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|
/*
* keys.c - decoding a public key or signature and verifying them
*
* This file is part of the SSH Library
*
* Copyright (c) 2003-2005 by Aris Adamantiadis
*
* The SSH Library is free software; you can redistribute it and/or modify
* it under the terms of the GNU Lesser General Public License as published by
* the Free Software Foundation; either version 2.1 of the License, or (at your
* option) any later version.
*
* The SSH Library 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 Lesser General Public
* License for more details.
*
* You should have received a copy of the GNU Lesser General Public License
* along with the SSH Library; see the file COPYING. If not, write to
* the Free Software Foundation, Inc., 59 Temple Place - Suite 330, Boston,
* MA 02111-1307, USA.
*/
#include <stdlib.h>
#include <string.h>
#ifdef HAVE_LIBCRYPTO
#include <openssl/dsa.h>
#include <openssl/rsa.h>
#endif
#include "libssh/priv.h"
#include "libssh/ssh2.h"
#include "libssh/server.h"
#include "libssh/buffer.h"
#include "libssh/agent.h"
#include "libssh/session.h"
#include "libssh/keys.h"
#include "libssh/dh.h"
#include "libssh/messages.h"
#include "libssh/string.h"
/**
* @addtogroup libssh_auth
*
* @{
*/
void publickey_free(ssh_public_key key) {
if (key == NULL) {
return;
}
switch(key->type) {
case SSH_KEYTYPE_DSS:
#ifdef HAVE_LIBGCRYPT
gcry_sexp_release(key->dsa_pub);
#elif HAVE_LIBCRYPTO
DSA_free(key->dsa_pub);
#endif
break;
case SSH_KEYTYPE_RSA:
case SSH_KEYTYPE_RSA1:
#ifdef HAVE_LIBGCRYPT
gcry_sexp_release(key->rsa_pub);
#elif defined HAVE_LIBCRYPTO
RSA_free(key->rsa_pub);
#endif
break;
default:
break;
}
SAFE_FREE(key);
}
/**
* @brief Make a public_key object out of a private_key object.
*
* @param[in] prv The private key to generate the public key.
*
* @returns The generated public key, NULL on error.
*
* @see publickey_to_string()
*/
ssh_public_key publickey_from_privatekey(ssh_private_key prv) {
ssh_public_key key = NULL;
#ifdef HAVE_LIBGCRYPT
gcry_sexp_t sexp;
const char *tmp = NULL;
size_t size;
ssh_string p = NULL;
ssh_string q = NULL;
ssh_string g = NULL;
ssh_string y = NULL;
ssh_string e = NULL;
ssh_string n = NULL;
#endif /* HAVE_LIBGCRYPT */
key = malloc(sizeof(struct ssh_public_key_struct));
if (key == NULL) {
return NULL;
}
ZERO_STRUCTP(key);
key->type = prv->type;
switch(key->type) {
case SSH_KEYTYPE_DSS:
#ifdef HAVE_LIBGCRYPT
sexp = gcry_sexp_find_token(prv->dsa_priv, "p", 0);
if (sexp == NULL) {
goto error;
}
tmp = gcry_sexp_nth_data(sexp, 1, &size);
p = ssh_string_new(size);
if (p == NULL) {
goto error;
}
ssh_string_fill(p,(char *) tmp, size);
gcry_sexp_release(sexp);
sexp = gcry_sexp_find_token(prv->dsa_priv,"q",0);
if (sexp == NULL) {
goto error;
}
tmp = gcry_sexp_nth_data(sexp,1,&size);
q = ssh_string_new(size);
if (q == NULL) {
goto error;
}
ssh_string_fill(q,(char *) tmp,size);
gcry_sexp_release(sexp);
sexp = gcry_sexp_find_token(prv->dsa_priv, "g", 0);
if (sexp == NULL) {
goto error;
}
tmp = gcry_sexp_nth_data(sexp,1,&size);
g = ssh_string_new(size);
if (g == NULL) {
goto error;
}
ssh_string_fill(g,(char *) tmp,size);
gcry_sexp_release(sexp);
sexp = gcry_sexp_find_token(prv->dsa_priv,"y",0);
if (sexp == NULL) {
goto error;
}
tmp = gcry_sexp_nth_data(sexp,1,&size);
y = ssh_string_new(size);
if (y == NULL) {
goto error;
}
ssh_string_fill(y,(char *) tmp,size);
gcry_sexp_release(sexp);
gcry_sexp_build(&key->dsa_pub, NULL,
"(public-key(dsa(p %b)(q %b)(g %b)(y %b)))",
ssh_string_len(p), ssh_string_data(p),
ssh_string_len(q), ssh_string_data(q),
ssh_string_len(g), ssh_string_data(g),
ssh_string_len(y), ssh_string_data(y));
ssh_string_burn(p);
ssh_string_free(p);
ssh_string_burn(q);
ssh_string_free(q);
ssh_string_burn(g);
ssh_string_free(g);
ssh_string_burn(y);
ssh_string_free(y);
#elif defined HAVE_LIBCRYPTO
key->dsa_pub = DSA_new();
if (key->dsa_pub == NULL) {
goto error;
}
key->dsa_pub->p = BN_dup(prv->dsa_priv->p);
key->dsa_pub->q = BN_dup(prv->dsa_priv->q);
key->dsa_pub->g = BN_dup(prv->dsa_priv->g);
key->dsa_pub->pub_key = BN_dup(prv->dsa_priv->pub_key);
if (key->dsa_pub->p == NULL ||
key->dsa_pub->q == NULL ||
key->dsa_pub->g == NULL ||
key->dsa_pub->pub_key == NULL) {
goto error;
}
#endif /* HAVE_LIBCRYPTO */
break;
case SSH_KEYTYPE_RSA:
case SSH_KEYTYPE_RSA1:
#ifdef HAVE_LIBGCRYPT
sexp = gcry_sexp_find_token(prv->rsa_priv, "n", 0);
if (sexp == NULL) {
goto error;
}
tmp = gcry_sexp_nth_data(sexp, 1, &size);
n = ssh_string_new(size);
if (n == NULL) {
goto error;
}
ssh_string_fill(n, (char *) tmp, size);
gcry_sexp_release(sexp);
sexp = gcry_sexp_find_token(prv->rsa_priv, "e", 0);
if (sexp == NULL) {
goto error;
}
tmp = gcry_sexp_nth_data(sexp, 1, &size);
e = ssh_string_new(size);
if (e == NULL) {
goto error;
}
ssh_string_fill(e, (char *) tmp, size);
gcry_sexp_release(sexp);
gcry_sexp_build(&key->rsa_pub, NULL,
"(public-key(rsa(n %b)(e %b)))",
ssh_string_len(n), ssh_string_data(n),
ssh_string_len(e), ssh_string_data(e));
if (key->rsa_pub == NULL) {
goto error;
}
ssh_string_burn(e);
ssh_string_free(e);
ssh_string_burn(n);
ssh_string_free(n);
#elif defined HAVE_LIBCRYPTO
key->rsa_pub = RSA_new();
if (key->rsa_pub == NULL) {
goto error;
}
key->rsa_pub->e = BN_dup(prv->rsa_priv->e);
key->rsa_pub->n = BN_dup(prv->rsa_priv->n);
if (key->rsa_pub->e == NULL ||
key->rsa_pub->n == NULL) {
goto error;
}
#endif
break;
default:
publickey_free(key);
return NULL;
}
key->type_c = ssh_type_to_char(prv->type);
return key;
error:
#ifdef HAVE_LIBGCRYPT
gcry_sexp_release(sexp);
ssh_string_burn(p);
ssh_string_free(p);
ssh_string_burn(q);
ssh_string_free(q);
ssh_string_burn(g);
ssh_string_free(g);
ssh_string_burn(y);
ssh_string_free(y);
ssh_string_burn(e);
ssh_string_free(e);
ssh_string_burn(n);
ssh_string_free(n);
#endif
publickey_free(key);
return NULL;
}
void signature_free(SIGNATURE *sign) {
if (sign == NULL) {
return;
}
switch(sign->type) {
case SSH_KEYTYPE_DSS:
#ifdef HAVE_LIBGCRYPT
gcry_sexp_release(sign->dsa_sign);
#elif defined HAVE_LIBCRYPTO
DSA_SIG_free(sign->dsa_sign);
#endif
break;
case SSH_KEYTYPE_RSA:
case SSH_KEYTYPE_RSA1:
#ifdef HAVE_LIBGCRYPT
gcry_sexp_release(sign->rsa_sign);
#elif defined HAVE_LIBCRYPTO
SAFE_FREE(sign->rsa_sign);
#endif
break;
default:
/* FIXME Passing NULL segfaults */
#if 0
ssh_log(NULL, SSH_LOG_RARE, "Freeing a signature with no type!\n"); */
#endif
break;
}
SAFE_FREE(sign);
}
#ifdef HAVE_LIBCRYPTO
/*
* Maybe the missing function from libcrypto
*
* I think now, maybe it's a bad idea to name it has it should have be
* named in libcrypto
*/
ssh_string RSA_do_sign(const unsigned char *payload, int len, RSA *privkey) {
ssh_string sign = NULL;
unsigned char *buffer = NULL;
unsigned int size;
buffer = malloc(RSA_size(privkey));
if (buffer == NULL) {
return NULL;
}
if (RSA_sign(NID_sha1, payload, len, buffer, &size, privkey) == 0) {
SAFE_FREE(buffer);
return NULL;
}
sign = ssh_string_new(size);
if (sign == NULL) {
SAFE_FREE(buffer);
return NULL;
}
ssh_string_fill(sign, buffer, size);
SAFE_FREE(buffer);
return sign;
}
#endif
#ifndef _WIN32
ssh_string ssh_do_sign_with_agent(ssh_session session,
struct ssh_buffer_struct *buf, struct ssh_public_key_struct *publickey) {
struct ssh_buffer_struct *sigbuf = NULL;
struct ssh_string_struct *signature = NULL;
struct ssh_string_struct *session_id = NULL;
struct ssh_crypto_struct *crypto = NULL;
if (session->current_crypto) {
crypto = session->current_crypto;
} else {
crypto = session->next_crypto;
}
/* prepend session identifier */
session_id = ssh_string_new(crypto->digest_len);
if (session_id == NULL) {
return NULL;
}
ssh_string_fill(session_id, crypto->session_id, crypto->digest_len);
sigbuf = ssh_buffer_new();
if (sigbuf == NULL) {
ssh_string_free(session_id);
return NULL;
}
if (buffer_add_ssh_string(sigbuf, session_id) < 0) {
ssh_buffer_free(sigbuf);
ssh_string_free(session_id);
return NULL;
}
ssh_string_free(session_id);
/* append out buffer */
if (buffer_add_buffer(sigbuf, buf) < 0) {
ssh_buffer_free(sigbuf);
return NULL;
}
/* create signature */
signature = agent_sign_data(session, sigbuf, publickey);
ssh_buffer_free(sigbuf);
return signature;
}
#endif /* _WIN32 */
/*
* This function signs the session id (known as H) as a string then
* the content of sigbuf */
ssh_string ssh_do_sign(ssh_session session, ssh_buffer sigbuf,
ssh_private_key privatekey) {
struct ssh_crypto_struct *crypto = session->current_crypto ? session->current_crypto :
session->next_crypto;
unsigned char hash[SHA_DIGEST_LEN + 1] = {0};
ssh_string session_str = NULL;
ssh_string signature = NULL;
SIGNATURE *sign = NULL;
SHACTX ctx = NULL;
#ifdef HAVE_LIBGCRYPT
gcry_sexp_t gcryhash;
#endif
session_str = ssh_string_new(crypto->digest_len);
if (session_str == NULL) {
return NULL;
}
ssh_string_fill(session_str, crypto->session_id, crypto->digest_len);
ctx = sha1_init();
if (ctx == NULL) {
ssh_string_free(session_str);
return NULL;
}
sha1_update(ctx, session_str, ssh_string_len(session_str) + 4);
ssh_string_free(session_str);
sha1_update(ctx, buffer_get_rest(sigbuf), buffer_get_rest_len(sigbuf));
sha1_final(hash + 1,ctx);
hash[0] = 0;
#ifdef DEBUG_CRYPTO
ssh_print_hexa("Hash being signed with dsa", hash + 1, SHA_DIGEST_LEN);
#endif
sign = malloc(sizeof(SIGNATURE));
if (sign == NULL) {
return NULL;
}
switch(privatekey->type) {
case SSH_KEYTYPE_DSS:
#ifdef HAVE_LIBGCRYPT
if (gcry_sexp_build(&gcryhash, NULL, "%b", SHA_DIGEST_LEN + 1, hash) ||
gcry_pk_sign(&sign->dsa_sign, gcryhash, privatekey->dsa_priv)) {
ssh_set_error(session, SSH_FATAL, "Signing: libcrypt error");
gcry_sexp_release(gcryhash);
signature_free(sign);
return NULL;
}
#elif defined HAVE_LIBCRYPTO
sign->dsa_sign = DSA_do_sign(hash + 1, SHA_DIGEST_LEN,
privatekey->dsa_priv);
if (sign->dsa_sign == NULL) {
ssh_set_error(session, SSH_FATAL, "Signing: openssl error");
signature_free(sign);
return NULL;
}
#ifdef DEBUG_CRYPTO
ssh_print_bignum("r", sign->dsa_sign->r);
ssh_print_bignum("s", sign->dsa_sign->s);
#endif
#endif /* HAVE_LIBCRYPTO */
sign->rsa_sign = NULL;
break;
case SSH_KEYTYPE_RSA:
#ifdef HAVE_LIBGCRYPT
if (gcry_sexp_build(&gcryhash, NULL, "(data(flags pkcs1)(hash sha1 %b))",
SHA_DIGEST_LEN, hash + 1) ||
gcry_pk_sign(&sign->rsa_sign, gcryhash, privatekey->rsa_priv)) {
ssh_set_error(session, SSH_FATAL, "Signing: libcrypt error");
gcry_sexp_release(gcryhash);
signature_free(sign);
return NULL;
}
#elif defined HAVE_LIBCRYPTO
sign->rsa_sign = RSA_do_sign(hash + 1, SHA_DIGEST_LEN,
privatekey->rsa_priv);
if (sign->rsa_sign == NULL) {
ssh_set_error(session, SSH_FATAL, "Signing: openssl error");
signature_free(sign);
return NULL;
}
#endif
sign->dsa_sign = NULL;
break;
default:
signature_free(sign);
return NULL;
}
#ifdef HAVE_LIBGCRYPT
gcry_sexp_release(gcryhash);
#endif
sign->type = privatekey->type;
signature = signature_to_string(sign);
signature_free(sign);
return signature;
}
/** @} */
/* vim: set ts=4 sw=4 et cindent: */
|