--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/libtomcrypt/src/pk/katja/katja_encrypt_key.c	Sun Sep 14 06:47:51 2008 +0000
@@ -0,0 +1,87 @@
+/* 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.com
+ */
+#include "tomcrypt.h"
+
+/**
+  @file katja_encrypt_key.c
+  Katja PKCS-style OAEP encryption, Tom St Denis
+*/  
+
+#ifdef MKAT
+
+/**
+    (PKCS #1 v2.0) OAEP pad then encrypt
+    @param in          The plaintext
+    @param inlen       The length of the plaintext (octets)
+    @param out         [out] The ciphertext
+    @param outlen      [in/out] The max size and resulting size of the ciphertext
+    @param lparam      The system "lparam" for the encryption
+    @param lparamlen   The length of lparam (octets)
+    @param prng        An active PRNG
+    @param prng_idx    The index of the desired prng
+    @param hash_idx    The index of the desired hash
+    @param key         The Katja key to encrypt to
+    @return CRYPT_OK if successful
+*/    
+int katja_encrypt_key(const unsigned char *in,     unsigned long inlen,
+                          unsigned char *out,    unsigned long *outlen,
+                    const unsigned char *lparam, unsigned long lparamlen,
+                    prng_state *prng, int prng_idx, int hash_idx, katja_key *key)
+{
+  unsigned long modulus_bitlen, modulus_bytelen, x;
+  int           err;
+  
+  LTC_ARGCHK(in     != NULL);
+  LTC_ARGCHK(out    != NULL);
+  LTC_ARGCHK(outlen != NULL);
+  LTC_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));
+
+  /* payload is upto pq, so we know q is 1/3rd the size of N and therefore pq is 2/3th the size */
+  modulus_bitlen = ((modulus_bitlen << 1) / 3);
+
+  /* round down to next byte */
+  modulus_bitlen -= (modulus_bitlen & 7) + 8;
+
+  /* outlen must be at least the size of the modulus */
+  modulus_bytelen = mp_unsigned_bin_size((key->N));
+  if (modulus_bytelen > *outlen) {
+     *outlen = modulus_bytelen;
+     return CRYPT_BUFFER_OVERFLOW;
+  }
+
+  /* OAEP pad the key */
+  x = *outlen;
+  if ((err = pkcs_1_oaep_encode(in, inlen, lparam, 
+                                lparamlen, modulus_bitlen, prng, prng_idx, hash_idx, 
+                                out, &x)) != CRYPT_OK) {
+     return err;
+  }                          
+
+  /* Katja exptmod the OAEP pad */
+  return katja_exptmod(out, x, out, outlen, PK_PUBLIC, key);
+}
+
+#endif /* MRSA */
+
+/* $Source: /cvs/libtom/libtomcrypt/src/pk/katja/katja_encrypt_key.c,v $ */
+/* $Revision: 1.5 $ */
+/* $Date: 2006/06/16 21:53:41 $ */