unify the prng's export() functions

This also makes fortuna_export() compliant to the "Write seed file"
behavior of the original paper.

src/headers/tomcrypt_prng.h

@@ -212,6 +212,31 @@ int register_all_prngs(void);
 int prng_is_valid(int idx);
 LTC_MUTEX_PROTO(ltc_prng_mutex)
 
+#ifdef LTC_SOURCE
+/* internal helper functions */
+#define _LTC_PRNG_EXPORT(which) \
+int which ## _export(unsigned char *out, unsigned long *outlen, prng_state *prng)      \
+{                                                                                      \
+   unsigned long len = which ## _desc.export_size;                                     \
+                                                                                       \
+   LTC_ARGCHK(prng   != NULL);                                                         \
+   LTC_ARGCHK(out    != NULL);                                                         \
+   LTC_ARGCHK(outlen != NULL);                                                         \
+                                                                                       \
+   if (*outlen < len) {                                                                \
+      *outlen = len;                                                                   \
+      return CRYPT_BUFFER_OVERFLOW;                                                    \
+   }                                                                                   \
+                                                                                       \
+   if (which ## _read(out, len, prng) != len) {                                        \
+      return CRYPT_ERROR_READPRNG;                                                     \
+   }                                                                                   \
+                                                                                       \
+   *outlen = len;                                                                      \
+   return CRYPT_OK;                                                                    \
+}
+#endif
+
 /* Slow RNG you **might** be able to use to seed a PRNG with.  Be careful as this
  * might not work on all platforms as planned
  */

src/prngs/chacha20.c

@@ -150,26 +150,7 @@ int chacha20_prng_done(prng_state *prng)
   @param prng      The PRNG to export
   @return CRYPT_OK if successful
 */
-int chacha20_prng_export(unsigned char *out, unsigned long *outlen, prng_state *prng)
-{
-   unsigned long len = chacha20_prng_desc.export_size;
-
-   LTC_ARGCHK(prng   != NULL);
-   LTC_ARGCHK(out    != NULL);
-   LTC_ARGCHK(outlen != NULL);
-
-   if (*outlen < len) {
-      *outlen = len;
-      return CRYPT_BUFFER_OVERFLOW;
-   }
-
-   if (chacha20_prng_read(out, len, prng) != len) {
-      return CRYPT_ERROR_READPRNG;
-   }
-
-   *outlen = len;
-   return CRYPT_OK;
-}
+_LTC_PRNG_EXPORT(chacha20_prng)
 
 /**
   Import a PRNG state

src/prngs/fortuna.c

@@ -37,7 +37,7 @@ we reseed automatically when len(pool0) >= 64 or every LTC_FORTUNA_WD calls to t
 
 const struct ltc_prng_descriptor fortuna_desc = {
     "fortuna",
-    (32 * LTC_FORTUNA_POOLS), /* default: 1024 */
+    64,
     &fortuna_start,
     &fortuna_add_entropy,
     &fortuna_ready,
@@ -337,71 +337,7 @@ LBL_UNLOCK:
   @param prng      The PRNG to export
   @return CRYPT_OK if successful
 */
-int fortuna_export(unsigned char *out, unsigned long *outlen, prng_state *prng)
-{
-   int         x, err;
-   hash_state *md;
-   unsigned long len = fortuna_desc.export_size;
-
-   LTC_ARGCHK(out    != NULL);
-   LTC_ARGCHK(outlen != NULL);
-   LTC_ARGCHK(prng   != NULL);
-
-   LTC_MUTEX_LOCK(&prng->lock);
-
-   if (!prng->ready) {
-      err = CRYPT_ERROR;
-      goto LBL_UNLOCK;
-   }
-
-   /* we'll write bytes for s&g's */
-   if (*outlen < len) {
-      *outlen = len;
-      err = CRYPT_BUFFER_OVERFLOW;
-      goto LBL_UNLOCK;
-   }
-
-   md = XMALLOC(sizeof(hash_state));
-   if (md == NULL) {
-      err = CRYPT_MEM;
-      goto LBL_UNLOCK;
-   }
-
-   /* to emit the state we copy each pool, terminate it then hash it again so
-    * an attacker who sees the state can't determine the current state of the PRNG
-    */
-   for (x = 0; x < LTC_FORTUNA_POOLS; x++) {
-      /* copy the PRNG */
-      XMEMCPY(md, &(prng->fortuna.pool[x]), sizeof(*md));
-
-      /* terminate it */
-      if ((err = sha256_done(md, out+x*32)) != CRYPT_OK) {
-         goto LBL_ERR;
-      }
-
-      /* now hash it */
-      if ((err = sha256_init(md)) != CRYPT_OK) {
-         goto LBL_ERR;
-      }
-      if ((err = sha256_process(md, out+x*32, 32)) != CRYPT_OK) {
-         goto LBL_ERR;
-      }
-      if ((err = sha256_done(md, out+x*32)) != CRYPT_OK) {
-         goto LBL_ERR;
-      }
-   }
-   *outlen = len;
-   err = CRYPT_OK;
-
-LBL_ERR:
-#ifdef LTC_CLEAN_STACK
-   zeromem(md, sizeof(*md));
-#endif
-   XFREE(md);
-LBL_UNLOCK:
-   LTC_MUTEX_UNLOCK(&prng->lock);
-   return err;
-}
+_LTC_PRNG_EXPORT(fortuna)
 
 /**
   Import a PRNG state

src/prngs/rc4.c

@@ -153,26 +153,7 @@ int rc4_done(prng_state *prng)
   @param prng      The PRNG to export
   @return CRYPT_OK if successful
 */
-int rc4_export(unsigned char *out, unsigned long *outlen, prng_state *prng)
-{
-   unsigned long len = rc4_desc.export_size;
-
-   LTC_ARGCHK(prng   != NULL);
-   LTC_ARGCHK(out    != NULL);
-   LTC_ARGCHK(outlen != NULL);
-
-   if (*outlen < len) {
-      *outlen = len;
-      return CRYPT_BUFFER_OVERFLOW;
-   }
-
-   if (rc4_read(out, len, prng) != len) {
-      return CRYPT_ERROR_READPRNG;
-   }
-
-   *outlen = len;
-   return CRYPT_OK;
-}
+_LTC_PRNG_EXPORT(rc4)
 
 /**
   Import a PRNG state

src/prngs/sober128.c

@@ -152,26 +152,7 @@ int sober128_done(prng_state *prng)
   @param prng      The PRNG to export
   @return CRYPT_OK if successful
 */
-int sober128_export(unsigned char *out, unsigned long *outlen, prng_state *prng)
-{
-   unsigned long len = sober128_desc.export_size;
-
-   LTC_ARGCHK(prng   != NULL);
-   LTC_ARGCHK(out    != NULL);
-   LTC_ARGCHK(outlen != NULL);
-
-   if (*outlen < len) {
-      *outlen = len;
-      return CRYPT_BUFFER_OVERFLOW;
-   }
-
-   if (sober128_read(out, len, prng) != len) {
-      return CRYPT_ERROR_READPRNG;
-   }
-
-   *outlen = len;
-   return CRYPT_OK;
-}
+_LTC_PRNG_EXPORT(sober128)
 
 /**
   Import a PRNG state

src/prngs/yarrow.c

@@ -273,26 +273,7 @@ int yarrow_done(prng_state *prng)
   @param prng      The PRNG to export
   @return CRYPT_OK if successful
 */
-int yarrow_export(unsigned char *out, unsigned long *outlen, prng_state *prng)
-{
-   unsigned long len = yarrow_desc.export_size;
-
-   LTC_ARGCHK(out    != NULL);
-   LTC_ARGCHK(outlen != NULL);
-   LTC_ARGCHK(prng   != NULL);
-
-   if (*outlen < len) {
-      *outlen = len;
-      return CRYPT_BUFFER_OVERFLOW;
-   }
-
-   if (yarrow_read(out, len, prng) != len) {
-      return CRYPT_ERROR_READPRNG;
-   }
-
-   *outlen = len;
-   return CRYPT_OK;
-}
+_LTC_PRNG_EXPORT(yarrow)
 
 /**
   Import a PRNG state