1 files changed, 86 insertions, 0 deletions
diff --git a/libtomcrypt/src/pk/rsa/rsa_verify_hash.c b/libtomcrypt/src/pk/rsa/rsa_verify_hash.c
new file mode 100644
index 0000000..690364d
--- /dev/null
+++ b/libtomcrypt/src/pk/rsa/rsa_verify_hash.c
@@ -0,0 +1,86 @@
+/* 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, tomstdenis@gmail.com, http://libtomcrypt.org
+ */
+#include "tomcrypt.h"
+
+/**
+  @file rsa_verify_hash.c
+  RSA PKCS v2 PSS signature verification, Tom St Denis
+*/  
+
+#ifdef MRSA
+
+/**
+  (PKCS #1, v2.0) de-sign then PSS depad
+  @param sig              The signature data
+  @param siglen           The length of the signature data (octets)
+  @param hash             The hash of the message that was signed
+  @param hashlen          The length of the hash of the message that was signed (octets)
+  @param hash_idx         The index of the desired hash
+  @param saltlen          The length of the salt used during signature
+  @param stat             [out] The result of the signature comparison, 1==valid, 0==invalid
+  @param key              The public RSA key corresponding to the key that performed the signature
+  @return CRYPT_OK on success (even if the signature is invalid)
+*/
+int rsa_verify_hash(const unsigned char *sig,      unsigned long siglen,
+                    const unsigned char *hash,     unsigned long hashlen,
+                          int            hash_idx, unsigned long saltlen,
+                          int           *stat,     rsa_key      *key)
+{
+   unsigned long modulus_bitlen, modulus_bytelen, x;
+   int           err;
+   unsigned char *tmpbuf;
+   
+  LTC_ARGCHK(hash  != NULL);
+  LTC_ARGCHK(sig      != NULL);
+  LTC_ARGCHK(stat     != NULL);
+  LTC_ARGCHK(key      != NULL);
+
+  /* default to invalid */
+  *stat = 0;
+  
+  /* valid hash ? */
+  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_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, key)) != CRYPT_OK) {
+     XFREE(tmpbuf);
+     return err;
+  }
+  
+  /* PSS decode it */
+  err = pkcs_1_pss_decode(hash, hashlen, tmpbuf, x, saltlen, hash_idx, modulus_bitlen, stat);
+  XFREE(tmpbuf);
+  return err;
+}
+
+#endif /* MRSA */
+
+/* $Source: /cvs/libtom/libtomcrypt/src/pk/rsa/rsa_verify_hash.c,v $ */
+/* $Revision: 1.3 $ */
+/* $Date: 2005/05/05 14:35:59 $ */