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- import StringIO
- import hashlib
- def md5_encrypt(data, key):
- if len(data) % 16 != 0:
- data += (16 - (len(data) % 16)) * '\x00'
- hash_block = []
- output = ''
- last_hash = ''
- for c in data:
- md5_ctx = hashlib.md5()
- md5_ctx.update(c)
- md5_ctx.update(key)
- md5_ctx.update(last_hash)
- hash_block.append(md5_ctx.digest())
- last_hash = hash_block[-1]
- if len(hash_block) == 16:
- cur_block = ''
- for b in hash_block:
- cur_block += b
- md5_ctx = hashlib.md5()
- md5_ctx.update(cur_block)
- last_hash = md5_ctx.digest()
- output += cur_block + last_hash
- hash_block = []
- return output
- def md5_decrypt(data, key):
- reader = StringIO.StringIO(data)
- output = ''
- last_hash = ''
- while 1:
- cur_block = ''
- for i in range(16):
- cur_hash = reader.read(16)
- if len(cur_hash) != 16:
- return output
- cur_block += cur_hash
- cur_byte = '\x00'
- for i in range(0x100):
- md5_ctx = hashlib.md5()
- cur_byte = chr(i)
- md5_ctx.update(cur_byte)
- md5_ctx.update(key)
- md5_ctx.update(last_hash)
- if cur_hash == md5_ctx.digest():
- break
- output += cur_byte
- last_hash = cur_hash
- md5_ctx = hashlib.md5()
- md5_ctx.update(cur_block)
- last_hash = reader.read(16)
- if last_hash != md5_ctx.digest():
- raise Exception("Hash mismatch! Incorrect key or corrupt data")
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