PKCS1_v1_5.py 文件源码

def encrypt(self, message):
        """Produce the PKCS#1 v1.5 encryption of a message.

        This function is named ``RSAES-PKCS1-V1_5-ENCRYPT``, and is specified in
        section 7.2.1 of RFC3447.
        For a complete example see `Crypto.Cipher.PKCS1_v1_5`.

        :Parameters:
         message : byte string
                The message to encrypt, also known as plaintext. It can be of
                variable length, but not longer than the RSA modulus (in bytes) minus 11.

        :Return: A byte string, the ciphertext in which the message is encrypted.
            It is as long as the RSA modulus (in bytes).
        :Raise ValueError:
            If the RSA key length is not sufficiently long to deal with the given
            message.

        """
        # TODO: Verify the key is RSA

        randFunc = self._key._randfunc

        # See 7.2.1 in RFC3447
        modBits = Crypto.Util.number.size(self._key.n)
        k = ceil_div(modBits,8) # Convert from bits to bytes
        mLen = len(message)

        # Step 1
        if mLen > k-11:
            raise ValueError("Plaintext is too long.")
        # Step 2a
        class nonZeroRandByte:
            def __init__(self, rf): self.rf=rf
            def __call__(self, c):
                while bord(c)==0x00: c=self.rf(1)[0]
                return c
        ps = tobytes(map(nonZeroRandByte(randFunc), randFunc(k-mLen-3)))
        # Step 2b
        em = b('\x00\x02') + ps + bchr(0x00) + message
        # Step 3a (OS2IP), step 3b (RSAEP), part of step 3c (I2OSP)
        m = self._key.encrypt(em, 0)[0]
        # Complete step 3c (I2OSP)
        c = bchr(0x00)*(k-len(m)) + m
        return c