--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/src/pk/rsa/rsa_export.c	Fri May 06 13:23:02 2005 +0000
@@ -0,0 +1,98 @@
+/* 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 rsa_export.c
+  Export RSA PKCS keys, Tom St Denis
+*/  
+
+#ifdef MRSA
+
+/**
+    This will export either an RSAPublicKey or RSAPrivateKey [defined in PKCS #1 v2.1] 
+    @param out       [out] Destination of the packet
+    @param outlen    [in/out] The max size and resulting size of the packet
+    @param type      The type of exported key (PK_PRIVATE or PK_PUBLIC)
+    @param key       The RSA key to export
+    @return CRYPT_OK if successful
+*/    
+int rsa_export(unsigned char *out, unsigned long *outlen, int type, rsa_key *key)
+{
+   int err, x;
+
+   LTC_ARGCHK(out    != NULL);
+   LTC_ARGCHK(outlen != NULL);
+   LTC_ARGCHK(key    != NULL);
+
+   /* type valid? */
+   if (!(key->type == PK_PRIVATE) && (type == PK_PRIVATE)) {
+      return CRYPT_PK_INVALID_TYPE;
+   }
+   if (*outlen < 4) {
+      return CRYPT_BUFFER_OVERFLOW;
+   }
+  
+   /* Mental Note: push space for the header 0x30 0x82 LL LL (LL = length of packet EXcluding 4 bytes) 
+    * we assume LL > 255 which is true since the smallest RSA key has a 128-byte modulus (1024-bit)
+    */
+   *outlen -= 4;
+
+   if (type == PK_PRIVATE) {
+      /* private key */
+      mp_int zero;
+
+      /* first INTEGER == 0 to signify two-prime RSA */
+      if ((err = mp_init(&zero)) != MP_OKAY) {
+         return mpi_to_ltc_error(err);
+      }
+ 
+      /* output is 
+            Version, n, e, d, p, q, d mod (p-1), d mod (q - 1), 1/q mod p
+       */
+      if ((err = der_put_multi_integer(
+                          out+4, outlen, &zero, &key->N, &key->e,
+                          &key->d, &key->p, &key->q, &key->dP,
+                          &key->dQ, &key->qP, NULL)) != CRYPT_OK) {
+         mp_clear(&zero);
+         return err;
+      }
+ 
+      /* clear zero and return */
+      mp_clear(&zero);
+   } else {
+      /* public key */
+      if ((err = der_put_multi_integer(out+4, outlen, &key->N, &key->e, NULL)) != CRYPT_OK) {
+         return err;
+      }
+   }
+
+   /* store the header */
+   out[0] = 0x30;
+   if (*outlen < 256) {
+      /* shift the output up one byte if the header is only 3 bytes */
+      for (x = 0; x < *outlen; x++) {
+          out[x+3] = out[x+4];
+      }
+      out[1] = 0x81;
+      out[2] = (*outlen & 255);
+      *outlen += 3;
+   } else {
+      out[1] = 0x82;
+      out[2] = (*outlen >> 8) & 255;
+      out[3] = (*outlen & 255);
+      *outlen += 4;
+   }
+   return err;
+}
+
+#endif /* MRSA */
+