--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/chc.c	Sun Dec 19 11:34:45 2004 +0000
@@ -0,0 +1,261 @@
+/* LibTomCrypt, modular cryptographic library -- Tom St Denis
+ *
+ * LibTomCrypt is a library that provides various cryptographic
+ * algorithms in a highly modular and flexible manner.
+ *
+ * The library is free for all purposes without any express
+ * guarantee it works.
+ *
+ * Tom St Denis, [email protected], http://libtomcrypt.org
+ */
+
+#include "mycrypt.h"
+
+#ifdef CHC_HASH
+
+#define UNDEFED_HASH  -17
+
+/* chc settings */
+static int            cipher_idx=UNDEFED_HASH,        /* which cipher */
+                      cipher_blocksize;               /* blocksize of cipher */
+
+
+const struct _hash_descriptor chc_desc = {
+   "chc_hash", 12, 0, 0, { 0 }, 0,
+   &chc_init,
+   &chc_process,
+   &chc_done,
+   &chc_test
+};
+
+/* initialize the CHC state with a given cipher */
+int chc_register(int cipher)
+{
+   int err, kl, idx;
+
+   if ((err = cipher_is_valid(cipher)) != CRYPT_OK) {
+      return err;
+   }
+
+   /* will it be valid? */
+   kl = cipher_descriptor[cipher].block_length;
+
+   /* must be >64 bit block */
+   if (kl <= 8) {
+      return CRYPT_INVALID_CIPHER;
+   }
+
+   /* can we use the ideal keysize? */
+   if ((err = cipher_descriptor[cipher].keysize(&kl)) != CRYPT_OK) {
+      return err;
+   }
+   /* we require that key size == block size be a valid choice */
+   if (kl != cipher_descriptor[cipher].block_length) {
+      return CRYPT_INVALID_CIPHER;
+   }
+
+   /* determine if chc_hash has been register_hash'ed already */
+   if ((err = hash_is_valid(idx = find_hash("chc_hash"))) != CRYPT_OK) {
+      return err;
+   }
+
+   /* store into descriptor */
+   hash_descriptor[idx].hashsize  = 
+   hash_descriptor[idx].blocksize = cipher_descriptor[cipher].block_length;
+
+   /* store the idx and block size */
+   cipher_idx       = cipher;
+   cipher_blocksize = cipher_descriptor[cipher].block_length;
+   return CRYPT_OK;
+}
+
+/* "hash init" is simply encrypt 0 with the 0 key.  Simple way to make an IV */
+int chc_init(hash_state *md)
+{
+   symmetric_key *key;
+   unsigned char  buf[MAXBLOCKSIZE];
+   int            err;
+ 
+   _ARGCHK(md != NULL);
+
+   /* is the cipher valid? */
+   if ((err = cipher_is_valid(cipher_idx)) != CRYPT_OK) {
+      return err;
+   }
+
+   if (cipher_blocksize != cipher_descriptor[cipher_idx].block_length) {
+      return CRYPT_INVALID_CIPHER;
+   }
+
+   if ((key = XMALLOC(sizeof(*key))) == NULL) {
+      return CRYPT_MEM;
+   }
+
+   /* zero key and what not */   
+   zeromem(buf, cipher_blocksize);
+   if ((err = cipher_descriptor[cipher_idx].setup(buf, cipher_blocksize, 0, key)) != CRYPT_OK) {
+      XFREE(key);
+      return err;
+   }
+
+   /* encrypt zero block */
+   cipher_descriptor[cipher_idx].ecb_encrypt(buf, md->chc.state, key);
+
+   /* zero other members */
+   md->chc.length = 0;
+   md->chc.curlen = 0;
+   zeromem(md->chc.buf, sizeof(md->chc.buf));
+   XFREE(key);
+   return CRYPT_OK;
+}
+
+/* 
+   key    <= state
+   T0,T1  <= block
+   T0     <= encrypt T0
+   state  <= state xor T0 xor T1
+*/
+static int chc_compress(hash_state *md, unsigned char *buf)
+{
+   unsigned char  T[2][MAXBLOCKSIZE];
+   symmetric_key *key;
+   int            err, x;
+
+   if ((key = XMALLOC(sizeof(*key))) == NULL) {
+      return CRYPT_MEM;
+   }
+   if ((err = cipher_descriptor[cipher_idx].setup(md->chc.state, cipher_blocksize, 0, key)) != CRYPT_OK) {
+      XFREE(key);
+      return err;
+   }
+   memcpy(T[1], buf, cipher_blocksize);
+   cipher_descriptor[cipher_idx].ecb_encrypt(buf, T[0], key);
+   for (x = 0; x < cipher_blocksize; x++) {
+       md->chc.state[x] ^= T[0][x] ^ T[1][x];
+   }
+   XFREE(key);
+#ifdef CLEAN_STACK
+   zeromem(T, sizeof(T));
+   zeromem(&key, sizeof(key));
+#endif
+   return CRYPT_OK;
+}
+
+HASH_PROCESS(_chc_process, chc_compress, chc, (unsigned long)cipher_blocksize)
+
+int chc_process(hash_state * md, const unsigned char *buf, unsigned long len)
+{
+   int err;
+
+   _ARGCHK(md   != NULL);
+   _ARGCHK(buf  != NULL);
+
+   /* is the cipher valid? */
+   if ((err = cipher_is_valid(cipher_idx)) != CRYPT_OK) {
+      return err;
+   }
+   if (cipher_blocksize != cipher_descriptor[cipher_idx].block_length) {
+      return CRYPT_INVALID_CIPHER;
+   }
+
+   return _chc_process(md, buf, len);
+}
+
+int chc_done(hash_state *md, unsigned char *buf)
+{
+    int err;
+
+    _ARGCHK(md   != NULL);
+    _ARGCHK(buf  != NULL);
+
+    /* is the cipher valid? */
+    if ((err = cipher_is_valid(cipher_idx)) != CRYPT_OK) {
+       return err;
+    }
+    if (cipher_blocksize != cipher_descriptor[cipher_idx].block_length) {
+       return CRYPT_INVALID_CIPHER;
+    }
+
+    if (md->chc.curlen >= sizeof(md->chc.buf)) {
+       return CRYPT_INVALID_ARG;
+    }
+
+    /* increase the length of the message */
+    md->chc.length += md->chc.curlen * 8;
+
+    /* append the '1' bit */
+    md->chc.buf[md->chc.curlen++] = (unsigned char)0x80;
+
+    /* if the length is currently above l-8 bytes we append zeros
+     * then compress.  Then we can fall back to padding zeros and length
+     * encoding like normal.
+     */
+    if (md->chc.curlen > (unsigned long)(cipher_blocksize - 8)) {
+        while (md->chc.curlen < (unsigned long)cipher_blocksize) {
+            md->chc.buf[md->chc.curlen++] = (unsigned char)0;
+        }
+        chc_compress(md, md->chc.buf);
+        md->chc.curlen = 0;
+    }
+
+    /* pad upto l-8 bytes of zeroes */
+    while (md->chc.curlen < (unsigned long)(cipher_blocksize - 8)) {
+        md->chc.buf[md->chc.curlen++] = (unsigned char)0;
+    }
+
+    /* store length */
+    STORE64L(md->chc.length, md->chc.buf+(cipher_blocksize-8));
+    chc_compress(md, md->chc.buf);
+
+    /* copy output */
+    XMEMCPY(buf, md->chc.state, cipher_blocksize);
+
+#ifdef CLEAN_STACK
+    zeromem(md, sizeof(hash_state));
+#endif
+    return CRYPT_OK;
+}
+
+int chc_test(void)
+{
+   static const struct {
+      unsigned char *msg,
+                    md[MAXBLOCKSIZE];
+      int            len;
+   } tests[] = {
+{
+   (unsigned char *)"hello world",
+   { 0xcf, 0x57, 0x9d, 0xc3, 0x0a, 0x0e, 0xea, 0x61, 
+     0x0d, 0x54, 0x47, 0xc4, 0x3c, 0x06, 0xf5, 0x4e },
+   16
+}
+};
+   int x, oldhashidx, idx;
+   unsigned char out[MAXBLOCKSIZE];
+   hash_state md;
+
+   /* AES can be under rijndael or aes... try to find it */
+   if ((idx = find_cipher("aes")) == -1) {
+      if ((idx = find_cipher("rijndael")) == -1) {
+         return CRYPT_NOP;
+      }
+   }
+   oldhashidx = cipher_idx;
+   chc_register(idx);
+
+   for (x = 0; x < (int)(sizeof(tests)/sizeof(tests[0])); x++) {
+       chc_init(&md);
+       chc_process(&md, tests[x].msg, strlen((char *)tests[x].msg));
+       chc_done(&md, out);
+       if (memcmp(out, tests[x].md, tests[x].len)) {
+          return CRYPT_FAIL_TESTVECTOR;
+       }
+   }
+   if (oldhashidx != UNDEFED_HASH) {
+      chc_register(oldhashidx);
+   }
+
+   return CRYPT_OK;
+}
+
+#endif