--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/libtomcrypt/src/pk/pkcs1/pkcs_1_mgf1.c	Fri Mar 10 06:31:29 2006 +0000
@@ -0,0 +1,108 @@
+/* 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 "tomcrypt.h"
+
+/** 
+  @file pkcs_1_mgf1.c
+  The Mask Generation Function (MGF1) for PKCS #1, Tom St Denis 
+*/
+
+#ifdef PKCS_1
+
+/**
+   Perform PKCS #1 MGF1 (internal)
+   @param seed        The seed for MGF1
+   @param seedlen     The length of the seed
+   @param hash_idx    The index of the hash desired
+   @param mask        [out] The destination
+   @param masklen     The length of the mask desired
+   @return CRYPT_OK if successful
+*/
+int pkcs_1_mgf1(const unsigned char *seed, unsigned long seedlen,
+                      int            hash_idx,
+                      unsigned char *mask, unsigned long masklen)
+{
+   unsigned long hLen, x;
+   ulong32       counter;
+   int           err;
+   hash_state    *md;
+   unsigned char *buf;
+ 
+   LTC_ARGCHK(seed != NULL);
+   LTC_ARGCHK(mask != NULL);
+
+   /* ensure valid hash */
+   if ((err = hash_is_valid(hash_idx)) != CRYPT_OK) { 
+      return err;
+   }
+
+   /* get hash output size */
+   hLen = hash_descriptor[hash_idx].hashsize;
+
+   /* allocate memory */
+   md  = XMALLOC(sizeof(hash_state));
+   buf = XMALLOC(hLen);
+   if (md == NULL || buf == NULL) {
+      if (md != NULL) {
+         XFREE(md);
+      }
+      if (buf != NULL) {
+         XFREE(buf);
+      }
+      return CRYPT_MEM;
+   }
+
+   /* start counter */
+   counter = 0;
+
+   while (masklen > 0) {
+       /* handle counter */
+       STORE32H(counter, buf);
+       ++counter;
+
+       /* get hash of seed || counter */
+       if ((err = hash_descriptor[hash_idx].init(md)) != CRYPT_OK) {
+          goto LBL_ERR;
+       }
+       if ((err = hash_descriptor[hash_idx].process(md, seed, seedlen)) != CRYPT_OK) {
+          goto LBL_ERR;
+       }
+       if ((err = hash_descriptor[hash_idx].process(md, buf, 4)) != CRYPT_OK) {
+          goto LBL_ERR;
+       }
+       if ((err = hash_descriptor[hash_idx].done(md, buf)) != CRYPT_OK) {
+          goto LBL_ERR;
+       }
+
+       /* store it */
+       for (x = 0; x < hLen && masklen > 0; x++, masklen--) {
+          *mask++ = buf[x];
+       }
+   }
+
+   err = CRYPT_OK;
+LBL_ERR:
+#ifdef LTC_CLEAN_STACK
+   zeromem(buf, hLen);
+   zeromem(md,  sizeof(hash_state));
+#endif
+
+   XFREE(buf);
+   XFREE(md);
+
+   return err;
+}
+
+#endif /* PKCS_1 */
+
+/* $Source: /cvs/libtom/libtomcrypt/src/pk/pkcs1/pkcs_1_mgf1.c,v $ */
+/* $Revision: 1.4 $ */
+/* $Date: 2005/05/05 14:35:59 $ */