Created
July 14, 2013 01:53
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#!/usr/bin/python | |
import hashlib, string, sys | |
ROUNDS = 20000 | |
def xor(a, b): | |
l = min(len(a), len(b)) | |
return ''.join([chr(ord(x) ^ ord(y)) for x,y in zip(a[:l], b[:l])]) | |
def h(x): | |
x = hashlib.sha256(x).digest() | |
x = xor(x[:16], x[16:]) | |
return x | |
def verify(x): | |
return all([ord(c) < 127 for c in x]) | |
def crypt(msg, passwd): | |
k = h(passwd) | |
for i in xrange(ROUNDS): | |
k = h(k) | |
out = '' | |
for i in xrange(0, len(msg), 16): | |
out += xor(msg[i:i+16], k) | |
k = h(k + str(len(msg))) | |
return out | |
def encrypt(msg, passwd): | |
msg = crypt(msg, passwd) | |
return msg.encode('base64') | |
def decrypt(msg, passwd): | |
msg = crypt(msg.decode('base64'), passwd) | |
if verify(msg): | |
return msg | |
else: | |
sys.stderr.write('Looks like a bad decrypt\n') | |
sys.exit(1) | |
if len(sys.argv) < 5 or sys.argv[1] not in ('encrypt', 'decrypt'): | |
print 'Usage:\tcrypto.py encrypt <password> <infile> <outfile>' | |
print '\tcrypto.py decrypt <password> <infile> <outfile>' | |
sys.exit(1) | |
op, passwd, infile, outfile = sys.argv[1:] | |
inp = open(infile).read() | |
if op == 'encrypt': | |
ct = encrypt(inp, passwd) | |
open(outfile, 'w').write(ct) | |
elif op == 'decrypt': | |
pt = decrypt(inp, passwd) | |
open(outfile, 'w').write(pt) |
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