def des_string_to_key(str_key):
# Result variable
key = bytearray(8)
# Doing some bit shifting, please refer to the URL above
for index in range(0,len(str_key)):
# This is not mandatory as Python seems to handle unsigned bytes by default
b_val = ord(str_key[index]) & 0xff
if (index % 16) < 8:
key[index % 8] = key[index % 8] ^ (b_val<<1)
else:
b_val = ((b_val << 4) & 0xf0) | (ror(b_val,4) & 0x0f)
b_val = ((b_val << 2) & 0xcc) | (ror(b_val,2) & 0x33)
b_val = ((b_val << 1) & 0xaa) | (ror(b_val,1) & 0x55)
key[7- (index % 8)] ^= b_val;
index = index + 1
# Getting odd parity
key = set_odd_parity(key)
# Computing CBC checksum (generating key)
key = des_cbc_checksum(str_key, key, key)
# Getting odd parity
key = set_odd_parity(key)
return key
def des_string_to_2keys(str_key):
key1 = bytearray(8)
key2 = bytearray(8)
for index in range(0,len(str_key)):
# This is not mandatory as Python seems to handle unsigned bytes by default
b_val = ord(str_key[index]) & 0xff
# Doing some bit shifting, please refer to the URL above
if (index % 32) < 16:
if (index % 16) < 8:
key1[index % 8] ^= (b_val<<1)
else:
key2[index % 8] ^= (b_val<<1)
else:
b_val = ((b_val << 4) & 0xf0) | (ror(b_val,4) & 0x0f)
b_val = ((b_val << 2) & 0xcc) | (ror(b_val,2) & 0x33)
b_val = ((b_val << 1) & 0xaa) | (ror(b_val,1) & 0x55)
if (index % 16) < 8:
key1[7-(index % 8)] ^= b_val
else:
key2[7-(index % 8)] ^= b_val
if len(str_key)<=8:
for index in range(0,8):
key2[index] = key1[index]
# Getting odd parity
key1 = set_odd_parity(key1)
# Computing CBC checksum (generating key)
key1 = des_cbc_checksum(str_key, key1, key1)
# Getting odd parity
key1 = set_odd_parity(key1)
# Getting odd parity
key2 = set_odd_parity(key2)
# Computing CBC checksum (generating key)
key2 = des_cbc_checksum(str_key, key2, key2)
# Getting odd parity
key2 = set_odd_parity(key2)
return key1.extend(key2).extend(key1)
