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// Copyright (c) 2009 The Chromium Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.
#include "base/sha1.h"
#include "base/basictypes.h"
namespace base {
// Implementation of SHA-1. Only handles data in byte-sized blocks,
// which simplifies the code a fair bit.
// This file also contains an HMAC implementation using SHA-1
// Identifier names follow notation in FIPS PUB 180-3, where you'll
// also find a description of the algorithm:
// http://csrc.nist.gov/publications/fips/fips180-3/fips180-3_final.pdf
// Usage example:
//
// SecureHashAlgorithm sha;
// while(there is data to hash)
// sha.Update(moredata, size of data);
// sha.Final();
// memcpy(somewhere, sha.Digest(), 20);
//
// to reuse the instance of sha, call sha.Init();
// TODO(jhawkins): Replace this implementation with a per-platform
// implementation using each platform's crypto library.
class SecureHashAlgorithm {
public:
SecureHashAlgorithm() { Init(); }
static const int kDigestSizeBytes;
void Init();
void Update(const void* data, size_t nbytes);
void Final();
// 20 bytes of message digest.
const unsigned char* Digest() const {
return reinterpret_cast<const unsigned char*>(H);
}
private:
void Pad();
void Process();
uint32 A, B, C, D, E;
uint32 H[5];
union {
uint32 W[80];
uint8 M[64];
};
uint32 cursor;
uint32 l;
};
static inline uint32 f(uint32 t, uint32 B, uint32 C, uint32 D) {
if (t < 20) {
return (B & C) | ((~B) & D);
} else if (t < 40) {
return B ^ C ^ D;
} else if (t < 60) {
return (B & C) | (B & D) | (C & D);
} else {
return B ^ C ^ D;
}
}
static inline uint32 S(uint32 n, uint32 X) {
return (X << n) | (X >> (32-n));
}
static inline uint32 K(uint32 t) {
if (t < 20) {
return 0x5a827999;
} else if (t < 40) {
return 0x6ed9eba1;
} else if (t < 60) {
return 0x8f1bbcdc;
} else {
return 0xca62c1d6;
}
}
static inline void swapends(uint32& t) {
t = ((t & 0xff000000) >> 24) |
((t & 0xff0000) >> 8) |
((t & 0xff00) << 8) |
((t & 0xff) << 24);
}
const int SecureHashAlgorithm::kDigestSizeBytes = 20;
void SecureHashAlgorithm::Init() {
cursor = 0;
l = 0;
H[0] = 0x67452301;
H[1] = 0xefcdab89;
H[2] = 0x98badcfe;
H[3] = 0x10325476;
H[4] = 0xc3d2e1f0;
}
void SecureHashAlgorithm::Final() {
Pad();
Process();
for (int t = 0; t < 5; ++t)
swapends(H[t]);
}
void SecureHashAlgorithm::Update(const void* data, size_t nbytes) {
const uint8* d = reinterpret_cast<const uint8*>(data);
while (nbytes--) {
M[cursor++] = *d++;
if (cursor >= 64)
Process();
l += 8;
}
}
void SecureHashAlgorithm::Pad() {
M[cursor++] = 0x80;
if (cursor > 64-8) {
// pad out to next block
while (cursor < 64)
M[cursor++] = 0;
Process();
}
while (cursor < 64-4)
M[cursor++] = 0;
M[64-4] = (l & 0xff000000) >> 24;
M[64-3] = (l & 0xff0000) >> 16;
M[64-2] = (l & 0xff00) >> 8;
M[64-1] = (l & 0xff);
}
void SecureHashAlgorithm::Process() {
uint32 t;
// Each a...e corresponds to a section in the FIPS 180-3 algorithm.
// a.
//
// W and M are in a union, so no need to memcpy.
// memcpy(W, M, sizeof(M));
for (t = 0; t < 16; ++t)
swapends(W[t]);
// b.
for (t = 16; t < 80; ++t)
W[t] = S(1, W[t - 3] ^ W[t - 8] ^ W[t - 14] ^ W[t - 16]);
// c.
A = H[0];
B = H[1];
C = H[2];
D = H[3];
E = H[4];
// d.
for (t = 0; t < 80; ++t) {
uint32 TEMP = S(5, A) + f(t, B, C, D) + E + W[t] + K(t);
E = D;
D = C;
C = S(30, B);
B = A;
A = TEMP;
}
// e.
H[0] += A;
H[1] += B;
H[2] += C;
H[3] += D;
H[4] += E;
cursor = 0;
}
std::string SHA1HashString(const std::string& str) {
SecureHashAlgorithm sha;
sha.Update(str.c_str(), str.length());
sha.Final();
std::string out(reinterpret_cast<const char*>(sha.Digest()),
SecureHashAlgorithm::kDigestSizeBytes);
return out;
}
} // namespace base
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