/*
HMAC-SHA1 according to FIPS-198

http://www.opensource.org/licenses/mit-license.php

The MIT License

Copyright (c) 2008 Mark Weaver <mark@npsl.co.uk>

Permission is hereby granted, free of charge, to any person obtaining a copy
of this software and associated documentation files (the "Software"), to deal
in the Software without restriction, including without limitation the rights
to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
copies of the Software, and to permit persons to whom the Software is
furnished to do so, subject to the following conditions:

The above copyright notice and this permission notice shall be included in
all copies or substantial portions of the Software.

THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
THE SOFTWARE.

Note that the sha1.cpp included here is licensed separately.
*/

#include <stdio.h>
#include <string.h>
#include "sha1.h"

/*
extern void sha1_init(struct sha1_ctxt *);
extern void sha1_pad(struct sha1_ctxt *);
extern void sha1_loop(struct sha1_ctxt *, const uint8_t *, size_t);
extern void sha1_result(struct sha1_ctxt *, uint8_t result[20]);
*/

/* FIPS 198-a */
void hmac_sha1(const uint8_t *k, size_t kL, const uint8_t *text, size_t textLen, uint8_t result[20])
{
	const size_t B = 64, L = 20;
	const uint8_t ipad = 0x36, opad = 0x5c;

	uint8_t	k0[B]; /* block size of sha1 = 512 bits */
	if (kL == B) { /* step 1: if K=B set K0 =  K, goto step 4 */
		memcpy(k0, k, B);
	} else if (kL > B) {
		/* step 2: K0 = H(K) || (00 x B-L) */
		sha1(k, kL, k0);
		memset(k0 + L, 0, B - L);
	} else { /* kL < B */
		/* step 3: k0 = k || (00 x B - kL) */
		memcpy(k0, k, kL);
		memset(k0 + kL, 0, B - kL);
	}
	sha1_ctxt r;
	sha1_init(&r);

	/* step 7: k0 XOR opad */
	uint8_t w[B];
	for (size_t i = 0; i < B; ++i) {
		w[i] = k0[i] ^ opad;
	}
	/* steps 8,9: H((k0 XOR opad) ... */
	sha1_loop(&r, w, B);

	/* step 4: Ko XOR ipad */
	for (size_t i = 0; i < B; ++i) {
		w[i] = k0[i] ^ ipad;
	}
	sha1_ctxt s;
	sha1_init(&s);
	/* steps 5,6: H((k0 XOR IPAD) ... */
	sha1_loop(&s, w, B);
	/* steps 5,6: H((k0 XOR IPAD) || text) */
	sha1_loop(&s, text, textLen);
	/* steps 8, 9: H((k0 XOR opad) || H((k0 XOR IPAD) || text)) */
	sha1_result(&s, w);
	sha1_loop(&r, w, L);
	/* step 10: leftmost 't' bytes of (t=L) */
	sha1_result(&r, result);
}

void print_hmac(const uint8_t hmac[], size_t hmacLen)
{
	for (size_t i = 0; i < hmacLen; ++i) {
		printf("%.2x", hmac[i]);
	}
	printf("\n");
}

void test(
	int				n, 
	const uint8_t	key[], 
	size_t			keyLen, 
	const uint8_t	text[], 
	size_t			textLen, 
	const uint8_t	expect[], 
	size_t			expectLen)
{
	uint8_t result[20];
	hmac_sha1(key, keyLen, text, textLen, result);
	if (memcmp(expect, result, expectLen) != 0)
	{
		printf("test %d: results differ.  got:\n", n);
		print_hmac(result, sizeof(result));
		printf("but expected:\n");
		print_hmac(expect, expectLen);
	}
}

void test1()
{
	const uint8_t key[] = {
		0x00, 0x01, 0x02, 0x03, 0x04, 0x05, 0x06, 0x07,
		0x08, 0x09, 0x0a, 0x0b, 0x0c, 0x0d, 0x0e, 0x0f,
		0x10, 0x11, 0x12, 0x13, 0x14, 0x15, 0x16, 0x17,
		0x18, 0x19, 0x1a, 0x1b, 0x1c, 0x1d, 0x1e, 0x1f,
		0x20, 0x21, 0x22, 0x23, 0x24, 0x25, 0x26, 0x27,
		0x28, 0x29, 0x2a, 0x2b, 0x2c, 0x2d, 0x2e, 0x2f,
		0x30, 0x31, 0x32, 0x33, 0x34, 0x35, 0x36, 0x37,
		0x38, 0x39, 0x3a, 0x3b, 0x3c, 0x3d, 0x3e, 0x3f
	};
	const uint8_t text[] = { /* "Sample #1" */
		0x53, 0x61, 0x6d, 0x70, 0x6c, 0x65, 0x20, 0x23, 0x31 };
	const uint8_t expect[] = {
		0x4f, 0x4c, 0xa3, 0xd5, 
		0xd6, 0x8b, 0xa7, 0xcc, 
		0x0a, 0x12, 0x08, 0xc9, 
		0xc6, 0x1e, 0x9c, 0x5d, 
		0xa0, 0x40, 0x3c, 0x0a
	};
	test(1, key, sizeof(key), text, sizeof(text), expect, sizeof(expect));
}

void test2()
{
	const uint8_t key[] = {
		0x30, 0x31, 0x32, 0x33, 0x34, 0x35, 0x36, 0x37,
		0x38, 0x39, 0x3a, 0x3b, 0x3c, 0x3d, 0x3e, 0x3f,
		0x40, 0x41, 0x42, 0x43
	};
	const uint8_t text[] = { /* "Sample #2" */
		0x53, 0x61, 0x6d, 0x70, 0x6c, 0x65, 0x20, 0x23, 0x32 };
	const uint8_t expect[] = {
		0x09, 0x22, 0xd3, 0x40,
		0x5f, 0xaa, 0x3d, 0x19,
		0x4f, 0x82, 0xa4, 0x58,
		0x30, 0x73, 0x7d, 0x5c,
		0xc6, 0xc7, 0x5d, 0x24
	};
	test(2, key, sizeof(key), text, sizeof(text), expect, sizeof(expect));
}

void test3()
{
	const uint8_t key[] = {
		0x50, 0x51, 0x52, 0x53, 0x54, 0x55, 0x56, 0x57,
		0x58, 0x59, 0x5a, 0x5b, 0x5c, 0x5d, 0x5e, 0x5f,
		0x60, 0x61, 0x62, 0x63, 0x64, 0x65, 0x66, 0x67,
		0x68, 0x69, 0x6a, 0x6b, 0x6c, 0x6d, 0x6e, 0x6f,
		0x70, 0x71, 0x72, 0x73, 0x74, 0x75, 0x76, 0x77,
		0x78, 0x79, 0x7a, 0x7b, 0x7c, 0x7d, 0x7e, 0x7f,
		0x80, 0x81, 0x82, 0x83, 0x84, 0x85, 0x86, 0x87,
		0x88, 0x89, 0x8a, 0x8b, 0x8c, 0x8d, 0x8e, 0x8f,
		0x90, 0x91, 0x92, 0x93, 0x94, 0x95, 0x96, 0x97,
		0x98, 0x99, 0x9a, 0x9b, 0x9c, 0x9d, 0x9e, 0x9f,
		0xa0, 0xa1, 0xa2, 0xa3, 0xa4, 0xa5, 0xa6, 0xa7,
		0xa8, 0xa9, 0xaa, 0xab, 0xac, 0xad, 0xae, 0xaf,
		0xb0, 0xb1, 0xb2, 0xb3
	};
	const uint8_t text[] = { /* "Sample #3" */
		0x53, 0x61, 0x6d, 0x70, 0x6c, 0x65, 0x20, 0x23, 0x33 };
	const uint8_t expect[] = {
		0xbc, 0xf4, 0x1e, 0xab, 
		0x8b, 0xb2, 0xd8, 0x02, 
		0xf3, 0xd0, 0x5c, 0xaf, 
		0x7c, 0xb0, 0x92, 0xec, 
		0xf8, 0xd1, 0xa3, 0xaa
	};
	test(3, key, sizeof(key), text, sizeof(text), expect, sizeof(expect));
}

void test4()
{
	const uint8_t key[] = {
		0x70, 0x71, 0x72, 0x73, 0x74, 0x75, 0x76, 0x77, 
		0x78, 0x79, 0x7a, 0x7b, 0x7c, 0x7d, 0x7e, 0x7f, 
		0x80, 0x81, 0x82, 0x83, 0x84, 0x85, 0x86, 0x87, 
		0x88, 0x89, 0x8a, 0x8b, 0x8c, 0x8d, 0x8e, 0x8f, 
		0x90, 0x91, 0x92, 0x93, 0x94, 0x95, 0x96, 0x97, 
		0x98, 0x99, 0x9a, 0x9b, 0x9c, 0x9d, 0x9e, 0x9f, 
		0xa0
	};
	const uint8_t text[] = { /* "Sample #4" */
		0x53, 0x61, 0x6d, 0x70, 0x6c, 0x65, 0x20, 0x23, 0x34 };
	const uint8_t expect[] = {
		0x9e, 0xa8, 0x86, 0xef,
		0xe2, 0x68, 0xdb, 0xec,
		0xce, 0x42, 0x0c, 0x75
	};
	test(4, key, sizeof(key), text, sizeof(text), expect, sizeof(expect));
}

int main()
{
	test1();
	test2();
	test3();
	test4();
	return 0;
}