic protocol that

allows two parties to establish a shared key over an insecure channel. Often used to allow parties to

exchange a symmetric key through some unsecure medium, such as the Internet. It was developed

by Whitfield Diffie and Martin Helmann in 1976.

DES - The Data Encryption Standard is a symmetric-key algorithm for the encryption of digital data.

Although its short key length of 56 bits makes it too insecure for applications, it has been highly

influential in the advancement of cryptography.

Developed in the early 1970s at IBM and based on an earlier design by Horst Feistel, the algorithm

was submitted to the National Bureau of Standards (NBS) following the agency's invitation to

propose a candidate for the protection of sensitive, unclassified electronic government data. In 1976,

after consultation with the National Security Agency (NSA), the NBS selected a slightly modified

version (strengthened against differential cryptanalysis, but weakened against brute-force attacks),

which was published as an official Federal Information Processing Standard (FIPS) for the United

States in 1977.

PKI - A public key infrastructure is a set of roles, policies, hardware, software and procedures needed

to create, manage, distribute, use, store and revoke digital certificates and manage public-key

encryption. The purpose of a PKI is to facilitate the secure electronic transfer of information for a

range of network activities such as e-commerce, internet banking and confidential email. It is

required for activities where simple passwords are an inadequate authentication method and more

rigorous proof is required to confirm the identity of the parties involved in the communication and to

validate the information being transferred.

DH

https://en.wikipedia.org/wiki/Diffie%E2%80%93Hellman_key_exchange

Diffie–Hellman key exchange is a method of securely exchanging cryptographic keys over a public

channel and was one of the first public-key protocols as conceived by Ralph Merkle and named after

Whitfield Diffie and Martin Hellman. DH is one of the earliest practical examples of public key

exchange implemented within the field of cryptography. Published in 1976 by Diffie and Hellman,

this is the earliest publicly known work that proposed the idea of a private key and a corresponding

public key.

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EC - Elliptic-curve cryptography (ECC) is an approach to public-key cryptography based on the

algebraic structure of elliptic curves over finite fields. ECC allows smaller keys compared to non-EC

cryptography (based on plain Galois fields) to provide equivalent security.

RSA - (Rivest–Shamir–Adleman) is a public-key cryptosystem that is widely used for secure data

transmission. It is also one of the oldest. The acronym RSA comes from the surnames of Ron Rivest,

Adi Shamir, and Leonard Adleman, who publicly described the algorithm in 1977. An equivalent

system was developed secretly, in 1973 at GCHQ (the British signals intelligence agency), by the

English mathematician Clifford Cocks. That system was declassified in 1997.

AES - also known by its original name Rijndael, is a specification for the encryption of electronic data

established by the U.S. National Institute of Standards and Technology (NIST) in 2001. AES is a subset

of the Rijndael block cipher developed by two Belgian cryptographers, Vincent Rijmen and Joan

Daemen, who submitted a proposal[5] to NIST during the AES selection process. Rijndael is a family

of ciphers with different key and block sizes. For AES, NIST selected three members of the Rijndael

family, each with a block size of 128 bits, but three different key lengths: 128, 192 and 256 bits.

y^2 = x^3 + Ax + B

https://en.wikipedia.org/wiki/Elliptic-curve_cryptography

For current cryptographic purposes, an elliptic curve is a plane curve over a finite field (rather than

the real numbers) which consists of the points satisfying the equation:

The key expansion phase

https://en.wikipedia.org/wiki/Advanced_Encryption_Standard

KeyExpansion – round keys are derived from the cipher key using the AES key schedule. AES requires

a separate 128-bit round key block for each round plus one more.