pycrypt-lib 1.1.4

A pure Python implementation of cryptographic primitives, written in a clean, Pythonic, and type-safe way.

pycrypt

A pure Python implementation of cryptographic primitives, written in a clean, Pythonic, and type-safe way.

⚠️ Disclaimer: pycrypt is an educational cryptography library. It is not safe for production use. Use only for learning how cryptographic algorithms work under the hood.

Do not roll your own crypto in production code. Use a safe, audited library that has been vetted by professionals.

Overview

pycrypt implements major cryptographic primitives from scratch in pure Python with minimal dependencies. It is designed for learners and developers interested in the inner workings of cryptography.

Features

Category	Algorithm	Description
Asymmetric	RSA	OAEP encryption/decryption, PSS signing/verification
	Diffie–Hellman (DH)	Modular exponentiation and HKDF-based key derivation
Symmetric	AES	ECB, CBC, CTR, and GCM modes
Hashing	SHA-1, SHA-256	HMAC and HKDF included

Project Structure

pycrypt/
├── asymmetric/
│   ├── dh/
│   │   ├── core.py
│   │   ├── groups.py
│   │   └── keyformat.py
│   └── rsa/
│       ├── core.py
│       ├── keyformat.py
│       └── utils.py
├── hash/
│   ├── sha/
│   │   ├── core.py
│   │   ├── hmac.py
│   │   └── variants.py
├── symmetric/
│   └── aes/
│       ├── core.py
│       ├── modes.py
│       └── utils.py
├── utils/
│   ├── asn1.py
│   ├── padding.py
│   └── utils.py
└── main.py

Installation

pip install pycrypt-lib

Examples

Diffie–Hellman (DH) Key Exchange

from pycrypt.asymmetric import DH

params = DH.generate_parameters(2048)

alice_priv = params.generate_private_key()
bob_priv = params.generate_private_key()

alice_shared = alice_priv.exchange(bob_priv.public_key())
bob_shared = bob_priv.exchange(alice_priv.public_key())

assert alice_shared == bob_shared
print(f"Shared secret: {alice_shared.hex()}")

RSA Encryption and Signing

from pycrypt.asymmetric import RSAKey

key = RSAKey.generate(2048)
message = b"Hello RSA!"

cipher = key.oaep_encrypt(message)
plain = key.oaep_decrypt(cipher)

signature = key.pss_sign(message)
assert key.pss_verify(message, signature)

AES (GCM Mode)

from secrets import token_bytes
from pycrypt.symmetric import AES_GCM

key = token_bytes(16)
nonce = token_bytes(12)

aes = AES_GCM(key)
ciphertext, tag = aes.encrypt(b"Top Secret", nonce=nonce)
plaintext = aes.decrypt(ciphertext, nonce=nonce, tag=tag)

print(plaintext.decode())

SHA-256 Hash

from pycrypt.hash import SHA256

sha = SHA256()
sha.update(b"hello world")
print(sha.hexdigest())

License

pycrypt is licensed under the MIT License.

See LICENSE for the full text.

⚠️ Note: This library is not secure for production use. It is a learning and exploration tool only.

Links

• Documentation
• Github Repository
• PyPI Package

Cryptography Reference Standards

• FIPS PUB 197 – Advanced Encryption Standard (AES)
• FIPS PUB 180-4 – Secure Hash Standard (SHS)
• RFC 8017 – RSA Cryptography Standard (PKCS #1 v2.2)
• RFC 2631 - Diffie-Hellman Key Agreement Method