Changelog

All notable changes to ciphertrust are documented here.

[0.1.0] — 2026-03-13

Initial release of ciphertrust, a pure-Python RSA library and drop-in replacement for the archived python-rsa package.

Core math — modular exponentiation, inverse, CRT, GCD primitives; always-on RSA blinding to prevent timing side-channels
Prime generation — Miller-Rabin primality testing, random prime generation
Key generation — RSA key pair generation (512–4096+ bit), configurable public exponent
Key serialization — PKCS#1 and PKCS#8 private key formats, PEM and DER encoding/decoding
Parallel key generation — multiprocessing-based key pair generation for faster results
PKCS#1 v1.5 — encrypt, decrypt (constant-time padding validation), sign, and verify with SHA-1 through SHA-512
OAEP (PKCS#1 v2.1) — encrypt and decrypt with configurable hash algorithm and MGF; timing-hardened implementation
python-rsa compatibility shim — import ciphertrust as rsa works as a drop-in replacement; compat.py re-exports the full rsa public API
Cross-verification test suite — round-trip tests against python-rsa to confirm wire compatibility
Typed — fully annotated, passes mypy --strict; ships py.typed marker (PEP 561)
CI — GitHub Actions matrix across Python 3.9–3.13 and PyPy 3.10; ruff lint and mypy typecheck

OAEP implementation avoids early-exit branches on padding errors (timing leak fix)
PKCS#1 v1.5 decrypt uses constant-time padding comparison
PKCS#8 OID and BIT STRING validation hardened
Hash length validation per RFC 8017
MD5 signing not supported (unlike python-rsa)