Refactoring and Bugfixing:
- CryptoUtils:
- removing hard coded keylength from append_padding in CryptoUtils
- rewrote append_padding, slightly modified strip_padding in CryptoUtils
- added get_cipher_keylen and get_cipher_blocklen to CryptoUtils
- Updated UnitTest in CryptoUtils. Note: PBKDF2.self_test() fails!!!
- added new function protect_string to encrypt and authenticate a string
- Removed hard coded padding pattern
- VirtualICC:
- Added and integrated functions to load and save VirtualICC objects
- Added exception handling for opening of the socket
- SmartcardSAM:
- Removed all object persistance functionaliy from SmartcardSAM
- Changed the constructors of the *SAM classes
- Moved all the functionality to create cards (especially the pre-initialized filesystems for each card type) to the new file GenerateCards.py
- Added minimal command line based interface to GenerateCards.py to generate customized cards and store them in a file
- Removed default sam and mf files (testconfig.mf and testconfig.sam)
git-svn-id: https://vsmartcard.svn.sourceforge.net/svnroot/vsmartcard@35 96b47cad-a561-4643-ad3b-153ac7d7599c
This commit is contained in:
oepen
@@ -23,6 +23,7 @@ from binascii import b2a_hex
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from random import randint
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from utils import inttostring, stringtoint, hexdump
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import string
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import re
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try:
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# Use PyCrypto (if available)
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@@ -33,8 +34,7 @@ except ImportError:
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import hmac as HMAC
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import sha as SHA1
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iv = '\x00' * 8
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PADDING = '\x80' + '\x00' * 7
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CYBERFLEX_IV = '\x00' * 8
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## *******************************************************************
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## * Generic methods *
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@@ -63,38 +63,64 @@ def get_cipher(cipherspec, key, iv = None):
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return cipher
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def append_padding(cipherspec, data, padding_class=0x01,keylength = 16):
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def get_cipher_keylen(cipherspec):
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cipherparts = cipherspec.split("-")
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if len(cipherparts) > 2:
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raise ValueError, 'cipherspec must be of the form "cipher-mode" or "cipher"'
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cipher = cipherparts[0].upper()
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#cipher = globals().get(cipherparts[0].upper(), None)
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#Note: return cipher.key_size does not work on Ubuntu, because e.g. AES.key_size == 0
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if cipher == "AES": #Pycrypto uses AES128
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return 16
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elif cipher == "DES":
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return 8
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elif cipher == "DES3":
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return 16
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else:
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raise ValueError, "Unsupported Encryption Algorithm: " + cipher
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def get_cipher_blocklen(cipherspec):
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cipherparts = cipherspec.split("-")
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if len(cipherparts) > 2:
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raise ValueError, 'cipherspec must be of the form "cipher-mode" or "cipher"'
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cipher = globals().get(cipherparts[0].upper(), None)
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return cipher.block_size
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def append_padding(cipherspec, data, padding_class=0x01):
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"""Append padding to the data.
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Length of padding depends on length of data and the block size of the
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specified encryption algorithm.
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Different types of padding may be selected via the padding_class parameter
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"""
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key = "DUMMYKEY" * (keylength / 8) #Key doesn't matter for padding
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cipher = get_cipher(cipherspec,key,iv)
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if padding_class == 0x01: #ISO padding
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last_block_length = len(data) % cipher.block_size
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padding_length = cipher.block_size - last_block_length
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if padding_length == 0:
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padding = PADDING
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else:
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padding = PADDING[:padding_length]
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blocklen = get_cipher_blocklen(cipherspec)
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if padding_class == 0x01: #ISO padding
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last_block_length = len(data) % blocklen
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padding_length = blocklen - last_block_length
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if padding_length == 0:
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padding = '\x80' + '\x00' * (blocklen - 1)
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else:
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padding = '\x80' + '\x00' * (blocklen - last_block_length - 1)
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del cipher
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return data + padding
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def strip_padding(cipherspec,data,padding_class=0x01,keylength = 16):
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def strip_padding(cipherspec,data,padding_class=0x01):
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"""
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Strip the padding of decrypted data. Returns data without padding
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"""
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key = "DUMMYKEY" * (keylength / 8) #Key doesn't matter for padding
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cipher = get_cipher(cipherspec,key,iv)
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#TODO: Sanity check
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if padding_class == 0x01:
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tail = len(data) - 1
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while data[tail] != '\x80':
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tail = tail - 1
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return data[:tail]
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def crypto_checksum(algo,key,data,iv=None,ssc=None):
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def crypto_checksum(algo, key, data, iv=None, ssc=None):
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if algo not in ("HMAC","MAC","CC"):
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raise ValueError, "Unknown Algorithm %s" % algo
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@@ -119,7 +145,7 @@ def cipher(do_encrypt, cipherspec, key, data, iv = None):
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operation = do_encrypt ? encrypt : decrypt,
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cipherspec must be of the form "cipher-mode", or "cipher\""""
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cipher = get_cipher(cipherspec,key,iv)
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cipher = get_cipher(cipherspec, key, iv)
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result = None
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if do_encrypt:
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@@ -148,37 +174,92 @@ def operation_on_string(string1, string2, op):
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result.append( chr(op(ord(string1[i]),ord(string2[i]))) )
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return "".join(result)
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def protect_string(string, password, cipherspec=None):
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"""
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Encrypt and authenticate a string
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"""
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#Derive a key and a salt from password
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pbk = crypt(password)
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regex = re.compile('\$p5k2\$\$[\w./]*\$')
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match = regex.match(pbk)
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if match != None:
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salt = pbk[7:match.end()-1]
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key = pbk[match.end():]
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else:
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raise ValueError
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#Encrypt the string, authenticate and format it
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if cipherspec == None:
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cipherspec = "AES-CBC"
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else:
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pass #TODO: Sanity check for cipher
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paddedString = append_padding(cipherspec, string)
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cryptedString = cipher(True, cipherspec, key, paddedString)
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hmac = crypto_checksum("HMAC", key, cryptedString)
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protectedString = "$p5k2$$" + salt + "$" + cryptedString + hmac
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return protectedString
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def read_protected_string(string, password, cipherspec=None):
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"""
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Decrypt a protected string and verify the authentication data
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"""
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hmac_length = 32 #FIXME: Ugly
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#Check if the string has the structure, that is generated by protect_string
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regex = re.compile('\$p5k2\$\$[\w./]*\$') #TODO: Ensure the right format!
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match = regex.match(string)
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if match != None:
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crypted = string[match.end():len(string) - hmac_length]
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salt = string[7:match.end() - 1]
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hmac = string[len(string) - hmac_length:]
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else:
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raise ValueError, "Wrong string format"
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#Derive key
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pbk = crypt(password, salt)
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match = regex.match(pbk)
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key = pbk[match.end():]
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#Verify HMAC
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checksum = crypto_checksum("HMAC", key, crypted)
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if checksum != hmac:
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print "Found HMAC %s expected %s" % (str(hmac), str(checksum))
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raise ValueError, "Failed to authenticate data. Wrong password?"
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#Decrypt data
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if cipherspec == None:
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cipherspec = "AES-CBC"
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decrypted = cipher(False, cipherspec, key, crypted)
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return strip_padding(cipherspec, decrypted)
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## *******************************************************************
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## * Cyberflex specific methods *
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## *******************************************************************
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def verify_card_cryptogram(session_key, host_challenge,
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card_challenge, card_cryptogram):
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def verify_card_cryptogram(session_key, host_challenge, card_challenge, card_cryptogram):
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message = host_challenge + card_challenge
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expected = calculate_MAC(session_key, message, iv)
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print >>sys.stderr, "Original: %s" % binascii.b2a_hex(card_cryptogram)
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print >>sys.stderr, "Expected: %s" % binascii.b2a_hex(expected)
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expected = calculate_MAC(session_key, message, CYBERFLEX_IV)
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return card_cryptogram == expected
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def calculate_host_cryptogram(session_key, card_challenge,
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host_challenge):
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def calculate_host_cryptogram(session_key, card_challenge, host_challenge):
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message = card_challenge + host_challenge
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return calculate_MAC(session_key, message, iv)
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return calculate_MAC(session_key, message, CYBERFLEX_IV)
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def calculate_MAC(session_key, message, iv):
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print >>sys.stderr, "Doing MAC for: %s" % utils.hexdump(message, indent = 17)
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def calculate_MAC(session_key, message, iv=CYBERFLEX_IV):
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""""
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Cyberflex MAC is the last Block of the input encrypted with DES3-CBC
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"""
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cipher = DES3.new(session_key, DES3.MODE_CBC, iv)
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block_count = len(message) / cipher.block_size
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for i in range(block_count):
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cipher.encrypt(message[i*cipher.block_size:(i+1)*cipher.block_size])
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last_block_length = len(message) % cipher.block_size
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last_block = (message[len(message)-last_block_length:]+PADDING)[:cipher.block_size]
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return cipher.encrypt( last_block )
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padded = append_padding("DES3", message, 0x01)
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block_count = len(padded) / cipher.block_size
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crypted = cipher.encrypt(padded)
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return crypted[len(padded) - cipher.block_size : ]
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def get_derivation_data(host_challenge, card_challenge):
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return card_challenge[4:8] + host_challenge[:4] + \
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@@ -546,11 +627,22 @@ if __name__ == "__main__":
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print "Host-Crypto: ", utils.hexdump( host_crypto )
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external_authenticate = binascii.a2b_hex("".join("84 82 01 00 10".split())) + host_crypto
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print utils.hexdump(calculate_MAC(session_key, external_authenticate, iv))
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print utils.hexdump(calculate_MAC(session_key, external_authenticate))
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too_short = binascii.a2b_hex("".join("89 45 19 BF".split()))
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padded = append_padding("DES3-ECB",len(too_short),too_short)
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padded = append_padding("DES3-ECB", too_short)
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print "Padded data: " + utils.hexdump(padded)
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unpadded = strip_padding("DES3-ECB",padded)
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unpadded = strip_padding("DES3-ECB", padded)
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print "Without padding: " + utils.hexdump(unpadded)
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test_pbkdf2()
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teststring = "DEADBEEFistatsyksdvhihewohfwoehcowc8hw8rogfq8whv75tsgohsav8wress"
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foo = append_padding("AES", teststring)
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print len(foo)
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print strip_padding("AES", foo)
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testpass = "SomeRandomPassphrase"
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protectedString = protect_string(teststring, testpass)
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unprotectedString = read_protected_string(protectedString, testpass)
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if teststring != unprotectedString:
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print "protect_string test failed"
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#test_pbkdf2()
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