pyaes

library1.6.1pypypi✓ verified 26d ago

PyAES provides a pure-Python implementation of the Advanced Encryption Standard (AES) block cipher, along with common modes of operation like CBC, CTR, and OFB. Currently at version 1.6.1, it offers a lightweight cryptographic option for environments where C extensions are not feasible or desired. Its release cadence is low, with updates typically addressing bug fixes or minor enhancements.

auth-security

pip install pyaes

github ↗package ↗

INSTALL

IMPORT

SIG · PYAES

pyaes

auth-securitypythonv1.6.1

Install

2.4s avg

Import

10ms

Disk

17MB

Pass rate

10/ 10

Env Coverage10 / 10

glibc

3.9–3.13

musl

3.9–3.13

Install & Compatibility

Where this runs

tested against v1.6.1 · pip install

no network on importno background threads

Install × environment matrix

Each cell = how many times install + import succeeded across repeated harness runs. Partial = flaky.
glibc = Debian/Ubuntu slim · musl = Alpine Linux

musl

py 3.10–3.95 runs

installs and imports cleanly · install 0.0s · import 0.010s · 19.3MB

glibc

py 3.10–3.95 runs

installs and imports cleanly · install 2.4s · import 0.000s · 20MB

17MB installed

● package 17MB

Code

Verified usage

Verified import paths — ran on the pinned version, not inferred.

AESModeOfOperationCBC

✓ from pyaes import AESModeOfOperationCBC

AESModeOfOperationCTR

✓ from pyaes import AESModeOfOperationCTR

AES

✓ from pyaes import AES

Use this for the raw block cipher; typically prefer mode-of-operation classes for common use cases.

This example demonstrates encrypting and decrypting data using AES in CBC mode with a 256-bit key. It highlights the use of `AESModeOfOperationCBC` and the necessity of providing a unique IV for each encryption operation. PyAES uses zero-padding by default if the plaintext length is not a multiple of the block size.

import pyaes import os # AES in CBC mode (with default zero-padding) key = os.urandom(32) # 256-bit key iv = os.urandom(16) # 128-bit Initialization Vector aes_cbc_encrypt = pyaes.AESModeOfOperationCBC(key, iv=iv) plaintext = b"This is some plaintext to encrypt. It will be zero-padded if not a multiple of 16 bytes." ciphertext = aes_cbc_encrypt.encrypt(plaintext) # Decrypt using a new AES object with the same key and IV aes_cbc_decrypt = pyaes.AESModeOfOperationCBC(key, iv=iv) decrypted_text = aes_cbc_decrypt.decrypt(ciphertext) print(f"Original: {plaintext}") print(f"Encrypted: {ciphertext.hex()}") print(f"Decrypted: {decrypted_text}") assert decrypted_text == plaintext

Debug

Known issues

gotchaAES key lengths must be 16, 24, or 32 bytes (for AES-128, AES-192, AES-256 respectively). Initialization Vector (IV) for CBC mode must be 16 bytes. Providing incorrect lengths will result in errors or insecure operation.

fix

Ensure `key` is 16, 24, or 32 bytes long, and `iv` (for CBC/CTR/OFB) is 16 bytes long. Use `os.urandom()` for cryptographically secure random values.

affects: All versions

breakingThe stream API (e.g., `encrypt_stream`, `decrypt_stream`) was broken in version 1.5.0 and fixed in 1.6.0. Users upgrading from 1.5.0 to 1.6.0 will find their stream operations now function correctly, which might be a 'breaking change' if their code had workarounds for the 1.5.0 bug.

fix

Ensure you are using version 1.6.0 or higher for reliable stream API functionality. Review code that interacted with the stream API in 1.5.0 as workarounds may no longer be necessary or compatible.

affects: 1.5.0 (bugged), 1.6.0+

gotchaPyAES uses simple zero-padding by default when input data is not a multiple of the AES block size (16 bytes). This can lead to security vulnerabilities (e.g., padding oracle attacks) or data loss if the original plaintext legitimately ends with null bytes, as zero-padding cannot distinguish between actual nulls and padding nulls.

fix

For robust applications, implement a cryptographically secure padding scheme like PKCS7 or ISO 10126 before encryption and unpadding after decryption, rather than relying on `pyaes`'s default zero-padding.

affects: All versions

gotchaReusing the same Initialization Vector (IV) with the same key for multiple encryptions in CBC mode significantly compromises confidentiality, making the encryption vulnerable to attacks. A unique, unpredictable IV is crucial for each encryption operation.

fix

Always generate a new, cryptographically random IV (e.g., `os.urandom(16)`) for every distinct encryption operation with the same key in CBC mode. Store and transmit the IV alongside the ciphertext (it does not need to be secret).

affects: All versions (when using CBC mode)

Errors

Common errors & fixes

ModuleNotFoundError: No module named 'pyaes'

The 'pyaes' library is not installed in the current Python environment or is not accessible within the Python path.

fix

Install the library using pip: `pip install pyaes`

ValueError: Invalid key size

The AES key provided for encryption or decryption does not meet the required length of 16, 24, or 32 bytes.

fix

Ensure the key is exactly 16, 24, or 32 bytes long. Example: `key = b'This is a 16-byte key'`

ValueError: plaintext block must be 16 bytes

When using `AESModeOfOperationCBC` (or other block modes) directly, the `encrypt` method expects plaintext to be an exact multiple of the AES block size (16 bytes); for arbitrary length data, `pyaes.BlockFeeder` should be used.

fix

Utilize `pyaes.Encrypter` and `pyaes.Decrypter` with `feed` and `feed_final` methods to handle plaintext of any length, as these classes include automatic padding. Example: `encrypter = pyaes.Encrypter(aes_mode); ciphertext = encrypter.feed(plaintext); ciphertext += encrypter.feed_final()`

TypeError: a bytes-like object is required, not 'str'

Cryptographic functions in `pyaes` (and Python 3 generally for bytes-oriented operations) expect byte strings (e.g., `b'hello'`) rather than regular Unicode strings (`'hello'`).

fix

Encode your string data to bytes before passing it to `pyaes` functions. Example: `plaintext.encode('utf-8')` or `key_string.encode('utf-8')`

Upgrade

Version history

1.6.1latest on PyPI · released Sep 20, 2017

Audit

Dependencies

No dependency data recorded yet.

Agent activity

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Resources

githubhttps://github.com/ricmoo/pyaes ↗

packagehttps://pypi.org/project/pyaes/ ↗