1/*
2 * Copyright 2008, Ingo Weinhold, ingo_weinhold@gmx.de.
3 * Distributed under the terms of the MIT License.
4 */
5
6
7#include "SHA256.h"
8
9#include <stdio.h>
10#include <string.h>
11
12#include <ByteOrder.h>
13
14
15namespace BPrivate {
16
17
18static const uint32 kChunkSize = 64;	// 64 bytes == 512 bits
19
20static const uint32 kRounds[64] = {
21   0x428a2f98, 0x71374491, 0xb5c0fbcf, 0xe9b5dba5, 0x3956c25b, 0x59f111f1, 0x923f82a4, 0xab1c5ed5,
22   0xd807aa98, 0x12835b01, 0x243185be, 0x550c7dc3, 0x72be5d74, 0x80deb1fe, 0x9bdc06a7, 0xc19bf174,
23   0xe49b69c1, 0xefbe4786, 0x0fc19dc6, 0x240ca1cc, 0x2de92c6f, 0x4a7484aa, 0x5cb0a9dc, 0x76f988da,
24   0x983e5152, 0xa831c66d, 0xb00327c8, 0xbf597fc7, 0xc6e00bf3, 0xd5a79147, 0x06ca6351, 0x14292967,
25   0x27b70a85, 0x2e1b2138, 0x4d2c6dfc, 0x53380d13, 0x650a7354, 0x766a0abb, 0x81c2c92e, 0x92722c85,
26   0xa2bfe8a1, 0xa81a664b, 0xc24b8b70, 0xc76c51a3, 0xd192e819, 0xd6990624, 0xf40e3585, 0x106aa070,
27   0x19a4c116, 0x1e376c08, 0x2748774c, 0x34b0bcb5, 0x391c0cb3, 0x4ed8aa4a, 0x5b9cca4f, 0x682e6ff3,
28   0x748f82ee, 0x78a5636f, 0x84c87814, 0x8cc70208, 0x90befffa, 0xa4506ceb, 0xbef9a3f7, 0xc67178f2
29};
30static const uint32 kHash[8] = {
31	0x6a09e667, 0xbb67ae85, 0x3c6ef372, 0xa54ff53a,
32	0x510e527f, 0x9b05688c, 0x1f83d9ab, 0x5be0cd19
33};
34
35
36static inline uint32
37rotate_right(uint32 value, int bits)
38{
39	return (value >> bits) | (value << (32 - bits));
40}
41
42
43//	#pragma mark -
44
45
46SHA256::SHA256()
47{
48	Init();
49}
50
51
52SHA256::~SHA256()
53{
54}
55
56
57void
58SHA256::Init()
59{
60	memcpy(fHash, kHash, sizeof(kHash));
61
62	fBytesInBuffer = 0;
63	fMessageSize = 0;
64	fDigested = false;
65}
66
67
68void
69SHA256::Update(const void* _buffer, size_t size)
70{
71	const uint8* buffer = (const uint8*)_buffer;
72	fMessageSize += size;
73
74	while (fBytesInBuffer + size >= kChunkSize) {
75		size_t toCopy = kChunkSize - fBytesInBuffer;
76		memcpy((uint8*)fBuffer + fBytesInBuffer, buffer, toCopy);
77		buffer += toCopy;
78		size -= toCopy;
79
80		_ProcessChunk();
81		fBytesInBuffer = 0;
82	}
83
84	if (size > 0) {
85		memcpy((uint8*)fBuffer + fBytesInBuffer, buffer, size);
86		fBytesInBuffer += size;
87	}
88}
89
90
91const uint8*
92SHA256::Digest()
93{
94	if (!fDigested) {
95		// We need to append a 1 bit, append padding with 0 bits, and append
96		// the message size in bits (64 bit big-endian int), so that the whole
97		// is chunk-aligned. So we either have to process one last chunk or two
98		// chunks.
99
100		// append the 1 bit
101		((uint8*)fBuffer)[fBytesInBuffer] = 0x80;
102		fBytesInBuffer++;
103
104		// if the message size doesn't fit anymore, we pad the chunk and
105		// process it
106		if (fBytesInBuffer > kChunkSize - 8) {
107			memset((uint8*)fBuffer + fBytesInBuffer, 0,
108				kChunkSize - fBytesInBuffer);
109			_ProcessChunk();
110			fBytesInBuffer = 0;
111		}
112
113		// pad the buffer
114		if (fBytesInBuffer < kChunkSize - 8) {
115			memset((uint8*)fBuffer + fBytesInBuffer, 0,
116				kChunkSize - 8 - fBytesInBuffer);
117		}
118
119		// write the (big-endian) message size in bits
120		uint64* target = (uint64*)((uint8*)fBuffer + kChunkSize - 8);
121		*target = B_HOST_TO_BENDIAN_INT64((uint64)fMessageSize * 8);
122
123		_ProcessChunk();
124
125		// set digest
126		for (int i = 0; i < 8; i++)
127			fDigest[i] = B_HOST_TO_BENDIAN_INT32(fHash[i]);
128
129		fDigested = true;
130	}
131
132	return (uint8*)fDigest;
133}
134
135
136void
137SHA256::_ProcessChunk()
138{
139	// convert endianess -- the data are supposed to be a stream of
140	// 32 bit big-endian integers
141	#if B_HOST_IS_LENDIAN
142		for (int i = 0; i < (int)kChunkSize / 4; i++)
143			fBuffer[i] = B_SWAP_INT32(fBuffer[i]);
144	#endif
145
146	// pre-process buffer (extend to 64 elements)
147	for (int i = 16; i < 64; i++) {
148		uint32 v0 = fBuffer[i - 15];
149		uint32 v1 = fBuffer[i - 2];
150		uint32 s0 = rotate_right(v0, 7) ^ rotate_right(v0, 18) ^ (v0 >> 3);
151		uint32 s1 = rotate_right(v1, 17) ^ rotate_right(v1, 19) ^ (v1 >> 10);
152		fBuffer[i] = fBuffer[i - 16] + s0 + fBuffer[i - 7] + s1;
153	}
154
155	uint32 a = fHash[0];
156	uint32 b = fHash[1];
157	uint32 c = fHash[2];
158	uint32 d = fHash[3];
159	uint32 e = fHash[4];
160	uint32 f = fHash[5];
161	uint32 g = fHash[6];
162	uint32 h = fHash[7];
163
164	// process the buffer
165	for (int i = 0; i < 64; i++) {
166		uint32 s0 = rotate_right(a, 2) ^ rotate_right(a, 13)
167			^ rotate_right(a, 22);
168		uint32 maj = (a & b) ^ (a & c) ^ (b & c);
169		uint32 t2 = s0 + maj;
170		uint32 s1 = rotate_right(e, 6) ^ rotate_right(e, 11)
171			^ rotate_right(e, 25);
172		uint32 ch = (e & f) ^ (~e & g);
173		uint32 t1 = h + s1 + ch + kRounds[i] + fBuffer[i];
174
175		h = g;
176		g = f;
177		f = e;
178		e = d + t1;
179		d = c;
180		c = b;
181		b = a;
182		a = t1 + t2;
183	}
184
185	fHash[0] += a;
186	fHash[1] += b;
187	fHash[2] += c;
188	fHash[3] += d;
189	fHash[4] += e;
190	fHash[5] += f;
191	fHash[6] += g;
192	fHash[7] += h;
193}
194
195
196} // namespace BPrivate
197