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authorMatt Johnston <matt@ucc.asn.au>2007-01-11 02:41:05 +0000
committerMatt Johnston <matt@ucc.asn.au>2007-01-11 02:41:05 +0000
commita938f4cfe140e8561d9dbf108b896492a662a893 (patch)
treef2a74322f959ff6a505ba5e87274ebe3d17d5e74 /libtomcrypt/src/pk/ecc/ecc_shared_secret.c
parent692d737a821c5e401c227d936b8f0d76b955650f (diff)
parent28ad393b008b34bc3cdbaa192440b8cc615329f0 (diff)
propagate from branch 'au.asn.ucc.matt.ltc.dropbear' (head 2af22fb4e878750b88f80f90d439b316d229796f)
to branch 'au.asn.ucc.matt.dropbear' (head 02c413252c90e9de8e03d91e9939dde3029f5c0a) --HG-- extra : convert_revision : 52ccb0ad0587a62bc64aecb939adbb76546aac16
Diffstat (limited to 'libtomcrypt/src/pk/ecc/ecc_shared_secret.c')
-rw-r--r--libtomcrypt/src/pk/ecc/ecc_shared_secret.c95
1 files changed, 95 insertions, 0 deletions
diff --git a/libtomcrypt/src/pk/ecc/ecc_shared_secret.c b/libtomcrypt/src/pk/ecc/ecc_shared_secret.c
new file mode 100644
index 0000000..ddef847
--- /dev/null
+++ b/libtomcrypt/src/pk/ecc/ecc_shared_secret.c
@@ -0,0 +1,95 @@
+/* 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.com
+ */
+
+/* Implements ECC over Z/pZ for curve y^2 = x^3 - 3x + b
+ *
+ * All curves taken from NIST recommendation paper of July 1999
+ * Available at http://csrc.nist.gov/cryptval/dss.htm
+ */
+#include "tomcrypt.h"
+
+/**
+ @file ecc_shared_secret.c
+ ECC Crypto, Tom St Denis
+*/
+
+#ifdef MECC
+
+/**
+ Create an ECC shared secret between two keys
+ @param private_key The private ECC key
+ @param public_key The public key
+ @param out [out] Destination of the shared secret (Conforms to EC-DH from ANSI X9.63)
+ @param outlen [in/out] The max size and resulting size of the shared secret
+ @return CRYPT_OK if successful
+*/
+int ecc_shared_secret(ecc_key *private_key, ecc_key *public_key,
+ unsigned char *out, unsigned long *outlen)
+{
+ unsigned long x;
+ ecc_point *result;
+ void *prime;
+ int err;
+
+ LTC_ARGCHK(private_key != NULL);
+ LTC_ARGCHK(public_key != NULL);
+ LTC_ARGCHK(out != NULL);
+ LTC_ARGCHK(outlen != NULL);
+
+ /* type valid? */
+ if (private_key->type != PK_PRIVATE) {
+ return CRYPT_PK_NOT_PRIVATE;
+ }
+
+ if (ltc_ecc_is_valid_idx(private_key->idx) == 0 || ltc_ecc_is_valid_idx(public_key->idx) == 0) {
+ return CRYPT_INVALID_ARG;
+ }
+
+ if (XSTRCMP(private_key->dp->name, public_key->dp->name) != 0) {
+ return CRYPT_PK_TYPE_MISMATCH;
+ }
+
+ /* make new point */
+ result = ltc_ecc_new_point();
+ if (result == NULL) {
+ return CRYPT_MEM;
+ }
+
+ if ((err = mp_init(&prime)) != CRYPT_OK) {
+ ltc_ecc_del_point(result);
+ return err;
+ }
+
+ if ((err = mp_read_radix(prime, (char *)private_key->dp->prime, 16)) != CRYPT_OK) { goto done; }
+ if ((err = ltc_mp.ecc_ptmul(private_key->k, &public_key->pubkey, result, prime, 1)) != CRYPT_OK) { goto done; }
+
+ x = (unsigned long)mp_unsigned_bin_size(prime);
+ if (*outlen < x) {
+ *outlen = x;
+ err = CRYPT_BUFFER_OVERFLOW;
+ goto done;
+ }
+ zeromem(out, x);
+ if ((err = mp_to_unsigned_bin(result->x, out + (x - mp_unsigned_bin_size(result->x)))) != CRYPT_OK) { goto done; }
+
+ err = CRYPT_OK;
+ *outlen = x;
+done:
+ mp_clear(prime);
+ ltc_ecc_del_point(result);
+ return err;
+}
+
+#endif
+/* $Source: /cvs/libtom/libtomcrypt/src/pk/ecc/ecc_shared_secret.c,v $ */
+/* $Revision: 1.8 $ */
+/* $Date: 2006/12/04 02:19:48 $ */
+