encrypted-modular-crypt-format

Encrypted Modular Crypt Format (EMCF)

Examples

Given the following inputs:

• Algorithm: aes-256-gcm
• Key Identifier: K
• IV: IV
• Ciphertext: C
• Authentication Tag: T

A compliant EMCF string will be formatted to output:

$aes-256-gcm$K$IV||C||T

Password-based symmetric encryption

Given the following inputs:

• KDF: 7 scrypt¹
• Salt: S

$aes-256-gcm$7$S$IV||C||T

Envelope encryption

Given the following inputs:

• Wrapped DEK: D

$aes-256-gcm$D$IV||C||T

Prior art

• Modular Crypt Format
  https://passlib.readthedocs.io/en/stable/modular_crypt_format.html
• PHC String Format
  https://github.com/P-H-C/phc-string-format/blob/master/phc-sf-spec.md

See also

• Binary Modular Crypt Format (BMCF)
  https://github.com/ademarre/binary-mcf
• SP 800-38D, Recommendation for Block Cipher Modes of Operation: Galois/Counter Mode (GCM) and GMAC
  https://csrc.nist.gov/pubs/sp/800/38/d/final

License

Creative Commons Zero v1.0 Universal

Footnotes

1. https://en.wikipedia.org/wiki/Crypt_(C)#Key_derivation_functions_supported_by_crypt ↩