ARC4 Encryption (ARCFOUR)

Demonstrates simple ARC4 encryption to match some simple test vectors published by Wikipedia. ARC4 is a fast stream cipher supporting key lengths from 8 to 2048 bits (i.e. from 1 to 256 bytes). It is not a block cipher, so there is no padding, no modes, and no initialization vector.

Download Chilkat Python Library

import sys
import chilkat

crypt = chilkat.CkCrypt2()

success = crypt.UnlockComponent("Anything for 30-day trial")
if (success != True):
    print "Crypt component unlock failed"
    sys.exit()

#  Set the encryption algorithm to ARC4:
crypt.put_CryptAlgorithm("arc4")

#  We want the encrypted output to be a hex-encoded string.
crypt.put_EncodingMode("hex")

#  Encrypt some test vectors from Wikipedia:

#  The key length (in bits) is equal to the number of us-ascii
#  bytes in our key string * 8.

# ARC4( "Key", "Plaintext" ) == BBF316E8D940AF0AD3
crypt.put_KeyLength(24)
crypt.SetEncodedKey("Key","ascii")
cipherText = crypt.encryptStringENC("Plaintext")
print cipherText
plainText = crypt.decryptStringENC(cipherText)
print plainText

# ARC4( "Wiki", "pedia" ) == 1021BF0420
crypt.put_KeyLength(32)
crypt.SetEncodedKey("Wiki","ascii")
cipherText = crypt.encryptStringENC("pedia")
print cipherText
plainText = crypt.decryptStringENC(cipherText)
print plainText

# ARC4( "Secret", "Attack at dawn" ) == 45A01F645FC35B383552544B9BF5
crypt.put_KeyLength(48)
crypt.SetEncodedKey("Secret","ascii")
cipherText = crypt.encryptStringENC("Attack at dawn")
print cipherText
plainText = crypt.decryptStringENC(cipherText)
print plainText

#  Note: The call to SetEncodedKey serves to set the key
#  to the us-ascii bytes of the string.