cryptography.md

Cryptography

Diffie–Hellman key exchange

• also called: 'DH'
• https://en.wikipedia.org/wiki/Diffie%E2%80%93Hellman_key_exchange
• is a: 'Key-agreement protocol'
• based on: 'Diffie–Hellman problem', 'Discrete logarithm problem'
• implemented in: 'C OpenSSL'
• domain: 'Public-key cryptography'
• licence: 'Public domain' (since 1997)

X3DH

• also called: 'Extended Triple Diffie-Hellman'
• https://signal.org/docs/specifications/x3dh/
• based on: 'Diffie–Hellman key exchange'
• is a: 'Key-agreement protocol'

Elliptic-curve Diffie–Hellman

• also called: 'ECDH'
• https://en.wikipedia.org/wiki/Elliptic-curve_Diffie%E2%80%93Hellman
• is a: 'Key-agreement protocol'
• based on: 'Elliptic-curve cryptography'
• domain: 'Public-key cryptography'
• variant of: 'Diffie–Hellman key exchange'
• implemented in (libraries): 'C OpenSSL'
• implemented by (applications): 'Line'
• used by (protocols): 'Signal Protocol'

Curve25519

• paper: 'Curve25519: new Diffie-Hellman speed records' (2006)
• https://en.wikipedia.org/wiki/Curve25519
• is a: 'Elliptic curve'
• for use with: 'Elliptic-curve Diffie–Hellman'
• implemented in (libraries): 'C NaCl'
• used by (protocols): 'OMEMO', 'Secure Shell', 'Transport Layer Security', 'Tox'
• implemented by (applications): 'Wire', 'Threema'

RSA

• also called: 'Rivest–Shamir–Adleman'
• https://en.wikipedia.org/wiki/RSA_(cryptosystem)
• depends on computational hardness of: 'RSA problem'
• domain: 'Public-key cryptography'
• licence: 'Public domain' (since 2000)

Asynchronous Ratcheting Tree

• also called: 'ART'
• paper: 'On Ends-to-Ends Encryption: Asynchronous Group Messaging with Strong Security Guarantees' (2017)
• https://github.com/facebookresearch/asynchronousratchetingtree
• is a: 'Cryptographic protocol'

TreeKEM

• also called: 'MLS ratchet tree'
• based on: 'Asynchronous Ratcheting Tree'

Double Ratchet algorithm

• also called: 'Axolotl Ratchet'
• whitepaper: 'The Double Ratchet Algorithm' (2016)
• https://en.wikipedia.org/wiki/Double_Ratchet_Algorithm
• https://signal.org/docs/specifications/doubleratchet/
• is a: 'key management algorithm'
• based on: 'X3DH', 'Key derivation function'
• implemented by: 'Signal Protocol', 'Signal', 'WhatsApp'
• implemented in: 'C++ Olm', 'python-doubleratchet'
• applications: 'End-to-end encryption', 'Instant messaging'
• features: 'Post-compromise security'

Square

• also called: 'SQUARE'
• https://en.wikipedia.org/wiki/Square_(cipher)
• paper: 'The Block Cipher SQUARE' (1997)
• is a: 'Block cipher'
• bits: '128'
• implemented in: 'Crypto++'

Advanced Encryption Standard

• also called: 'AES', 'Rijndael'
• https://en.wikipedia.org/wiki/Advanced_Encryption_Standard
• is a: 'Block cipher', 'Symmetric-key algorithm'
• bits: '128', '192', '256'
• based on: 'Square'
• implemented in: 'Crypto++', 'C OpenSSL', 'C NaCl'

Salsa20

• https://en.wikipedia.org/wiki/Salsa20
• paper: 'The Salsa20 Family of Stream Ciphers' (2008)
• is a: 'Stream cipher', 'Symmetric-key algorithm'
• implemented in: 'Crypto++', 'C NaCl'

ChaCha20

• based on: 'Salsa20'
• is a: 'Stream cipher', 'Symmetric-key algorithm'
• RFC: 7539, 8439
• implemented in: 'Crypto++', 'C OpenSSL'

Poly1305

• is a: 'Message authentication code'
• RFC: 7539, 8439
• implemented in: 'Crypto++', 'C OpenSSL', 'C NaCl'

-- key derivation function

Lyra2

• https://en.wikipedia.org/wiki/Lyra2
• is a: 'Key derivation function'
• applications: 'Proof of work', 'Cryptocurrency'

scrypt

• https://en.wikipedia.org/wiki/Scrypt
• is a: 'Key derivation function'
• applications: 'Proof of work', 'Cryptocurrency'
• RFC: 7914

PBKDF2

• also called: 'Password-Based Key Derivation Function 2'
• https://en.wikipedia.org/wiki/PBKDF2
• is a: 'Key derivation function'
• recommended by: 'PKCS #5'

Argon2

• https://en.wikipedia.org/wiki/Argon2
• is a: 'Key derivation function'
• winner of: 'Password Hashing Competition' (2015)

-- block cipher modes of operation

ECB

• also called: 'Electronic Codebook'
• susceptible to: 'replay attacks'
• encryption parallelizable: Yes
• decryption parallelizable: Yes
• random read access: Yes
• don't use

CBC

• also called: 'Cipher-block chaining'
• patent: 'Message verification and transmission error detection by block chaining' (1976)
• https://en.wikipedia.org/wiki/Block_cipher_mode_of_operation#CBC
• encryption parallelizable: No
• decryption parallelizable: Yes
• random read access: Yes
• susceptible to: 'padding oracle attacks', 'malleability attacks'

CFB

• also called: 'Cipher Feedback'
• encryption parallelizable: No
• decryption parallelizable: Yes
• random read access: Yes

CTR

• also called: 'Counter'
• paper: 'Privacy and authentication: An introduction to cryptography' (1979)
• encryption parallelizable: Yes
• decryption parallelizable: Yes
• random read access: Yes
• susceptible to: 'malleability attacks'

XTS

• also called: 'XEX-based tweaked-codebook mode with ciphertext stealing'
• paper: '1619-2007 - IEEE Standard for Cryptographic Protection of Data on Block-Oriented Storage Devices' (2008)
• https://en.wikipedia.org/wiki/Disk_encryption_theory#XEX-based_tweaked-codebook_mode_with_ciphertext_stealing_(XTS)
• applications: 'Full disk encryption'
• authentication: no
• implemented by (applications): 'VeraCrypt', 'Android', 'dm-crypt'

CMC

• also called: 'CBC–mask–CBC'

EME

• also called: 'ECB–mask–ECB', 'ECB-Mix-ECB', 'Encrypt-Mix-Encrypt'
• paper: 'A Parallelizable Enciphering Mode' (2003)
• patent: 'Block cipher mode of operation for constructing a wide-blocksize block cipher from a conventional block cipher' (2003)
• wide-block encryption

EME*

• also called: 'EME2'
• paper: 'EME*: Extending EME to Handle Arbitrary-Length Messages with Associated Data' (2004)
• wide-block encryption
• refinement of: 'EME'

XCB

• also called: 'Extended codebook mode'
• paper: 'The Extended Codebook (XCB) Mode of Operation' (2004)
• analysis paper: 'The Security of the Extended Codebook (XCB) Mode of Operation' (2007)

-- Authenticated block cipher modes of operation

GCM

• also called: 'Galios/Counter Mode'
• https://en.wikipedia.org/wiki/Galois/Counter_Mode

CCM

• also called: 'Counter with CBC-MAC'
• https://en.wikipedia.org/wiki/CCM_mode

CCM*

• variant of: 'CCM'
• used by: 'ZigBee'

EAX

• also called: 'Encrypt-then-authenticate-then-translate mode'
• https://en.wikipedia.org/wiki/EAX_mode

OCB

• also called: 'Offset codebook mode'
• https://en.wikipedia.org/wiki/OCB_mode
• patented

CWC

• also called: 'Carter–Wegman + CTR mode'
• https://en.wikipedia.org/wiki/CWC_mode