--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/pkcs_1_v15_es_decode.c	Tue Jun 15 14:07:21 2004 +0000
@@ -0,0 +1,61 @@
+/* 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"
+
+/* PKCS #1 v1.5 Encryption Padding -- Tom St Denis */
+
+#ifdef PKCS_1
+
+int pkcs_1_v15_es_decode(const unsigned char *msg,  unsigned long msglen,
+                               unsigned long modulus_bitlen,
+                               unsigned char *out,  unsigned long outlen,
+                               int           *res)
+{
+   unsigned long x, modulus_bytelen;
+
+   _ARGCHK(msg != NULL);
+   _ARGCHK(out != NULL);
+   _ARGCHK(res != NULL);
+   
+   /* default to failed */
+   *res = 0;
+
+   /* must be at least 12 bytes long */
+   if (msglen < 12) {
+      return CRYPT_INVALID_ARG;
+   }
+
+   modulus_bytelen = (modulus_bitlen>>3) + (modulus_bitlen & 7 ? 1 : 0);
+
+   /* should start with 0x00 0x02 */
+   if (msg[0] != 0x00 || msg[1] != 0x02) {
+      return CRYPT_OK;
+   }
+   
+   /* skip over PS */
+   x = 2 + (modulus_bytelen - outlen - 3);
+
+   /* should be 0x00 */
+   if (msg[x++] != 0x00) {
+      return CRYPT_OK;
+   }
+
+   /* the message is left */
+   if (x + outlen > modulus_bytelen) {
+      return CRYPT_PK_INVALID_SIZE;
+   }
+   memcpy(out, msg + x, outlen);
+   *res = 1;
+   return CRYPT_OK;
+}
+
+#endif 
+