--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/rsa_v15_verify_hash.c	Sun Dec 19 11:34:45 2004 +0000
@@ -0,0 +1,72 @@
+/* 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 MRSA
+
+/* de-sign then PKCS v1.5 depad */
+int rsa_v15_verify_hash(const unsigned char *sig,      unsigned long siglen,
+                        const unsigned char *msghash,  unsigned long msghashlen,
+                              prng_state    *prng,     int           prng_idx,
+                              int            hash_idx, int          *stat,     
+                              rsa_key       *key)
+{
+   unsigned long modulus_bitlen, modulus_bytelen, x;
+   int           err;
+   unsigned char *tmpbuf;
+   
+  _ARGCHK(msghash  != NULL);
+  _ARGCHK(sig      != NULL);
+  _ARGCHK(stat     != NULL);
+  _ARGCHK(key      != NULL);
+
+  /* default to invalid */
+  *stat = 0;
+  
+  /* valid hash ? */
+  if ((err = hash_is_valid(hash_idx)) != CRYPT_OK) {
+     return err;
+  }
+
+  if ((err = prng_is_valid(prng_idx)) != CRYPT_OK) {
+     return err;
+  }
+  
+  /* get modulus len in bits */
+  modulus_bitlen = mp_count_bits(&(key->N));
+
+  /* outlen must be at least the size of the modulus */
+  modulus_bytelen = mp_unsigned_bin_size(&(key->N));
+  if (modulus_bytelen != siglen) {
+     return CRYPT_INVALID_PACKET;
+  }
+  
+  /* allocate temp buffer for decoded sig */
+  tmpbuf = XMALLOC(siglen);
+  if (tmpbuf == NULL) {
+     return CRYPT_MEM;
+  }
+      
+  /* RSA decode it  */
+  x = siglen;
+  if ((err = rsa_exptmod(sig, siglen, tmpbuf, &x, PK_PUBLIC, prng, prng_idx, key)) != CRYPT_OK) {
+     XFREE(tmpbuf);
+     return err;
+  }
+  
+  /* PSS decode it */
+  err = pkcs_1_v15_sa_decode(msghash, msghashlen, tmpbuf, x, hash_idx, modulus_bitlen, stat);
+  XFREE(tmpbuf);
+  return err;
+}
+
+#endif