| 0,0 → 1,75 |
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| """ crypto.entropy.pagingEntropy |
| |
| Uses variations in disk access time to generator entropy. A long string is |
| created that is bigger than available memory. Virtual memory access' create |
| random variations in retrieval time. |
| |
| Just an experiment, not recommended for use at this time. |
| |
| Copyright © (c) 2002 by Paul A. Lambert |
| Read LICENSE.txt for license information. |
| """ |
| import struct |
| |
| class PagingEntropyCollector: |
| """ collect entropy from memory paging """ |
| def __init__(self, memSize=500000000L): #? how should this be picked? |
| """ Initialize paging entropy collector, |
| memSize must be larger than allocated memory """ |
| self.size = memSize |
| self.memBlock = self.size*chr(0) # long string of length self.size |
| self.index = 0 |
| import random |
| self.rand = random.Random(1555551) |
| |
| def randomBytes(self, numberOfBytes, secondsPerBit=.05): |
| byteString = '' |
| for b in range(numberOfBytes): |
| aByte = 0 |
| for bit in range(8): |
| aByte = aByte << 1 |
| aByte = aByte ^ self.collectBit(secondsPerBit) |
| byteString += chr(aByte) |
| return byteString |
| |
| def collectBit(self, secondsPerBit=1.0): |
| """ Collect an entropy bit by jumping around a long string and |
| collecting the variation in time and number of samples per |
| time interval """ |
| t1 = time() |
| count = 0 |
| while (time()-t1) < secondsPerBit: # seconds per sample |
| # use random to sample various virtual memory locations |
| sample = self.memBlock[int(self.rand.random()*self.size)] |
| count += 1 |
| randomBit = intToParity(count)^floatToParity(time()-t1) |
| return randomBit |
| |
| def intToParity(integer): |
| s = struct.pack('i',integer) |
| parity = 0 |
| for character in s: |
| byte = ord(character) |
| parity = parity^(0x01&(byte^(byte>>1)^(byte>>2)^(byte>>3)^(byte>>4)^(byte>>5)^(byte>>6)^(byte>>7))) |
| return parity |
| |
| def floatToParity(float): |
| s = struct.pack('d',float) |
| parity = 0 |
| for character in s: |
| byte = ord(character) |
| parity = parity^(0x01&(byte^(byte>>1)^(byte>>2)^(byte>>3)^(byte>>4)^(byte>>5)^(byte>>6)^(byte>>7))) |
| return parity |
| |
| if __name__ == "__main__": |
| from binascii import b2a_hex |
| e = PagingEntropyCollector() |
| for i in range(20): |
| e.rand.seed(1) # make each sample set the same to allow examination of statistics |
| print b2a_hex( e.randomBytes(16) ) |
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