SCRAM68

About

SCRAM68 is a small file encryption utility written in ALGOL 68 for Algol 68 Genie. It uses a 256-bit ChaCha-style stream cipher and an HMAC-SHA256 integrity check.

Usage

a68g scram68.a68 -- -e <passphrase> <in_file> <out_file>
a68g scram68.a68 -- -d <passphrase> <in_file> <out_file>

Encrypted output is text-safe and formatted as:

CHCA + hex(nonce) + hex(ciphertext) + hex(tag)

Notes

• Key derivation is currently SHA-256 of the passphrase.
• The nonce is generated internally.
• The whole file is buffered in memory.
• Decryption fails if MAC verification fails.

Challenge

A sample encrypted challenge file is part of the project.

If you want to try cracking it, grab the ciphertext file and the source and have fun.

Files

• scram68.a68 — source.
• README.md — project notes.
• challenge-crypt.txt — encrypted challenge file.