* @file util/crypto_ecc.c
* @brief public key cryptography (ECC) with libgcrypt
* @author Christian Grothoff
- *
- * This is just a first, completely untested, draft hack for future ECC support.
- * TODO:
- * - fix public key generation; somehow the result is currently considered invalid by libgcrypt
- * => suspect that libgcrypt does NOT take pabgn from "CURVE" for public key if not
- * explicitly given!
- * - actually test it!
*/
#include "platform.h"
#include <gcrypt.h>
* @return string representing 'pub'
*/
char *
-GNUNET_CRYPTO_ecc_public_key_to_string (struct GNUNET_CRYPTO_EccPublicKeyBinaryEncoded *pub)
+GNUNET_CRYPTO_ecc_public_key_to_string (const struct GNUNET_CRYPTO_EccPublicKeyBinaryEncoded *pub)
{
char *pubkeybuf;
size_t keylen = (sizeof (struct GNUNET_CRYPTO_EccPublicKeyBinaryEncoded)) * 8;
if (len < sizeof (uint16_t))
return NULL;
memcpy (&be, buf, sizeof (be));
- if (len != ntohs (be))
+ if (len < ntohs (be))
return NULL;
+ len = ntohs (be);
if (0 != (rc = gcry_sexp_sscan (&sexp,
&erroff,
&buf[2],
*
* @return fresh private key
*/
-static struct GNUNET_CRYPTO_EccPrivateKey *
-ecc_key_create ()
+struct GNUNET_CRYPTO_EccPrivateKey *
+GNUNET_CRYPTO_ecc_key_create ()
{
struct GNUNET_CRYPTO_EccPrivateKey *ret;
gcry_sexp_t s_key;
}
LOG (GNUNET_ERROR_TYPE_INFO,
_("Creating a new private key. This may take a while.\n"));
- ret = ecc_key_create ();
+ ret = GNUNET_CRYPTO_ecc_key_create ();
GNUNET_assert (ret != NULL);
enc = GNUNET_CRYPTO_ecc_encode_key (ret);
GNUNET_assert (enc != NULL);
GNUNET_assert (fs == GNUNET_DISK_file_read (fd, enc, fs));
len = ntohs (enc->size);
ret = NULL;
- if ((len != fs) ||
+ if ((len > fs) ||
(NULL == (ret = GNUNET_CRYPTO_ecc_decode_key ((char *) enc, len))))
{
LOG (GNUNET_ERROR_TYPE_ERROR,
{
struct GNUNET_CRYPTO_EccKeyGenerationContext *gc;
struct GNUNET_CRYPTO_EccPrivateKey *pk;
- const char *weak_random;
if (NULL != (pk = try_read_key (filename)))
{
GNUNET_free (gc);
return NULL;
}
- weak_random = NULL;
- if (GNUNET_YES ==
- GNUNET_CRYPTO_random_is_weak ())
- weak_random = "-w";
gc->gnunet_ecc = GNUNET_OS_start_process (GNUNET_NO,
GNUNET_OS_INHERIT_STD_ERR,
NULL,
"gnunet-ecc",
"gnunet-ecc",
gc->filename,
- weak_random,
NULL);
if (NULL == gc->gnunet_ecc)
{
gcry_sexp_t data;
GNUNET_CRYPTO_short_hash (purpose, ntohl (purpose->size), &hc);
-#define FORMATSTRING "(4:data(32:01234567890123456789012345678901))"
-#define FORMATSTRING2 "(4:data(4:hash6:sha25632:01234567890123456789012345678901))"
+#define FORMATSTRING "(4:data(5:flags3:raw)(5:value32:01234567890123456789012345678901))"
bufSize = strlen (FORMATSTRING) + 1;
{
char buff[bufSize];
}
+/**
+ * Derive key material from a public and a private ECC key.
+ *
+ * @param key private key to use for the ECDH (x)
+ * @param pub public key to use for the ECDY (yG)
+ * @param key_material where to write the key material (xyG)
+ * @return GNUNET_SYSERR on error, GNUNET_OK on success
+ */
+int
+GNUNET_CRYPTO_ecc_ecdh (const struct GNUNET_CRYPTO_EccPrivateKey *key,
+ const struct GNUNET_CRYPTO_EccPublicKeyBinaryEncoded *pub,
+ struct GNUNET_HashCode *key_material)
+{
+ size_t size;
+ size_t slen;
+ int rc;
+ gcry_sexp_t data;
+ unsigned char sdata_buf[2048]; /* big enough to print 'sdata' and 'r_sig' */
+
+ /* first, extract the q value from the public key */
+ {
+ gcry_sexp_t psexp;
+ gcry_mpi_t sdata;
+
+ if (! (psexp = decode_public_key (pub)))
+ return GNUNET_SYSERR;
+ rc = key_from_sexp (&sdata, psexp, "public-key", "q");
+ if (rc)
+ rc = key_from_sexp (&sdata, psexp, "ecc", "q");
+ GNUNET_assert (0 == rc);
+ gcry_sexp_release (psexp);
+ size = sizeof (sdata_buf);
+ GNUNET_assert (0 ==
+ gcry_mpi_print (GCRYMPI_FMT_USG, sdata_buf, size, &size,
+ sdata));
+ gcry_mpi_release (sdata);
+ }
+ /* convert q value into an S-expression -- whatever format libgcrypt wants,
+ re-using format from sign operation for now... */
+ {
+ char *sexp_string;
+
+#define FORMATPREFIX "(4:data(5:flags3:raw)(5:value%u:"
+#define FORMATPOSTFIX "))"
+ sexp_string = GNUNET_malloc (strlen (FORMATPREFIX) + size + 12 +
+ strlen (FORMATPOSTFIX) + 1);
+ GNUNET_snprintf (sexp_string,
+ strlen (FORMATPREFIX) + 12,
+ FORMATPREFIX,
+ size);
+ slen = strlen (sexp_string);
+ memcpy (&sexp_string[slen],
+ sdata_buf,
+ size);
+ memcpy (&sexp_string[slen + size],
+ FORMATPOSTFIX,
+ strlen (FORMATPOSTFIX) + 1);
+ GNUNET_assert (0 == gcry_sexp_new (&data,
+ sexp_string,
+ slen + size + strlen (FORMATPOSTFIX),
+ 0));
+ GNUNET_free (sexp_string);
+ }
+ /* then call the 'multiply' function, hoping it simply multiplies the points;
+ here we need essentially a WRAPPER around _gcry_mpi_ex_mul_point! - FIXME-WK!*/
+#if WK
+ {
+ gcry_sexp_t result;
+
+ rc = gcry_ecc_mul_point (&result, data /* scalar */, key->sexp /* point and ctx */);
+ GNUNET_assert (0 == rc);
+ slen = gcry_sexp_sprint (result, GCRYSEXP_FMT_DEFAULT, sdata_buf, sizeof (sdata_buf));
+ GNUNET_assert (0 != slen);
+ }
+#else
+ /* use broken version, insecure! */
+ GNUNET_log (GNUNET_ERROR_TYPE_WARNING, _("To be implemented: not secure at the moment, please read README"));
+ slen = sprintf ((char*) sdata_buf, "FIXME-this is not key material");
+#endif
+ gcry_sexp_release (data);
+
+ /* finally, get a string of the resulting S-expression and hash it to generate the key material */
+ GNUNET_CRYPTO_hash (sdata_buf, slen, key_material);
+ return GNUNET_OK;
+}
+
+
/* end of crypto_ecc.c */
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