text: #include "poly1305-donna.h"
  #include "poly1305-donna-32.h"
  
  void
  poly1305_update(poly1305_context *ctx, const unsigned char *m, size_t bytes) {
  	poly1305_state_internal_t *st = (poly1305_state_internal_t *)ctx;
  	size_t i;
  
  	/* handle leftover */
  	if (st->leftover) {
  		size_t want = (poly1305_block_size - st->leftover);
  		if (want > bytes)
  			want = bytes;
  		for (i = 0; i < want; i++)
  			st->buffer[st->leftover + i] = m[i];
  		bytes -= want;
  		m += want;
  		st->leftover += want;
  		if (st->leftover < poly1305_block_size)
  			return;
  		poly1305_blocks(st, st->buffer, poly1305_block_size);
  		st->leftover = 0;
  	}
  
  	/* process full blocks */
  	if (bytes >= poly1305_block_size) {
  		size_t want = (bytes & ~(poly1305_block_size - 1));
  		poly1305_blocks(st, m, want);
  		m += want;
  		bytes -= want;
  	}
  
  	/* store leftover */
  	if (bytes) {
  		for (i = 0; i < bytes; i++)
  			st->buffer[st->leftover + i] = m[i];
  		st->leftover += bytes;
  	}
  }
  
  void
  poly1305_auth(unsigned char mac[16], const unsigned char *m, size_t bytes, const unsigned char key[32]) {
  	poly1305_context ctx;
  	poly1305_init_trezor(&ctx, key);
  	poly1305_update(&ctx, m, bytes);
  	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;
  	poly1305_init_trezor(&ctx, nacl_key);
  	poly1305_update(&ctx, nacl_msg +   0, 32);
  	poly1305_update(&ctx, nacl_msg +  32, 64);
  	poly1305_update(&ctx, nacl_msg +  96, 16);
  	poly1305_update(&ctx, nacl_msg + 112,  8);
  	poly1305_update(&ctx, nacl_msg + 120,  4);
  	poly1305_update(&ctx, nacl_msg + 124,  2);
  	poly1305_update(&ctx, nacl_msg + 126,  1);
  	poly1305_update(&ctx, nacl_msg + 127,  1);
  	poly1305_update(&ctx, nacl_msg + 128,  1);
  	poly1305_update(&ctx, nacl_msg + 129,  1);
  	poly1305_update(&ctx, nacl_msg + 130,  1);
  	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);
  
  	poly1305_init_trezor(&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);
  		poly1305_update(&total_ctx, mac, 16);
  	}
  	poly1305_finish(&total_ctx, mac);
  	result &= poly1305_verify(total_mac, mac);
  
  	return result;
  }
  