sslcrypto

5.3 verified Fri May 01 auth: no python

sslcrypto is a Python library providing ECIES (Elliptic Curve Integrated Encryption Scheme), AES, and RSA encryption with OpenSSL-based implementation and a pure Python fallback. Current version 5.3 offers multiple backends (OpenSSL, LibreSSL, cryptography, pure Python) and supports a wide range of curves and RSA key sizes. Release cadence is irregular, with occasional major version bumps due to API changes.

pip install sslcrypto

Common errors

error ModuleNotFoundError: No module named 'sslcrypto' ↓

cause sslcrypto is not installed.

fix

Run pip install sslcrypto

error sslcrypto.lib.backend.UnavailableBackendError: Cannot find any suitable backend ↓

cause No OpenSSL, LibreSSL, or cryptography library found. Pure Python fallback not available because optional dependencies are missing.

fix

Install sslcrypto with 'all' extra: pip install sslcrypto[all]

error TypeError: initial_value must be bytes or None ↓

cause Passed a non-bytes value (e.g., string) to AES initialization (iv argument).

fix

Ensure iv is bytes: iv = b'some_16_byte_iv' or iv = os.urandom(16)

Warnings

breaking Version 4.x to 5.x broke named curve arguments: use curve name as string directly, not as key in a dict. Previous usage `curve='secp256k1'` still works, but internal API changed. ↓

fix Update to new pattern if you were passing curve as keyword to low-level functions; generally safe if using high-level wrappers.

breaking AES encryption in version 5 returns bytes object in Python 3, not base64 string as in older versions. Decryption expects raw bytes. ↓

fix Encode/decode to base64 manually if needed: base64.b64encode(encrypted)

deprecated The `ciphertext` attribute of AES objects is deprecated; use `cipher.encrypt()` return value directly. ↓

fix Use cipher.encrypt(data) instead of cipher.ciphertext

gotcha Default backend selection may fail on systems without OpenSSL. Install with `[all]` extra to ensure fallback works. ↓

fix pip install sslcrypto[all]

Install

pip install sslcrypto[all]

Imports

aes

wrong

from sslcrypto import AES

correct

from sslcrypto import aes

Module is lowercase 'aes' in version 5.x

ecc
wrong
```
from sslcrypto.ecc import ECC
```
correct
```
from sslcrypto import ecc
```
Module is 'ecc' and does not export 'ECC' class

rsa

wrong

from sslcrypto.rsa import RSA

correct

from sslcrypto import rsa

Module is 'rsa', not 'RSA'

Quickstart

Generate an AES key, IV, encrypt and decrypt a message using CBC mode.

from sslcrypto import aes

key = aes.generate_key()
iv = aes.generate_iv()

cipher = aes.new(key, aes.MODE_CBC, iv=iv)
encrypted = cipher.encrypt(b'secret message')

decipher = aes.new(key, aes.MODE_CBC, iv=iv)
decrypted = decipher.decrypt(encrypted)
print(decrypted)