README
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JDC - A Custom Digest Cipher in Go
A 256-bit cryptographic cipher using a one-way cryptographic hash function, similar to MDC. It is a CFB-mode (cipher feedback) cipher utilizing SHA-256 as both a key-generation function and as a cipher function.
SHA-256 was chosen as it is compliant with both FIPS-180 and NIST SP 800-108 (US Federal Government standards).
Cipher Diagram
For the first block of plaintext, a 256-bit random initialization vector is used instead of a ciphertext block.
Standard Disclaimer
I am neither a cryptographer or a mathematician. This project is purely for educational and experimental use. Please never use this is a system that requires any real security.
This software is licensed under the MIT License, see LICENSE.txt
API/Usage
go test -v to run the included unit tests.
Encrypt(data []byte, password string) []byte - Encrypts a given byte array with a key derived from a plaintext password. Appends the initialization vector to the beginning of the encrypted data
Decrypt(data []byte, password string) []byte - Decrypts data that has been encrypted with Encrypt. Strips off the initialization vector and block padding and returns the original data only.
References/Acknowledgements
I took this idea from Chapter 14.11 in Bruce Schneier's "Applied Cryptography". The algorithm takes inspiration from the MDC cipher and various techniques defined therein.
- https://nvlpubs.nist.gov/nistpubs/FIPS/NIST.FIPS.180-4.pdf
- https://nvlpubs.nist.gov/nistpubs/SpecialPublications/NIST.SP.800-56Cr1.pdf
- Bruce Schneier, "Applied Cryptography" (print)
TODO
- Key generation
- IV generation
- Padding
- Use an approved padding scheme such as PKCS #7
- Cipher + feedback
- (Bonus) Robust Decryption validation using a CRC or cryptographic hash
- (Bonus) Benchmark/Speed tests
- (Bonus) Refactor/Optimize so that operations are in-place whenever possible
Documentation
Source Files