405 lines
11 KiB
Python
405 lines
11 KiB
Python
"""cryptomath module
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This module has basic math/crypto code."""
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import os
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import sys
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import math
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import base64
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import binascii
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if sys.version_info[:2] <= (2, 4):
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from sha import sha as sha1
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else:
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from hashlib import sha1
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from compat import *
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# **************************************************************************
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# Load Optional Modules
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# **************************************************************************
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# Try to load M2Crypto/OpenSSL
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try:
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from M2Crypto import m2
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m2cryptoLoaded = True
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except ImportError:
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m2cryptoLoaded = False
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# Try to load cryptlib
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try:
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import cryptlib_py
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try:
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cryptlib_py.cryptInit()
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except cryptlib_py.CryptException, e:
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#If tlslite and cryptoIDlib are both present,
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#they might each try to re-initialize this,
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#so we're tolerant of that.
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if e[0] != cryptlib_py.CRYPT_ERROR_INITED:
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raise
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cryptlibpyLoaded = True
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except ImportError:
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cryptlibpyLoaded = False
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#Try to load GMPY
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try:
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import gmpy
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gmpyLoaded = True
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except ImportError:
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gmpyLoaded = False
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#Try to load pycrypto
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try:
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import Crypto.Cipher.AES
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pycryptoLoaded = True
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except ImportError:
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pycryptoLoaded = False
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# **************************************************************************
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# PRNG Functions
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# **************************************************************************
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# Get os.urandom PRNG
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try:
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os.urandom(1)
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def getRandomBytes(howMany):
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return stringToBytes(os.urandom(howMany))
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prngName = "os.urandom"
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except:
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# Else get cryptlib PRNG
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if cryptlibpyLoaded:
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def getRandomBytes(howMany):
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randomKey = cryptlib_py.cryptCreateContext(cryptlib_py.CRYPT_UNUSED,
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cryptlib_py.CRYPT_ALGO_AES)
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cryptlib_py.cryptSetAttribute(randomKey,
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cryptlib_py.CRYPT_CTXINFO_MODE,
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cryptlib_py.CRYPT_MODE_OFB)
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cryptlib_py.cryptGenerateKey(randomKey)
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bytes = createByteArrayZeros(howMany)
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cryptlib_py.cryptEncrypt(randomKey, bytes)
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return bytes
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prngName = "cryptlib"
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else:
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#Else get UNIX /dev/urandom PRNG
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try:
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devRandomFile = open("/dev/urandom", "rb")
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def getRandomBytes(howMany):
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return stringToBytes(devRandomFile.read(howMany))
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prngName = "/dev/urandom"
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except IOError:
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#Else get Win32 CryptoAPI PRNG
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try:
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import win32prng
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def getRandomBytes(howMany):
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s = win32prng.getRandomBytes(howMany)
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if len(s) != howMany:
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raise AssertionError()
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return stringToBytes(s)
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prngName ="CryptoAPI"
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except ImportError:
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#Else no PRNG :-(
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def getRandomBytes(howMany):
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raise NotImplementedError("No Random Number Generator "\
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"available.")
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prngName = "None"
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# **************************************************************************
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# Converter Functions
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# **************************************************************************
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def bytesToNumber(bytes):
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total = 0L
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multiplier = 1L
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for count in range(len(bytes)-1, -1, -1):
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byte = bytes[count]
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total += multiplier * byte
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multiplier *= 256
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return total
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def numberToBytes(n):
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howManyBytes = numBytes(n)
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bytes = createByteArrayZeros(howManyBytes)
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for count in range(howManyBytes-1, -1, -1):
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bytes[count] = int(n % 256)
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n >>= 8
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return bytes
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def bytesToBase64(bytes):
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s = bytesToString(bytes)
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return stringToBase64(s)
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def base64ToBytes(s):
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s = base64ToString(s)
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return stringToBytes(s)
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def numberToBase64(n):
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bytes = numberToBytes(n)
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return bytesToBase64(bytes)
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def base64ToNumber(s):
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bytes = base64ToBytes(s)
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return bytesToNumber(bytes)
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def stringToNumber(s):
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bytes = stringToBytes(s)
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return bytesToNumber(bytes)
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def numberToString(s):
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bytes = numberToBytes(s)
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return bytesToString(bytes)
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def base64ToString(s):
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try:
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return base64.decodestring(s)
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except binascii.Error, e:
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raise SyntaxError(e)
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except binascii.Incomplete, e:
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raise SyntaxError(e)
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def stringToBase64(s):
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return base64.encodestring(s).replace("\n", "")
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def mpiToNumber(mpi): #mpi is an openssl-format bignum string
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if (ord(mpi[4]) & 0x80) !=0: #Make sure this is a positive number
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raise AssertionError()
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bytes = stringToBytes(mpi[4:])
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return bytesToNumber(bytes)
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def numberToMPI(n):
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bytes = numberToBytes(n)
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ext = 0
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#If the high-order bit is going to be set,
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#add an extra byte of zeros
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if (numBits(n) & 0x7)==0:
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ext = 1
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length = numBytes(n) + ext
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bytes = concatArrays(createByteArrayZeros(4+ext), bytes)
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bytes[0] = (length >> 24) & 0xFF
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bytes[1] = (length >> 16) & 0xFF
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bytes[2] = (length >> 8) & 0xFF
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bytes[3] = length & 0xFF
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return bytesToString(bytes)
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# **************************************************************************
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# Misc. Utility Functions
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# **************************************************************************
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def numBytes(n):
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if n==0:
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return 0
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bits = numBits(n)
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return int(math.ceil(bits / 8.0))
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def hashAndBase64(s):
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return stringToBase64(sha1(s).digest())
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def getBase64Nonce(numChars=22): #defaults to an 132 bit nonce
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bytes = getRandomBytes(numChars)
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bytesStr = "".join([chr(b) for b in bytes])
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return stringToBase64(bytesStr)[:numChars]
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# **************************************************************************
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# Big Number Math
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# **************************************************************************
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def getRandomNumber(low, high):
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if low >= high:
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raise AssertionError()
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howManyBits = numBits(high)
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howManyBytes = numBytes(high)
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lastBits = howManyBits % 8
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while 1:
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bytes = getRandomBytes(howManyBytes)
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if lastBits:
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bytes[0] = bytes[0] % (1 << lastBits)
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n = bytesToNumber(bytes)
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if n >= low and n < high:
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return n
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def gcd(a,b):
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a, b = max(a,b), min(a,b)
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while b:
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a, b = b, a % b
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return a
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def lcm(a, b):
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#This will break when python division changes, but we can't use // cause
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#of Jython
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return (a * b) / gcd(a, b)
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#Returns inverse of a mod b, zero if none
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#Uses Extended Euclidean Algorithm
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def invMod(a, b):
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c, d = a, b
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uc, ud = 1, 0
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while c != 0:
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#This will break when python division changes, but we can't use //
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#cause of Jython
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q = d / c
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c, d = d-(q*c), c
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uc, ud = ud - (q * uc), uc
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if d == 1:
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return ud % b
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return 0
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if gmpyLoaded:
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def powMod(base, power, modulus):
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base = gmpy.mpz(base)
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power = gmpy.mpz(power)
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modulus = gmpy.mpz(modulus)
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result = pow(base, power, modulus)
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return long(result)
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else:
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#Copied from Bryan G. Olson's post to comp.lang.python
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#Does left-to-right instead of pow()'s right-to-left,
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#thus about 30% faster than the python built-in with small bases
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def powMod(base, power, modulus):
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nBitScan = 5
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""" Return base**power mod modulus, using multi bit scanning
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with nBitScan bits at a time."""
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#TREV - Added support for negative exponents
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negativeResult = False
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if (power < 0):
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power *= -1
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negativeResult = True
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exp2 = 2**nBitScan
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mask = exp2 - 1
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# Break power into a list of digits of nBitScan bits.
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# The list is recursive so easy to read in reverse direction.
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nibbles = None
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while power:
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nibbles = int(power & mask), nibbles
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power = power >> nBitScan
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# Make a table of powers of base up to 2**nBitScan - 1
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lowPowers = [1]
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for i in xrange(1, exp2):
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lowPowers.append((lowPowers[i-1] * base) % modulus)
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# To exponentiate by the first nibble, look it up in the table
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nib, nibbles = nibbles
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prod = lowPowers[nib]
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# For the rest, square nBitScan times, then multiply by
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# base^nibble
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while nibbles:
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nib, nibbles = nibbles
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for i in xrange(nBitScan):
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prod = (prod * prod) % modulus
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if nib: prod = (prod * lowPowers[nib]) % modulus
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#TREV - Added support for negative exponents
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if negativeResult:
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prodInv = invMod(prod, modulus)
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#Check to make sure the inverse is correct
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if (prod * prodInv) % modulus != 1:
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raise AssertionError()
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return prodInv
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return prod
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#Pre-calculate a sieve of the ~100 primes < 1000:
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def makeSieve(n):
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sieve = range(n)
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for count in range(2, int(math.sqrt(n))):
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if sieve[count] == 0:
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continue
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x = sieve[count] * 2
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while x < len(sieve):
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sieve[x] = 0
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x += sieve[count]
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sieve = [x for x in sieve[2:] if x]
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return sieve
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sieve = makeSieve(1000)
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def isPrime(n, iterations=5, display=False):
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#Trial division with sieve
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for x in sieve:
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if x >= n: return True
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if n % x == 0: return False
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#Passed trial division, proceed to Rabin-Miller
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#Rabin-Miller implemented per Ferguson & Schneier
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#Compute s, t for Rabin-Miller
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if display: print "*",
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s, t = n-1, 0
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while s % 2 == 0:
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s, t = s/2, t+1
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#Repeat Rabin-Miller x times
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a = 2 #Use 2 as a base for first iteration speedup, per HAC
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for count in range(iterations):
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v = powMod(a, s, n)
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if v==1:
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continue
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i = 0
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while v != n-1:
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if i == t-1:
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return False
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else:
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v, i = powMod(v, 2, n), i+1
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a = getRandomNumber(2, n)
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return True
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def getRandomPrime(bits, display=False):
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if bits < 10:
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raise AssertionError()
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#The 1.5 ensures the 2 MSBs are set
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#Thus, when used for p,q in RSA, n will have its MSB set
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#
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#Since 30 is lcm(2,3,5), we'll set our test numbers to
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#29 % 30 and keep them there
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low = (2L ** (bits-1)) * 3/2
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high = 2L ** bits - 30
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p = getRandomNumber(low, high)
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p += 29 - (p % 30)
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while 1:
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if display: print ".",
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p += 30
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if p >= high:
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p = getRandomNumber(low, high)
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p += 29 - (p % 30)
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if isPrime(p, display=display):
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return p
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#Unused at the moment...
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def getRandomSafePrime(bits, display=False):
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if bits < 10:
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raise AssertionError()
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#The 1.5 ensures the 2 MSBs are set
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#Thus, when used for p,q in RSA, n will have its MSB set
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#
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#Since 30 is lcm(2,3,5), we'll set our test numbers to
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#29 % 30 and keep them there
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low = (2 ** (bits-2)) * 3/2
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high = (2 ** (bits-1)) - 30
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q = getRandomNumber(low, high)
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q += 29 - (q % 30)
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while 1:
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if display: print ".",
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q += 30
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if (q >= high):
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q = getRandomNumber(low, high)
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q += 29 - (q % 30)
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#Ideas from Tom Wu's SRP code
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#Do trial division on p and q before Rabin-Miller
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if isPrime(q, 0, display=display):
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p = (2 * q) + 1
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if isPrime(p, display=display):
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if isPrime(q, display=display):
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return p
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