text: /*
   * SHA1 hash algorithm. Used in SSH-2 as a MAC, and the transform is
   * also used as a `stirring' function for the PuTTY random number
   * pool. Implemented directly from the specification by Simon
   * Tatham.
   */
  
  #include "ssh.h"
  
  /* ----------------------------------------------------------------------
   * Core SHA algorithm: processes 16-word blocks into a message digest.
   */
  
  #define rol(x,y) ( ((x) << (y)) | (((uint32)x) >> (32-y)) )
  
  static void SHA_Core_Init(uint32 h[5])
  {
      h[0] = 0x67452301;
      h[1] = 0xefcdab89;
      h[2] = 0x98badcfe;
      h[3] = 0x10325476;
      h[4] = 0xc3d2e1f0;
  }
  
  void SHATransform(word32 * digest, word32 * block)
  {
      word32 w[80];
      word32 a, b, c, d, e;
      int t;
  
      for (t = 0; t < 16; t++)
  	w[t] = block[t];
  
      for (t = 16; t < 80; t++) {
  	word32 tmp = w[t - 3] ^ w[t - 8] ^ w[t - 14] ^ w[t - 16];
  	w[t] = rol(tmp, 1);
      }
  
      a = digest[0];
      b = digest[1];
      c = digest[2];
      d = digest[3];
      e = digest[4];
  
      for (t = 0; t < 20; t++) {
  	word32 tmp =
  	    rol(a, 5) + ((b & c) | (d & ~b)) + e + w[t] + 0x5a827999;
  	e = d;
  	d = c;
  	c = rol(b, 30);
  	b = a;
  	a = tmp;
      }
      for (t = 20; t < 40; t++) {
  	word32 tmp = rol(a, 5) + (b ^ c ^ d) + e + w[t] + 0x6ed9eba1;
  	e = d;
  	d = c;
  	c = rol(b, 30);
  	b = a;
  	a = tmp;
      }
      for (t = 40; t < 60; t++) {
  	word32 tmp = rol(a,
  			 5) + ((b & c) | (b & d) | (c & d)) + e + w[t] +
  	    0x8f1bbcdc;
  	e = d;
  	d = c;
  	c = rol(b, 30);
  	b = a;
  	a = tmp;
      }
      for (t = 60; t < 80; t++) {
  	word32 tmp = rol(a, 5) + (b ^ c ^ d) + e + w[t] + 0xca62c1d6;
  	e = d;
  	d = c;
  	c = rol(b, 30);
  	b = a;
  	a = tmp;
      }
  
      digest[0] += a;
      digest[1] += b;
      digest[2] += c;
      digest[3] += d;
      digest[4] += e;
  }
  
  /* ----------------------------------------------------------------------
   * Outer SHA algorithm: take an arbitrary length byte string,
   * convert it into 16-word blocks with the prescribed padding at
   * the end, and pass those blocks to the core SHA algorithm.
   */
  
  void SHA_Init(SHA_State * s)
  {
      SHA_Core_Init(s->h);
      s->blkused = 0;
      s->lenhi = s->lenlo = 0;
  }
  
  void SHA_Bytes(SHA_State * s, void *p, int len)
  {
      unsigned char *q = (unsigned char *) p;
      uint32 wordblock[16];
      uint32 lenw = len;
      int i;
  
      /*
       * Update the length field.
       */
      s->lenlo += lenw;
      s->lenhi += (s->lenlo < lenw);
  
      if (s->blkused && s->blkused + len < 64) {
  	/*
  	 * Trivial case: just add to the block.
  	 */
  	memcpy(s->block + s->blkused, q, len);
  	s->blkused += len;
      } else {
  	/*
  	 * We must complete and process at least one block.
  	 */
  	while (s->blkused + len >= 64) {
  	    memcpy(s->block + s->blkused, q, 64 - s->blkused);
  	    q += 64 - s->blkused;
  	    len -= 64 - s->blkused;
  	    /* Now process the block. Gather bytes big-endian into words */
  	    for (i = 0; i < 16; i++) {
  		wordblock[i] =
  		    (((uint32) s->block[i * 4 + 0]) << 24) |
  		    (((uint32) s->block[i * 4 + 1]) << 16) |
  		    (((uint32) s->block[i * 4 + 2]) << 8) |
  		    (((uint32) s->block[i * 4 + 3]) << 0);
  	    }
  	    SHATransform(s->h, wordblock);
  	    s->blkused = 0;
  	}
  	memcpy(s->block, q, len);
  	s->blkused = len;
      }
  }
  
  void SHA_Final(SHA_State * s, unsigned char *output)
  {
      int i;
      int pad;
      unsigned char c[64];
      uint32 lenhi, lenlo;
  
      if (s->blkused >= 56)
  	pad = 56 + 64 - s->blkused;
      else
  	pad = 56 - s->blkused;
  
      lenhi = (s->lenhi << 3) | (s->lenlo >> (32 - 3));
      lenlo = (s->lenlo << 3);
  
      memset(c, 0, pad);
      c[0] = 0x80;
      SHA_Bytes(s, &c, pad);
  
      c[0] = (lenhi >> 24) & 0xFF;
      c[1] = (lenhi >> 16) & 0xFF;
      c[2] = (lenhi >> 8) & 0xFF;
      c[3] = (lenhi >> 0) & 0xFF;
      c[4] = (lenlo >> 24) & 0xFF;
      c[5] = (lenlo >> 16) & 0xFF;
      c[6] = (lenlo >> 8) & 0xFF;
      c[7] = (lenlo >> 0) & 0xFF;
  
      SHA_Bytes(s, &c, 8);
  
      for (i = 0; i < 5; i++) {
  	output[i * 4] = (s->h[i] >> 24) & 0xFF;
  	output[i * 4 + 1] = (s->h[i] >> 16) & 0xFF;
  	output[i * 4 + 2] = (s->h[i] >> 8) & 0xFF;
  	output[i * 4 + 3] = (s->h[i]) & 0xFF;
      }
  }
  
  void SHA_Simple(void *p, int len, unsigned char *output)
  {
      SHA_State s;
  
      SHA_Init(&s);
      SHA_Bytes(&s, p, len);
      SHA_Final(&s, output);
  }
  
  /*
   * Thin abstraction for things where hashes are pluggable.
   */
  
  static void *sha1_init(void)
  {
      SHA_State *s;
  
      s = snew(SHA_State);
      SHA_Init(s);
      return s;
  }
  
  static void sha1_bytes(void *handle, void *p, int len)
  {
      SHA_State *s = handle;
  
      SHA_Bytes(s, p, len);
  }
  
  static void sha1_final(void *handle, unsigned char *output)
  {
      SHA_State *s = handle;
  
      SHA_Final(s, output);
      sfree(s);
  }
  
  const struct ssh_hash ssh_sha1 = {
      sha1_init, sha1_bytes, sha1_final, 20, "SHA-1"
  };
  
  /* ----------------------------------------------------------------------
   * The above is the SHA-1 algorithm itself. Now we implement the
   * HMAC wrapper on it.
   */
  
  static void *sha1_make_context(void)
  {
      return snewn(3, SHA_State);
  }
  
  static void sha1_free_context(void *handle)
  {
      sfree(handle);
  }
  
  static void sha1_key_internal(void *handle, unsigned char *key, int len)
  {
      SHA_State *keys = (SHA_State *)handle;
      unsigned char foo[64];
      int i;
  
      memset(foo, 0x36, 64);
      for (i = 0; i < len && i < 64; i++)
  	foo[i] ^= key[i];
      SHA_Init(&keys[0]);
      SHA_Bytes(&keys[0], foo, 64);
  
      memset(foo, 0x5C, 64);
      for (i = 0; i < len && i < 64; i++)
  	foo[i] ^= key[i];
      SHA_Init(&keys[1]);
      SHA_Bytes(&keys[1], foo, 64);
  
      memset(foo, 0, 64);		       /* burn the evidence */
  }
  
  static void sha1_key(void *handle, unsigned char *key)
  {
      sha1_key_internal(handle, key, 20);
  }
  
  static void sha1_key_buggy(void *handle, unsigned char *key)
  {
      sha1_key_internal(handle, key, 16);
  }
  
  static void hmacsha1_start(void *handle)
  {
      SHA_State *keys = (SHA_State *)handle;
  
      keys[2] = keys[0];		      /* structure copy */
  }
  
  static void hmacsha1_bytes(void *handle, unsigned char const *blk, int len)
  {
      SHA_State *keys = (SHA_State *)handle;
      SHA_Bytes(&keys[2], (void *)blk, len);
  }
  
  static void hmacsha1_genresult(void *handle, unsigned char *hmac)
  {
      SHA_State *keys = (SHA_State *)handle;
      SHA_State s;
      unsigned char intermediate[20];
  
      s = keys[2];		       /* structure copy */
      SHA_Final(&s, intermediate);
      s = keys[1];		       /* structure copy */
      SHA_Bytes(&s, intermediate, 20);
      SHA_Final(&s, hmac);
  }
  
  static void sha1_do_hmac(void *handle, unsigned char *blk, int len,
  			 unsigned long seq, unsigned char *hmac)
  {
      unsigned char seqbuf[4];
  
      seqbuf[0] = (unsigned char) ((seq >> 24) & 0xFF);
      seqbuf[1] = (unsigned char) ((seq >> 16) & 0xFF);
      seqbuf[2] = (unsigned char) ((seq >> 8) & 0xFF);
      seqbuf[3] = (unsigned char) ((seq) & 0xFF);
  
      hmacsha1_start(handle);
      hmacsha1_bytes(handle, seqbuf, 4);
      hmacsha1_bytes(handle, blk, len);
      hmacsha1_genresult(handle, hmac);
  }
  
  static void sha1_generate(void *handle, unsigned char *blk, int len,
  			  unsigned long seq)
  {
      sha1_do_hmac(handle, blk, len, seq, blk + len);
  }
  
  static int hmacsha1_verresult(void *handle, unsigned char const *hmac)
  {
      unsigned char correct[20];
      hmacsha1_genresult(handle, correct);
      return !memcmp(correct, hmac, 20);
  }
  
  static int sha1_verify(void *handle, unsigned char *blk, int len,
  		       unsigned long seq)
  {
      unsigned char correct[20];
      sha1_do_hmac(handle, blk, len, seq, correct);
      return !memcmp(correct, blk + len, 20);
  }
  
  static void hmacsha1_96_genresult(void *handle, unsigned char *hmac)
  {
      unsigned char full[20];
      hmacsha1_genresult(handle, full);
      memcpy(hmac, full, 12);
  }
  
  static void sha1_96_generate(void *handle, unsigned char *blk, int len,
  			     unsigned long seq)
  {
      unsigned char full[20];
      sha1_do_hmac(handle, blk, len, seq, full);
      memcpy(blk + len, full, 12);
  }
  
  static int hmacsha1_96_verresult(void *handle, unsigned char const *hmac)
  {
      unsigned char correct[20];
      hmacsha1_genresult(handle, correct);
      return !memcmp(correct, hmac, 12);
  }
  
  static int sha1_96_verify(void *handle, unsigned char *blk, int len,
  		       unsigned long seq)
  {
      unsigned char correct[20];
      sha1_do_hmac(handle, blk, len, seq, correct);
      return !memcmp(correct, blk + len, 12);
  }
  
  void hmac_sha1_simple(void *key, int keylen, void *data, int datalen,
  		      unsigned char *output) {
      SHA_State states[2];
      unsigned char intermediate[20];
  
      sha1_key_internal(states, key, keylen);
      SHA_Bytes(&states[0], data, datalen);
      SHA_Final(&states[0], intermediate);
  
      SHA_Bytes(&states[1], intermediate, 20);
      SHA_Final(&states[1], output);
  }
  
  const struct ssh_mac ssh_hmac_sha1 = {
      sha1_make_context, sha1_free_context, sha1_key,
      sha1_generate, sha1_verify,
      hmacsha1_start, hmacsha1_bytes, hmacsha1_genresult, hmacsha1_verresult,
      "hmac-sha1",
      20,
      "HMAC-SHA1"
  };
  
  const struct ssh_mac ssh_hmac_sha1_96 = {
      sha1_make_context, sha1_free_context, sha1_key,
      sha1_96_generate, sha1_96_verify,
      hmacsha1_start, hmacsha1_bytes,
      hmacsha1_96_genresult, hmacsha1_96_verresult,
      "hmac-sha1-96",
      12,
      "HMAC-SHA1-96"
  };
  
  const struct ssh_mac ssh_hmac_sha1_buggy = {
      sha1_make_context, sha1_free_context, sha1_key_buggy,
      sha1_generate, sha1_verify,
      hmacsha1_start, hmacsha1_bytes, hmacsha1_genresult, hmacsha1_verresult,
      "hmac-sha1",
      20,
      "bug-compatible HMAC-SHA1"
  };
  
  const struct ssh_mac ssh_hmac_sha1_96_buggy = {
      sha1_make_context, sha1_free_context, sha1_key_buggy,
      sha1_96_generate, sha1_96_verify,
      hmacsha1_start, hmacsha1_bytes,
      hmacsha1_96_genresult, hmacsha1_96_verresult,
      "hmac-sha1-96",
      12,
      "bug-compatible HMAC-SHA1-96"
  };
  