tessl/pypi-oscrypto

Cross-platform cryptographic library providing TLS sockets, asymmetric/symmetric encryption, and key operations using OS-native crypto libraries

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Symmetric Cryptography

Name: tessl/pypi-oscrypto
Author: tessl

Symmetric encryption and decryption operations using AES, DES, 3DES, RC2, and RC4 algorithms. All operations use OS-native crypto libraries for optimal performance and security updates through the operating system.

from typing import Tuple

Capabilities

AES Encryption

Advanced Encryption Standard (AES) operations with CBC mode and various padding schemes.

def aes_cbc_pkcs7_encrypt(key: bytes, data: bytes, iv: bytes = None) -> Tuple[bytes, bytes]:
    """
    Encrypt data using AES-CBC with PKCS#7 padding.

    Parameters:
    - key: bytes - AES key (16, 24, or 32 bytes for AES-128/192/256)
    - data: bytes - Data to encrypt
    - iv: bytes - 16-byte initialization vector (None to generate random)

    Returns:
    Tuple of (iv, ciphertext) bytes
    """

def aes_cbc_pkcs7_decrypt(key: bytes, data: bytes, iv: bytes) -> bytes:
    """
    Decrypt AES-CBC data with PKCS#7 padding.

    Parameters:
    - key: bytes - AES key (16, 24, or 32 bytes)
    - data: bytes - Encrypted ciphertext
    - iv: bytes - 16-byte initialization vector

    Returns:
    Decrypted plaintext data
    """

def aes_cbc_no_padding_encrypt(key: bytes, data: bytes, iv: bytes = None) -> Tuple[bytes, bytes]:
    """
    Encrypt data using AES-CBC without padding.

    Parameters:
    - key: bytes - AES key (16, 24, or 32 bytes)
    - data: bytes - Data to encrypt (must be multiple of 16 bytes)
    - iv: bytes - 16-byte initialization vector (None to generate random)

    Returns:
    Tuple of (iv, ciphertext) bytes
    """

def aes_cbc_no_padding_decrypt(key: bytes, data: bytes, iv: bytes) -> bytes:
    """
    Decrypt AES-CBC data without padding.

    Parameters:
    - key: bytes - AES key (16, 24, or 32 bytes)
    - data: bytes - Ciphertext to decrypt
    - iv: bytes - 16-byte initialization vector

    Returns:
    Decrypted plaintext data
    """

DES Encryption

Data Encryption Standard (DES) operations with CBC mode and PKCS#5 padding.

def des_cbc_pkcs5_encrypt(key: bytes, data: bytes, iv: bytes = None) -> Tuple[bytes, bytes]:
    """
    Encrypt data using DES-CBC with PKCS#5 padding.

    Parameters:
    - key: bytes - DES key (8 bytes)
    - data: bytes - Data to encrypt
    - iv: bytes - 8-byte initialization vector (None to generate random)

    Returns:
    Tuple of (iv, ciphertext) bytes
    """

def des_cbc_pkcs5_decrypt(key: bytes, data: bytes, iv: bytes) -> bytes:
    """
    Decrypt DES-CBC data with PKCS#5 padding.

    Parameters:
    - key: bytes - DES key (8 bytes)
    - data: bytes - Ciphertext to decrypt
    - iv: bytes - 8-byte initialization vector

    Returns:
    Decrypted plaintext data
    """

Triple DES Encryption

Triple DES (3DES) operations with CBC mode and PKCS#5 padding.

def tripledes_cbc_pkcs5_encrypt(key: bytes, data: bytes, iv: bytes = None) -> Tuple[bytes, bytes]:
    """
    Encrypt data using 3DES-CBC with PKCS#5 padding.

    Parameters:
    - key: bytes - 3DES key (16 or 24 bytes)
    - data: bytes - Data to encrypt
    - iv: bytes - 8-byte initialization vector (None to generate random)

    Returns:
    Tuple of (iv, ciphertext) bytes
    """

def tripledes_cbc_pkcs5_decrypt(key: bytes, data: bytes, iv: bytes) -> bytes:
    """
    Decrypt 3DES-CBC data with PKCS#5 padding.

    Parameters:
    - key: bytes - 3DES key (16 or 24 bytes)
    - data: bytes - Ciphertext to decrypt
    - iv: bytes - 8-byte initialization vector

    Returns:
    Decrypted plaintext data
    """

RC2 Encryption

RC2 cipher operations with CBC mode and PKCS#5 padding.

def rc2_cbc_pkcs5_encrypt(key: bytes, data: bytes, iv: bytes = None) -> Tuple[bytes, bytes]:
    """
    Encrypt data using RC2-CBC with PKCS#5 padding.

    Parameters:
    - key: bytes - RC2 key (5-16 bytes for 40-128 bit keys)
    - data: bytes - Data to encrypt
    - iv: bytes - 8-byte initialization vector (None to generate random)

    Returns:
    Tuple of (iv, ciphertext) bytes
    """

def rc2_cbc_pkcs5_decrypt(key: bytes, data: bytes, iv: bytes) -> bytes:
    """
    Decrypt RC2-CBC data with PKCS#5 padding.

    Parameters:
    - key: bytes - RC2 key (5-16 bytes for 40-128 bit keys)
    - data: bytes - Ciphertext to decrypt
    - iv: bytes - 8-byte initialization vector

    Returns:
    Decrypted plaintext data
    """

RC4 Encryption

RC4 stream cipher operations (encryption and decryption use the same function).

def rc4_encrypt(key: bytes, data: bytes) -> bytes:
    """
    Encrypt data using RC4 stream cipher.

    Parameters:
    - key: bytes - RC4 key (5-16 bytes for 40-128 bit keys)
    - data: bytes - Data to encrypt

    Returns:
    Encrypted ciphertext
    """

def rc4_decrypt(key: bytes, data: bytes) -> bytes:
    """
    Decrypt RC4 data (same operation as encryption).

    Parameters:
    - key: bytes - RC4 key (5-16 bytes for 40-128 bit keys)
    - data: bytes - Ciphertext to decrypt

    Returns:
    Decrypted plaintext data
    """

Usage Examples

AES Encryption Example

from oscrypto.symmetric import aes_cbc_pkcs7_encrypt, aes_cbc_pkcs7_decrypt
from oscrypto.util import rand_bytes

# Generate a 256-bit (32-byte) AES key
key = rand_bytes(32)

# Encrypt data
plaintext = b"This is a secret message that needs to be encrypted"
iv, ciphertext = aes_cbc_pkcs7_encrypt(key, plaintext, None)

# Decrypt data
decrypted = aes_cbc_pkcs7_decrypt(key, ciphertext, iv)
assert decrypted == plaintext

print(f"Original: {plaintext}")
print(f"Encrypted length: {len(ciphertext)} bytes")
print(f"Decrypted: {decrypted}")

Multiple Algorithm Example

from oscrypto.symmetric import (
    aes_cbc_pkcs7_encrypt, aes_cbc_pkcs7_decrypt,
    des_cbc_pkcs5_encrypt, des_cbc_pkcs5_decrypt,
    rc4_encrypt, rc4_decrypt
)
from oscrypto.util import rand_bytes

message = b"Secret data"

# AES-256 encryption
aes_key = rand_bytes(32)
aes_iv, aes_ciphertext = aes_cbc_pkcs7_encrypt(aes_key, message, None)
aes_decrypted = aes_cbc_pkcs7_decrypt(aes_key, aes_ciphertext, aes_iv)

# DES encryption
des_key = rand_bytes(8)
des_iv, des_ciphertext = des_cbc_pkcs5_encrypt(des_key, message, None)
des_decrypted = des_cbc_pkcs5_decrypt(des_key, des_ciphertext, des_iv)

# RC4 encryption
rc4_key = rand_bytes(16)
rc4_encrypted = rc4_encrypt(rc4_key, message)
rc4_decrypted = rc4_decrypt(rc4_key, rc4_encrypted)

# All should decrypt to original message
assert aes_decrypted == des_decrypted == rc4_decrypted == message

Custom IV Example

from oscrypto.symmetric import aes_cbc_pkcs7_encrypt, aes_cbc_pkcs7_decrypt
from oscrypto.util import rand_bytes

key = rand_bytes(16)  # AES-128 key
iv = rand_bytes(16)   # AES block size IV
plaintext = b"Message with custom IV"

# Encrypt with custom IV
returned_iv, ciphertext = aes_cbc_pkcs7_encrypt(key, plaintext, iv)

# Decrypt with same IV
decrypted = aes_cbc_pkcs7_decrypt(key, ciphertext, iv)
assert decrypted == plaintext

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