зеркало из https://github.com/github/putty.git
300 строки
6.8 KiB
C
300 строки
6.8 KiB
C
/*
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* SHA1 hash algorithm. Used in SSH2 as a MAC, and the transform is
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* also used as a `stirring' function for the PuTTY random number
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* pool. Implemented directly from the specification by Simon
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* Tatham.
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*/
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#include "ssh.h"
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/* ----------------------------------------------------------------------
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* Core SHA algorithm: processes 16-word blocks into a message digest.
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*/
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#define rol(x,y) ( ((x) << (y)) | (((uint32)x) >> (32-y)) )
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static void SHA_Core_Init(uint32 h[5])
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{
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h[0] = 0x67452301;
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h[1] = 0xefcdab89;
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h[2] = 0x98badcfe;
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h[3] = 0x10325476;
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h[4] = 0xc3d2e1f0;
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}
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void SHATransform(word32 * digest, word32 * block)
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{
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word32 w[80];
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word32 a, b, c, d, e;
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int t;
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for (t = 0; t < 16; t++)
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w[t] = block[t];
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for (t = 16; t < 80; t++) {
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word32 tmp = w[t - 3] ^ w[t - 8] ^ w[t - 14] ^ w[t - 16];
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w[t] = rol(tmp, 1);
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}
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a = digest[0];
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b = digest[1];
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c = digest[2];
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d = digest[3];
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e = digest[4];
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for (t = 0; t < 20; t++) {
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word32 tmp =
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rol(a, 5) + ((b & c) | (d & ~b)) + e + w[t] + 0x5a827999;
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e = d;
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d = c;
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c = rol(b, 30);
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b = a;
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a = tmp;
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}
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for (t = 20; t < 40; t++) {
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word32 tmp = rol(a, 5) + (b ^ c ^ d) + e + w[t] + 0x6ed9eba1;
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e = d;
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d = c;
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c = rol(b, 30);
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b = a;
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a = tmp;
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}
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for (t = 40; t < 60; t++) {
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word32 tmp = rol(a,
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5) + ((b & c) | (b & d) | (c & d)) + e + w[t] +
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0x8f1bbcdc;
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e = d;
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d = c;
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c = rol(b, 30);
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b = a;
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a = tmp;
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}
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for (t = 60; t < 80; t++) {
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word32 tmp = rol(a, 5) + (b ^ c ^ d) + e + w[t] + 0xca62c1d6;
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e = d;
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d = c;
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c = rol(b, 30);
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b = a;
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a = tmp;
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}
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digest[0] += a;
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digest[1] += b;
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digest[2] += c;
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digest[3] += d;
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digest[4] += e;
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}
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/* ----------------------------------------------------------------------
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* Outer SHA algorithm: take an arbitrary length byte string,
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* convert it into 16-word blocks with the prescribed padding at
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* the end, and pass those blocks to the core SHA algorithm.
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*/
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void SHA_Init(SHA_State * s)
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{
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SHA_Core_Init(s->h);
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s->blkused = 0;
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s->lenhi = s->lenlo = 0;
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}
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void SHA_Bytes(SHA_State * s, void *p, int len)
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{
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unsigned char *q = (unsigned char *) p;
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uint32 wordblock[16];
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uint32 lenw = len;
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int i;
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/*
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* Update the length field.
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*/
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s->lenlo += lenw;
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s->lenhi += (s->lenlo < lenw);
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if (s->blkused && s->blkused + len < 64) {
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/*
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* Trivial case: just add to the block.
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*/
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memcpy(s->block + s->blkused, q, len);
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s->blkused += len;
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} else {
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/*
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* We must complete and process at least one block.
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*/
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while (s->blkused + len >= 64) {
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memcpy(s->block + s->blkused, q, 64 - s->blkused);
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q += 64 - s->blkused;
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len -= 64 - s->blkused;
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/* Now process the block. Gather bytes big-endian into words */
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for (i = 0; i < 16; i++) {
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wordblock[i] =
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(((uint32) s->block[i * 4 + 0]) << 24) |
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(((uint32) s->block[i * 4 + 1]) << 16) |
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(((uint32) s->block[i * 4 + 2]) << 8) |
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(((uint32) s->block[i * 4 + 3]) << 0);
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}
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SHATransform(s->h, wordblock);
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s->blkused = 0;
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}
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memcpy(s->block, q, len);
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s->blkused = len;
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}
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}
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void SHA_Final(SHA_State * s, unsigned char *output)
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{
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int i;
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int pad;
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unsigned char c[64];
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uint32 lenhi, lenlo;
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if (s->blkused >= 56)
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pad = 56 + 64 - s->blkused;
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else
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pad = 56 - s->blkused;
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lenhi = (s->lenhi << 3) | (s->lenlo >> (32 - 3));
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lenlo = (s->lenlo << 3);
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memset(c, 0, pad);
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c[0] = 0x80;
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SHA_Bytes(s, &c, pad);
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c[0] = (lenhi >> 24) & 0xFF;
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c[1] = (lenhi >> 16) & 0xFF;
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c[2] = (lenhi >> 8) & 0xFF;
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c[3] = (lenhi >> 0) & 0xFF;
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c[4] = (lenlo >> 24) & 0xFF;
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c[5] = (lenlo >> 16) & 0xFF;
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c[6] = (lenlo >> 8) & 0xFF;
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c[7] = (lenlo >> 0) & 0xFF;
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SHA_Bytes(s, &c, 8);
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for (i = 0; i < 5; i++) {
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output[i * 4] = (s->h[i] >> 24) & 0xFF;
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output[i * 4 + 1] = (s->h[i] >> 16) & 0xFF;
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output[i * 4 + 2] = (s->h[i] >> 8) & 0xFF;
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output[i * 4 + 3] = (s->h[i]) & 0xFF;
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}
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}
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void SHA_Simple(void *p, int len, unsigned char *output)
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{
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SHA_State s;
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SHA_Init(&s);
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SHA_Bytes(&s, p, len);
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SHA_Final(&s, output);
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}
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/* ----------------------------------------------------------------------
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* The above is the SHA-1 algorithm itself. Now we implement the
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* HMAC wrapper on it.
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*/
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static void *sha1_make_context(void)
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{
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return snewn(2, SHA_State);
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}
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static void sha1_free_context(void *handle)
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{
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sfree(handle);
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}
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static void sha1_key_internal(void *handle, unsigned char *key, int len)
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{
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SHA_State *keys = (SHA_State *)handle;
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unsigned char foo[64];
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int i;
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memset(foo, 0x36, 64);
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for (i = 0; i < len && i < 64; i++)
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foo[i] ^= key[i];
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SHA_Init(&keys[0]);
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SHA_Bytes(&keys[0], foo, 64);
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memset(foo, 0x5C, 64);
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for (i = 0; i < len && i < 64; i++)
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foo[i] ^= key[i];
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SHA_Init(&keys[1]);
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SHA_Bytes(&keys[1], foo, 64);
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memset(foo, 0, 64); /* burn the evidence */
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}
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static void sha1_key(void *handle, unsigned char *key)
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{
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sha1_key_internal(handle, key, 20);
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}
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static void sha1_key_buggy(void *handle, unsigned char *key)
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{
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sha1_key_internal(handle, key, 16);
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}
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static void sha1_do_hmac(void *handle, unsigned char *blk, int len,
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unsigned long seq, unsigned char *hmac)
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{
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SHA_State *keys = (SHA_State *)handle;
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SHA_State s;
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unsigned char intermediate[20];
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intermediate[0] = (unsigned char) ((seq >> 24) & 0xFF);
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intermediate[1] = (unsigned char) ((seq >> 16) & 0xFF);
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intermediate[2] = (unsigned char) ((seq >> 8) & 0xFF);
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intermediate[3] = (unsigned char) ((seq) & 0xFF);
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s = keys[0]; /* structure copy */
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SHA_Bytes(&s, intermediate, 4);
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SHA_Bytes(&s, blk, len);
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SHA_Final(&s, intermediate);
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s = keys[1]; /* structure copy */
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SHA_Bytes(&s, intermediate, 20);
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SHA_Final(&s, hmac);
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}
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static void sha1_generate(void *handle, unsigned char *blk, int len,
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unsigned long seq)
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{
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sha1_do_hmac(handle, blk, len, seq, blk + len);
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}
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static int sha1_verify(void *handle, unsigned char *blk, int len,
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unsigned long seq)
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{
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unsigned char correct[20];
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sha1_do_hmac(handle, blk, len, seq, correct);
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return !memcmp(correct, blk + len, 20);
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}
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void hmac_sha1_simple(void *key, int keylen, void *data, int datalen,
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unsigned char *output) {
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SHA_State states[2];
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unsigned char intermediate[20];
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sha1_key_internal(states, key, keylen);
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SHA_Bytes(&states[0], data, datalen);
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SHA_Final(&states[0], intermediate);
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SHA_Bytes(&states[1], intermediate, 20);
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SHA_Final(&states[1], output);
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}
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const struct ssh_mac ssh_sha1 = {
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sha1_make_context, sha1_free_context, sha1_key,
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sha1_generate, sha1_verify,
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"hmac-sha1",
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20,
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"HMAC-SHA1"
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};
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const struct ssh_mac ssh_sha1_buggy = {
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sha1_make_context, sha1_free_context, sha1_key_buggy,
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sha1_generate, sha1_verify,
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"hmac-sha1",
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20,
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"bug-compatible HMAC-SHA1"
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};
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