--- /dev/null
+#!/bin/env python\r
+\r
+"""\r
+Python implementation of Bruce Schneier's Solitaire Encryption\r
+Algorithm (http://www.counterpane.com/solitaire.html).\r
+\r
+John Dell'Aquila <jbd@alum.mit.edu>\r
+"""\r
+\r
+import string, sys\r
+\r
+def toNumber(c):\r
+ """\r
+ Convert letter to number: Aa->1, Bb->2, ..., Zz->26.\r
+ Non-letters are treated as X's.\r
+ """\r
+ if c in string.letters:\r
+ return ord(string.upper(c)) - 64\r
+ return 24 # 'X'\r
+\r
+def toChar(n):\r
+ """\r
+ Convert number to letter: 1->A, 2->B, ..., 26->Z,\r
+ 27->A, 28->B, ... ad infitum\r
+ """\r
+ return chr((n-1)%26+65)\r
+\r
+\r
+class Solitaire:\r
+ """ Solitaire Encryption Algorithm\r
+ http://www.counterpane.com/solitaire.html\r
+ """\r
+\r
+ def _setKey(self, passphrase):\r
+ """\r
+ Order deck according to passphrase.\r
+ """\r
+ self.deck = range(1,55)\r
+ # card numbering:\r
+ # 1, 2,...,13 are A,2,...,K of clubs\r
+ # 14,15,...,26 are A,2,...,K of diamonds\r
+ # 27,28,...,39 are A,2,...,K of hearts\r
+ # 40,41,...,52 are A,2,...,K of spades\r
+ # 53 & 54 are the A & B jokers\r
+ for c in passphrase:\r
+ self._round()\r
+ self._countCut(toNumber(c))\r
+\r
+ def _down1(self, card):\r
+ """\r
+ Move designated card down 1 position, treating\r
+ deck as circular.\r
+ """\r
+ d = self.deck\r
+ n = d.index(card)\r
+ if n < 53: # not last card - swap with successor\r
+ d[n], d[n+1] = d[n+1], d[n]\r
+ else: # last card - move below first card\r
+ d[1:] = d[-1:] + d[1:-1]\r
+ \r
+ def _tripleCut(self):\r
+ """\r
+ Swap cards above first joker with cards below\r
+ second joker.\r
+ """\r
+ d = self.deck\r
+ a, b = d.index(53), d.index(54)\r
+ if a > b:\r
+ a, b = b, a\r
+ d[:] = d[b+1:] + d[a:b+1] + d[:a]\r
+ \r
+ def _countCut(self, n):\r
+ """\r
+ Cut after the n-th card, leaving the bottom\r
+ card in place.\r
+ """\r
+ d = self.deck\r
+ n = min(n, 53) # either joker is 53\r
+ d[:-1] = d[n:-1] + d[:n]\r
+\r
+ def _round(self):\r
+ """\r
+ Perform one round of keystream generation.\r
+ """\r
+ self._down1(53) # move A joker down 1\r
+ self._down1(54) # move B joker down 2\r
+ self._down1(54)\r
+ self._tripleCut()\r
+ self._countCut(self.deck[-1])\r
+\r
+ def _output(self):\r
+ """\r
+ Return next output card.\r
+ """\r
+ d = self.deck\r
+ while 1:\r
+ self._round()\r
+ topCard = min(d[0], 53) # either joker is 53\r
+ if d[topCard] < 53: # don't return a joker\r
+ return d[topCard]\r
+\r
+ def encrypt(self, txt, key):\r
+ """\r
+ Return 'txt' encrypted using 'key'.\r
+ """\r
+ self._setKey(key)\r
+ # pad with X's to multiple of 5\r
+ txt = txt + 'X' * ((5-len(txt))%5)\r
+ cipher = [None] * len(txt)\r
+ for n in range(len(txt)):\r
+ cipher[n] = toChar(toNumber(txt[n]) + self._output())\r
+ # add spaces to make 5 letter blocks\r
+ for n in range(len(cipher)-5, 4, -5):\r
+ cipher[n:n] = [' ']\r
+ return string.join(cipher, '')\r
+\r
+ def decrypt(self, cipher, key):\r
+ """\r
+ Return 'cipher' decrypted using 'key'.\r
+ """\r
+ self._setKey(key)\r
+ # remove white space between code blocks\r
+ cipher = string.join(string.split(cipher), '')\r
+ txt = [None] * len(cipher)\r
+ for n in range(len(cipher)):\r
+ txt[n] = toChar(toNumber(cipher[n]) - self._output())\r
+ return string.join(txt, '')\r
+ \r
+testCases = ( # test vectors from Schneier paper\r
+ ('AAAAAAAAAAAAAAA', '', 'EXKYI ZSGEH UNTIQ'),\r
+ ('AAAAAAAAAAAAAAA', 'f', 'XYIUQ BMHKK JBEGY'),\r
+ ('AAAAAAAAAAAAAAA', 'fo', 'TUJYM BERLG XNDIW'), \r
+ ('AAAAAAAAAAAAAAA', 'foo', 'ITHZU JIWGR FARMW'),\r
+ ('AAAAAAAAAAAAAAA', 'a', 'XODAL GSCUL IQNSC'), \r
+ ('AAAAAAAAAAAAAAA', 'aa', 'OHGWM XXCAI MCIQP'), \r
+ ('AAAAAAAAAAAAAAA', 'aaa', 'DCSQY HBQZN GDRUT'),\r
+ ('AAAAAAAAAAAAAAA', 'b', 'XQEEM OITLZ VDSQS'), \r
+ ('AAAAAAAAAAAAAAA', 'bc', 'QNGRK QIHCL GWSCE'), \r
+ ('AAAAAAAAAAAAAAA', 'bcd', 'FMUBY BMAXH NQXCJ'), \r
+ ('AAAAAAAAAAAAAAAAAAAAAAAAA', 'cryptonomicon', \r
+ 'SUGSR SXSWQ RMXOH IPBFP XARYQ'),\r
+ ('SOLITAIRE','cryptonomicon','KIRAK SFJAN')\r
+)\r
+\r
+def usage():\r
+ print """Usage:\r
+ sol.py {-e | -d} _key_ < _file_\r
+ sol.py -test\r
+ \r
+ N.B. WinNT requires "python sol.py ..."\r
+ for input redirection to work (NT bug).\r
+ """\r
+ sys.exit(2)\r
+\r
+if __name__ == '__main__':\r
+ args = sys.argv\r
+ if len(args) < 2:\r
+ usage()\r
+ elif args[1] == '-test':\r
+ s = Solitaire()\r
+ for txt, key, cipher in testCases:\r
+ coded = s.encrypt(txt, key)\r
+ assert cipher == coded\r
+ decoded = s.decrypt(coded, key)\r
+ assert decoded[:len(txt)] == string.upper(txt)\r
+ print 'All tests passed.'\r
+ elif len(args) < 3:\r
+ usage()\r
+ elif args[1] == '-e':\r
+ print Solitaire().encrypt(sys.stdin.read(), args[2])\r
+ elif args[1] == '-d':\r
+ print Solitaire().decrypt(sys.stdin.read(), args[2])\r
+ else:\r
+ usage()\r
projects / cipher-tools.git / blobdiff