public byte[] Final()
{
byte[] digest;
/* outer padding - key XORd with opad */
byte[] k_opad = new byte[HMAC_SHA1_PAD_SIZE];
int i;
mem._set(ref k_opad, 0, 0, k_opad.Length);
mem._cpy(ref k_opad, 0, key_ctx, 0, key_len_ctx);
/* XOR key with ipad and opad values */
for (i = 0; i < k_opad.Length; i++)
{
k_opad[i] ^= 0x5c;
}
digest = sha_ctx.Final(); /* finish up 1st pass */
/*
* perform outer SHA1
*/
sha_ctx.Init(); /* init context for 2nd pass */
/* start with outer pad */
sha_ctx.Update(k_opad);
/* then results of 1st hash */
sha_ctx.Update(digest);
digest = sha_ctx.Final(); /* finish up 2nd pass */
return(digest);
}
public void Init(byte[] key)
{
byte[] k_ipad = new byte[HMAC_SHA1_PAD_SIZE];
int i, key_len = key.Length;
sha_ctx = new sha1();
/* if key is longer than 64 bytes reset it to key=SHA-1(key) */
if (key_len > HMAC_SHA1_PAD_SIZE)
{
sha_ctx.Init();
sha_ctx.Update(key);
temp_key_ctx = sha_ctx.Final();
key = temp_key_ctx;
key_len = HMAC_SHA1_DIGEST_SIZE;
}
/*
* the HMAC_SHA1 transform looks like:
*
* SHA1(K XOR opad, SHA1(K XOR ipad, text))
*
* where K is an n byte key
* ipad is the byte 0x36 repeated 64 times
* opad is the byte 0x5c repeated 64 times
* and text is the data being protected
*/
/* start out by storing key in pads */
mem._set(ref k_ipad, 0, 0, k_ipad.Length);
mem._cpy(ref k_ipad, 0, key, 0, key_len);
/* XOR key with ipad and opad values */
for (i = 0; i < k_ipad.Length; i++)
{
k_ipad[i] ^= 0x36;
}
/*
* perform inner SHA1
*/
sha_ctx.Init(); /* init context for 1st pass */
/* start with inner pad */
sha_ctx.Update(k_ipad);
/* Stash the key and it's length into the context. */
key_ctx = key;
key_len_ctx = key_len;
}
public void Init(byte[] key)
{
byte[] k_ipad = new byte[HMAC_SHA1_PAD_SIZE];
int i, key_len = key.Length;
sha_ctx = new sha1();
/* if key is longer than 64 bytes reset it to key=SHA-1(key) */
if (key_len > HMAC_SHA1_PAD_SIZE)
{
sha_ctx.Init();
sha_ctx.Update(key);
temp_key_ctx = sha_ctx.Final();
key = temp_key_ctx;
key_len = HMAC_SHA1_DIGEST_SIZE;
}
/*
* the HMAC_SHA1 transform looks like:
*
* SHA1(K XOR opad, SHA1(K XOR ipad, text))
*
* where K is an n byte key
* ipad is the byte 0x36 repeated 64 times
* opad is the byte 0x5c repeated 64 times
* and text is the data being protected
*/
/* start out by storing key in pads */
mem._set(ref k_ipad, 0, 0, k_ipad.Length);
mem._cpy(ref k_ipad, 0, key, 0, key_len);
/* XOR key with ipad and opad values */
for (i = 0; i < k_ipad.Length; i++)
{
k_ipad[i] ^= 0x36;
}
/*
* perform inner SHA1
*/
sha_ctx.Init(); /* init context for 1st pass */
/* start with inner pad */
sha_ctx.Update(k_ipad);
/* Stash the key and it's length into the context. */
key_ctx = key;
key_len_ctx = key_len;
}
