Andrew Boyson / crypto

A simple library to support serving https.

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sha/sha256.c@3:e6a2c4579a4d, 2019-08-02 (annotated)

Committer:
andrewboyson
Date:
Fri Aug 02 15:07:18 2019 +0000
Revision:
3:e6a2c4579a4d
Child:
4:6a1d887f1cad
Changed SHA-256 to be addable rather than all at once so that it can be used with TLS handshakes.

Who changed what in which revision?

UserRevisionLine numberNew contents of line
andrewboyson 3:e6a2c4579a4d 1 #include <stdint.h>
andrewboyson 3:e6a2c4579a4d 2 #include <string.h>
andrewboyson 3:e6a2c4579a4d 3
andrewboyson 3:e6a2c4579a4d 4 #include "sha256.h"
andrewboyson 3:e6a2c4579a4d 5
andrewboyson 3:e6a2c4579a4d 6 #define BLOCK_SIZE 64
andrewboyson 3:e6a2c4579a4d 7
andrewboyson 3:e6a2c4579a4d 8 /**
andrewboyson 3:e6a2c4579a4d 9 * sha256_vector - SHA256 hash for data vector
andrewboyson 3:e6a2c4579a4d 10 * @num_elem: Number of elements in the data vector
andrewboyson 3:e6a2c4579a4d 11 * @addr: Pointers to the data areas
andrewboyson 3:e6a2c4579a4d 12 * @len: Lengths of the data blocks
andrewboyson 3:e6a2c4579a4d 13 * @mac: Buffer for the hash
andrewboyson 3:e6a2c4579a4d 14
andrewboyson 3:e6a2c4579a4d 15 void sha256_vector(int num_elem, const u8 *addr[], const int *len, u8 *mac)
andrewboyson 3:e6a2c4579a4d 16 {
andrewboyson 3:e6a2c4579a4d 17 struct sha256_state ctx;
andrewboyson 3:e6a2c4579a4d 18 int i;
andrewboyson 3:e6a2c4579a4d 19 sha256_init(&ctx);
andrewboyson 3:e6a2c4579a4d 20 for (i = 0; i < num_elem; i++) sha256_process(&ctx, addr[i], len[i]);
andrewboyson 3:e6a2c4579a4d 21 sha256_done(&ctx, mac);
andrewboyson 3:e6a2c4579a4d 22 }
andrewboyson 3:e6a2c4579a4d 23 */
andrewboyson 3:e6a2c4579a4d 24 /* ===== start - public domain SHA256 implementation ===== */
andrewboyson 3:e6a2c4579a4d 25 /* This is based on SHA256 implementation in LibTomCrypt that was released into
andrewboyson 3:e6a2c4579a4d 26 * public domain by Tom St Denis. */
andrewboyson 3:e6a2c4579a4d 27 /* the K array */
andrewboyson 3:e6a2c4579a4d 28 static const uint32_t K[64] =
andrewboyson 3:e6a2c4579a4d 29 {
andrewboyson 3:e6a2c4579a4d 30 0x428a2f98UL, 0x71374491UL, 0xb5c0fbcfUL, 0xe9b5dba5UL, 0x3956c25bUL,
andrewboyson 3:e6a2c4579a4d 31 0x59f111f1UL, 0x923f82a4UL, 0xab1c5ed5UL, 0xd807aa98UL, 0x12835b01UL,
andrewboyson 3:e6a2c4579a4d 32 0x243185beUL, 0x550c7dc3UL, 0x72be5d74UL, 0x80deb1feUL, 0x9bdc06a7UL,
andrewboyson 3:e6a2c4579a4d 33 0xc19bf174UL, 0xe49b69c1UL, 0xefbe4786UL, 0x0fc19dc6UL, 0x240ca1ccUL,
andrewboyson 3:e6a2c4579a4d 34 0x2de92c6fUL, 0x4a7484aaUL, 0x5cb0a9dcUL, 0x76f988daUL, 0x983e5152UL,
andrewboyson 3:e6a2c4579a4d 35 0xa831c66dUL, 0xb00327c8UL, 0xbf597fc7UL, 0xc6e00bf3UL, 0xd5a79147UL,
andrewboyson 3:e6a2c4579a4d 36 0x06ca6351UL, 0x14292967UL, 0x27b70a85UL, 0x2e1b2138UL, 0x4d2c6dfcUL,
andrewboyson 3:e6a2c4579a4d 37 0x53380d13UL, 0x650a7354UL, 0x766a0abbUL, 0x81c2c92eUL, 0x92722c85UL,
andrewboyson 3:e6a2c4579a4d 38 0xa2bfe8a1UL, 0xa81a664bUL, 0xc24b8b70UL, 0xc76c51a3UL, 0xd192e819UL,
andrewboyson 3:e6a2c4579a4d 39 0xd6990624UL, 0xf40e3585UL, 0x106aa070UL, 0x19a4c116UL, 0x1e376c08UL,
andrewboyson 3:e6a2c4579a4d 40 0x2748774cUL, 0x34b0bcb5UL, 0x391c0cb3UL, 0x4ed8aa4aUL, 0x5b9cca4fUL,
andrewboyson 3:e6a2c4579a4d 41 0x682e6ff3UL, 0x748f82eeUL, 0x78a5636fUL, 0x84c87814UL, 0x8cc70208UL,
andrewboyson 3:e6a2c4579a4d 42 0x90befffaUL, 0xa4506cebUL, 0xbef9a3f7UL, 0xc67178f2UL
andrewboyson 3:e6a2c4579a4d 43 };
andrewboyson 3:e6a2c4579a4d 44
andrewboyson 3:e6a2c4579a4d 45 static uint32_t rotate(uint32_t x, int count) { return x >> count | x << (32 - count); }
andrewboyson 3:e6a2c4579a4d 46
andrewboyson 3:e6a2c4579a4d 47 static int compress(struct Sha256State *md, const uint8_t *buf) // compress 512-bits
andrewboyson 3:e6a2c4579a4d 48 {
andrewboyson 3:e6a2c4579a4d 49 uint32_t s[8], w[64];
andrewboyson 3:e6a2c4579a4d 50
andrewboyson 3:e6a2c4579a4d 51 // copy state into s
andrewboyson 3:e6a2c4579a4d 52 for (int i = 0; i < 8; i++) s[i] = md->state[i];
andrewboyson 3:e6a2c4579a4d 53
andrewboyson 3:e6a2c4579a4d 54 // copy the state into 512-bits into w[0..15]
andrewboyson 3:e6a2c4579a4d 55 for (int i = 0; i < 16; i++) w[i] = (uint32_t)*(buf + 4 * i + 0) << 24 |
andrewboyson 3:e6a2c4579a4d 56 (uint32_t)*(buf + 4 * i + 1) << 16 |
andrewboyson 3:e6a2c4579a4d 57 (uint32_t)*(buf + 4 * i + 2) << 8 |
andrewboyson 3:e6a2c4579a4d 58 (uint32_t)*(buf + 4 * i + 3);
andrewboyson 3:e6a2c4579a4d 59
andrewboyson 3:e6a2c4579a4d 60 // fill w[16..63]
andrewboyson 3:e6a2c4579a4d 61 for (int i = 16; i < 64; i++)
andrewboyson 3:e6a2c4579a4d 62 {
andrewboyson 3:e6a2c4579a4d 63 const uint32_t s0 = rotate(w[i - 15], 7) ^ rotate(w[i - 15], 18) ^ (w[i - 15] >> 3);
andrewboyson 3:e6a2c4579a4d 64 const uint32_t s1 = rotate(w[i - 2], 17) ^ rotate(w[i - 2], 19) ^ (w[i - 2] >> 10);
andrewboyson 3:e6a2c4579a4d 65 w[i] = w[i - 16] + s0 + w[i - 7] + s1;
andrewboyson 3:e6a2c4579a4d 66 }
andrewboyson 3:e6a2c4579a4d 67
andrewboyson 3:e6a2c4579a4d 68 // Compress
andrewboyson 3:e6a2c4579a4d 69 for (int i = 0; i < 64; ++i)
andrewboyson 3:e6a2c4579a4d 70 {
andrewboyson 3:e6a2c4579a4d 71 const uint32_t s1 = rotate(s[4], 6) ^ rotate(s[4], 11) ^ rotate(s[4], 25);
andrewboyson 3:e6a2c4579a4d 72 const uint32_t ch = (s[4] & s[5]) ^ (~s[4] & s[6]);
andrewboyson 3:e6a2c4579a4d 73 const uint32_t t0 = s[7] + s1 + ch + K[i] + w[i];
andrewboyson 3:e6a2c4579a4d 74 const uint32_t s0 = rotate(s[0], 2) ^ rotate(s[0], 13) ^ rotate(s[0], 22);
andrewboyson 3:e6a2c4579a4d 75 const uint32_t maj = (s[0] & s[1]) ^ (s[0] & s[2]) ^ (s[1] & s[2]);
andrewboyson 3:e6a2c4579a4d 76 const uint32_t t1 = s0 + maj;
andrewboyson 3:e6a2c4579a4d 77
andrewboyson 3:e6a2c4579a4d 78 s[7] = s[6];
andrewboyson 3:e6a2c4579a4d 79 s[6] = s[5];
andrewboyson 3:e6a2c4579a4d 80 s[5] = s[4];
andrewboyson 3:e6a2c4579a4d 81 s[4] = s[3] + t0;
andrewboyson 3:e6a2c4579a4d 82 s[3] = s[2];
andrewboyson 3:e6a2c4579a4d 83 s[2] = s[1];
andrewboyson 3:e6a2c4579a4d 84 s[1] = s[0];
andrewboyson 3:e6a2c4579a4d 85 s[0] = t0 + t1;
andrewboyson 3:e6a2c4579a4d 86 }
andrewboyson 3:e6a2c4579a4d 87
andrewboyson 3:e6a2c4579a4d 88 // feedback
andrewboyson 3:e6a2c4579a4d 89 for (int i = 0; i < 8; i++) md->state[i] = md->state[i] + s[i];
andrewboyson 3:e6a2c4579a4d 90
andrewboyson 3:e6a2c4579a4d 91 return 0;
andrewboyson 3:e6a2c4579a4d 92 }
andrewboyson 3:e6a2c4579a4d 93
andrewboyson 3:e6a2c4579a4d 94 void Sha256Start(struct Sha256State *md) // Initialize the hash state
andrewboyson 3:e6a2c4579a4d 95 {
andrewboyson 3:e6a2c4579a4d 96 md->curlen = 0;
andrewboyson 3:e6a2c4579a4d 97 md->length = 0;
andrewboyson 3:e6a2c4579a4d 98 md->state[0] = 0x6A09E667UL;
andrewboyson 3:e6a2c4579a4d 99 md->state[1] = 0xBB67AE85UL;
andrewboyson 3:e6a2c4579a4d 100 md->state[2] = 0x3C6EF372UL;
andrewboyson 3:e6a2c4579a4d 101 md->state[3] = 0xA54FF53AUL;
andrewboyson 3:e6a2c4579a4d 102 md->state[4] = 0x510E527FUL;
andrewboyson 3:e6a2c4579a4d 103 md->state[5] = 0x9B05688CUL;
andrewboyson 3:e6a2c4579a4d 104 md->state[6] = 0x1F83D9ABUL;
andrewboyson 3:e6a2c4579a4d 105 md->state[7] = 0x5BE0CD19UL;
andrewboyson 3:e6a2c4579a4d 106 }
andrewboyson 3:e6a2c4579a4d 107
andrewboyson 3:e6a2c4579a4d 108 int Sha256Add(struct Sha256State *md, const uint8_t *in, int inlen) //Return 0 if ok; -1 on error
andrewboyson 3:e6a2c4579a4d 109 {
andrewboyson 3:e6a2c4579a4d 110 if (md->curlen > sizeof(md->buf)) return -1;
andrewboyson 3:e6a2c4579a4d 111
andrewboyson 3:e6a2c4579a4d 112 while (inlen > 0)
andrewboyson 3:e6a2c4579a4d 113 {
andrewboyson 3:e6a2c4579a4d 114 if (md->curlen == 0 && inlen >= BLOCK_SIZE)
andrewboyson 3:e6a2c4579a4d 115 {
andrewboyson 3:e6a2c4579a4d 116 if (compress(md, in) < 0) return -1;
andrewboyson 3:e6a2c4579a4d 117 md->length += BLOCK_SIZE * 8;
andrewboyson 3:e6a2c4579a4d 118 in += BLOCK_SIZE;
andrewboyson 3:e6a2c4579a4d 119 inlen -= BLOCK_SIZE;
andrewboyson 3:e6a2c4579a4d 120 }
andrewboyson 3:e6a2c4579a4d 121 else
andrewboyson 3:e6a2c4579a4d 122 {
andrewboyson 3:e6a2c4579a4d 123 int n = inlen < BLOCK_SIZE - md->curlen ? inlen : BLOCK_SIZE - md->curlen;
andrewboyson 3:e6a2c4579a4d 124 memcpy(md->buf + md->curlen, in, n);
andrewboyson 3:e6a2c4579a4d 125 md->curlen += n;
andrewboyson 3:e6a2c4579a4d 126 in += n;
andrewboyson 3:e6a2c4579a4d 127 inlen -= n;
andrewboyson 3:e6a2c4579a4d 128 if (md->curlen == BLOCK_SIZE)
andrewboyson 3:e6a2c4579a4d 129 {
andrewboyson 3:e6a2c4579a4d 130 if (compress(md, md->buf) < 0) return -1;
andrewboyson 3:e6a2c4579a4d 131 md->length += 8 * BLOCK_SIZE;
andrewboyson 3:e6a2c4579a4d 132 md->curlen = 0;
andrewboyson 3:e6a2c4579a4d 133 }
andrewboyson 3:e6a2c4579a4d 134 }
andrewboyson 3:e6a2c4579a4d 135 }
andrewboyson 3:e6a2c4579a4d 136 return 0;
andrewboyson 3:e6a2c4579a4d 137 }
andrewboyson 3:e6a2c4579a4d 138
andrewboyson 3:e6a2c4579a4d 139 int Sha256Finish(struct Sha256State *md, uint8_t *out) //returns 0 on success; -1 on failure
andrewboyson 3:e6a2c4579a4d 140 {
andrewboyson 3:e6a2c4579a4d 141 if (md->curlen >= sizeof(md->buf)) return -1;
andrewboyson 3:e6a2c4579a4d 142
andrewboyson 3:e6a2c4579a4d 143 // increase the length of the message
andrewboyson 3:e6a2c4579a4d 144 md->length += md->curlen * 8;
andrewboyson 3:e6a2c4579a4d 145
andrewboyson 3:e6a2c4579a4d 146 // append the '1' bit
andrewboyson 3:e6a2c4579a4d 147 md->buf[md->curlen++] = 0x80;
andrewboyson 3:e6a2c4579a4d 148
andrewboyson 3:e6a2c4579a4d 149 /* if the length is currently above 56 bytes we append zeros
andrewboyson 3:e6a2c4579a4d 150 * then compress. Then we can fall back to padding zeros and length
andrewboyson 3:e6a2c4579a4d 151 * encoding like normal.
andrewboyson 3:e6a2c4579a4d 152 */
andrewboyson 3:e6a2c4579a4d 153 if (md->curlen > 56)
andrewboyson 3:e6a2c4579a4d 154 {
andrewboyson 3:e6a2c4579a4d 155 while (md->curlen < 64) md->buf[md->curlen++] = 0;
andrewboyson 3:e6a2c4579a4d 156 compress(md, md->buf);
andrewboyson 3:e6a2c4579a4d 157 md->curlen = 0;
andrewboyson 3:e6a2c4579a4d 158 }
andrewboyson 3:e6a2c4579a4d 159 // pad upto 56 bytes of zeroes
andrewboyson 3:e6a2c4579a4d 160 while (md->curlen < 56) md->buf[md->curlen++] = 0;
andrewboyson 3:e6a2c4579a4d 161
andrewboyson 3:e6a2c4579a4d 162 // store length
andrewboyson 3:e6a2c4579a4d 163 *(md->buf + 56 + 0) = (uint8_t) (md->length >> 56);
andrewboyson 3:e6a2c4579a4d 164 *(md->buf + 56 + 1) = (uint8_t) (md->length >> 48);
andrewboyson 3:e6a2c4579a4d 165 *(md->buf + 56 + 2) = (uint8_t) (md->length >> 40);
andrewboyson 3:e6a2c4579a4d 166 *(md->buf + 56 + 3) = (uint8_t) (md->length >> 32);
andrewboyson 3:e6a2c4579a4d 167 *(md->buf + 56 + 4) = (uint8_t) (md->length >> 24);
andrewboyson 3:e6a2c4579a4d 168 *(md->buf + 56 + 5) = (uint8_t) (md->length >> 16);
andrewboyson 3:e6a2c4579a4d 169 *(md->buf + 56 + 6) = (uint8_t) (md->length >> 8);
andrewboyson 3:e6a2c4579a4d 170 *(md->buf + 56 + 7) = (uint8_t) (md->length >> 0);
andrewboyson 3:e6a2c4579a4d 171
andrewboyson 3:e6a2c4579a4d 172
andrewboyson 3:e6a2c4579a4d 173 compress(md, md->buf);
andrewboyson 3:e6a2c4579a4d 174
andrewboyson 3:e6a2c4579a4d 175 // copy output
andrewboyson 3:e6a2c4579a4d 176 for (int i = 0; i < 8; i++)
andrewboyson 3:e6a2c4579a4d 177 {
andrewboyson 3:e6a2c4579a4d 178 *(out + 4 * i + 0) = (uint8_t) (md->state[i] >> 24);
andrewboyson 3:e6a2c4579a4d 179 *(out + 4 * i + 1) = (uint8_t) (md->state[i] >> 16);
andrewboyson 3:e6a2c4579a4d 180 *(out + 4 * i + 2) = (uint8_t) (md->state[i] >> 8);
andrewboyson 3:e6a2c4579a4d 181 *(out + 4 * i + 3) = (uint8_t) (md->state[i] >> 0);
andrewboyson 3:e6a2c4579a4d 182 }
andrewboyson 3:e6a2c4579a4d 183
andrewboyson 3:e6a2c4579a4d 184 return 0;
andrewboyson 3:e6a2c4579a4d 185 }