/*
 * Public Domain poly1305 from Andrew Moon
 * Based on poly1305-donna.c from:
 *   https://github.com/floodyberry/poly1305-donna
 */

#include <stdio.h>

#include <openssl/poly1305.h>

void poly1305_auth(unsigned char mac[16], const unsigned char *m, size_t bytes,
    const unsigned char key[32]);

int poly1305_verify(const unsigned char mac1[16], const unsigned char mac2[16]);
int poly1305_power_on_self_test(void);

void
poly1305_auth(unsigned char mac[16], const unsigned char *m, size_t bytes,
const unsigned char key[32]) {
	poly1305_context ctx;
	CRYPTO_poly1305_init(&ctx, key);
	CRYPTO_poly1305_update(&ctx, m, bytes);
	CRYPTO_poly1305_finish(&ctx, mac);
}

int
poly1305_verify(const unsigned char mac1[16], const unsigned char mac2[16])
{
	size_t i;
	unsigned int dif = 0;
	for (i = 0; i < 16; i++)
		dif |= (mac1[i] ^ mac2[i]);
	dif = (dif - 1) >> ((sizeof(unsigned int) * 8) - 1);
	return (dif & 1);
}

/* test a few basic operations */
int
poly1305_power_on_self_test(void)
{
	/* example from nacl */
	static const unsigned char nacl_key[32] = {
		0xee, 0xa6, 0xa7, 0x25, 0x1c, 0x1e, 0x72, 0x91,
		0x6d, 0x11, 0xc2, 0xcb, 0x21, 0x4d, 0x3c, 0x25,
		0x25, 0x39, 0x12, 0x1d, 0x8e, 0x23, 0x4e, 0x65,
		0x2d, 0x65, 0x1f, 0xa4, 0xc8, 0xcf, 0xf8, 0x80,
	};

	static const unsigned char nacl_msg[131] = {
		0x8e, 0x99, 0x3b, 0x9f, 0x48, 0x68, 0x12, 0x73,
		0xc2, 0x96, 0x50, 0xba, 0x32, 0xfc, 0x76, 0xce,
		0x48, 0x33, 0x2e, 0xa7, 0x16, 0x4d, 0x96, 0xa4,
		0x47, 0x6f, 0xb8, 0xc5, 0x31, 0xa1, 0x18, 0x6a,
		0xc0, 0xdf, 0xc1, 0x7c, 0x98, 0xdc, 0xe8, 0x7b,
		0x4d, 0xa7, 0xf0, 0x11, 0xec, 0x48, 0xc9, 0x72,
		0x71, 0xd2, 0xc2, 0x0f, 0x9b, 0x92, 0x8f, 0xe2,
		0x27, 0x0d, 0x6f, 0xb8, 0x63, 0xd5, 0x17, 0x38,
		0xb4, 0x8e, 0xee, 0xe3, 0x14, 0xa7, 0xcc, 0x8a,
		0xb9, 0x32, 0x16, 0x45, 0x48, 0xe5, 0x26, 0xae,
		0x90, 0x22, 0x43, 0x68, 0x51, 0x7a, 0xcf, 0xea,
		0xbd, 0x6b, 0xb3, 0x73, 0x2b, 0xc0, 0xe9, 0xda,
		0x99, 0x83, 0x2b, 0x61, 0xca, 0x01, 0xb6, 0xde,
		0x56, 0x24, 0x4a, 0x9e, 0x88, 0xd5, 0xf9, 0xb3,
		0x79, 0x73, 0xf6, 0x22, 0xa4, 0x3d, 0x14, 0xa6,
		0x59, 0x9b, 0x1f, 0x65, 0x4c, 0xb4, 0x5a, 0x74,
		0xe3, 0x55, 0xa5
	};

	static const unsigned char nacl_mac[16] = {
		0xf3, 0xff, 0xc7, 0x70, 0x3f, 0x94, 0x00, 0xe5,
		0x2a, 0x7d, 0xfb, 0x4b, 0x3d, 0x33, 0x05, 0xd9
	};

	/* generates a final value of (2^130 - 2) == 3 */
	static const unsigned char wrap_key[32] = {
		0x02, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
		0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
		0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
		0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
	};

	static const unsigned char wrap_msg[16] = {
		0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff,
		0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff
	};

	static const unsigned char wrap_mac[16] = {
		0x03, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
		0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
	};

	/*
		mac of the macs of messages of length 0 to 256, where the key and messages
		have all their values set to the length
	*/
	static const unsigned char total_key[32] = {
		0x01, 0x02, 0x03, 0x04, 0x05, 0x06, 0x07,
		0xff, 0xfe, 0xfd, 0xfc, 0xfb, 0xfa, 0xf9,
		0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff,
		0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff
	};

	static const unsigned char total_mac[16] = {
		0x64, 0xaf, 0xe2, 0xe8, 0xd6, 0xad, 0x7b, 0xbd,
		0xd2, 0x87, 0xf9, 0x7c, 0x44, 0x62, 0x3d, 0x39
	};

	poly1305_context ctx;
	poly1305_context total_ctx;
	unsigned char all_key[32];
	unsigned char all_msg[256];
	unsigned char mac[16];
	size_t i, j;
	int result = 1;

	for (i = 0; i < sizeof(mac); i++)
		mac[i] = 0;
	poly1305_auth(mac, nacl_msg, sizeof(nacl_msg), nacl_key);
	result &= poly1305_verify(nacl_mac, mac);

	for (i = 0; i < sizeof(mac); i++)
		mac[i] = 0;
	CRYPTO_poly1305_init(&ctx, nacl_key);
	CRYPTO_poly1305_update(&ctx, nacl_msg +   0, 32);
	CRYPTO_poly1305_update(&ctx, nacl_msg +  32, 64);
	CRYPTO_poly1305_update(&ctx, nacl_msg +  96, 16);
	CRYPTO_poly1305_update(&ctx, nacl_msg + 112,  8);
	CRYPTO_poly1305_update(&ctx, nacl_msg + 120,  4);
	CRYPTO_poly1305_update(&ctx, nacl_msg + 124,  2);
	CRYPTO_poly1305_update(&ctx, nacl_msg + 126,  1);
	CRYPTO_poly1305_update(&ctx, nacl_msg + 127,  1);
	CRYPTO_poly1305_update(&ctx, nacl_msg + 128,  1);
	CRYPTO_poly1305_update(&ctx, nacl_msg + 129,  1);
	CRYPTO_poly1305_update(&ctx, nacl_msg + 130,  1);
	CRYPTO_poly1305_finish(&ctx, mac);
	result &= poly1305_verify(nacl_mac, mac);

	for (i = 0; i < sizeof(mac); i++)
		mac[i] = 0;
	poly1305_auth(mac, wrap_msg, sizeof(wrap_msg), wrap_key);
	result &= poly1305_verify(wrap_mac, mac);

	CRYPTO_poly1305_init(&total_ctx, total_key);
	for (i = 0; i < 256; i++) {
		/* set key and message to 'i,i,i..' */
		for (j = 0; j < sizeof(all_key); j++)
			all_key[j] = i;
		for (j = 0; j < i; j++)
			all_msg[j] = i;
		poly1305_auth(mac, all_msg, i, all_key);
		CRYPTO_poly1305_update(&total_ctx, mac, 16);
	}
	CRYPTO_poly1305_finish(&total_ctx, mac);
	result &= poly1305_verify(total_mac, mac);

	return result;
}

int
main(int argc, char **argv)
{
	if (!poly1305_power_on_self_test()) {
		fprintf(stderr, "One or more self tests failed!\n");
		return 1;
	}

	return 0;
}
