SHA256 - A fine-tuned implementation of the SHA256 hashing…

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A fine-tuned implementation of the SHA256 hashing algorithm.

SHA256.cpp@6:c0ed1bf37651, 2011-06-20 (annotated)

Committer:: Remco
Date:: Mon Jun 20 13:21:38 2011 +0000
Revision:: 6:c0ed1bf37651
Parent:: 3:f19b10394f9c

Who changed what in which revision?

User	Revision	Line number	New contents of line
Remco	6:c0ed1bf37651	1	// Author: Remco Bloemen
Remco	6:c0ed1bf37651	2	// Based on:
Remco	6:c0ed1bf37651	3	// http://en.wikipedia.org/wiki/SHA-2
Remco	6:c0ed1bf37651	4	// http://www.iwar.org.uk/comsec/resources/cipher/sha256-384-512.pdf
Remco	6:c0ed1bf37651	5	// some of the OpenSSL optimizations
Remco	6:c0ed1bf37651	6
Remco	6:c0ed1bf37651	7	#include "SHA256.h"
Remco	6:c0ed1bf37651	8
Remco	6:c0ed1bf37651	9	inline unsigned int reverse_bytes(unsigned int x)
Remco	6:c0ed1bf37651	10	{
Remco	6:c0ed1bf37651	11	return __rev(x);
Remco	6:c0ed1bf37651	12	}
Remco	6:c0ed1bf37651	13
Remco	6:c0ed1bf37651	14	inline unsigned int rotate_right(unsigned int x, int shift)
Remco	6:c0ed1bf37651	15	{
Remco	6:c0ed1bf37651	16	// return (x >> shift) \| (x << (32 - shift));
Remco	6:c0ed1bf37651	17	return __ror(x, shift);
Remco	6:c0ed1bf37651	18	}
Remco	6:c0ed1bf37651	19
Remco	6:c0ed1bf37651	20	void SHA256::reset()
Remco	6:c0ed1bf37651	21	{
Remco	6:c0ed1bf37651	22	hash[0] = 0x6A09E667;
Remco	6:c0ed1bf37651	23	hash[1] = 0xBB67AE85;
Remco	6:c0ed1bf37651	24	hash[2] = 0x3C6EF372;
Remco	6:c0ed1bf37651	25	hash[3] = 0xA54FF53A;
Remco	6:c0ed1bf37651	26	hash[4] = 0x510E527F;
Remco	6:c0ed1bf37651	27	hash[5] = 0x9B05688C;
Remco	6:c0ed1bf37651	28	hash[6] = 0x1F83D9AB;
Remco	6:c0ed1bf37651	29	hash[7] = 0x5BE0CD19;
Remco	6:c0ed1bf37651	30	length = 0;
Remco	6:c0ed1bf37651	31	}
Remco	6:c0ed1bf37651	32
Remco	6:c0ed1bf37651	33	void SHA256::append(const char* data, int size)
Remco	6:c0ed1bf37651	34	{
Remco	6:c0ed1bf37651	35	int index = length % 64;
Remco	6:c0ed1bf37651	36	length += size;
Remco	6:c0ed1bf37651	37	const char* end = data + size;
Remco	6:c0ed1bf37651	38
Remco	6:c0ed1bf37651	39	// Word align data
Remco	6:c0ed1bf37651	40	char* bytes = reinterpret_cast<char*>(w + (index / 4));
Remco	6:c0ed1bf37651	41	switch(index % 4)
Remco	6:c0ed1bf37651	42	{
Remco	6:c0ed1bf37651	43	// Remember to reverse! (little endian!)
Remco	6:c0ed1bf37651	44	case 1: bytes[2] = *data++; ++index;
Remco	6:c0ed1bf37651	45	case 2: bytes[1] = *data++; ++index;
Remco	6:c0ed1bf37651	46	case 3: bytes[0] = *data++; ++index;
Remco	6:c0ed1bf37651	47	case 0: break;
Remco	6:c0ed1bf37651	48	}
Remco	6:c0ed1bf37651	49	if(data > end) {
Remco	6:c0ed1bf37651	50	// We have overshot reading data
Remco	6:c0ed1bf37651	51	// but w and length are correct
Remco	6:c0ed1bf37651	52	return;
Remco	6:c0ed1bf37651	53	}
Remco	6:c0ed1bf37651	54
Remco	6:c0ed1bf37651	55	// Index is now word alligned
Remco	6:c0ed1bf37651	56	index /= 4;
Remco	6:c0ed1bf37651	57	if(index == 16) {
Remco	6:c0ed1bf37651	58	process_chunk();
Remco	6:c0ed1bf37651	59	index = 0;
Remco	6:c0ed1bf37651	60	}
Remco	6:c0ed1bf37651	61
Remco	6:c0ed1bf37651	62	// Process whole words
Remco	6:c0ed1bf37651	63	int num_words = (end - data) / 4;
Remco	6:c0ed1bf37651	64	const unsigned int* data_words = reinterpret_cast<const unsigned int*>(data);
Remco	6:c0ed1bf37651	65	const unsigned int* data_words_end = data_words + num_words;
Remco	6:c0ed1bf37651	66	while(data_words != data_words_end)
Remco	6:c0ed1bf37651	67	{
Remco	6:c0ed1bf37651	68	w[index++] = reverse_bytes(*data_words++);
Remco	6:c0ed1bf37651	69	if(index == 16) {
Remco	6:c0ed1bf37651	70	process_chunk();
Remco	6:c0ed1bf37651	71	index = 0;
Remco	6:c0ed1bf37651	72	}
Remco	6:c0ed1bf37651	73	}
Remco	6:c0ed1bf37651	74
Remco	6:c0ed1bf37651	75	// Process trailing data bytes
Remco	6:c0ed1bf37651	76	// Again, we won't worry about overshooting data
Remco	6:c0ed1bf37651	77	w[index] = reverse_bytes(*data_words);
Remco	6:c0ed1bf37651	78	}
Remco	6:c0ed1bf37651	79
Remco	6:c0ed1bf37651	80	void SHA256::finalize()
Remco	6:c0ed1bf37651	81	{
Remco	6:c0ed1bf37651	82	int trailing = length % 64;
Remco	6:c0ed1bf37651	83
Remco	6:c0ed1bf37651	84	// Append the bit '1' to the message
Remco	6:c0ed1bf37651	85	int last_block = trailing / 4;
Remco	6:c0ed1bf37651	86	unsigned int bit_in_block = 0x80 << (24 - (trailing % 4) * 8);
Remco	6:c0ed1bf37651	87	w[last_block] \|= bit_in_block;
Remco	6:c0ed1bf37651	88
Remco	6:c0ed1bf37651	89	// Set all other bits to zero
Remco	6:c0ed1bf37651	90	w[last_block] &= ~(bit_in_block - 1);
Remco	6:c0ed1bf37651	91	for(int i = last_block + 1; i < 16; ++i)
Remco	6:c0ed1bf37651	92	w[i] = 0;
Remco	6:c0ed1bf37651	93
Remco	6:c0ed1bf37651	94	// Make room for the length if necessary
Remco	6:c0ed1bf37651	95	if(trailing >= 56) {
Remco	6:c0ed1bf37651	96	process_chunk();
Remco	6:c0ed1bf37651	97	for(int i = 0; i <= last_block; ++i)
Remco	6:c0ed1bf37651	98	w[i] = 0;
Remco	6:c0ed1bf37651	99	}
Remco	6:c0ed1bf37651	100
Remco	6:c0ed1bf37651	101	// Append the length in bits
Remco	6:c0ed1bf37651	102	w[14] = length >> (32 - 3);
Remco	6:c0ed1bf37651	103	w[15] = length << 3;
Remco	6:c0ed1bf37651	104	process_chunk();
Remco	6:c0ed1bf37651	105
Remco	6:c0ed1bf37651	106	// Convert the result to big endian
Remco	6:c0ed1bf37651	107	for(int i = 0; i < 8; ++i)
Remco	6:c0ed1bf37651	108	hash[i] = reverse_bytes(hash[i]);
Remco	6:c0ed1bf37651	109	}
Remco	6:c0ed1bf37651	110
Remco	6:c0ed1bf37651	111	#define s0(x) (rotate_right(x, 7) ^ rotate_right(x, 18) ^ (x >> 3))
Remco	6:c0ed1bf37651	112	#define s1(x) (rotate_right(x, 17) ^ rotate_right(x, 19) ^ (x >> 10))
Remco	6:c0ed1bf37651	113	#define s2(x) (rotate_right(x, 2) ^ rotate_right(x, 13) ^ rotate_right(x, 22))
Remco	6:c0ed1bf37651	114	#define s3(x) (rotate_right(x, 6) ^ rotate_right(x, 11) ^ rotate_right(x, 25))
Remco	6:c0ed1bf37651	115	#define maj(a,b,c) ((a & b) ^ (a & c) ^ (b & c))
Remco	6:c0ed1bf37651	116	#define ch(a,b,c) ((a & b) ^ ((~a) & c))
Remco	6:c0ed1bf37651	117
Remco	6:c0ed1bf37651	118	const unsigned int k[64] = {
Remco	6:c0ed1bf37651	119	0x428A2F98, 0x71374491, 0xB5C0FBCF, 0xE9B5DBA5, 0x3956C25B, 0x59F111F1, 0x923F82A4, 0xAB1C5ED5,
Remco	6:c0ed1bf37651	120	0xD807AA98, 0x12835B01, 0x243185BE, 0x550C7DC3, 0x72BE5D74, 0x80DEB1FE, 0x9BDC06A7, 0xC19BF174,
Remco	6:c0ed1bf37651	121	0xE49B69C1, 0xEFBE4786, 0x0FC19DC6, 0x240CA1CC, 0x2DE92C6F, 0x4A7484AA, 0x5CB0A9DC, 0x76F988DA,
Remco	6:c0ed1bf37651	122	0x983E5152, 0xA831C66D, 0xB00327C8, 0xBF597FC7, 0xC6E00BF3, 0xD5A79147, 0x06CA6351, 0x14292967,
Remco	6:c0ed1bf37651	123	0x27B70A85, 0x2E1B2138, 0x4D2C6DFC, 0x53380D13, 0x650A7354, 0x766A0ABB, 0x81C2C92E, 0x92722C85,
Remco	6:c0ed1bf37651	124	0xA2BFE8A1, 0xA81A664B, 0xC24B8B70, 0xC76C51A3, 0xD192E819, 0xD6990624, 0xF40E3585, 0x106AA070,
Remco	6:c0ed1bf37651	125	0x19A4C116, 0x1E376C08, 0x2748774C, 0x34B0BCB5, 0x391C0CB3, 0x4ED8AA4A, 0x5B9CCA4F, 0x682E6FF3,
Remco	6:c0ed1bf37651	126	0x748F82EE, 0x78A5636F, 0x84C87814, 0x8CC70208, 0x90BEFFFA, 0xA4506CEB, 0xBEF9A3F7, 0xC67178F2
Remco	6:c0ed1bf37651	127	};
Remco	6:c0ed1bf37651	128
Remco	6:c0ed1bf37651	129	#define ROUND(a,b,c,d,e,f,g,h,i) \
Remco	6:c0ed1bf37651	130	h += w[i];\
Remco	6:c0ed1bf37651	131	h += *K++;\
Remco	6:c0ed1bf37651	132	h += s3(e); \
Remco	6:c0ed1bf37651	133	h += ch(e, f, g); \
Remco	6:c0ed1bf37651	134	d += h;\
Remco	6:c0ed1bf37651	135	h += s2(a);\
Remco	6:c0ed1bf37651	136	h += maj(a, b, c);
Remco	6:c0ed1bf37651	137
Remco	6:c0ed1bf37651	138	#define W(n) w[(n) & 0xf]
Remco	6:c0ed1bf37651	139
Remco	6:c0ed1bf37651	140	#define ROUND2(a,b,c,d,e,f,g,h,i) \
Remco	6:c0ed1bf37651	141	W(i) += s0(W(i+1)) + W(i+9) + s1(W(i+14));\
Remco	6:c0ed1bf37651	142	h += W(i); \
Remco	6:c0ed1bf37651	143	h += *K++;\
Remco	6:c0ed1bf37651	144	h += s3(e);\
Remco	6:c0ed1bf37651	145	h += ch(e, f, g); \
Remco	6:c0ed1bf37651	146	d += h;\
Remco	6:c0ed1bf37651	147	h += s2(a);\
Remco	6:c0ed1bf37651	148	h += maj(a, b, c);
Remco	6:c0ed1bf37651	149
Remco	6:c0ed1bf37651	150	// Process a 512 bit chunk stored in w[1...15]
Remco	6:c0ed1bf37651	151	void SHA256::process_chunk()
Remco	6:c0ed1bf37651	152	{
Remco	6:c0ed1bf37651	153	// Initialize using current hash
Remco	6:c0ed1bf37651	154	unsigned int a = hash[0];
Remco	6:c0ed1bf37651	155	unsigned int b = hash[1];
Remco	6:c0ed1bf37651	156	unsigned int c = hash[2];
Remco	6:c0ed1bf37651	157	unsigned int d = hash[3];
Remco	6:c0ed1bf37651	158	unsigned int e = hash[4];
Remco	6:c0ed1bf37651	159	unsigned int f = hash[5];
Remco	6:c0ed1bf37651	160	unsigned int g = hash[6];
Remco	6:c0ed1bf37651	161	unsigned int h = hash[7];
Remco	6:c0ed1bf37651	162
Remco	6:c0ed1bf37651	163	// Main loop
Remco	6:c0ed1bf37651	164	const unsigned int* K = k;
Remco	6:c0ed1bf37651	165	const unsigned int* K_end = k + 64;
Remco	6:c0ed1bf37651	166	ROUND(a,b,c,d,e,f,g,h,0);
Remco	6:c0ed1bf37651	167	ROUND(h,a,b,c,d,e,f,g,1);
Remco	6:c0ed1bf37651	168	ROUND(g,h,a,b,c,d,e,f,2);
Remco	6:c0ed1bf37651	169	ROUND(f,g,h,a,b,c,d,e,3);
Remco	6:c0ed1bf37651	170	ROUND(e,f,g,h,a,b,c,d,4);
Remco	6:c0ed1bf37651	171	ROUND(d,e,f,g,h,a,b,c,5);
Remco	6:c0ed1bf37651	172	ROUND(c,d,e,f,g,h,a,b,6);
Remco	6:c0ed1bf37651	173	ROUND(b,c,d,e,f,g,h,a,7);
Remco	6:c0ed1bf37651	174	ROUND(a,b,c,d,e,f,g,h,8);
Remco	6:c0ed1bf37651	175	ROUND(h,a,b,c,d,e,f,g,9);
Remco	6:c0ed1bf37651	176	ROUND(g,h,a,b,c,d,e,f,10);
Remco	6:c0ed1bf37651	177	ROUND(f,g,h,a,b,c,d,e,11);
Remco	6:c0ed1bf37651	178	ROUND(e,f,g,h,a,b,c,d,12);
Remco	6:c0ed1bf37651	179	ROUND(d,e,f,g,h,a,b,c,13);
Remco	6:c0ed1bf37651	180	ROUND(c,d,e,f,g,h,a,b,14);
Remco	6:c0ed1bf37651	181	ROUND(b,c,d,e,f,g,h,a,15);
Remco	6:c0ed1bf37651	182	do {
Remco	6:c0ed1bf37651	183	ROUND2(a,b,c,d,e,f,g,h,0);
Remco	6:c0ed1bf37651	184	ROUND2(h,a,b,c,d,e,f,g,1);
Remco	6:c0ed1bf37651	185	ROUND2(g,h,a,b,c,d,e,f,2);
Remco	6:c0ed1bf37651	186	ROUND2(f,g,h,a,b,c,d,e,3);
Remco	6:c0ed1bf37651	187	ROUND2(e,f,g,h,a,b,c,d,4);
Remco	6:c0ed1bf37651	188	ROUND2(d,e,f,g,h,a,b,c,5);
Remco	6:c0ed1bf37651	189	ROUND2(c,d,e,f,g,h,a,b,6);
Remco	6:c0ed1bf37651	190	ROUND2(b,c,d,e,f,g,h,a,7);
Remco	6:c0ed1bf37651	191	ROUND2(a,b,c,d,e,f,g,h,8);
Remco	6:c0ed1bf37651	192	ROUND2(h,a,b,c,d,e,f,g,9);
Remco	6:c0ed1bf37651	193	ROUND2(g,h,a,b,c,d,e,f,10);
Remco	6:c0ed1bf37651	194	ROUND2(f,g,h,a,b,c,d,e,11);
Remco	6:c0ed1bf37651	195	ROUND2(e,f,g,h,a,b,c,d,12);
Remco	6:c0ed1bf37651	196	ROUND2(d,e,f,g,h,a,b,c,13);
Remco	6:c0ed1bf37651	197	ROUND2(c,d,e,f,g,h,a,b,14);
Remco	6:c0ed1bf37651	198	ROUND2(b,c,d,e,f,g,h,a,15);
Remco	6:c0ed1bf37651	199	} while(K != K_end);
Remco	6:c0ed1bf37651	200
Remco	6:c0ed1bf37651	201	// Update hash
Remco	6:c0ed1bf37651	202	hash[0] += a;
Remco	6:c0ed1bf37651	203	hash[1] += b;
Remco	6:c0ed1bf37651	204	hash[2] += c;
Remco	6:c0ed1bf37651	205	hash[3] += d;
Remco	6:c0ed1bf37651	206	hash[4] += e;
Remco	6:c0ed1bf37651	207	hash[5] += f;
Remco	6:c0ed1bf37651	208	hash[6] += g;
Remco	6:c0ed1bf37651	209	hash[7] += h;
Remco	6:c0ed1bf37651	210	}
Remco	6:c0ed1bf37651	211
Remco	6:c0ed1bf37651	212	std::string SHA256::hexString()
Remco	6:c0ed1bf37651	213	{
Remco	6:c0ed1bf37651	214	const char* hex = "0123456789abcdef";
Remco	6:c0ed1bf37651	215	std::string hexstr(64, '0');
Remco	6:c0ed1bf37651	216	for(int i = 0; i < 32; ++i) {
Remco	6:c0ed1bf37651	217	hexstr[2 * i + 0] = hex[digest()[i] >> 4];
Remco	6:c0ed1bf37651	218	hexstr[2 * i + 1] = hex[digest()[i] & 0xf];
Remco	6:c0ed1bf37651	219	}
Remco	6:c0ed1bf37651	220	return hexstr;
Remco	6:c0ed1bf37651	221	}

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Type:	Library
Created:	20 Jun 2011
Imports:	134
Forks:	0
Commits:	7
Dependents:	2
Dependencies:	0
Followers:	9

SHA256.cpp@6:c0ed1bf37651, 2011-06-20 (annotated)

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