sslcrypto

sslcrypto is a fast and simple library for AES, ECIES and ECDSA for Python.

License: MIT + BSD-2 for ripemd implementation (see _ripemd.py).

Why?

sslcrypto can use OpenSSL in case it's available in your system for speedup, but pure-Python code is also available and is heavily optimized.

N.B. There are alternatives like coincurve which are faster in some cases (e.g. when using secp256k1). They don't include ECIES implementation and some useful ECDSA features and are specialized on a single curve. If that's enough for you and libsecp256k1 bindings are available for all OSes you need to support, use those libraries. Coincurve, in particular, ships pre-compiled packages for all major OSes and building from source does not require an existing libsecp256k1 installation.

N.B. While there are other mature cryptography libraries, they are too heavy for simple stuff and require OpenSSL that is not available by default on Windows (most likely many other OSes as well). That said, in case you're processing big data, not much data, the speed advantage you get from libraries is too small to use heavy alternatives.

Installation

pip install sslcrypto

Additionally, you can download this repository and run python setup.py install.

Usage

AES

import sslcrypto

# Generate random key
key = sslcrypto.aes.new_key()

# Encrypt something
data = b"Hello, world!"
ciphertext, iv = sslcrypto.aes.encrypt(data, key)

# Decrypt
assert sslcrypto.aes.decrypt(ciphertext, iv, key) == data

By default, aes-256-cbc cipher is used. You can specify another one if you want. The following ciphers are supported:

• aes-128-cbc, aes-192-cbc, aes-256-cbc
• aes-128-ctr, aes-192-ctr, aes-256-ctr
• aes-128-cfb, aes-192-cfb, aes-256-cfb
• aes-128-ofb, aes-192-ofb, aes-256-ofb

import sslcrypto

# Generate random key
key = sslcrypto.aes.new_key(algo="aes-192-cfb")

# Encrypt something
data = b"Hello, world!"
ciphertext, iv = sslcrypto.aes.encrypt(data, key, algo="aes-192-cfb")

# Decrypt
assert sslcrypto.aes.decrypt(ciphertext, iv, key, algo="aes-192-cfb") == data

ECIES

The following curves are supported:

• secp112r1, secp112r2
• secp128r1, secp128r2
• secp160k1, secp160r1, secp160r2, brainpoolP160r1
• secp192k1, prime192v1, brainpoolP192r1
• secp224k1, secp224r1, brainpoolP224r1
• secp256k1, prime256v1, brainpoolP256r1
• brainpoolP320r1
• secp384r1, brainpoolP384r1
• brainpoolP512r1
• secp521r1

Please tell me if you want to add any other curves.

import sslcrypto

# Create curve object
curve = sslcrypto.ecc.get_curve("brainpoolP256r1")

# Generate private key, both compressed and uncompressed keys are supported
private_key = curve.new_private_key(is_compressed=True)

# Find a matching public key
public_key = curve.private_to_public(private_key)

# If required, you can change public key format to whatever you want
x, y = curve.decode_public_key(public_key)
electrum_public_key = x + y

# Encrypt something. You can specify a cipher if you want to, aes-256-cbc is the
# default value
data = b"Hello, world!"
ciphertext = curve.encrypt(data, public_key, algo="aes-256-ofb")

# Decrypt
assert curve.decrypt(ciphertext, private_key, algo="aes-256-ofb") == data

ECDSA

import sslcrypto

# Create curve object
curve = sslcrypto.ecc.get_curve("brainpoolP256r1")

# Generate private key
private_key = curve.new_private_key()

# Find a matching public key
public_key = curve.private_to_public(private_key)

# Sign something
data = b"Hello, world!"
signature = curve.sign(data, private_key)

# Verify
assert curve.verify(signature, data, public_key) == True  # Would raise on error

Additionally, you can create recoverable signatures:

import sslcrypto

# Create curve object
curve = sslcrypto.ecc.get_curve("brainpoolP256r1")

# Generate private key
private_key = curve.new_private_key()

# Find a matching public key
public_key = curve.private_to_public(private_key)

# Sign something
data = b"Hello, world!"
signature = curve.sign(data, private_key, recoverable=True)

# Recover public key
assert curve.recover(signature, data) == public_key  # Would raise on error

Bitcoin-related functions

import sslcrypto
curve = sslcrypto.ecc.get_curve("secp256k1")
private_key = curve.new_private_key()
public_key = curve.private_to_public(private_key)

wif = curve.private_to_wif(private_key)  # Transform to mainnet private key
assert curve.wif_to_private(wif) == private_key

address = curve.private_to_address(private_key)
assert address == curve.public_to_address(public_key)

# Based on BIP32. Hardened indexes aren't supported yet
curve.child_derive(private_key, 123)

Misc

import sslcrypto
print(sslcrypto.ecc.get_backend())  # Either "fallback" or OpenSSL info

You can override OpenSSL path discovery:

from sslcrypto.openssl import discovery
discovery.discover = lambda: ["openssl_lib.dll"]

If you want to go low-level, you can get curve parameters:

import sslcrypto
curve = sslcrypto.ecc.get_curve("secp256k1")
assert curve.params["n"] == 0xFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFEBAAEDCE6AF48A03BBFD25E8CD0364141

Running tests

sslcrypto uses pytest framework. Install it with pip and run python3 -m pytest test in sslcrypto repository.