--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/rsa_v15_sign_hash.c	Sun Dec 19 11:34:45 2004 +0000
@@ -0,0 +1,57 @@
+/* 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
+
+/* PKCS #1 v1.5 pad then sign */
+int rsa_v15_sign_hash(const unsigned char *msghash,  unsigned long  msghashlen, 
+                            unsigned char *sig,      unsigned long *siglen, 
+                            prng_state    *prng,     int            prng_idx,
+                            int            hash_idx, rsa_key       *key)
+{
+   unsigned long modulus_bitlen, modulus_bytelen, x;
+   int           err;
+   
+  _ARGCHK(msghash  != NULL);
+  _ARGCHK(sig      != NULL);
+  _ARGCHK(siglen   != NULL);
+  _ARGCHK(key      != NULL);
+  
+  /* valid prng and hash ? */
+  if ((err = prng_is_valid(prng_idx)) != CRYPT_OK) {
+     return err;
+  }
+  if ((err = hash_is_valid(hash_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_BUFFER_OVERFLOW;
+  }
+      
+  /* PKCS #1 v1.5 pad the key */
+  x = *siglen;
+  if ((err = pkcs_1_v15_sa_encode(msghash, msghashlen, hash_idx, modulus_bitlen, sig, &x)) != CRYPT_OK) {
+     return err;
+  }
+
+  /* RSA encode it */
+  return rsa_exptmod(sig, x, sig, siglen, PK_PRIVATE, prng, prng_idx, key);
+}
+
+#endif