Method UnPad

extra/yassl/taocrypt/src/rsa.cpp:105–137

}

word32 RSA_BlockType2::UnPad(const byte *pkcsBlock, unsigned int pkcsBlockLen,
                           byte *output) const
{
    bool invalid = false;
    unsigned int maxOutputLen = SaturatingSubtract(pkcsBlockLen / 8, 10U);

    // convert from bit length to byte length
    if (pkcsBlockLen % 8 != 0)
    {
        invalid = (pkcsBlock[0] != 0) || invalid;
        pkcsBlock++;
    }
    pkcsBlockLen /= 8;

    // Require block type 2.
    invalid = (pkcsBlock[0] != 2) || invalid;

    // skip past the padding until we find the separator
    unsigned i=1;
    while (i<pkcsBlockLen && pkcsBlock[i++]) { // null body
        }
    if (!(i==pkcsBlockLen || pkcsBlock[i-1]==0))
        return 0;

    unsigned int outputLen = pkcsBlockLen - i;
    invalid = (outputLen > maxOutputLen) || invalid;

    if (invalid)
        return 0;

    memcpy (output, pkcsBlock+i, outputLen);
    return outputLen;
}


void RSA_BlockType1::Pad(const byte* input, word32 inputLen, byte* pkcsBlock,