merge: md5 improvements

 * Remove unused functions, unexpose implementation functions
 * Implement and use mutt_md5_toascii
 * Initial tests
 * Use mutt_md5_toascii some more
 * Add and use an API to process a NULL-terminated string
 * More API polishing
 * Rename test cases to better reflect what they're doing

hcache/hcache.c

@@ -606,12 +606,8 @@ static const char *hcache_per_folder(const char *path, const char *folder, hcach
     unsigned char m[16]; /* binary md5sum */
     char name[_POSIX_PATH_MAX];
     snprintf(name, sizeof(name), "%s|%s", hcache_get_ops()->name, folder);
-    mutt_md5_buf(name, strlen(name), &m);
-    snprintf(name, sizeof(name),
-             "%02x%02x%02x%02x%02x%02x%02x%02x%02x%02x%02x%02x%02x%02x%02x%02x",
-             m[0], m[1], m[2], m[3], m[4], m[5], m[6], m[7], m[8], m[9], m[10],
-             m[11], m[12], m[13], m[14], m[15]);
-
+    mutt_md5(name, m);
+    mutt_md5_toascii(m, name);
     rc = snprintf(hcpath, sizeof(hcpath), "%s%s%s%s", path, slash ? "" : "/", name, suffix);
   }
 
@@ -758,14 +754,14 @@ header_cache_t *mutt_hcache_open(const char *path, const char *folder, hcache_na
     /* Mix in user's spam list */
     for (spam = SpamList; spam; spam = spam->next)
     {
-      mutt_md5_process_bytes(spam->regex->pattern, strlen(spam->regex->pattern), &ctx);
-      mutt_md5_process_bytes(spam->template, strlen(spam->template), &ctx);
+      mutt_md5_process(spam->regex->pattern, &ctx);
+      mutt_md5_process(spam->template, &ctx);
     }
 
     /* Mix in user's nospam list */
     for (nospam = NoSpamList; nospam; nospam = nospam->next)
     {
-      mutt_md5_process_bytes(nospam->regex->pattern, strlen(nospam->regex->pattern), &ctx);
+      mutt_md5_process(nospam->regex->pattern, &ctx);
     }
 
     /* Get a hash and take its bytes as an (unsigned int) hash version */

imap/auth_cram.c

@@ -58,16 +58,15 @@ static void hmac_md5(const char *password, char *challenge, unsigned char *respo
   unsigned char ipad[MD5_BLOCK_LEN], opad[MD5_BLOCK_LEN];
   unsigned char secret[MD5_BLOCK_LEN + 1];
   unsigned char hash_passwd[MD5_DIGEST_LEN];
-  size_t secret_len, chal_len;
+  size_t secret_len;
 
   secret_len = strlen(password);
-  chal_len = strlen(challenge);
 
   /* passwords longer than MD5_BLOCK_LEN bytes are substituted with their MD5
    * digests */
   if (secret_len > MD5_BLOCK_LEN)
   {
-    mutt_md5_buf(password, secret_len, hash_passwd);
+    mutt_md5_bytes(password, secret_len, hash_passwd);
     mutt_str_strfcpy((char *) secret, (char *) hash_passwd, MD5_DIGEST_LEN);
     secret_len = MD5_DIGEST_LEN;
   }
@@ -88,7 +87,7 @@ static void hmac_md5(const char *password, char *challenge, unsigned char *respo
   /* inner hash: challenge and ipadded secret */
   mutt_md5_init_ctx(&ctx);
   mutt_md5_process_bytes(ipad, MD5_BLOCK_LEN, &ctx);
-  mutt_md5_process_bytes(challenge, chal_len, &ctx);
+  mutt_md5_process(challenge, &ctx);
   mutt_md5_finish_ctx(&ctx, response);
 
   /* outer hash: inner hash and opadded secret */
@@ -163,14 +162,8 @@ enum ImapAuthRes imap_auth_cram_md5(struct ImapData *idata, const char *method)
    */
   hmac_md5(idata->conn->account.pass, obuf, hmac_response);
   /* dubious optimisation I saw elsewhere: make the whole string in one call */
-  snprintf(
-      obuf, sizeof(obuf),
-      "%s %02x%02x%02x%02x%02x%02x%02x%02x%02x%02x%02x%02x%02x%02x%02x%02x",
-      idata->conn->account.user, hmac_response[0], hmac_response[1],
-      hmac_response[2], hmac_response[3], hmac_response[4], hmac_response[5],
-      hmac_response[6], hmac_response[7], hmac_response[8], hmac_response[9],
-      hmac_response[10], hmac_response[11], hmac_response[12],
-      hmac_response[13], hmac_response[14], hmac_response[15]);
+  int off = snprintf(obuf, sizeof(obuf), "%s ", idata->conn->account.user);
+  mutt_md5_toascii(hmac_response, obuf + off);
   mutt_debug(2, "CRAM response: %s\n", obuf);
 
   /* ibuf must be long enough to store the base64 encoding of obuf,