/* This file is part of GNUnet. Copyright (C) 2012, 2013, 2015 GNUnet e.V. 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 3, or (at your option) any later version. GNUnet is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for more details. You should have received a copy of the GNU General Public License along with GNUnet; see the file COPYING. If not, write to the Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA. */ /** * @file util/crypto_ecc.c * @brief public key cryptography (ECC) with libgcrypt * @author Christian Grothoff */ #include "platform.h" #include #include "gnunet_crypto_lib.h" #include "gnunet_strings_lib.h" #define EXTRA_CHECKS 0 /** * 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. */ #define CURVE "Ed25519" #define LOG(kind,...) GNUNET_log_from (kind, "util-crypto-ecc", __VA_ARGS__) #define LOG_STRERROR(kind,syscall) GNUNET_log_from_strerror (kind, "util-crypto-ecc", syscall) #define LOG_STRERROR_FILE(kind,syscall,filename) GNUNET_log_from_strerror_file (kind, "util-crypto-ecc", syscall, filename) /** * Log an error message at log-level 'level' that indicates * 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) #include "crypto_bug.c" /** * Extract values from an S-expression. * * @param array where to store the result(s) * @param sexp S-expression to parse * @param topname top-level name in the S-expression that is of interest * @param elems names of the elements to extract * @return 0 on success */ static int key_from_sexp (gcry_mpi_t * array, gcry_sexp_t sexp, const char *topname, const char *elems) { gcry_sexp_t list; gcry_sexp_t l2; const char *s; unsigned int i; unsigned int idx; list = gcry_sexp_find_token (sexp, topname, 0); if (! list) return 1; l2 = gcry_sexp_cadr (list); gcry_sexp_release (list); list = l2; if (! list) return 2; idx = 0; for (s = elems; *s; s++, idx++) { l2 = gcry_sexp_find_token (list, s, 1); if (! l2) { for (i = 0; i < idx; i++) { gcry_free (array[i]); array[i] = NULL; } gcry_sexp_release (list); return 3; /* required parameter not found */ } array[idx] = gcry_sexp_nth_mpi (l2, 1, GCRYMPI_FMT_USG); gcry_sexp_release (l2); if (! array[idx]) { for (i = 0; i < idx; i++) { gcry_free (array[i]); array[i] = NULL; } gcry_sexp_release (list); return 4; /* required parameter is invalid */ } } gcry_sexp_release (list); return 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_ecdsa_key (const struct GNUNET_CRYPTO_EcdsaPrivateKey *priv) { gcry_sexp_t result; int rc; rc = gcry_sexp_build (&result, NULL, "(private-key(ecc(curve \"" CURVE "\")" "(d %b)))", (int) sizeof (priv->d), priv->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; } /** * 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_eddsa_key (const struct GNUNET_CRYPTO_EddsaPrivateKey *priv) { gcry_sexp_t result; int rc; rc = gcry_sexp_build (&result, NULL, "(private-key(ecc(curve \"" CURVE "\")" "(flags eddsa)(d %b)))", (int)sizeof (priv->d), priv->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; } /** * 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_ecdhe_key (const struct GNUNET_CRYPTO_EcdhePrivateKey *priv) { gcry_sexp_t result; int rc; rc = gcry_sexp_build (&result, NULL, "(private-key(ecc(curve \"" CURVE "\")" "(d %b)))", (int)sizeof (priv->d), priv->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; } /** * 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_ecdsa_key_get_public (const struct GNUNET_CRYPTO_EcdsaPrivateKey *priv, struct GNUNET_CRYPTO_EcdsaPublicKey *pub) { gcry_sexp_t sexp; gcry_ctx_t ctx; gcry_mpi_t q; sexp = decode_private_ecdsa_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_mpi ("q@eddsa", ctx, 0); GNUNET_assert (NULL != q); GNUNET_CRYPTO_mpi_print_unsigned (pub->q_y, sizeof (pub->q_y), q); gcry_mpi_release (q); gcry_ctx_release (ctx); } /** * 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_eddsa_key_get_public (const struct GNUNET_CRYPTO_EddsaPrivateKey *priv, struct GNUNET_CRYPTO_EddsaPublicKey *pub) { gcry_sexp_t sexp; gcry_ctx_t ctx; gcry_mpi_t q; sexp = decode_private_eddsa_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_mpi ("q@eddsa", ctx, 0); GNUNET_assert (q); GNUNET_CRYPTO_mpi_print_unsigned (pub->q_y, sizeof (pub->q_y), q); gcry_mpi_release (q); gcry_ctx_release (ctx); } /** * 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_ecdhe_key_get_public (const struct GNUNET_CRYPTO_EcdhePrivateKey *priv, struct GNUNET_CRYPTO_EcdhePublicKey *pub) { gcry_sexp_t sexp; gcry_ctx_t ctx; gcry_mpi_t q; sexp = decode_private_ecdhe_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_mpi ("q@eddsa", ctx, 0); GNUNET_assert (q); GNUNET_CRYPTO_mpi_print_unsigned (pub->q_y, sizeof (pub->q_y), q); gcry_mpi_release (q); gcry_ctx_release (ctx); } /** * Convert a public key to a string. * * @param pub key to convert * @return string representing @a pub */ char * GNUNET_CRYPTO_ecdsa_public_key_to_string (const struct GNUNET_CRYPTO_EcdsaPublicKey *pub) { char *pubkeybuf; size_t keylen = (sizeof (struct GNUNET_CRYPTO_EcdsaPublicKey)) * 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_EcdsaPublicKey), pubkeybuf, keylen); if (NULL == end) { GNUNET_free (pubkeybuf); return NULL; } *end = '\0'; return pubkeybuf; } /** * Convert a public key to a string. * * @param pub key to convert * @return string representing @a pub */ char * GNUNET_CRYPTO_eddsa_public_key_to_string (const struct GNUNET_CRYPTO_EddsaPublicKey *pub) { char *pubkeybuf; size_t keylen = (sizeof (struct GNUNET_CRYPTO_EddsaPublicKey)) * 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_EddsaPublicKey), pubkeybuf, keylen); if (NULL == end) { GNUNET_free (pubkeybuf); return NULL; } *end = '\0'; return pubkeybuf; } /** * Convert a private key to a string. * * @param priv key to convert * @return string representing @a pub */ char * GNUNET_CRYPTO_eddsa_private_key_to_string (const struct GNUNET_CRYPTO_EddsaPrivateKey *priv) { char *privkeybuf; size_t keylen = (sizeof (struct GNUNET_CRYPTO_EddsaPrivateKey)) * 8; char *end; if (keylen % 5 > 0) keylen += 5 - keylen % 5; keylen /= 5; privkeybuf = GNUNET_malloc (keylen + 1); end = GNUNET_STRINGS_data_to_string ((unsigned char *) priv, sizeof (struct GNUNET_CRYPTO_EddsaPrivateKey), privkeybuf, keylen); if (NULL == end) { GNUNET_free (privkeybuf); return NULL; } *end = '\0'; return privkeybuf; } /** * Convert a string representing a public key to a public key. * * @param enc encoded public key * @param enclen number of bytes in @a enc (without 0-terminator) * @param pub where to store the public key * @return #GNUNET_OK on success */ int GNUNET_CRYPTO_ecdsa_public_key_from_string (const char *enc, size_t enclen, struct GNUNET_CRYPTO_EcdsaPublicKey *pub) { size_t keylen = (sizeof (struct GNUNET_CRYPTO_EcdsaPublicKey)) * 8; if (keylen % 5 > 0) keylen += 5 - keylen % 5; keylen /= 5; if (enclen != keylen) return GNUNET_SYSERR; if (GNUNET_OK != GNUNET_STRINGS_string_to_data (enc, enclen, pub, sizeof (struct GNUNET_CRYPTO_EcdsaPublicKey))) return GNUNET_SYSERR; return GNUNET_OK; } /** * Convert a string representing a public key to a public key. * * @param enc encoded public key * @param enclen number of bytes in @a enc (without 0-terminator) * @param pub where to store the public key * @return #GNUNET_OK on success */ int GNUNET_CRYPTO_eddsa_public_key_from_string (const char *enc, size_t enclen, struct GNUNET_CRYPTO_EddsaPublicKey *pub) { size_t keylen = (sizeof (struct GNUNET_CRYPTO_EddsaPublicKey)) * 8; if (keylen % 5 > 0) keylen += 5 - keylen % 5; keylen /= 5; if (enclen != keylen) return GNUNET_SYSERR; if (GNUNET_OK != GNUNET_STRINGS_string_to_data (enc, enclen, pub, sizeof (struct GNUNET_CRYPTO_EddsaPublicKey))) return GNUNET_SYSERR; return GNUNET_OK; } /** * Convert a string representing a private key to a private key. * * @param enc encoded public key * @param enclen number of bytes in @a enc (without 0-terminator) * @param priv where to store the private key * @return #GNUNET_OK on success */ int GNUNET_CRYPTO_eddsa_private_key_from_string (const char *enc, size_t enclen, struct GNUNET_CRYPTO_EddsaPrivateKey *priv) { size_t keylen = (sizeof (struct GNUNET_CRYPTO_EddsaPrivateKey)) * 8; if (keylen % 5 > 0) keylen += 5 - keylen % 5; keylen /= 5; if (enclen != keylen) return GNUNET_SYSERR; if (GNUNET_OK != GNUNET_STRINGS_string_to_data (enc, enclen, priv, sizeof (struct GNUNET_CRYPTO_EddsaPrivateKey))) return GNUNET_SYSERR; #if CRYPTO_BUG if (GNUNET_OK != check_eddsa_key (priv)) { GNUNET_break (0); return GNUNET_OK; } #endif return GNUNET_OK; } /** * @ingroup crypto * Clear memory that was used to store a private key. * * @param pk location of the key */ void GNUNET_CRYPTO_ecdhe_key_clear (struct GNUNET_CRYPTO_EcdhePrivateKey *pk) { memset (pk, 0, sizeof (struct GNUNET_CRYPTO_EcdhePrivateKey)); } /** * @ingroup crypto * Clear memory that was used to store a private key. * * @param pk location of the key */ void GNUNET_CRYPTO_ecdsa_key_clear (struct GNUNET_CRYPTO_EcdsaPrivateKey *pk) { memset (pk, 0, sizeof (struct GNUNET_CRYPTO_EcdsaPrivateKey)); } /** * @ingroup crypto * Clear memory that was used to store a private key. * * @param pk location of the key */ void GNUNET_CRYPTO_eddsa_key_clear (struct GNUNET_CRYPTO_EddsaPrivateKey *pk) { memset (pk, 0, sizeof (struct GNUNET_CRYPTO_EddsaPrivateKey)); } /** * Create a new private key. Caller must free return value. * * @return fresh private key */ struct GNUNET_CRYPTO_EcdhePrivateKey * GNUNET_CRYPTO_ecdhe_key_create () { struct GNUNET_CRYPTO_EcdhePrivateKey *priv; priv = GNUNET_new (struct GNUNET_CRYPTO_EcdhePrivateKey); if (GNUNET_OK != GNUNET_CRYPTO_ecdhe_key_create2 (priv)) { GNUNET_free (priv); return NULL; } return priv; } /** * @ingroup crypto * Create a new private key. Clear with #GNUNET_CRYPTO_ecdhe_key_clear(). * * @param[out] pk set to fresh private key; * @return #GNUNET_OK on success, #GNUNET_SYSERR on failure */ int GNUNET_CRYPTO_ecdhe_key_create2 (struct GNUNET_CRYPTO_EcdhePrivateKey *pk) { gcry_sexp_t priv_sexp; gcry_sexp_t s_keyparam; gcry_mpi_t d; int rc; /* NOTE: For libgcrypt >= 1.7, we do not need the 'eddsa' flag here, but should also be harmless. For libgcrypt < 1.7, using 'eddsa' disables an expensive key testing routine. We do not want to run the expensive check for ECDHE, as we generate TONS of keys to use for a very short time. */ if (0 != (rc = gcry_sexp_build (&s_keyparam, NULL, "(genkey(ecc(curve \"" CURVE "\")" "(flags eddsa no-keytest)))"))) { LOG_GCRY (GNUNET_ERROR_TYPE_ERROR, "gcry_sexp_build", rc); return GNUNET_SYSERR; } 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); return GNUNET_SYSERR; } gcry_sexp_release (s_keyparam); #if EXTRA_CHECKS if (0 != (rc = gcry_pk_testkey (priv_sexp))) { LOG_GCRY (GNUNET_ERROR_TYPE_ERROR, "gcry_pk_testkey", rc); gcry_sexp_release (priv_sexp); return GNUNET_SYSERR; } #endif 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 GNUNET_SYSERR; } gcry_sexp_release (priv_sexp); GNUNET_CRYPTO_mpi_print_unsigned (pk->d, sizeof (pk->d), d); gcry_mpi_release (d); return GNUNET_OK; } /** * Create a new private key. Caller must free return value. * * @return fresh private key */ struct GNUNET_CRYPTO_EcdsaPrivateKey * GNUNET_CRYPTO_ecdsa_key_create () { struct GNUNET_CRYPTO_EcdsaPrivateKey *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, "(genkey(ecc(curve \"" CURVE "\")" "(flags)))"))) { LOG_GCRY (GNUNET_ERROR_TYPE_ERROR, "gcry_sexp_build", rc); return NULL; } 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); return NULL; } gcry_sexp_release (s_keyparam); #if EXTRA_CHECKS if (0 != (rc = gcry_pk_testkey (priv_sexp))) { LOG_GCRY (GNUNET_ERROR_TYPE_ERROR, "gcry_pk_testkey", rc); gcry_sexp_release (priv_sexp); return NULL; } #endif 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_EcdsaPrivateKey); GNUNET_CRYPTO_mpi_print_unsigned (priv->d, sizeof (priv->d), d); gcry_mpi_release (d); return priv; } /** * Create a new private key. Caller must free return value. * * @return fresh private key */ struct GNUNET_CRYPTO_EddsaPrivateKey * GNUNET_CRYPTO_eddsa_key_create () { struct GNUNET_CRYPTO_EddsaPrivateKey *priv; gcry_sexp_t priv_sexp; gcry_sexp_t s_keyparam; gcry_mpi_t d; int rc; #if CRYPTO_BUG again: #endif if (0 != (rc = gcry_sexp_build (&s_keyparam, NULL, "(genkey(ecc(curve \"" CURVE "\")" "(flags eddsa)))"))) { LOG_GCRY (GNUNET_ERROR_TYPE_ERROR, "gcry_sexp_build", rc); return NULL; } 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); return NULL; } gcry_sexp_release (s_keyparam); #if EXTRA_CHECKS if (0 != (rc = gcry_pk_testkey (priv_sexp))) { LOG_GCRY (GNUNET_ERROR_TYPE_ERROR, "gcry_pk_testkey", rc); gcry_sexp_release (priv_sexp); return NULL; } #endif 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_EddsaPrivateKey); GNUNET_CRYPTO_mpi_print_unsigned (priv->d, sizeof (priv->d), d); gcry_mpi_release (d); #if CRYPTO_BUG if (GNUNET_OK != check_eddsa_key (priv)) { GNUNET_break (0); GNUNET_free (priv); goto again; } #endif return priv; } /** * Get the shared private key we use for anonymous users. * * @return "anonymous" private key */ const struct GNUNET_CRYPTO_EcdsaPrivateKey * GNUNET_CRYPTO_ecdsa_key_get_anonymous () { /** * 'anonymous' pseudonym (global static, d=1, public key = G * (generator). */ static struct GNUNET_CRYPTO_EcdsaPrivateKey anonymous; static int once; if (once) return &anonymous; GNUNET_CRYPTO_mpi_print_unsigned (anonymous.d, sizeof (anonymous.d), GCRYMPI_CONST_ONE); once = 1; return &anonymous; } /** * Compare two Peer Identities. * * @param first first peer identity * @param second second peer identity * @return bigger than 0 if first > second, * 0 if they are the same * smaller than 0 if second > first */ int GNUNET_CRYPTO_cmp_peer_identity (const struct GNUNET_PeerIdentity *first, const struct GNUNET_PeerIdentity *second) { return memcmp (first, second, sizeof (struct GNUNET_PeerIdentity)); } /** * Convert the data specified in the given purpose argument to an * S-expression suitable for signature operations. * * @param purpose data to convert * @return converted s-expression */ static gcry_sexp_t data_to_eddsa_value (const struct GNUNET_CRYPTO_EccSignaturePurpose *purpose) { struct GNUNET_HashCode hc; gcry_sexp_t data; int rc; GNUNET_CRYPTO_hash (purpose, ntohl (purpose->size), &hc); if (0 != (rc = gcry_sexp_build (&data, NULL, "(data(flags eddsa)(hash-algo %s)(value %b))", "sha512", (int)sizeof (hc), &hc))) { LOG_GCRY (GNUNET_ERROR_TYPE_ERROR, "gcry_sexp_build", rc); return NULL; } return data; } /** * Convert the data specified in the given purpose argument to an * S-expression suitable for signature operations. * * @param purpose data to convert * @return converted s-expression */ static gcry_sexp_t data_to_ecdsa_value (const struct GNUNET_CRYPTO_EccSignaturePurpose *purpose) { struct GNUNET_HashCode hc; gcry_sexp_t data; int rc; GNUNET_CRYPTO_hash (purpose, ntohl (purpose->size), &hc); if (0 != (rc = gcry_sexp_build (&data, NULL, "(data(flags rfc6979)(hash %s %b))", "sha512", (int)sizeof (hc), &hc))) { LOG_GCRY (GNUNET_ERROR_TYPE_ERROR, "gcry_sexp_build", rc); return NULL; } return data; } /** * Sign a given block. * * @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 */ int GNUNET_CRYPTO_ecdsa_sign (const struct GNUNET_CRYPTO_EcdsaPrivateKey *priv, const struct GNUNET_CRYPTO_EccSignaturePurpose *purpose, struct GNUNET_CRYPTO_EcdsaSignature *sig) { gcry_sexp_t priv_sexp; gcry_sexp_t sig_sexp; gcry_sexp_t data; int rc; gcry_mpi_t rs[2]; priv_sexp = decode_private_ecdsa_key (priv); data = data_to_ecdsa_value (purpose); 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); /* 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; } gcry_sexp_release (sig_sexp); GNUNET_CRYPTO_mpi_print_unsigned (sig->r, sizeof (sig->r), rs[0]); GNUNET_CRYPTO_mpi_print_unsigned (sig->s, sizeof (sig->s), rs[1]); gcry_mpi_release (rs[0]); gcry_mpi_release (rs[1]); return GNUNET_OK; } /** * Sign a given block. * * @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 */ int GNUNET_CRYPTO_eddsa_sign (const struct GNUNET_CRYPTO_EddsaPrivateKey *priv, const struct GNUNET_CRYPTO_EccSignaturePurpose *purpose, struct GNUNET_CRYPTO_EddsaSignature *sig) { gcry_sexp_t priv_sexp; gcry_sexp_t sig_sexp; gcry_sexp_t data; int rc; gcry_mpi_t rs[2]; priv_sexp = decode_private_eddsa_key (priv); data = data_to_eddsa_value (purpose); if (0 != (rc = gcry_pk_sign (&sig_sexp, data, priv_sexp))) { LOG (GNUNET_ERROR_TYPE_WARNING, _("EdDSA 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); /* 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; } gcry_sexp_release (sig_sexp); GNUNET_CRYPTO_mpi_print_unsigned (sig->r, sizeof (sig->r), rs[0]); GNUNET_CRYPTO_mpi_print_unsigned (sig->s, sizeof (sig->s), rs[1]); gcry_mpi_release (rs[0]); gcry_mpi_release (rs[1]); return GNUNET_OK; } /** * Verify signature. * * @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 pub public key of the signer * @returns #GNUNET_OK if ok, #GNUNET_SYSERR if invalid */ int GNUNET_CRYPTO_ecdsa_verify (uint32_t purpose, const struct GNUNET_CRYPTO_EccSignaturePurpose *validate, const struct GNUNET_CRYPTO_EcdsaSignature *sig, const struct GNUNET_CRYPTO_EcdsaPublicKey *pub) { gcry_sexp_t data; gcry_sexp_t sig_sexpr; gcry_sexp_t pub_sexpr; int rc; if (purpose != ntohl (validate->purpose)) return GNUNET_SYSERR; /* purpose mismatch */ /* build s-expression for signature */ if (0 != (rc = gcry_sexp_build (&sig_sexpr, NULL, "(sig-val(ecdsa(r %b)(s %b)))", (int) sizeof (sig->r), sig->r, (int) sizeof (sig->s), sig->s))) { LOG_GCRY (GNUNET_ERROR_TYPE_ERROR, "gcry_sexp_build", rc); return GNUNET_SYSERR; } data = data_to_ecdsa_value (validate); if (0 != (rc = gcry_sexp_build (&pub_sexpr, NULL, "(public-key(ecc(curve " CURVE ")(q %b)))", (int) sizeof (pub->q_y), pub->q_y))) { gcry_sexp_release (data); gcry_sexp_release (sig_sexpr); return GNUNET_SYSERR; } rc = gcry_pk_verify (sig_sexpr, data, pub_sexpr); gcry_sexp_release (pub_sexpr); gcry_sexp_release (data); gcry_sexp_release (sig_sexpr); if (0 != rc) { LOG (GNUNET_ERROR_TYPE_INFO, _("ECDSA signature verification failed at %s:%d: %s\n"), __FILE__, __LINE__, gcry_strerror (rc)); return GNUNET_SYSERR; } return GNUNET_OK; } /** * Verify signature. * * @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 pub public key of the signer * @returns #GNUNET_OK if ok, #GNUNET_SYSERR if invalid */ int GNUNET_CRYPTO_eddsa_verify (uint32_t purpose, const struct GNUNET_CRYPTO_EccSignaturePurpose *validate, const struct GNUNET_CRYPTO_EddsaSignature *sig, const struct GNUNET_CRYPTO_EddsaPublicKey *pub) { gcry_sexp_t data; gcry_sexp_t sig_sexpr; gcry_sexp_t pub_sexpr; int rc; if (purpose != ntohl (validate->purpose)) return GNUNET_SYSERR; /* purpose mismatch */ /* build s-expression for signature */ if (0 != (rc = gcry_sexp_build (&sig_sexpr, NULL, "(sig-val(eddsa(r %b)(s %b)))", (int)sizeof (sig->r), sig->r, (int)sizeof (sig->s), sig->s))) { LOG_GCRY (GNUNET_ERROR_TYPE_ERROR, "gcry_sexp_build", rc); return GNUNET_SYSERR; } data = data_to_eddsa_value (validate); if (0 != (rc = gcry_sexp_build (&pub_sexpr, NULL, "(public-key(ecc(curve " CURVE ")(flags eddsa)(q %b)))", (int)sizeof (pub->q_y), pub->q_y))) { gcry_sexp_release (data); gcry_sexp_release (sig_sexpr); return GNUNET_SYSERR; } rc = gcry_pk_verify (sig_sexpr, data, pub_sexpr); gcry_sexp_release (pub_sexpr); gcry_sexp_release (data); gcry_sexp_release (sig_sexpr); if (0 != rc) { LOG (GNUNET_ERROR_TYPE_INFO, _("EdDSA signature verification failed at %s:%d: %s\n"), __FILE__, __LINE__, gcry_strerror (rc)); return GNUNET_SYSERR; } return GNUNET_OK; } /** * Derive key material from a public and a private ECDHE key. * * @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 */ int GNUNET_CRYPTO_ecc_ecdh (const struct GNUNET_CRYPTO_EcdhePrivateKey *priv, const struct GNUNET_CRYPTO_EcdhePublicKey *pub, struct GNUNET_HashCode *key_material) { gcry_mpi_point_t result; gcry_mpi_point_t q; gcry_mpi_t d; gcry_ctx_t ctx; gcry_sexp_t pub_sexpr; gcry_mpi_t result_x; unsigned char xbuf[256 / 8]; size_t rsize; /* first, extract the q = dP value from the public key */ if (0 != gcry_sexp_build (&pub_sexpr, NULL, "(public-key(ecc(curve " CURVE ")(q %b)))", (int)sizeof (pub->q_y), pub->q_y)) return GNUNET_SYSERR; 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); /* second, extract the d value from our private key */ GNUNET_CRYPTO_mpi_scan_unsigned (&d, priv->d, sizeof (priv->d)); /* then call the 'multiply' function, to compute the product */ result = gcry_mpi_point_new (0); gcry_mpi_ec_mul (result, d, q, ctx); gcry_mpi_point_release (q); gcry_mpi_release (d); /* finally, convert point to string for hashing */ result_x = gcry_mpi_new (256); if (gcry_mpi_ec_get_affine (result_x, NULL, result, ctx)) { LOG_GCRY (GNUNET_ERROR_TYPE_ERROR, "get_affine failed", 0); gcry_mpi_point_release (result); gcry_ctx_release (ctx); return GNUNET_SYSERR; } gcry_mpi_point_release (result); gcry_ctx_release (ctx); rsize = sizeof (xbuf); GNUNET_assert (! gcry_mpi_get_flag (result_x, GCRYMPI_FLAG_OPAQUE)); /* result_x can be negative here, so we do not use 'GNUNET_CRYPTO_mpi_print_unsigned' as that does not include the sign bit; x should be a 255-bit value, so with the sign it should fit snugly into the 256-bit xbuf */ GNUNET_assert (0 == gcry_mpi_print (GCRYMPI_FMT_STD, xbuf, rsize, &rsize, result_x)); GNUNET_CRYPTO_hash (xbuf, rsize, key_material); gcry_mpi_release (result_x); 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_EcdsaPublicKey *pub, const char *label, const char *context) { gcry_mpi_t h; struct GNUNET_HashCode hc; static const char *const salt = "key-derivation"; GNUNET_CRYPTO_kdf (&hc, sizeof (hc), salt, strlen (salt), pub, sizeof (*pub), label, strlen (label), context, strlen (context), NULL, 0); GNUNET_CRYPTO_mpi_scan_unsigned (&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_EcdsaPrivateKey * GNUNET_CRYPTO_ecdsa_private_key_derive (const struct GNUNET_CRYPTO_EcdsaPrivateKey *priv, const char *label, const char *context) { struct GNUNET_CRYPTO_EcdsaPublicKey pub; struct GNUNET_CRYPTO_EcdsaPrivateKey *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_ecdsa_key_get_public (priv, &pub); h = derive_h (&pub, label, context); GNUNET_CRYPTO_mpi_scan_unsigned (&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_EcdsaPrivateKey); GNUNET_CRYPTO_mpi_print_unsigned (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 derivation * @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_ecdsa_public_key_derive (const struct GNUNET_CRYPTO_EcdsaPublicKey *pub, const char *label, const char *context, struct GNUNET_CRYPTO_EcdsaPublicKey *result) { gcry_ctx_t ctx; gcry_mpi_t q_y; gcry_mpi_t h; gcry_mpi_t n; gcry_mpi_t h_mod_n; 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. The provided 'q' is compressed thus we first store it in the context and then get it back as a (decompresssed) point. */ q_y = gcry_mpi_set_opaque_copy (NULL, pub->q_y, 8*sizeof (pub->q_y)); GNUNET_assert (NULL != q_y); GNUNET_assert (0 == gcry_mpi_ec_set_mpi ("q", q_y, ctx)); gcry_mpi_release (q_y); q = gcry_mpi_ec_get_point ("q", ctx, 0); GNUNET_assert (q); /* calculate 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 */ GNUNET_assert (0 == gcry_mpi_ec_set_point ("q", v, ctx)); gcry_mpi_point_release (v); q_y = gcry_mpi_ec_get_mpi ("q@eddsa", ctx, 0); GNUNET_assert (q_y); GNUNET_CRYPTO_mpi_print_unsigned (result->q_y, sizeof (result->q_y), q_y); gcry_mpi_release (q_y); gcry_ctx_release (ctx); } /** * Reverse the sequence of the bytes in @a buffer * * @param[in|out] buffer buffer to invert * @param length number of bytes in @a buffer */ static void reverse_buffer (unsigned char *buffer, size_t length) { unsigned char tmp; size_t i; for (i=0; i < length/2; i++) { tmp = buffer[i]; buffer[i] = buffer[length-1-i]; buffer[length-1-i] = tmp; } } /** * Convert the secret @a d of an EdDSA key to the * value that is actually used in the EdDSA computation. * * @param d secret input * @return value used for the calculation in EdDSA */ static gcry_mpi_t eddsa_d_to_a (gcry_mpi_t d) { unsigned char rawmpi[32]; /* 256-bit value */ size_t rawmpilen; unsigned char digest[64]; /* 512-bit hash value */ gcry_buffer_t hvec[2]; unsigned int b; gcry_mpi_t a; b = 256 / 8; /* number of bytes in `d` */ /* Note that we clear DIGEST so we can use it as input to left pad the key with zeroes for hashing. */ memset (hvec, 0, sizeof hvec); rawmpilen = sizeof (rawmpi); GNUNET_assert (0 == gcry_mpi_print (GCRYMPI_FMT_USG, rawmpi, rawmpilen, &rawmpilen, d)); if (rawmpilen < 32) { memmove (rawmpi + 32 - rawmpilen, rawmpi, rawmpilen); memset (rawmpi, 0, 32 - rawmpilen); rawmpilen = 32; } hvec[0].data = digest; hvec[0].off = 0; hvec[0].len = b > rawmpilen ? (b - rawmpilen) : 0; hvec[1].data = rawmpi; hvec[1].off = 0; hvec[1].len = rawmpilen; GNUNET_assert (0 == gcry_md_hash_buffers (GCRY_MD_SHA512, 0 /* flags */, digest, hvec, 2)); /* Compute the A value. */ reverse_buffer (digest, 32); /* Only the first half of the hash. */ digest[0] = (digest[0] & 0x7f) | 0x40; digest[31] &= 0xf8; GNUNET_CRYPTO_mpi_scan_unsigned (&a, digest, 32); return a; } /** * Take point from ECDH and convert it to key material. * * @param result point from ECDH * @param ctx ECC context * @param key_material[out] set to derived key material * @return #GNUNET_OK on success */ static int point_to_hash (gcry_mpi_point_t result, gcry_ctx_t ctx, struct GNUNET_HashCode *key_material) { gcry_mpi_t result_x; unsigned char xbuf[256 / 8]; size_t rsize; /* finally, convert point to string for hashing */ result_x = gcry_mpi_new (256); if (gcry_mpi_ec_get_affine (result_x, NULL, result, ctx)) { LOG_GCRY (GNUNET_ERROR_TYPE_ERROR, "get_affine failed", 0); return GNUNET_SYSERR; } rsize = sizeof (xbuf); GNUNET_assert (! gcry_mpi_get_flag (result_x, GCRYMPI_FLAG_OPAQUE)); /* result_x can be negative here, so we do not use 'GNUNET_CRYPTO_mpi_print_unsigned' as that does not include the sign bit; x should be a 255-bit value, so with the sign it should fit snugly into the 256-bit xbuf */ GNUNET_assert (0 == gcry_mpi_print (GCRYMPI_FMT_STD, xbuf, rsize, &rsize, result_x)); GNUNET_CRYPTO_hash (xbuf, rsize, key_material); gcry_mpi_release (result_x); return GNUNET_OK; } /** * @ingroup crypto * Derive key material from a ECDH public key and a private EdDSA key. * Dual to #GNUNET_CRRYPTO_ecdh_eddsa. * * @param priv private key from EdDSA 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 H(h(x)yG) * @return #GNUNET_SYSERR on error, #GNUNET_OK on success */ int GNUNET_CRYPTO_eddsa_ecdh (const struct GNUNET_CRYPTO_EddsaPrivateKey *priv, const struct GNUNET_CRYPTO_EcdhePublicKey *pub, struct GNUNET_HashCode *key_material) { gcry_mpi_point_t result; gcry_mpi_point_t q; gcry_mpi_t d; gcry_mpi_t a; gcry_ctx_t ctx; gcry_sexp_t pub_sexpr; int ret; /* first, extract the q = dP value from the public key */ if (0 != gcry_sexp_build (&pub_sexpr, NULL, "(public-key(ecc(curve " CURVE ")(q %b)))", (int)sizeof (pub->q_y), pub->q_y)) return GNUNET_SYSERR; 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); /* second, extract the d value from our private key */ GNUNET_CRYPTO_mpi_scan_unsigned (&d, priv->d, sizeof (priv->d)); /* NOW, because this is EdDSA, HASH 'd' first! */ a = eddsa_d_to_a (d); gcry_mpi_release (d); /* then call the 'multiply' function, to compute the product */ result = gcry_mpi_point_new (0); gcry_mpi_ec_mul (result, a, q, ctx); gcry_mpi_point_release (q); gcry_mpi_release (a); ret = point_to_hash (result, ctx, key_material); gcry_mpi_point_release (result); gcry_ctx_release (ctx); return ret; } /** * @ingroup crypto * Derive key material from a ECDH public key and a private ECDSA key. * Dual to #GNUNET_CRRYPTO_ecdh_eddsa. * * @param priv private key from ECDSA 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 H(h(x)yG) * @return #GNUNET_SYSERR on error, #GNUNET_OK on success */ int GNUNET_CRYPTO_ecdsa_ecdh (const struct GNUNET_CRYPTO_EcdsaPrivateKey *priv, const struct GNUNET_CRYPTO_EcdhePublicKey *pub, struct GNUNET_HashCode *key_material) { gcry_mpi_point_t result; gcry_mpi_point_t q; gcry_mpi_t d; gcry_ctx_t ctx; gcry_sexp_t pub_sexpr; int ret; /* first, extract the q = dP value from the public key */ if (0 != gcry_sexp_build (&pub_sexpr, NULL, "(public-key(ecc(curve " CURVE ")(q %b)))", (int)sizeof (pub->q_y), pub->q_y)) return GNUNET_SYSERR; 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); /* second, extract the d value from our private key */ GNUNET_CRYPTO_mpi_scan_unsigned (&d, priv->d, sizeof (priv->d)); /* then call the 'multiply' function, to compute the product */ result = gcry_mpi_point_new (0); gcry_mpi_ec_mul (result, d, q, ctx); gcry_mpi_point_release (q); gcry_mpi_release (d); /* finally, convert point to string for hashing */ ret = point_to_hash (result, ctx, key_material); gcry_mpi_point_release (result); gcry_ctx_release (ctx); return ret; } /** * @ingroup crypto * Derive key material from a EdDSA public key and a private ECDH key. * Dual to #GNUNET_CRRYPTO_eddsa_ecdh. * * @param priv private key to use for the ECDH (y) * @param pub public key from EdDSA to use for the ECDH (X=h(x)G) * @param key_material where to write the key material H(yX)=H(h(x)yG) * @return #GNUNET_SYSERR on error, #GNUNET_OK on success */ int GNUNET_CRYPTO_ecdh_eddsa (const struct GNUNET_CRYPTO_EcdhePrivateKey *priv, const struct GNUNET_CRYPTO_EddsaPublicKey *pub, struct GNUNET_HashCode *key_material) { gcry_mpi_point_t result; gcry_mpi_point_t q; gcry_mpi_t d; gcry_ctx_t ctx; gcry_sexp_t pub_sexpr; int ret; /* first, extract the q = dP value from the public key */ if (0 != gcry_sexp_build (&pub_sexpr, NULL, "(public-key(ecc(curve " CURVE ")(q %b)))", (int)sizeof (pub->q_y), pub->q_y)) return GNUNET_SYSERR; 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); /* second, extract the d value from our private key */ GNUNET_CRYPTO_mpi_scan_unsigned (&d, priv->d, sizeof (priv->d)); /* then call the 'multiply' function, to compute the product */ result = gcry_mpi_point_new (0); gcry_mpi_ec_mul (result, d, q, ctx); gcry_mpi_point_release (q); gcry_mpi_release (d); /* finally, convert point to string for hashing */ ret = point_to_hash (result, ctx, key_material); gcry_mpi_point_release (result); gcry_ctx_release (ctx); return ret; } /** * @ingroup crypto * Derive key material from a ECDSA public key and a private ECDH key. * Dual to #GNUNET_CRRYPTO_eddsa_ecdh. * * @param priv private key to use for the ECDH (y) * @param pub public key from ECDSA to use for the ECDH (X=h(x)G) * @param key_material where to write the key material H(yX)=H(h(x)yG) * @return #GNUNET_SYSERR on error, #GNUNET_OK on success */ int GNUNET_CRYPTO_ecdh_ecdsa (const struct GNUNET_CRYPTO_EcdhePrivateKey *priv, const struct GNUNET_CRYPTO_EcdsaPublicKey *pub, struct GNUNET_HashCode *key_material) { return GNUNET_CRYPTO_ecdh_eddsa (priv, (const struct GNUNET_CRYPTO_EddsaPublicKey *)pub, key_material); } /* end of crypto_ecc.c */