GNUnet is free software; you can redistribute it and/or modify
it under the terms of the GNU General Public License as published
- by the Free Software Foundation; either version 2, or (at your
+ by the Free Software Foundation; either version 3, or (at your
option) any later version.
GNUnet is distributed in the hope that it will be useful, but
*/
#include "platform.h"
#include <gcrypt.h>
-#include "gnunet_common.h"
#include "gnunet_util_lib.h"
-#define EXTRA_CHECKS ALLOW_EXTRA_CHECKS
+#define EXTRA_CHECKS ALLOW_EXTRA_CHECKS
+/**
+ * Name of the curve we are using. Note that we have hard-coded
+ * structs that use 256 bits, so using a bigger curve will require
+ * changes that break stuff badly. The name of the curve given here
+ * must be agreed by all peers and be supported by libgcrypt.
+ *
+ * NOTE: this will change to Curve25519 before GNUnet 0.10.0.
+ */
#define CURVE "NIST P-256"
#define LOG(kind,...) GNUNET_log_from (kind, "util", __VA_ARGS__)
* a failure of the command 'cmd' with the message given
* by gcry_strerror(rc).
*/
-#define LOG_GCRY(level, cmd, rc) do { LOG(level, _("`%s' failed at %s:%d with error: %s\n"), cmd, __FILE__, __LINE__, gcry_strerror(rc)); } while(0);
-
-
-/**
- * The private information of an ECC private key.
- */
-struct GNUNET_CRYPTO_EccPrivateKey
-{
-
- /**
- * Libgcrypt S-expression for the ECC key.
- */
- gcry_sexp_t sexp;
-};
-
-
-/**
- * Free memory occupied by ECC key
- *
- * @param privatekey pointer to the memory to free
- */
-void
-GNUNET_CRYPTO_ecc_key_free (struct GNUNET_CRYPTO_EccPrivateKey *privatekey)
-{
- gcry_sexp_release (privatekey->sexp);
- GNUNET_free (privatekey);
-}
+#define LOG_GCRY(level, cmd, rc) do { LOG(level, _("`%s' failed at %s:%d with error: %s\n"), cmd, __FILE__, __LINE__, gcry_strerror(rc)); } while(0)
/**
unsigned int idx;
list = gcry_sexp_find_token (sexp, topname, 0);
- if (! list)
- return 1;
+ if (! list)
+ return 1;
l2 = gcry_sexp_cadr (list);
gcry_sexp_release (list);
list = l2;
- if (! list)
- return 2;
+ if (! list)
+ return 2;
idx = 0;
for (s = elems; *s; s++, idx++)
}
+/**
+ * If target != size, move @a target bytes to the end of the size-sized
+ * buffer and zero out the first @a target - @a size bytes.
+ *
+ * @param buf original buffer
+ * @param size number of bytes in @a buf
+ * @param target target size of the buffer
+ */
+static void
+adjust (unsigned char *buf,
+ size_t size,
+ size_t target)
+{
+ if (size < target)
+ {
+ memmove (&buf[target - size], buf, size);
+ memset (buf, 0, target - size);
+ }
+}
+
+
+/**
+ * Output the given MPI value to the given buffer.
+ *
+ * @param buf where to output to
+ * @param size number of bytes in @a buf
+ * @param val value to write to @a buf
+ */
+static void
+mpi_print (unsigned char *buf,
+ size_t size,
+ gcry_mpi_t val)
+{
+ size_t rsize;
+
+ rsize = size;
+ GNUNET_assert (0 ==
+ gcry_mpi_print (GCRYMPI_FMT_USG, buf, rsize, &rsize,
+ val));
+ adjust (buf, rsize, size);
+}
+
+
+/**
+ * Convert data buffer into MPI value.
+ *
+ * @param result where to store MPI value (allocated)
+ * @param data raw data (GCRYMPI_FMT_USG)
+ * @param size number of bytes in data
+ */
+static void
+mpi_scan (gcry_mpi_t *result,
+ const unsigned char *data,
+ size_t size)
+{
+ int rc;
+
+ if (0 != (rc = gcry_mpi_scan (result,
+ GCRYMPI_FMT_USG,
+ data, size, &size)))
+ {
+ LOG_GCRY (GNUNET_ERROR_TYPE_ERROR, "gcry_mpi_scan", rc);
+ GNUNET_assert (0);
+ }
+}
+
+
+/**
+ * Convert the given private key from the network format to the
+ * S-expression that can be used by libgcrypt.
+ *
+ * @param priv private key to decode
+ * @return NULL on error
+ */
+static gcry_sexp_t
+decode_private_key (const struct GNUNET_CRYPTO_EccPrivateKey *priv)
+{
+ gcry_sexp_t result;
+ gcry_mpi_t d;
+ int rc;
+
+ mpi_scan (&d,
+ priv->d,
+ sizeof (priv->d));
+ rc = gcry_sexp_build (&result, NULL,
+ "(private-key(ecdsa(curve \"" CURVE "\")(d %m)))",
+ d);
+ gcry_mpi_release (d);
+ if (0 != rc)
+ {
+ LOG_GCRY (GNUNET_ERROR_TYPE_ERROR, "gcry_sexp_build", rc);
+ GNUNET_assert (0);
+ }
+#if EXTRA_CHECKS
+ if (0 != (rc = gcry_pk_testkey (result)))
+ {
+ LOG_GCRY (GNUNET_ERROR_TYPE_ERROR, "gcry_pk_testkey", rc);
+ GNUNET_assert (0);
+ }
+#endif
+ return result;
+}
+
+
+/**
+ * Initialize public key struct from the respective point
+ * on the curve.
+ *
+ * @param q point on curve
+ * @param pub public key struct to initialize
+ * @param ctx context to use for ECC operations
+ */
+static void
+point_to_public_sign_key (gcry_mpi_point_t q,
+ gcry_ctx_t ctx,
+ struct GNUNET_CRYPTO_EccPublicSignKey *pub)
+{
+ gcry_mpi_t q_x;
+ gcry_mpi_t q_y;
+
+ q_x = gcry_mpi_new (256);
+ q_y = gcry_mpi_new (256);
+ if (gcry_mpi_ec_get_affine (q_x, q_y, q, ctx))
+ {
+ LOG_GCRY (GNUNET_ERROR_TYPE_ERROR, "get_affine failed", 0);
+ return;
+ }
+
+ mpi_print (pub->q_x, sizeof (pub->q_x), q_x);
+ mpi_print (pub->q_y, sizeof (pub->q_y), q_y);
+ gcry_mpi_release (q_x);
+ gcry_mpi_release (q_y);
+}
+
+
+/**
+ * Initialize public key struct from the respective point
+ * on the curve.
+ *
+ * @param q point on curve
+ * @param pub public key struct to initialize
+ * @param ctx context to use for ECC operations
+ */
+static void
+point_to_public_encrypt_key (gcry_mpi_point_t q,
+ gcry_ctx_t ctx,
+ struct GNUNET_CRYPTO_EccPublicEncryptKey *pub)
+{
+ gcry_mpi_t q_x;
+ gcry_mpi_t q_y;
+
+ q_x = gcry_mpi_new (256);
+ q_y = gcry_mpi_new (256);
+ if (gcry_mpi_ec_get_affine (q_x, q_y, q, ctx))
+ {
+ LOG_GCRY (GNUNET_ERROR_TYPE_ERROR, "get_affine failed", 0);
+ return;
+ }
+
+ mpi_print (pub->q_x, sizeof (pub->q_x), q_x);
+ mpi_print (pub->q_y, sizeof (pub->q_y), q_y);
+ gcry_mpi_release (q_x);
+ gcry_mpi_release (q_y);
+}
+
+
/**
* Extract the public key for the given private key.
*
* @param pub where to write the public key
*/
void
-GNUNET_CRYPTO_ecc_key_get_public (const struct GNUNET_CRYPTO_EccPrivateKey *priv,
- struct GNUNET_CRYPTO_EccPublicKeyBinaryEncoded *pub)
+GNUNET_CRYPTO_ecc_key_get_public_for_signature (const struct GNUNET_CRYPTO_EccPrivateKey *priv,
+ struct GNUNET_CRYPTO_EccPublicSignKey *pub)
{
- gcry_mpi_t skey;
- size_t size;
- int rc;
+ gcry_sexp_t sexp;
+ gcry_ctx_t ctx;
+ gcry_mpi_point_t q;
- memset (pub, 0, sizeof (struct GNUNET_CRYPTO_EccPublicKeyBinaryEncoded));
- rc = key_from_sexp (&skey, priv->sexp, "public-key", "q");
- if (rc)
- rc = key_from_sexp (&skey, priv->sexp, "private-key", "q");
- if (rc)
- rc = key_from_sexp (&skey, priv->sexp, "ecc", "q");
- GNUNET_assert (0 == rc);
- pub->size = htons (sizeof (struct GNUNET_CRYPTO_EccPublicKeyBinaryEncoded));
- size = GNUNET_CRYPTO_ECC_MAX_PUBLIC_KEY_LENGTH;
- GNUNET_assert (0 ==
- gcry_mpi_print (GCRYMPI_FMT_USG, pub->key, size, &size,
- skey));
- pub->len = htons (size);
- gcry_mpi_release (skey);
+ sexp = decode_private_key (priv);
+ GNUNET_assert (NULL != sexp);
+ GNUNET_assert (0 == gcry_mpi_ec_new (&ctx, sexp, NULL));
+ gcry_sexp_release (sexp);
+ q = gcry_mpi_ec_get_point ("q", ctx, 0);
+ point_to_public_sign_key (q, ctx, pub);
+ gcry_ctx_release (ctx);
+ gcry_mpi_point_release (q);
+}
+
+
+/**
+ * Extract the public key for the given private key.
+ *
+ * @param priv the private key
+ * @param pub where to write the public key
+ */
+void
+GNUNET_CRYPTO_ecc_key_get_public_for_encryption (const struct GNUNET_CRYPTO_EccPrivateKey *priv,
+ struct GNUNET_CRYPTO_EccPublicEncryptKey *pub)
+{
+ gcry_sexp_t sexp;
+ gcry_ctx_t ctx;
+ gcry_mpi_point_t q;
+
+ sexp = decode_private_key (priv);
+ GNUNET_assert (NULL != sexp);
+ GNUNET_assert (0 == gcry_mpi_ec_new (&ctx, sexp, NULL));
+ gcry_sexp_release (sexp);
+ q = gcry_mpi_ec_get_point ("q", ctx, 0);
+ point_to_public_encrypt_key (q, ctx, pub);
+ gcry_ctx_release (ctx);
+ gcry_mpi_point_release (q);
}
* Convert a public key to a string.
*
* @param pub key to convert
- * @return string representing 'pub'
+ * @return string representing @a pub
*/
char *
-GNUNET_CRYPTO_ecc_public_key_to_string (const struct GNUNET_CRYPTO_EccPublicKeyBinaryEncoded *pub)
+GNUNET_CRYPTO_ecc_public_sign_key_to_string (const struct GNUNET_CRYPTO_EccPublicSignKey *pub)
{
char *pubkeybuf;
- size_t keylen = (sizeof (struct GNUNET_CRYPTO_EccPublicKeyBinaryEncoded)) * 8;
+ size_t keylen = (sizeof (struct GNUNET_CRYPTO_EccPublicSignKey)) * 8;
char *end;
if (keylen % 5 > 0)
keylen += 5 - keylen % 5;
keylen /= 5;
pubkeybuf = GNUNET_malloc (keylen + 1);
- end = GNUNET_STRINGS_data_to_string ((unsigned char *) pub,
- sizeof (struct GNUNET_CRYPTO_EccPublicKeyBinaryEncoded),
- pubkeybuf,
+ end = GNUNET_STRINGS_data_to_string ((unsigned char *) pub,
+ sizeof (struct GNUNET_CRYPTO_EccPublicSignKey),
+ pubkeybuf,
keylen);
if (NULL == end)
{
* Convert a string representing a public key to a public key.
*
* @param enc encoded public key
- * @param enclen number of bytes in enc (without 0-terminator)
+ * @param enclen number of bytes in @a enc (without 0-terminator)
* @param pub where to store the public key
- * @return GNUNET_OK on success
+ * @return #GNUNET_OK on success
*/
int
-GNUNET_CRYPTO_ecc_public_key_from_string (const char *enc,
+GNUNET_CRYPTO_ecc_public_sign_key_from_string (const char *enc,
size_t enclen,
- struct GNUNET_CRYPTO_EccPublicKeyBinaryEncoded *pub)
+ struct GNUNET_CRYPTO_EccPublicSignKey *pub)
{
- size_t keylen = (sizeof (struct GNUNET_CRYPTO_EccPublicKeyBinaryEncoded)) * 8;
+ size_t keylen = (sizeof (struct GNUNET_CRYPTO_EccPublicSignKey)) * 8;
if (keylen % 5 > 0)
keylen += 5 - keylen % 5;
if (GNUNET_OK != GNUNET_STRINGS_string_to_data (enc, enclen,
pub,
- sizeof (struct GNUNET_CRYPTO_EccPublicKeyBinaryEncoded)))
- return GNUNET_SYSERR;
- if ( (ntohs (pub->size) != sizeof (struct GNUNET_CRYPTO_EccPublicKeyBinaryEncoded)) ||
- (ntohs (pub->len) > GNUNET_CRYPTO_ECC_SIGNATURE_DATA_ENCODING_LENGTH) )
+ sizeof (struct GNUNET_CRYPTO_EccPublicSignKey)))
return GNUNET_SYSERR;
return GNUNET_OK;
}
* Convert the given public key from the network format to the
* S-expression that can be used by libgcrypt.
*
- * @param publicKey public key to decode
+ * @param pub public key to decode
* @return NULL on error
*/
static gcry_sexp_t
-decode_public_key (const struct GNUNET_CRYPTO_EccPublicKeyBinaryEncoded *publicKey)
+decode_public_sign_key (const struct GNUNET_CRYPTO_EccPublicSignKey *pub)
{
- gcry_sexp_t result;
- gcry_mpi_t q;
- size_t size;
- size_t erroff;
- int rc;
-
- if (ntohs (publicKey->len) > GNUNET_CRYPTO_ECC_SIGNATURE_DATA_ENCODING_LENGTH)
- {
- GNUNET_break (0);
- return NULL;
- }
- size = ntohs (publicKey->len);
- if (0 != (rc = gcry_mpi_scan (&q, GCRYMPI_FMT_USG, publicKey->key, size, &size)))
- {
- LOG_GCRY (GNUNET_ERROR_TYPE_ERROR, "gcry_mpi_scan", rc);
- return NULL;
- }
-
- rc = gcry_sexp_build (&result, &erroff,
- "(public-key(ecdsa(curve \"" CURVE "\")(q %m)))",
- q);
- gcry_mpi_release (q);
- if (0 != rc)
- {
- LOG_GCRY (GNUNET_ERROR_TYPE_ERROR, "gcry_sexp_build", rc); /* erroff gives more info */
- return NULL;
- }
-#if EXTRA_CHECKS
- if (0 != (rc = gcry_pk_testkey (result)))
- {
- LOG_GCRY (GNUNET_ERROR_TYPE_ERROR, "gcry_pk_testkey", rc);
- gcry_sexp_release (result);
- return NULL;
- }
-#endif
- return result;
-}
+ gcry_sexp_t pub_sexp;
+ gcry_mpi_t q_x;
+ gcry_mpi_t q_y;
+ gcry_mpi_point_t q;
+ gcry_ctx_t ctx;
+ mpi_scan (&q_x, pub->q_x, sizeof (pub->q_x));
+ mpi_scan (&q_y, pub->q_y, sizeof (pub->q_y));
+ q = gcry_mpi_point_new (256);
+ gcry_mpi_point_set (q, q_x, q_y, GCRYMPI_CONST_ONE);
+ gcry_mpi_release (q_x);
+ gcry_mpi_release (q_y);
-/**
- * Encode the private key in a format suitable for
- * storing it into a file.
- *
- * @param key key to encode
- * @return encoding of the private key.
- * The first 4 bytes give the size of the array, as usual.
- */
-struct GNUNET_CRYPTO_EccPrivateKeyBinaryEncoded *
-GNUNET_CRYPTO_ecc_encode_key (const struct GNUNET_CRYPTO_EccPrivateKey *key)
-{
- struct GNUNET_CRYPTO_EccPrivateKeyBinaryEncoded *retval;
- char buf[65536];
- uint16_t be;
- size_t size;
+ /* initialize 'ctx' with 'q' */
+ GNUNET_assert (0 == gcry_mpi_ec_new (&ctx, NULL, CURVE));
+ gcry_mpi_ec_set_point ("q", q, ctx);
+ gcry_mpi_point_release (q);
-#if EXTRA_CHECKS
- if (0 != gcry_pk_testkey (key->sexp))
- {
- GNUNET_break (0);
- return NULL;
- }
-#endif
- size = gcry_sexp_sprint (key->sexp,
- GCRYSEXP_FMT_DEFAULT,
- &buf[2], sizeof (buf) - sizeof (uint16_t));
- if (0 == size)
- {
- GNUNET_break (0);
- return NULL;
- }
- GNUNET_assert (size < 65536 - sizeof (uint16_t));
- be = htons ((uint16_t) size + (sizeof (be)));
- memcpy (buf, &be, sizeof (be));
- size += sizeof (be);
- retval = GNUNET_malloc (size);
- memcpy (retval, buf, size);
- return retval;
+ /* convert 'ctx' to 'sexp' */
+ GNUNET_assert (0 == gcry_pubkey_get_sexp (&pub_sexp, GCRY_PK_GET_PUBKEY, ctx));
+ gcry_ctx_release (ctx);
+ return pub_sexp;
}
/**
- * Decode the private key from the file-format back
- * to the "normal", internal format.
+ * @ingroup crypto
+ * Clear memory that was used to store a private key.
*
- * @param buf the buffer where the private key data is stored
- * @param len the length of the data in 'buffer'
- * @param validate GNUNET_YES to validate that the key is well-formed,
- * GNUNET_NO if the key comes from a totally trusted source
- * and validation is considered too expensive
- * @return NULL on error
+ * @param pk location of the key
*/
-struct GNUNET_CRYPTO_EccPrivateKey *
-GNUNET_CRYPTO_ecc_decode_key (const char *buf,
- size_t len,
- int validate)
+void
+GNUNET_CRYPTO_ecc_key_clear (struct GNUNET_CRYPTO_EccPrivateKey *pk)
{
- struct GNUNET_CRYPTO_EccPrivateKey *ret;
- uint16_t be;
- gcry_sexp_t sexp;
- int rc;
- size_t erroff;
-
- if (len < sizeof (uint16_t))
- return NULL;
- memcpy (&be, buf, sizeof (be));
- if (len < ntohs (be))
- return NULL;
- len = ntohs (be);
- if (0 != (rc = gcry_sexp_sscan (&sexp,
- &erroff,
- &buf[2],
- len - sizeof (uint16_t))))
- {
- LOG_GCRY (GNUNET_ERROR_TYPE_ERROR, "gcry_sexp_scan", rc);
- return NULL;
- }
- if ( (GNUNET_YES == validate) &&
- (0 != (rc = gcry_pk_testkey (sexp))) )
- {
- LOG_GCRY (GNUNET_ERROR_TYPE_ERROR, "gcry_pk_testkey", rc);
- return NULL;
- }
- ret = GNUNET_malloc (sizeof (struct GNUNET_CRYPTO_EccPrivateKey));
- ret->sexp = sexp;
- return ret;
+ memset (pk, 0, sizeof (struct GNUNET_CRYPTO_EccPrivateKey));
}
struct GNUNET_CRYPTO_EccPrivateKey *
GNUNET_CRYPTO_ecc_key_create ()
{
- struct GNUNET_CRYPTO_EccPrivateKey *ret;
- gcry_sexp_t s_key;
+ struct GNUNET_CRYPTO_EccPrivateKey *priv;
+ gcry_sexp_t priv_sexp;
gcry_sexp_t s_keyparam;
+ gcry_mpi_t d;
int rc;
if (0 != (rc = gcry_sexp_build (&s_keyparam, NULL,
LOG_GCRY (GNUNET_ERROR_TYPE_ERROR, "gcry_sexp_build", rc);
return NULL;
}
- if (0 != (rc = gcry_pk_genkey (&s_key, s_keyparam)))
+ if (0 != (rc = gcry_pk_genkey (&priv_sexp, s_keyparam)))
{
LOG_GCRY (GNUNET_ERROR_TYPE_ERROR, "gcry_pk_genkey", rc);
gcry_sexp_release (s_keyparam);
}
gcry_sexp_release (s_keyparam);
#if EXTRA_CHECKS
- if (0 != (rc = gcry_pk_testkey (s_key)))
+ if (0 != (rc = gcry_pk_testkey (priv_sexp)))
{
LOG_GCRY (GNUNET_ERROR_TYPE_ERROR, "gcry_pk_testkey", rc);
- gcry_sexp_release (s_key);
+ gcry_sexp_release (priv_sexp);
return NULL;
}
#endif
- ret = GNUNET_malloc (sizeof (struct GNUNET_CRYPTO_EccPrivateKey));
- ret->sexp = s_key;
- return ret;
+ if (0 != (rc = key_from_sexp (&d, priv_sexp, "private-key", "d")))
+ {
+ LOG_GCRY (GNUNET_ERROR_TYPE_ERROR, "key_from_sexp", rc);
+ gcry_sexp_release (priv_sexp);
+ return NULL;
+ }
+ gcry_sexp_release (priv_sexp);
+ priv = GNUNET_new (struct GNUNET_CRYPTO_EccPrivateKey);
+ mpi_print (priv->d, sizeof (priv->d), d);
+ gcry_mpi_release (d);
+ return priv;
+}
+
+
+/**
+ * Get the shared private key we use for anonymous users.
+ *
+ * @return "anonymous" private key
+ */
+const struct GNUNET_CRYPTO_EccPrivateKey *
+GNUNET_CRYPTO_ecc_key_get_anonymous ()
+{
+ /**
+ * 'anonymous' pseudonym (global static, d=1, public key = G
+ * (generator).
+ */
+ static struct GNUNET_CRYPTO_EccPrivateKey anonymous;
+ static int once;
+
+ if (once)
+ return &anonymous;
+ mpi_print (anonymous.d,
+ sizeof (anonymous.d),
+ GCRYMPI_CONST_ONE);
+ once = 1;
+ return &anonymous;
}
* are invalid the old file is deleted and a fresh key is
* created.
*
+ * @param filename name of file to use to store the key
* @return new private key, NULL on error (for example,
* permission denied)
*/
struct GNUNET_CRYPTO_EccPrivateKey *
GNUNET_CRYPTO_ecc_key_create_from_file (const char *filename)
{
- struct GNUNET_CRYPTO_EccPrivateKey *ret;
- struct GNUNET_CRYPTO_EccPrivateKeyBinaryEncoded *enc;
- uint16_t len;
+ struct GNUNET_CRYPTO_EccPrivateKey *priv;
struct GNUNET_DISK_FileHandle *fd;
unsigned int cnt;
int ec;
uint64_t fs;
- struct GNUNET_CRYPTO_EccPublicKeyBinaryEncoded pub;
- struct GNUNET_PeerIdentity pid;
if (GNUNET_SYSERR == GNUNET_DISK_directory_create_for_file (filename))
return NULL;
GNUNET_DISK_PERM_USER_WRITE);
if (NULL == fd)
{
- if (errno == EEXIST)
+ if (EEXIST == errno)
{
if (GNUNET_YES != GNUNET_DISK_file_test (filename))
{
return NULL;
}
cnt = 0;
-
while (GNUNET_YES !=
GNUNET_DISK_file_lock (fd, 0,
- sizeof (struct GNUNET_CRYPTO_EccPrivateKeyBinaryEncoded),
+ sizeof (struct GNUNET_CRYPTO_EccPrivateKey),
GNUNET_YES))
{
short_wait ();
}
LOG (GNUNET_ERROR_TYPE_INFO,
_("Creating a new private key. This may take a while.\n"));
- ret = GNUNET_CRYPTO_ecc_key_create ();
- GNUNET_assert (ret != NULL);
- enc = GNUNET_CRYPTO_ecc_encode_key (ret);
- GNUNET_assert (enc != NULL);
- GNUNET_assert (ntohs (enc->size) ==
- GNUNET_DISK_file_write (fd, enc, ntohs (enc->size)));
- GNUNET_free (enc);
-
+ priv = GNUNET_CRYPTO_ecc_key_create ();
+ GNUNET_assert (NULL != priv);
+ GNUNET_assert (sizeof (*priv) ==
+ GNUNET_DISK_file_write (fd, priv, sizeof (*priv)));
GNUNET_DISK_file_sync (fd);
if (GNUNET_YES !=
GNUNET_DISK_file_unlock (fd, 0,
- sizeof (struct GNUNET_CRYPTO_EccPrivateKeyBinaryEncoded)))
+ sizeof (struct GNUNET_CRYPTO_EccPrivateKey)))
LOG_STRERROR_FILE (GNUNET_ERROR_TYPE_WARNING, "fcntl", filename);
GNUNET_assert (GNUNET_YES == GNUNET_DISK_file_close (fd));
- GNUNET_CRYPTO_ecc_key_get_public (ret, &pub);
- GNUNET_CRYPTO_hash (&pub, sizeof (pub), &pid.hashPubKey);
- return ret;
+ return priv;
}
/* key file exists already, read it! */
fd = GNUNET_DISK_file_open (filename, GNUNET_DISK_OPEN_READ,
{
if (GNUNET_YES !=
GNUNET_DISK_file_lock (fd, 0,
- sizeof (struct GNUNET_CRYPTO_EccPrivateKeyBinaryEncoded),
+ sizeof (struct GNUNET_CRYPTO_EccPrivateKey),
GNUNET_NO))
{
if (0 == ++cnt % 60)
LOG_STRERROR_FILE (GNUNET_ERROR_TYPE_WARNING, "stat", filename);
if (GNUNET_YES !=
GNUNET_DISK_file_unlock (fd, 0,
- sizeof (struct GNUNET_CRYPTO_EccPrivateKeyBinaryEncoded)))
+ sizeof (struct GNUNET_CRYPTO_EccPrivateKey)))
LOG_STRERROR_FILE (GNUNET_ERROR_TYPE_WARNING, "fcntl", filename);
GNUNET_assert (GNUNET_OK == GNUNET_DISK_file_close (fd));
}
if (GNUNET_OK != GNUNET_DISK_file_size (filename, &fs, GNUNET_YES, GNUNET_YES))
fs = 0;
- if (fs < sizeof (struct GNUNET_CRYPTO_EccPrivateKeyBinaryEncoded))
+ if (fs < sizeof (struct GNUNET_CRYPTO_EccPrivateKey))
{
/* maybe we got the read lock before the key generating
* process had a chance to get the write lock; give it up! */
if (GNUNET_YES !=
GNUNET_DISK_file_unlock (fd, 0,
- sizeof (struct GNUNET_CRYPTO_EccPrivateKeyBinaryEncoded)))
+ sizeof (struct GNUNET_CRYPTO_EccPrivateKey)))
LOG_STRERROR_FILE (GNUNET_ERROR_TYPE_WARNING, "fcntl", filename);
if (0 == ++cnt % 10)
{
_
("When trying to read key file `%s' I found %u bytes but I need at least %u.\n"),
filename, (unsigned int) fs,
- (unsigned int) sizeof (struct GNUNET_CRYPTO_EccPrivateKeyBinaryEncoded));
+ (unsigned int) sizeof (struct GNUNET_CRYPTO_EccPrivateKey));
LOG (GNUNET_ERROR_TYPE_ERROR,
_
("This may be ok if someone is currently generating a key.\n"));
}
break;
}
- enc = GNUNET_malloc (fs);
- GNUNET_assert (fs == GNUNET_DISK_file_read (fd, enc, fs));
- len = ntohs (enc->size);
- ret = NULL;
- if ((len > fs) ||
- (NULL == (ret = GNUNET_CRYPTO_ecc_decode_key ((char *) enc, len, GNUNET_YES))))
- {
- LOG (GNUNET_ERROR_TYPE_ERROR,
- _("File `%s' does not contain a valid private key. Deleting it.\n"),
- filename);
- if (0 != UNLINK (filename))
- {
- LOG_STRERROR_FILE (GNUNET_ERROR_TYPE_WARNING, "unlink", filename);
- }
- }
- GNUNET_free (enc);
+ fs = sizeof (struct GNUNET_CRYPTO_EccPrivateKey);
+ priv = GNUNET_malloc (fs);
+ GNUNET_assert (fs == GNUNET_DISK_file_read (fd, priv, fs));
if (GNUNET_YES !=
GNUNET_DISK_file_unlock (fd, 0,
- sizeof (struct GNUNET_CRYPTO_EccPrivateKeyBinaryEncoded)))
+ sizeof (struct GNUNET_CRYPTO_EccPrivateKey)))
LOG_STRERROR_FILE (GNUNET_ERROR_TYPE_WARNING, "fcntl", filename);
GNUNET_assert (GNUNET_YES == GNUNET_DISK_file_close (fd));
- if (ret != NULL)
- {
- GNUNET_CRYPTO_ecc_key_get_public (ret, &pub);
- GNUNET_CRYPTO_hash (&pub, sizeof (pub), &pid.hashPubKey);
- }
- return ret;
+ return priv;
}
* Create a new private key by reading our peer's key from
* the file specified in the configuration.
*
+ * @param cfg the configuration to use
* @return new private key, NULL on error (for example,
* permission denied)
*/
struct GNUNET_CRYPTO_EccPrivateKey *
GNUNET_CRYPTO_ecc_key_create_from_configuration (const struct GNUNET_CONFIGURATION_Handle *cfg)
{
- struct GNUNET_CRYPTO_EccPrivateKey *pk;
+ struct GNUNET_CRYPTO_EccPrivateKey *priv;
char *fn;
- if (GNUNET_OK !=
+ if (GNUNET_OK !=
GNUNET_CONFIGURATION_get_value_filename (cfg, "PEER", "PRIVATE_KEY", &fn))
return NULL;
- pk = GNUNET_CRYPTO_ecc_key_create_from_file (fn);
+ priv = GNUNET_CRYPTO_ecc_key_create_from_file (fn);
GNUNET_free (fn);
- return pk;
+ return priv;
}
GNUNET_CRYPTO_ecc_setup_key (const char *cfg_name)
{
struct GNUNET_CONFIGURATION_Handle *cfg;
- struct GNUNET_CRYPTO_EccPrivateKey *pk;
+ struct GNUNET_CRYPTO_EccPrivateKey *priv;
cfg = GNUNET_CONFIGURATION_create ();
(void) GNUNET_CONFIGURATION_load (cfg, cfg_name);
- pk = GNUNET_CRYPTO_ecc_key_create_from_configuration (cfg);
- if (NULL != pk)
- GNUNET_CRYPTO_ecc_key_free (pk);
+ priv = GNUNET_CRYPTO_ecc_key_create_from_configuration (cfg);
+ if (NULL != priv)
+ GNUNET_free (priv);
GNUNET_CONFIGURATION_destroy (cfg);
}
*
* @param cfg configuration to use
* @param dst pointer to where to write the peer identity
- * @return GNUNET_OK on success, GNUNET_SYSERR if the identity
+ * @return #GNUNET_OK on success, #GNUNET_SYSERR if the identity
* could not be retrieved
*/
int
-GNUNET_CRYPTO_get_host_identity (const struct GNUNET_CONFIGURATION_Handle *cfg,
+GNUNET_CRYPTO_get_peer_identity (const struct GNUNET_CONFIGURATION_Handle *cfg,
struct GNUNET_PeerIdentity *dst)
{
- struct GNUNET_CRYPTO_EccPrivateKey *my_private_key;
- struct GNUNET_CRYPTO_EccPublicKeyBinaryEncoded my_public_key;
+ struct GNUNET_CRYPTO_EccPrivateKey *priv;
- if (NULL == (my_private_key = GNUNET_CRYPTO_ecc_key_create_from_configuration (cfg)))
+ if (NULL == (priv = GNUNET_CRYPTO_ecc_key_create_from_configuration (cfg)))
{
GNUNET_log (GNUNET_ERROR_TYPE_ERROR,
_("Could not load peer's private key\n"));
return GNUNET_SYSERR;
}
- GNUNET_CRYPTO_ecc_key_get_public (my_private_key, &my_public_key);
- GNUNET_CRYPTO_ecc_key_free (my_private_key);
- GNUNET_CRYPTO_hash (&my_public_key, sizeof (my_public_key), &dst->hashPubKey);
+ GNUNET_CRYPTO_ecc_key_get_public_for_signature (priv, &dst->public_key);
+ GNUNET_free (priv);
return GNUNET_OK;
}
static gcry_sexp_t
data_to_pkcs1 (const struct GNUNET_CRYPTO_EccSignaturePurpose *purpose)
{
- struct GNUNET_CRYPTO_ShortHashCode hc;
- size_t bufSize;
+ struct GNUNET_HashCode hc;
gcry_sexp_t data;
+ int rc;
- GNUNET_CRYPTO_short_hash (purpose, ntohl (purpose->size), &hc);
-#define FORMATSTRING "(4:data(5:flags3:raw)(5:value32:01234567890123456789012345678901))"
- bufSize = strlen (FORMATSTRING) + 1;
+ GNUNET_CRYPTO_hash (purpose, ntohl (purpose->size), &hc);
+ if (0 != (rc = gcry_sexp_build (&data, NULL,
+ "(data(flags rfc6979)(hash %s %b))",
+ "sha512",
+ sizeof (hc),
+ &hc)))
{
- char buff[bufSize];
-
- memcpy (buff, FORMATSTRING, bufSize);
- memcpy (&buff
- [bufSize -
- strlen
- ("01234567890123456789012345678901))")
- - 1], &hc, sizeof (struct GNUNET_CRYPTO_ShortHashCode));
- GNUNET_assert (0 == gcry_sexp_new (&data, buff, bufSize, 0));
+ LOG_GCRY (GNUNET_ERROR_TYPE_ERROR, "gcry_sexp_build", rc);
+ return NULL;
}
-#undef FORMATSTRING
return data;
}
/**
* Sign a given block.
*
- * @param key private key to use for the signing
+ * @param priv private key to use for the signing
* @param purpose what to sign (size, purpose)
* @param sig where to write the signature
- * @return GNUNET_SYSERR on error, GNUNET_OK on success
+ * @return #GNUNET_SYSERR on error, #GNUNET_OK on success
*/
int
-GNUNET_CRYPTO_ecc_sign (const struct GNUNET_CRYPTO_EccPrivateKey *key,
+GNUNET_CRYPTO_ecc_sign (const struct GNUNET_CRYPTO_EccPrivateKey *priv,
const struct GNUNET_CRYPTO_EccSignaturePurpose *purpose,
struct GNUNET_CRYPTO_EccSignature *sig)
{
- gcry_sexp_t result;
+ gcry_sexp_t priv_sexp;
+ gcry_sexp_t sig_sexp;
gcry_sexp_t data;
- size_t ssize;
int rc;
+ gcry_mpi_t rs[2];
+ priv_sexp = decode_private_key (priv);
data = data_to_pkcs1 (purpose);
- if (0 != (rc = gcry_pk_sign (&result, data, key->sexp)))
+ if (0 != (rc = gcry_pk_sign (&sig_sexp, data, priv_sexp)))
{
LOG (GNUNET_ERROR_TYPE_WARNING,
_("ECC signing failed at %s:%d: %s\n"), __FILE__,
__LINE__, gcry_strerror (rc));
gcry_sexp_release (data);
+ gcry_sexp_release (priv_sexp);
return GNUNET_SYSERR;
}
+ gcry_sexp_release (priv_sexp);
gcry_sexp_release (data);
- ssize = gcry_sexp_sprint (result,
- GCRYSEXP_FMT_DEFAULT,
- sig->sexpr,
- GNUNET_CRYPTO_ECC_SIGNATURE_DATA_ENCODING_LENGTH);
- if (0 == ssize)
+
+ /* extract 'r' and 's' values from sexpression 'sig_sexp' and store in
+ 'signature' */
+ if (0 != (rc = key_from_sexp (rs, sig_sexp, "sig-val", "rs")))
{
GNUNET_break (0);
+ gcry_sexp_release (sig_sexp);
return GNUNET_SYSERR;
}
- sig->size = htons ((uint16_t) (ssize + sizeof (uint16_t)));
- /* padd with zeros */
- memset (&sig->sexpr[ssize], 0, GNUNET_CRYPTO_ECC_SIGNATURE_DATA_ENCODING_LENGTH - ssize);
- gcry_sexp_release (result);
+ gcry_sexp_release (sig_sexp);
+ mpi_print (sig->r, sizeof (sig->r), rs[0]);
+ mpi_print (sig->s, sizeof (sig->s), rs[1]);
+ gcry_mpi_release (rs[0]);
+ gcry_mpi_release (rs[1]);
return GNUNET_OK;
}
* @param purpose what is the purpose that the signature should have?
* @param validate block to validate (size, purpose, data)
* @param sig signature that is being validated
- * @param publicKey public key of the signer
- * @returns GNUNET_OK if ok, GNUNET_SYSERR if invalid
+ * @param pub public key of the signer
+ * @returns #GNUNET_OK if ok, #GNUNET_SYSERR if invalid
*/
int
GNUNET_CRYPTO_ecc_verify (uint32_t purpose,
const struct GNUNET_CRYPTO_EccSignaturePurpose
*validate,
const struct GNUNET_CRYPTO_EccSignature *sig,
- const struct GNUNET_CRYPTO_EccPublicKeyBinaryEncoded
- *publicKey)
+ const struct GNUNET_CRYPTO_EccPublicSignKey *pub)
{
gcry_sexp_t data;
- gcry_sexp_t sigdata;
- size_t size;
- gcry_sexp_t psexp;
- size_t erroff;
+ gcry_sexp_t sig_sexpr;
+ gcry_sexp_t pub_sexpr;
int rc;
+ gcry_mpi_t r;
+ gcry_mpi_t s;
if (purpose != ntohl (validate->purpose))
return GNUNET_SYSERR; /* purpose mismatch */
- size = ntohs (sig->size);
- if ( (size < sizeof (uint16_t)) ||
- (size > GNUNET_CRYPTO_ECC_SIGNATURE_DATA_ENCODING_LENGTH - sizeof (uint16_t)) )
- return GNUNET_SYSERR; /* size out of range */
+
+ /* build s-expression for signature */
+ mpi_scan (&r, sig->r, sizeof (sig->r));
+ mpi_scan (&s, sig->s, sizeof (sig->s));
+ if (0 != (rc = gcry_sexp_build (&sig_sexpr, NULL,
+ "(sig-val(ecdsa(r %m)(s %m)))",
+ r, s)))
+ {
+ LOG_GCRY (GNUNET_ERROR_TYPE_ERROR, "gcry_sexp_build", rc);
+ gcry_mpi_release (r);
+ gcry_mpi_release (s);
+ return GNUNET_SYSERR;
+ }
+ gcry_mpi_release (r);
+ gcry_mpi_release (s);
data = data_to_pkcs1 (validate);
- GNUNET_assert (0 ==
- gcry_sexp_sscan (&sigdata, &erroff,
- sig->sexpr, size - sizeof (uint16_t)));
- if (! (psexp = decode_public_key (publicKey)))
+ if (! (pub_sexpr = decode_public_sign_key (pub)))
{
gcry_sexp_release (data);
- gcry_sexp_release (sigdata);
+ gcry_sexp_release (sig_sexpr);
return GNUNET_SYSERR;
}
- rc = gcry_pk_verify (sigdata, data, psexp);
- gcry_sexp_release (psexp);
+ rc = gcry_pk_verify (sig_sexpr, data, pub_sexpr);
+ gcry_sexp_release (pub_sexpr);
gcry_sexp_release (data);
- gcry_sexp_release (sigdata);
+ gcry_sexp_release (sig_sexpr);
if (0 != rc)
{
- LOG (GNUNET_ERROR_TYPE_WARNING,
+ LOG (GNUNET_ERROR_TYPE_INFO,
_("ECC signature verification failed at %s:%d: %s\n"), __FILE__,
__LINE__, gcry_strerror (rc));
return GNUNET_SYSERR;
}
+/**
+ * Convert the given public key from the network format to the
+ * S-expression that can be used by libgcrypt.
+ *
+ * @param pub public key to decode
+ * @return NULL on error
+ */
+static gcry_sexp_t
+decode_public_encrypt_key (const struct GNUNET_CRYPTO_EccPublicEncryptKey *pub)
+{
+ gcry_sexp_t pub_sexp;
+ gcry_mpi_t q_x;
+ gcry_mpi_t q_y;
+ gcry_mpi_point_t q;
+ gcry_ctx_t ctx;
+
+ mpi_scan (&q_x, pub->q_x, sizeof (pub->q_x));
+ mpi_scan (&q_y, pub->q_y, sizeof (pub->q_y));
+ q = gcry_mpi_point_new (256);
+ gcry_mpi_point_set (q, q_x, q_y, GCRYMPI_CONST_ONE);
+ gcry_mpi_release (q_x);
+ gcry_mpi_release (q_y);
+
+ /* initialize 'ctx' with 'q' */
+ GNUNET_assert (0 == gcry_mpi_ec_new (&ctx, NULL, CURVE));
+ gcry_mpi_ec_set_point ("q", q, ctx);
+ gcry_mpi_point_release (q);
+
+ /* convert 'ctx' to 'sexp' */
+ GNUNET_assert (0 == gcry_pubkey_get_sexp (&pub_sexp, GCRY_PK_GET_PUBKEY, ctx));
+ gcry_ctx_release (ctx);
+ return pub_sexp;
+}
+
+
/**
* 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 priv private key to use for the ECDH (x)
+ * @param pub public key to use for the ECDH (yG)
* @param key_material where to write the key material (xyG)
- * @return GNUNET_SYSERR on error, GNUNET_OK on success
+ * @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,
+GNUNET_CRYPTO_ecc_ecdh (const struct GNUNET_CRYPTO_EccPrivateKey *priv,
+ const struct GNUNET_CRYPTO_EccPublicEncryptKey *pub,
struct GNUNET_HashCode *key_material)
-{
- size_t slen;
- size_t erroff;
- int rc;
- unsigned char sdata_buf[2048]; /* big enough to print dh-shared-secret as S-expression */
+{
gcry_mpi_point_t result;
gcry_mpi_point_t q;
gcry_mpi_t d;
gcry_ctx_t ctx;
- gcry_sexp_t psexp;
+ gcry_sexp_t pub_sexpr;
gcry_mpi_t result_x;
gcry_mpi_t result_y;
+ unsigned char xbuf[256 / 8];
/* first, extract the q = dP value from the public key */
- if (! (psexp = decode_public_key (pub)))
+ if (! (pub_sexpr = decode_public_encrypt_key (pub)))
return GNUNET_SYSERR;
- if (0 != (rc = gcry_mpi_ec_new (&ctx, psexp, NULL)))
- {
- LOG_GCRY (GNUNET_ERROR_TYPE_ERROR, "gcry_mpi_ec_new", rc); /* erroff gives more info */
- return GNUNET_SYSERR;
- }
- gcry_sexp_release (psexp);
+ GNUNET_assert (0 == gcry_mpi_ec_new (&ctx, pub_sexpr, NULL));
+ gcry_sexp_release (pub_sexpr);
q = gcry_mpi_ec_get_point ("q", ctx, 0);
- gcry_ctx_release (ctx);
/* second, extract the d value from our private key */
- rc = key_from_sexp (&d, key->sexp, "private-key", "d");
- if (rc)
- rc = key_from_sexp (&d, key->sexp, "ecc", "d");
- if (0 != rc)
- {
- GNUNET_break (0);
- gcry_mpi_point_release (q);
- return GNUNET_SYSERR;
- }
-
- /* create a new context for definitively the correct curve;
- theoretically the 'public_key' might not use the right curve */
- if (0 != (rc = gcry_mpi_ec_new (&ctx, NULL, "NIST P-256")))
- {
- LOG_GCRY (GNUNET_ERROR_TYPE_ERROR, "gcry_mpi_ec_new", rc); /* erroff gives more info */
- gcry_mpi_release (d);
- gcry_mpi_point_release (q);
- return GNUNET_SYSERR;
- }
+ mpi_scan (&d, priv->d, sizeof (priv->d));
/* then call the 'multiply' function, to compute the product */
- GNUNET_assert (NULL != ctx);
result = gcry_mpi_point_new (0);
gcry_mpi_ec_mul (result, d, q, ctx);
gcry_mpi_point_release (q);
}
gcry_mpi_point_release (result);
gcry_ctx_release (ctx);
- if (0 != (rc = gcry_sexp_build (&psexp, &erroff,
- "(dh-shared-secret (x %m)(y %m))",
- result_x,
- result_y)))
- {
- LOG_GCRY (GNUNET_ERROR_TYPE_ERROR, "gcry_sexp_build", rc); /* erroff gives more info */
- gcry_mpi_release (result_x);
- gcry_mpi_release (result_y);
- return GNUNET_SYSERR;
- }
+
+ mpi_print (xbuf, sizeof (xbuf), result_x);
+ GNUNET_CRYPTO_hash (xbuf, sizeof (xbuf), key_material);
gcry_mpi_release (result_x);
gcry_mpi_release (result_y);
- slen = gcry_sexp_sprint (psexp, GCRYSEXP_FMT_DEFAULT, sdata_buf, sizeof (sdata_buf));
- GNUNET_assert (0 != slen);
- gcry_sexp_release (psexp);
- /* 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;
}
+/**
+ * Derive the 'h' value for key derivation, where
+ * 'h = H(l,P)'.
+ *
+ * @param pub public key for deriviation
+ * @param label label for deriviation
+ * @param context additional context to use for HKDF of 'h';
+ * typically the name of the subsystem/application
+ * @return h value
+ */
+static gcry_mpi_t
+derive_h (const struct GNUNET_CRYPTO_EccPublicSignKey *pub,
+ const char *label,
+ const char *context)
+{
+ gcry_mpi_t h;
+ struct GNUNET_HashCode hc;
+
+ GNUNET_CRYPTO_kdf (&hc, sizeof (hc),
+ "key-derivation", strlen ("key-derivation"),
+ pub, sizeof (*pub),
+ label, strlen (label),
+ context, strlen (context),
+ NULL, 0);
+ mpi_scan (&h, (unsigned char *) &hc, sizeof (hc));
+ return h;
+}
+
+
+/**
+ * Derive a private key from a given private key and a label.
+ * Essentially calculates a private key 'd = H(l,P) * x mod n'
+ * where n is the size of the ECC group and P is the public
+ * key associated with the private key 'd'.
+ *
+ * @param priv original private key
+ * @param label label to use for key deriviation
+ * @param context additional context to use for HKDF of 'h';
+ * typically the name of the subsystem/application
+ * @return derived private key
+ */
+struct GNUNET_CRYPTO_EccPrivateKey *
+GNUNET_CRYPTO_ecc_key_derive (const struct GNUNET_CRYPTO_EccPrivateKey *priv,
+ const char *label,
+ const char *context)
+{
+ struct GNUNET_CRYPTO_EccPublicSignKey pub;
+ struct GNUNET_CRYPTO_EccPrivateKey *ret;
+ gcry_mpi_t h;
+ gcry_mpi_t x;
+ gcry_mpi_t d;
+ gcry_mpi_t n;
+ gcry_ctx_t ctx;
+
+ GNUNET_assert (0 == gcry_mpi_ec_new (&ctx, NULL, CURVE));
+ n = gcry_mpi_ec_get_mpi ("n", ctx, 1);
+ GNUNET_CRYPTO_ecc_key_get_public_for_signature (priv, &pub);
+ h = derive_h (&pub, label, context);
+ mpi_scan (&x, priv->d, sizeof (priv->d));
+ d = gcry_mpi_new (256);
+ gcry_mpi_mulm (d, h, x, n);
+ gcry_mpi_release (h);
+ gcry_mpi_release (x);
+ gcry_mpi_release (n);
+ gcry_ctx_release (ctx);
+ ret = GNUNET_new (struct GNUNET_CRYPTO_EccPrivateKey);
+ mpi_print (ret->d, sizeof (ret->d), d);
+ gcry_mpi_release (d);
+ return ret;
+}
+
+
+/**
+ * Derive a public key from a given public key and a label.
+ * Essentially calculates a public key 'V = H(l,P) * P'.
+ *
+ * @param pub original public key
+ * @param label label to use for key deriviation
+ * @param context additional context to use for HKDF of 'h';
+ * typically the name of the subsystem/application
+ * @param result where to write the derived public key
+ */
+void
+GNUNET_CRYPTO_ecc_public_key_derive (const struct GNUNET_CRYPTO_EccPublicSignKey *pub,
+ const char *label,
+ const char *context,
+ struct GNUNET_CRYPTO_EccPublicSignKey *result)
+{
+ gcry_ctx_t ctx;
+ gcry_mpi_t h;
+ gcry_mpi_t n;
+ gcry_mpi_t h_mod_n;
+ gcry_mpi_t q_x;
+ gcry_mpi_t q_y;
+ gcry_mpi_point_t q;
+ gcry_mpi_point_t v;
+
+ GNUNET_assert (0 == gcry_mpi_ec_new (&ctx, NULL, CURVE));
+
+ /* obtain point 'q' from original public key */
+ mpi_scan (&q_x, pub->q_x, sizeof (pub->q_x));
+ mpi_scan (&q_y, pub->q_y, sizeof (pub->q_y));
+
+ q = gcry_mpi_point_new (0);
+ gcry_mpi_point_set (q, q_x, q_y, GCRYMPI_CONST_ONE);
+ gcry_mpi_release (q_x);
+ gcry_mpi_release (q_y);
+
+ /* calulcate h_mod_n = h % n */
+ h = derive_h (pub, label, context);
+ n = gcry_mpi_ec_get_mpi ("n", ctx, 1);
+ h_mod_n = gcry_mpi_new (256);
+ gcry_mpi_mod (h_mod_n, h, n);
+ /* calculate v = h_mod_n * q */
+ v = gcry_mpi_point_new (0);
+ gcry_mpi_ec_mul (v, h_mod_n, q, ctx);
+ gcry_mpi_release (h_mod_n);
+ gcry_mpi_release (h);
+ gcry_mpi_release (n);
+ gcry_mpi_point_release (q);
+ /* convert point 'v' to public key that we return */
+ point_to_public_sign_key (v, ctx, result);
+ gcry_mpi_point_release (v);
+ gcry_ctx_release (ctx);
+}
+
+
/* end of crypto_ecc.c */