CipherStream class

class crsysapi.CipherStream

Stream cipher functions.

class Alg

Stream cipher algorithm.

ARCFOUR = 1

ARCFOUR (RC4) algorithm

CHACHA20 = 3

Chacha20 algorithm

SALSA20 = 2

Salsa20 algorithm

static bytes(data, key, iv, alg, counter=0)

Encipher data in array of bytes using specified stream cipher.

Parameters:

  • data (bytes) -- Input data to be encrypted.

  • key (bytes) -- Key (length restrictions apply, see Remarks).

  • iv (bytes) -- Initialization Vector (IV, nonce) or None for Arcfour.

  • alg (CipherStream.Alg) -- Stream cipher algorithm.

  • counter (int) -- Counter value for ChaCha20 only, otherwise ignored.

Returns:

Ciphertext in a byte array.

Return type:

bytes

Note

  • Arcfour: any length key; no IV.

  • Salsa20: key must be exactly 16 or 32 bytes and IV exactly 8 bytes long.

  • ChaCha20: key must be exactly 16 or 32 bytes and IV exactly 8, 12, or 16 bytes long. Counter is ignored if IV is 16 bytes.

static file(fileout, filein, key, iv, alg, counter=0)

Encipher data in a file using specified stream cipher.

Parameters:

  • fileout (str) -- Name of output file to be created or overwritten.

  • filein (str) -- Name of input file

  • key (bytes) -- Key (length restrictions apply, see Remarks).

  • iv (bytes) -- Initialization Vector (IV, nonce) or None for Arcfour.

  • alg (CipherStream.Alg) -- Stream cipher algorithm.

  • counter (int) -- Counter value for ChaCha20 only, otherwise ignored.

Returns:

0 if successful.

Return type:

int

Note

  • Arcfour: any length key; no IV.

  • Salsa20: key must be exactly 16 or 32 bytes and IV exactly 8 bytes long.

  • ChaCha20: key must be exactly 16 or 32 bytes and IV exactly 8, 12, or 16 bytes long. Counter is ignored if IV is 16 bytes.