from hashlib import md5

def s2ab(s):
    return Array[Byte](tuple(Byte(ord(c)) for c in s))

def ab2s(ab, len=0):
    if len == 0: len = ab.Length
    return ''.join([chr(ab[i]) for i in range(len)])

class descrypto():
    def __init__(self, password):
        pwmd5 = md5(password).digest()
        self.key = s2ab(pwmd5[:8])
        self.iv = s2ab(pwmd5[8:])
        self.des = DESCryptoServiceProvider() # 缺省 des.Mode = CipherMode.CBC

    def enc(self, input):
        ms = MemoryStream()
        encStream = CryptoStream(ms, self.des.CreateEncryptor(self.key, self.iv), CryptoStreamMode.Write)
        sw = StreamWriter(encStream)
        sw.Write(input)
        sw.Flush()
        encStream.FlushFinalBlock()
        return ab2s(ms.GetBuffer(), ms.Length)

    def dec(self, input):
        ms = MemoryStream(s2ab(input))
        length = len(input)
        decStream = CryptoStream(ms, self.des.CreateDecryptor(self.key, self.iv), CryptoStreamMode.Read)
        byteArray = Array.CreateInstance(Byte, length)
        length = decStream.Read(byteArray, 0, length)
        return ab2s(byteArray, length)

class descrypto():
    def __init__(self, password):
        pwmd5 = md5(password).digest()
        self.key = pwmd5[:8]
        self.iv = pwmd5[8:]

    def enc(self, input):
        des = DES.new(self.key, DES.MODE_CBC, self.iv)
        lastblock = len(input) % 8
        if lastblock > 0:
            padding = 8 - lastblock
            input += padding * chr(padding)

        return des.encrypt(input)

    def dec(self, input):
        des = DES.new(self.key, DES.MODE_CBC, self.iv)
        ret = des.decrypt(input)
        padding = ord(ret[-1])
        for i in range(padding):
            if ord(ret[-1 - i]) != padding:
                padding = 0
                break
        if padding > 0:
            ret = ret[:-padding]
        return ret