/* MD5 block update operation. Continues an MD5 message-digest
* operation, processing another message block, and updating the
* context. */
private static void MD5Update(MD5_CTX *context, byte *input, uint inputLen)
{
/* Compute number of bytes mod 64 */
var index = (context->count[0] >> 3) & 0x3F;
/* Update number of bits */
if ((context->count[0] += (inputLen << 3)) < (inputLen << 3))
{
context->count[1]++;
}
context->count[1] += (inputLen >> 29);
uint partLen = 64 - index;
/* Transform as many times as possible. */
uint i = 0;
if (inputLen >= partLen)
{
Buffer.BlockCopy(input, context->buffer + index, partLen);
MD5Transform(context->state, context->buffer);
for (i = partLen; i + 63 < inputLen; i += 64)
{
MD5Transform(context->state, input + i);
}
index = 0;
}
/* Buffer remaining input */
Buffer.BlockCopy(input + i, context->buffer + index, inputLen - i);
}
/* MD5 initialization. Begins an MD5 operation, writing a new context. */
private static void MD5Init(MD5_CTX *context) /* context */
{
context->count[0] = context->count[1] = 0;
/* Load magic initialization constants. */
context->state[0] = 0x67452301;
context->state[1] = 0xefcdab89;
context->state[2] = 0x98badcfe;
context->state[3] = 0x10325476;
}
/* MD5 finalization. Ends an MD5 message-digest operation, writing the
* the message digest and zeroizing the context. */
private static void MD5Final(byte *digest, MD5_CTX *context)
{
var bits = stackalloc byte[8];
/* Save number of bits */
Encode(bits, context->count, 8);
/* Pad out to 56 mod 64. */
uint index = (context->count[0] >> 3) & 0x3f;
uint padLen = (index < 56) ? (56 - index) : (120 - index);
fixed(byte *padding = PADDING)
MD5Update(context, padding, padLen);
/* Append length (before padding) */
MD5Update(context, bits, 8);
/* Store state in digest */
Encode(digest, context->state, 16);
/* Zeroize sensitive information. */
context->Clear();
}
