/*
This file is part of GNUnet.
- (C) 2001, 2002, 2003, 2004, 2005, 2006, 2009, 2012 Christian Grothoff (and other contributing authors)
+ (C) 2012, 2013 Christian Grothoff (and other contributing authors)
GNUnet is free software; you can redistribute it and/or modify
it under the terms of the GNU General Public License as published
* @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>
#include "gnunet_common.h"
#include "gnunet_util_lib.h"
-#define EXTRA_CHECKS ALLOW_EXTRA_CHECKS || 1
+#define EXTRA_CHECKS ALLOW_EXTRA_CHECKS
-#define CURVE "NIST P-521"
+#define CURVE "NIST P-256"
#define LOG(kind,...) GNUNET_log_from (kind, "util", __VA_ARGS__)
* @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;
return GNUNET_SYSERR;
if (GNUNET_OK != GNUNET_STRINGS_string_to_data (enc, enclen,
- (unsigned char*) pub,
- sizeof (struct GNUNET_CRYPTO_EccPublicKeyBinaryEncoded)))
+ 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) )
LOG_GCRY (GNUNET_ERROR_TYPE_ERROR, "gcry_sexp_build", rc); /* erroff gives more info */
return NULL;
}
- // FIXME: is this key expected to pass pk_testkey?
-#if 0
-#if EXTRA_CHECKS
+#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
#endif
return result;
}
*
* @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
*/
struct GNUNET_CRYPTO_EccPrivateKey *
GNUNET_CRYPTO_ecc_decode_key (const char *buf,
- size_t len)
+ size_t len,
+ int validate)
{
struct GNUNET_CRYPTO_EccPrivateKey *ret;
uint16_t be;
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],
{
LOG_GCRY (GNUNET_ERROR_TYPE_ERROR, "gcry_sexp_scan", rc);
return NULL;
- }
- if (0 != (rc = gcry_pk_testkey (sexp)))
+ }
+ if ( (GNUNET_YES == validate) &&
+ (0 != (rc = gcry_pk_testkey (sexp))) )
{
LOG_GCRY (GNUNET_ERROR_TYPE_ERROR, "gcry_pk_testkey", rc);
return NULL;
*
* @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;
}
-/**
- * Try to read the private key from the given file.
- *
- * @param filename file to read the key from
- * @return NULL on error
- */
-static struct GNUNET_CRYPTO_EccPrivateKey *
-try_read_key (const char *filename)
-{
- struct GNUNET_CRYPTO_EccPrivateKey *ret;
- struct GNUNET_DISK_FileHandle *fd;
- OFF_T fs;
-
- if (GNUNET_YES != GNUNET_DISK_file_test (filename))
- return NULL;
-
- /* key file exists already, read it! */
- if (NULL == (fd = GNUNET_DISK_file_open (filename, GNUNET_DISK_OPEN_READ,
- GNUNET_DISK_PERM_NONE)))
- {
- LOG_STRERROR_FILE (GNUNET_ERROR_TYPE_ERROR, "open", filename);
- return NULL;
- }
- if (GNUNET_OK != (GNUNET_DISK_file_handle_size (fd, &fs)))
- {
- LOG_STRERROR_FILE (GNUNET_ERROR_TYPE_ERROR, "stat", filename);
- (void) GNUNET_DISK_file_close (fd);
- return NULL;
- }
- if (0 == fs)
- {
- GNUNET_break (GNUNET_OK == GNUNET_DISK_file_close (fd));
- return NULL;
- }
- if (fs > UINT16_MAX)
- {
- LOG (GNUNET_ERROR_TYPE_ERROR,
- _("File `%s' does not contain a valid private key (too long, %llu bytes). Deleting it.\n"),
- filename,
- (unsigned long long) fs);
- GNUNET_break (GNUNET_OK == GNUNET_DISK_file_close (fd));
- if (0 != UNLINK (filename))
- LOG_STRERROR_FILE (GNUNET_ERROR_TYPE_WARNING, "unlink", filename);
- return NULL;
- }
- {
- char enc[fs];
-
- GNUNET_break (fs == GNUNET_DISK_file_read (fd, enc, fs));
- if (NULL == (ret = GNUNET_CRYPTO_ecc_decode_key ((char *) enc, fs)))
- {
- LOG (GNUNET_ERROR_TYPE_ERROR,
- _("File `%s' does not contain a valid private key (failed decode, %llu bytes). Deleting it.\n"),
- filename,
- (unsigned long long) fs);
- GNUNET_break (GNUNET_OK == GNUNET_DISK_file_close (fd));
- if (0 != UNLINK (filename))
- LOG_STRERROR_FILE (GNUNET_ERROR_TYPE_WARNING, "unlink", filename);
- return NULL;
- }
- }
- GNUNET_break (GNUNET_OK == GNUNET_DISK_file_close (fd));
- return ret;
-}
-
-
/**
* Wait for a short time (we're trying to lock a file or want
* to give another process a shot at finishing a disk write, etc.).
}
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) ||
- (NULL == (ret = GNUNET_CRYPTO_ecc_decode_key ((char *) enc, len))))
+ 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"),
/**
- * Handle to cancel private key generation and state for the
- * key generation operation.
- */
-struct GNUNET_CRYPTO_EccKeyGenerationContext
-{
-
- /**
- * Continuation to call upon completion.
- */
- GNUNET_CRYPTO_EccKeyCallback cont;
-
- /**
- * Closure for 'cont'.
- */
- void *cont_cls;
-
- /**
- * Name of the file.
- */
- char *filename;
-
- /**
- * Handle to the helper process which does the key generation.
- */
- struct GNUNET_OS_Process *gnunet_ecc;
-
- /**
- * Handle to 'stdout' of gnunet-ecc. We 'read' on stdout to detect
- * process termination (instead of messing with SIGCHLD).
- */
- struct GNUNET_DISK_PipeHandle *gnunet_ecc_out;
-
- /**
- * Location where we store the private key if it already existed.
- * (if this is used, 'filename', 'gnunet_ecc' and 'gnunet_ecc_out' will
- * not be used).
- */
- struct GNUNET_CRYPTO_EccPrivateKey *pk;
-
- /**
- * Task reading from 'gnunet_ecc_out' to wait for process termination.
- */
- GNUNET_SCHEDULER_TaskIdentifier read_task;
-
-};
-
-
-/**
- * Abort ECC key generation.
- *
- * @param gc key generation context to abort
- */
-void
-GNUNET_CRYPTO_ecc_key_create_stop (struct GNUNET_CRYPTO_EccKeyGenerationContext *gc)
-{
- if (GNUNET_SCHEDULER_NO_TASK != gc->read_task)
- {
- GNUNET_SCHEDULER_cancel (gc->read_task);
- gc->read_task = GNUNET_SCHEDULER_NO_TASK;
- }
- if (NULL != gc->gnunet_ecc)
- {
- (void) GNUNET_OS_process_kill (gc->gnunet_ecc, SIGKILL);
- GNUNET_break (GNUNET_OK ==
- GNUNET_OS_process_wait (gc->gnunet_ecc));
- GNUNET_OS_process_destroy (gc->gnunet_ecc);
- GNUNET_DISK_pipe_close (gc->gnunet_ecc_out);
- }
-
- if (NULL != gc->filename)
- {
- if (0 != UNLINK (gc->filename))
- GNUNET_log_strerror_file (GNUNET_ERROR_TYPE_WARNING, "unlink", gc->filename);
- GNUNET_free (gc->filename);
- }
- if (NULL != gc->pk)
- GNUNET_CRYPTO_ecc_key_free (gc->pk);
- GNUNET_free (gc);
-}
-
-
-/**
- * Task called upon shutdown or process termination of 'gnunet-ecc' during
- * ECC key generation. Check where we are and perform the appropriate
- * action.
+ * Create a new private key by reading our peer's key from
+ * the file specified in the configuration.
*
- * @param cls the 'struct GNUNET_CRYPTO_EccKeyGenerationContext'
- * @param tc scheduler context
- */
-static void
-check_key_generation_completion (void *cls,
- const struct GNUNET_SCHEDULER_TaskContext *tc)
-{
- struct GNUNET_CRYPTO_EccKeyGenerationContext *gc = cls;
- struct GNUNET_CRYPTO_EccPrivateKey *pk;
-
- gc->read_task = GNUNET_SCHEDULER_NO_TASK;
- if (0 != (tc->reason & GNUNET_SCHEDULER_REASON_SHUTDOWN))
- {
- gc->cont (gc->cont_cls, NULL, _("interrupted by shutdown"));
- GNUNET_CRYPTO_ecc_key_create_stop (gc);
- return;
- }
- GNUNET_assert (GNUNET_OK ==
- GNUNET_OS_process_wait (gc->gnunet_ecc));
- GNUNET_OS_process_destroy (gc->gnunet_ecc);
- gc->gnunet_ecc = NULL;
- if (NULL == (pk = try_read_key (gc->filename)))
- {
- GNUNET_break (0);
- gc->cont (gc->cont_cls, NULL, _("gnunet-ecc failed"));
- GNUNET_CRYPTO_ecc_key_create_stop (gc);
- return;
- }
- gc->cont (gc->cont_cls, pk, NULL);
- GNUNET_DISK_pipe_close (gc->gnunet_ecc_out);
- GNUNET_free (gc->filename);
- GNUNET_free (gc);
-}
-
-
-/**
- * Return the private ECC key which already existed on disk
- * (asynchronously) to the caller.
- *
- * @param cls the 'struct GNUNET_CRYPTO_EccKeyGenerationContext'
- * @param tc scheduler context (unused)
- */
-static void
-async_return_key (void *cls,
- const struct GNUNET_SCHEDULER_TaskContext *tc)
-{
- struct GNUNET_CRYPTO_EccKeyGenerationContext *gc = cls;
-
- gc->cont (gc->cont_cls,
- gc->pk,
- NULL);
- GNUNET_free (gc);
-}
-
-
-/**
- * Create a new private key by reading it from a file. If the files
- * does not exist, create a new key and write it to the file. If the
- * contents of the file are invalid the old file is deleted and a
- * fresh key is created.
- *
- * @param filename name of file to use for storage
- * @param cont function to call when done (or on errors)
- * @param cont_cls closure for 'cont'
- * @return handle to abort operation, NULL on fatal errors (cont will not be called if NULL is returned)
+ * @return new private key, NULL on error (for example,
+ * permission denied)
*/
-struct GNUNET_CRYPTO_EccKeyGenerationContext *
-GNUNET_CRYPTO_ecc_key_create_start (const char *filename,
- GNUNET_CRYPTO_EccKeyCallback cont,
- void *cont_cls)
+struct GNUNET_CRYPTO_EccPrivateKey *
+GNUNET_CRYPTO_ecc_key_create_from_configuration (const struct GNUNET_CONFIGURATION_Handle *cfg)
{
- struct GNUNET_CRYPTO_EccKeyGenerationContext *gc;
struct GNUNET_CRYPTO_EccPrivateKey *pk;
- const char *weak_random;
+ char *fn;
- if (NULL != (pk = try_read_key (filename)))
- {
- /* quick happy ending: key already exists! */
- gc = GNUNET_malloc (sizeof (struct GNUNET_CRYPTO_EccKeyGenerationContext));
- gc->pk = pk;
- gc->cont = cont;
- gc->cont_cls = cont_cls;
- gc->read_task = GNUNET_SCHEDULER_add_now (&async_return_key,
- gc);
- return gc;
- }
- gc = GNUNET_malloc (sizeof (struct GNUNET_CRYPTO_EccKeyGenerationContext));
- gc->filename = GNUNET_strdup (filename);
- gc->cont = cont;
- gc->cont_cls = cont_cls;
- gc->gnunet_ecc_out = GNUNET_DISK_pipe (GNUNET_NO,
- GNUNET_NO,
- GNUNET_NO,
- GNUNET_YES);
- if (NULL == gc->gnunet_ecc_out)
- {
- GNUNET_log_strerror (GNUNET_ERROR_TYPE_WARNING, "pipe");
- GNUNET_free (gc->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,
- gc->gnunet_ecc_out,
- "gnunet-ecc",
- "gnunet-ecc",
- gc->filename,
- weak_random,
- NULL);
- if (NULL == gc->gnunet_ecc)
- {
- GNUNET_log_strerror (GNUNET_ERROR_TYPE_WARNING, "fork");
- GNUNET_DISK_pipe_close (gc->gnunet_ecc_out);
- GNUNET_free (gc->filename);
- GNUNET_free (gc);
+ if (GNUNET_OK !=
+ GNUNET_CONFIGURATION_get_value_filename (cfg, "PEER", "PRIVATE_KEY", &fn))
return NULL;
- }
- GNUNET_assert (GNUNET_OK ==
- GNUNET_DISK_pipe_close_end (gc->gnunet_ecc_out,
- GNUNET_DISK_PIPE_END_WRITE));
- gc->read_task = GNUNET_SCHEDULER_add_read_file (GNUNET_TIME_UNIT_FOREVER_REL,
- GNUNET_DISK_pipe_handle (gc->gnunet_ecc_out,
- GNUNET_DISK_PIPE_END_READ),
- &check_key_generation_completion,
- gc);
- return gc;
+ pk = GNUNET_CRYPTO_ecc_key_create_from_file (fn);
+ GNUNET_free (fn);
+ return pk;
}
{
struct GNUNET_CONFIGURATION_Handle *cfg;
struct GNUNET_CRYPTO_EccPrivateKey *pk;
- char *fn;
cfg = GNUNET_CONFIGURATION_create ();
(void) GNUNET_CONFIGURATION_load (cfg, cfg_name);
- if (GNUNET_OK ==
- GNUNET_CONFIGURATION_get_value_filename (cfg, "PEER", "PRIVATE_KEY", &fn))
+ pk = GNUNET_CRYPTO_ecc_key_create_from_configuration (cfg);
+ if (NULL != pk)
+ GNUNET_CRYPTO_ecc_key_free (pk);
+ GNUNET_CONFIGURATION_destroy (cfg);
+}
+
+
+/**
+ * Retrieve the identity of the host's peer.
+ *
+ * @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
+ * could not be retrieved
+ */
+int
+GNUNET_CRYPTO_get_host_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;
+
+ if (NULL == (my_private_key = GNUNET_CRYPTO_ecc_key_create_from_configuration (cfg)))
{
- pk = GNUNET_CRYPTO_ecc_key_create_from_file (fn);
- if (NULL != pk)
- GNUNET_CRYPTO_ecc_key_free (pk);
- GNUNET_free (fn);
+ GNUNET_log (GNUNET_ERROR_TYPE_ERROR,
+ _("Could not load peer's private key\n"));
+ return GNUNET_SYSERR;
}
- GNUNET_CONFIGURATION_destroy (cfg);
+ 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);
+ return GNUNET_OK;
}
GNUNET_CRYPTO_short_hash (purpose, ntohl (purpose->size), &hc);
#define FORMATSTRING "(4:data(5:flags3:raw)(5:value32:01234567890123456789012345678901))"
-#define FORMATSTRING2 "(4:data(4:hash6:sha25632:01234567890123456789012345678901))"
bufSize = strlen (FORMATSTRING) + 1;
{
char buff[bufSize];
LOG (GNUNET_ERROR_TYPE_WARNING,
_("ECC signing failed at %s:%d: %s\n"), __FILE__,
__LINE__, gcry_strerror (rc));
+ gcry_sexp_release (data);
+ return GNUNET_SYSERR;
}
gcry_sexp_release (data);
ssize = gcry_sexp_sprint (result,
}
+/**
+ * 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 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_mpi_t result_x;
+ gcry_mpi_t result_y;
+
+ /* first, extract the q = dP value from the public key */
+ if (! (psexp = decode_public_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);
+ 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;
+ }
+
+ /* 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_release (d);
+
+ /* finally, convert point to string for hashing */
+ result_x = gcry_mpi_new (256);
+ result_y = gcry_mpi_new (256);
+ if (gcry_mpi_ec_get_affine (result_x, result_y, 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);
+ 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;
+ }
+ 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;
+}
+
+
/* end of crypto_ecc.c */
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