mirror of
https://git.tartarus.org/simon/putty.git
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aa5bae8916
zero but does it in such a way that over-clever compilers hopefully won't helpfully optimise the call away if you do it just before freeing something or letting it go out of scope. Use this for (hopefully) every memset whose job is to destroy sensitive data that might otherwise be left lying around in the process's memory. [originally from svn r9586]
345 lines
10 KiB
C
345 lines
10 KiB
C
#include "ssh.h"
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/*
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* MD5 implementation for PuTTY. Written directly from the spec by
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* Simon Tatham.
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*/
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/* ----------------------------------------------------------------------
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* Core MD5 algorithm: processes 16-word blocks into a message digest.
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*/
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#define F(x,y,z) ( ((x) & (y)) | ((~(x)) & (z)) )
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#define G(x,y,z) ( ((x) & (z)) | ((~(z)) & (y)) )
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#define H(x,y,z) ( (x) ^ (y) ^ (z) )
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#define I(x,y,z) ( (y) ^ ( (x) | ~(z) ) )
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#define rol(x,y) ( ((x) << (y)) | (((uint32)x) >> (32-y)) )
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#define subround(f,w,x,y,z,k,s,ti) \
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w = x + rol(w + f(x,y,z) + block[k] + ti, s)
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static void MD5_Core_Init(MD5_Core_State * s)
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{
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s->h[0] = 0x67452301;
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s->h[1] = 0xefcdab89;
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s->h[2] = 0x98badcfe;
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s->h[3] = 0x10325476;
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}
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static void MD5_Block(MD5_Core_State * s, uint32 * block)
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{
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uint32 a, b, c, d;
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a = s->h[0];
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b = s->h[1];
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c = s->h[2];
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d = s->h[3];
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subround(F, a, b, c, d, 0, 7, 0xd76aa478);
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subround(F, d, a, b, c, 1, 12, 0xe8c7b756);
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subround(F, c, d, a, b, 2, 17, 0x242070db);
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subround(F, b, c, d, a, 3, 22, 0xc1bdceee);
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subround(F, a, b, c, d, 4, 7, 0xf57c0faf);
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subround(F, d, a, b, c, 5, 12, 0x4787c62a);
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subround(F, c, d, a, b, 6, 17, 0xa8304613);
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subround(F, b, c, d, a, 7, 22, 0xfd469501);
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subround(F, a, b, c, d, 8, 7, 0x698098d8);
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subround(F, d, a, b, c, 9, 12, 0x8b44f7af);
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subround(F, c, d, a, b, 10, 17, 0xffff5bb1);
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subround(F, b, c, d, a, 11, 22, 0x895cd7be);
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subround(F, a, b, c, d, 12, 7, 0x6b901122);
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subround(F, d, a, b, c, 13, 12, 0xfd987193);
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subround(F, c, d, a, b, 14, 17, 0xa679438e);
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subround(F, b, c, d, a, 15, 22, 0x49b40821);
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subround(G, a, b, c, d, 1, 5, 0xf61e2562);
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subround(G, d, a, b, c, 6, 9, 0xc040b340);
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subround(G, c, d, a, b, 11, 14, 0x265e5a51);
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subround(G, b, c, d, a, 0, 20, 0xe9b6c7aa);
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subround(G, a, b, c, d, 5, 5, 0xd62f105d);
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subround(G, d, a, b, c, 10, 9, 0x02441453);
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subround(G, c, d, a, b, 15, 14, 0xd8a1e681);
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subround(G, b, c, d, a, 4, 20, 0xe7d3fbc8);
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subround(G, a, b, c, d, 9, 5, 0x21e1cde6);
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subround(G, d, a, b, c, 14, 9, 0xc33707d6);
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subround(G, c, d, a, b, 3, 14, 0xf4d50d87);
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subround(G, b, c, d, a, 8, 20, 0x455a14ed);
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subround(G, a, b, c, d, 13, 5, 0xa9e3e905);
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subround(G, d, a, b, c, 2, 9, 0xfcefa3f8);
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subround(G, c, d, a, b, 7, 14, 0x676f02d9);
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subround(G, b, c, d, a, 12, 20, 0x8d2a4c8a);
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subround(H, a, b, c, d, 5, 4, 0xfffa3942);
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subround(H, d, a, b, c, 8, 11, 0x8771f681);
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subround(H, c, d, a, b, 11, 16, 0x6d9d6122);
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subround(H, b, c, d, a, 14, 23, 0xfde5380c);
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subround(H, a, b, c, d, 1, 4, 0xa4beea44);
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subround(H, d, a, b, c, 4, 11, 0x4bdecfa9);
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subround(H, c, d, a, b, 7, 16, 0xf6bb4b60);
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subround(H, b, c, d, a, 10, 23, 0xbebfbc70);
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subround(H, a, b, c, d, 13, 4, 0x289b7ec6);
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subround(H, d, a, b, c, 0, 11, 0xeaa127fa);
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subround(H, c, d, a, b, 3, 16, 0xd4ef3085);
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subround(H, b, c, d, a, 6, 23, 0x04881d05);
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subround(H, a, b, c, d, 9, 4, 0xd9d4d039);
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subround(H, d, a, b, c, 12, 11, 0xe6db99e5);
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subround(H, c, d, a, b, 15, 16, 0x1fa27cf8);
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subround(H, b, c, d, a, 2, 23, 0xc4ac5665);
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subround(I, a, b, c, d, 0, 6, 0xf4292244);
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subround(I, d, a, b, c, 7, 10, 0x432aff97);
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subround(I, c, d, a, b, 14, 15, 0xab9423a7);
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subround(I, b, c, d, a, 5, 21, 0xfc93a039);
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subround(I, a, b, c, d, 12, 6, 0x655b59c3);
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subround(I, d, a, b, c, 3, 10, 0x8f0ccc92);
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subround(I, c, d, a, b, 10, 15, 0xffeff47d);
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subround(I, b, c, d, a, 1, 21, 0x85845dd1);
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subround(I, a, b, c, d, 8, 6, 0x6fa87e4f);
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subround(I, d, a, b, c, 15, 10, 0xfe2ce6e0);
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subround(I, c, d, a, b, 6, 15, 0xa3014314);
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subround(I, b, c, d, a, 13, 21, 0x4e0811a1);
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subround(I, a, b, c, d, 4, 6, 0xf7537e82);
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subround(I, d, a, b, c, 11, 10, 0xbd3af235);
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subround(I, c, d, a, b, 2, 15, 0x2ad7d2bb);
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subround(I, b, c, d, a, 9, 21, 0xeb86d391);
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s->h[0] += a;
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s->h[1] += b;
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s->h[2] += c;
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s->h[3] += d;
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}
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/* ----------------------------------------------------------------------
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* Outer MD5 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 MD5 algorithm.
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*/
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#define BLKSIZE 64
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void MD5Init(struct MD5Context *s)
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{
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MD5_Core_Init(&s->core);
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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 MD5Update(struct MD5Context *s, unsigned char const *p, unsigned 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 + len < BLKSIZE) {
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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 >= BLKSIZE) {
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memcpy(s->block + s->blkused, q, BLKSIZE - s->blkused);
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q += BLKSIZE - s->blkused;
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len -= BLKSIZE - s->blkused;
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/* Now process the block. Gather bytes little-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 + 3]) << 24) |
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(((uint32) s->block[i * 4 + 2]) << 16) |
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(((uint32) s->block[i * 4 + 1]) << 8) |
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(((uint32) s->block[i * 4 + 0]) << 0);
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}
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MD5_Block(&s->core, 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 MD5Final(unsigned char output[16], struct MD5Context *s)
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{
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int i;
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unsigned 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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MD5Update(s, c, pad);
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c[7] = (lenhi >> 24) & 0xFF;
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c[6] = (lenhi >> 16) & 0xFF;
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c[5] = (lenhi >> 8) & 0xFF;
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c[4] = (lenhi >> 0) & 0xFF;
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c[3] = (lenlo >> 24) & 0xFF;
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c[2] = (lenlo >> 16) & 0xFF;
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c[1] = (lenlo >> 8) & 0xFF;
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c[0] = (lenlo >> 0) & 0xFF;
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MD5Update(s, c, 8);
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for (i = 0; i < 4; i++) {
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output[4 * i + 3] = (s->core.h[i] >> 24) & 0xFF;
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output[4 * i + 2] = (s->core.h[i] >> 16) & 0xFF;
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output[4 * i + 1] = (s->core.h[i] >> 8) & 0xFF;
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output[4 * i + 0] = (s->core.h[i] >> 0) & 0xFF;
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}
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}
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void MD5Simple(void const *p, unsigned len, unsigned char output[16])
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{
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struct MD5Context s;
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MD5Init(&s);
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MD5Update(&s, (unsigned char const *)p, len);
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MD5Final(output, &s);
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}
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/* ----------------------------------------------------------------------
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* The above is the MD5 algorithm itself. Now we implement the
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* HMAC wrapper on it.
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*
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* Some of these functions are exported directly, because they are
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* useful elsewhere (SOCKS5 CHAP authentication uses HMAC-MD5).
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*/
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void *hmacmd5_make_context(void)
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{
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return snewn(3, struct MD5Context);
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}
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void hmacmd5_free_context(void *handle)
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{
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sfree(handle);
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}
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void hmacmd5_key(void *handle, void const *keyv, int len)
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{
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struct MD5Context *keys = (struct MD5Context *)handle;
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unsigned char foo[64];
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unsigned char const *key = (unsigned char const *)keyv;
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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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MD5Init(&keys[0]);
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MD5Update(&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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MD5Init(&keys[1]);
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MD5Update(&keys[1], foo, 64);
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smemclr(foo, 64); /* burn the evidence */
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}
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static void hmacmd5_key_16(void *handle, unsigned char *key)
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{
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hmacmd5_key(handle, key, 16);
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}
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static void hmacmd5_start(void *handle)
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{
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struct MD5Context *keys = (struct MD5Context *)handle;
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keys[2] = keys[0]; /* structure copy */
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}
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static void hmacmd5_bytes(void *handle, unsigned char const *blk, int len)
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{
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struct MD5Context *keys = (struct MD5Context *)handle;
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MD5Update(&keys[2], blk, len);
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}
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static void hmacmd5_genresult(void *handle, unsigned char *hmac)
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{
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struct MD5Context *keys = (struct MD5Context *)handle;
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struct MD5Context s;
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unsigned char intermediate[16];
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s = keys[2]; /* structure copy */
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MD5Final(intermediate, &s);
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s = keys[1]; /* structure copy */
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MD5Update(&s, intermediate, 16);
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MD5Final(hmac, &s);
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}
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static int hmacmd5_verresult(void *handle, unsigned char const *hmac)
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{
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unsigned char correct[16];
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hmacmd5_genresult(handle, correct);
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return !memcmp(correct, hmac, 16);
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}
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static void hmacmd5_do_hmac_internal(void *handle,
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unsigned char const *blk, int len,
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unsigned char const *blk2, int len2,
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unsigned char *hmac)
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{
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hmacmd5_start(handle);
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hmacmd5_bytes(handle, blk, len);
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if (blk2) hmacmd5_bytes(handle, blk2, len2);
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hmacmd5_genresult(handle, hmac);
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}
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void hmacmd5_do_hmac(void *handle, unsigned char const *blk, int len,
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unsigned char *hmac)
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{
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hmacmd5_do_hmac_internal(handle, blk, len, NULL, 0, hmac);
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}
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static void hmacmd5_do_hmac_ssh(void *handle, unsigned char const *blk, int len,
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unsigned long seq, unsigned char *hmac)
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{
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unsigned char seqbuf[16];
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seqbuf[0] = (unsigned char) ((seq >> 24) & 0xFF);
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seqbuf[1] = (unsigned char) ((seq >> 16) & 0xFF);
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seqbuf[2] = (unsigned char) ((seq >> 8) & 0xFF);
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seqbuf[3] = (unsigned char) ((seq) & 0xFF);
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hmacmd5_do_hmac_internal(handle, seqbuf, 4, blk, len, hmac);
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}
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static void hmacmd5_generate(void *handle, unsigned char *blk, int len,
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unsigned long seq)
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{
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hmacmd5_do_hmac_ssh(handle, blk, len, seq, blk + len);
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}
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static int hmacmd5_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[16];
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hmacmd5_do_hmac_ssh(handle, blk, len, seq, correct);
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return !memcmp(correct, blk + len, 16);
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}
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const struct ssh_mac ssh_hmac_md5 = {
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hmacmd5_make_context, hmacmd5_free_context, hmacmd5_key_16,
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hmacmd5_generate, hmacmd5_verify,
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hmacmd5_start, hmacmd5_bytes, hmacmd5_genresult, hmacmd5_verresult,
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"hmac-md5",
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16,
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"HMAC-MD5"
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};
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