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gnupg/g10/keygen.c

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/* keygen.c - generate a key pair
* Copyright (c) 1997 by Werner Koch (dd9jn)
*
* This file is part of G10.
*
* G10 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 of the License, or
* (at your option) any later version.
*
* G10 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 this program; if not, write to the Free Software
* Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA
*/
#include <config.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <errno.h>
#include <assert.h>
#include "util.h"
#include "main.h"
#include "packet.h"
#include "cipher.h"
#include "ttyio.h"
#include "options.h"
#include "keydb.h"
#if 0
#define TEST_ALGO 1
#define TEST_NBITS 256
#define TEST_UID "Karl Test"
#endif
#if defined(HAVE_RSA_CIPHER) && 0
#define ENABLE_RSA_KEYGEN 1
#endif
static u16
checksum_u16( unsigned n )
{
u16 a;
a = (n >> 8) & 0xff;
a |= n & 0xff;
return a;
}
static u16
checksum( byte *p, unsigned n )
{
u16 a;
for(a=0; n; n-- )
a += *p++;
return a;
}
static u16
checksum_mpi( MPI a )
{
u16 csum;
byte *buffer;
unsigned nbytes;
buffer = mpi_get_buffer( a, &nbytes, NULL );
csum = checksum_u16( nbytes*8 );
csum += checksum( buffer, nbytes );
m_free( buffer );
return csum;
}
static void
write_uid( KBNODE root, const char *s )
{
PACKET *pkt = m_alloc_clear(sizeof *pkt );
size_t n = strlen(s);
pkt->pkttype = PKT_USER_ID;
pkt->pkt.user_id = m_alloc( sizeof *pkt->pkt.user_id + n - 1 );
pkt->pkt.user_id->len = n;
strcpy(pkt->pkt.user_id->name, s);
add_kbnode( root, new_kbnode( pkt ) );
}
static int
write_selfsig( KBNODE root, KBNODE pub_root, PKT_secret_cert *skc )
{
PACKET *pkt;
PKT_signature *sig;
PKT_user_id *uid;
int rc=0;
KBNODE kbctx, node;
PKT_public_cert *pkc;
if( opt.verbose )
log_info("writing self signature\n");
/* get the uid packet from the tree */
for( kbctx=NULL; (node=walk_kbtree( root, &kbctx)) ; ) {
if( node->pkt->pkttype == PKT_USER_ID )
break;
}
if( !node )
log_bug(NULL); /* no user id packet in tree */
uid = node->pkt->pkt.user_id;
/* get the pkc packet from the pub_tree */
for( kbctx=NULL; (node=walk_kbtree( pub_root, &kbctx)) ; ) {
if( node->pkt->pkttype == PKT_PUBLIC_CERT )
break;
}
if( !node )
log_bug(NULL);
pkc = node->pkt->pkt.public_cert;
/* and make the signature */
rc = make_keysig_packet( &sig, pkc, uid, skc, 0x13, DIGEST_ALGO_RMD160 );
if( rc ) {
log_error("make_keysig_packet failed: %s\n", g10_errstr(rc) );
return rc;
}
pkt = m_alloc_clear( sizeof *pkt );
pkt->pkttype = PKT_SIGNATURE;
pkt->pkt.signature = sig;
add_kbnode( root, new_kbnode( pkt ) );
return rc;
}
static int
gen_elg(unsigned nbits, KBNODE pub_root, KBNODE sec_root, DEK *dek,
PKT_secret_cert **ret_skc )
{
int rc;
PACKET *pkt;
PKT_secret_cert *skc;
PKT_public_cert *pkc;
ELG_public_key pk;
ELG_secret_key sk;
unsigned nbytes;
elg_generate( &pk, &sk, nbits );
skc = m_alloc( sizeof *skc );
pkc = m_alloc( sizeof *pkc );
skc->timestamp = pkc->timestamp = make_timestamp();
skc->valid_days = pkc->valid_days = 0; /* fixme: make it configurable*/
skc->pubkey_algo = pkc->pubkey_algo = PUBKEY_ALGO_ELGAMAL;
memset(&pkc->mfx, 0, sizeof pkc->mfx);
pkc->d.elg.p = pk.p;
pkc->d.elg.g = pk.g;
pkc->d.elg.y = pk.y;
skc->d.elg.p = sk.p;
skc->d.elg.g = sk.g;
skc->d.elg.y = sk.y;
skc->d.elg.x = sk.x;
skc->d.elg.is_protected = 0;
skc->d.elg.protect_algo = 0;
skc->d.elg.csum = checksum_mpi( skc->d.elg.x );
/* return an unprotected version of the skc */
*ret_skc = copy_secret_cert( NULL, skc );
if( dek ) {
skc->d.elg.protect_algo = CIPHER_ALGO_BLOWFISH;
randomize_buffer(skc->d.elg.protect.blowfish.iv, 8, 1);
rc = protect_secret_key( skc, dek );
if( rc ) {
log_error("protect_secret_key failed: %s\n", g10_errstr(rc) );
free_public_cert(pkc);
free_secret_cert(skc);
return rc;
}
}
pkt = m_alloc_clear(sizeof *pkt);
pkt->pkttype = PKT_PUBLIC_CERT;
pkt->pkt.public_cert = pkc;
add_kbnode(pub_root, new_kbnode( pkt ));
pkt = m_alloc_clear(sizeof *pkt);
pkt->pkttype = PKT_SECRET_CERT;
pkt->pkt.secret_cert = skc;
add_kbnode(sec_root, new_kbnode( pkt ));
return 0;
}
#ifdef ENABLE_RSA_KEYGEN
static int
gen_rsa(unsigned nbits, IOBUF pub_io, IOBUF sec_io, DEK *dek,
PKT_public_cert **ret_pkc, PKT_secret_cert **ret_skc )
{
int rc;
PACKET pkt1, pkt2;
PKT_secret_cert *skc;
PKT_public_cert *pkc;
RSA_public_key pk;
RSA_secret_key sk;
init_packet(&pkt1);
init_packet(&pkt2);
rsa_generate( &pk, &sk, nbits );
skc = m_alloc( sizeof *skc );
pkc = m_alloc( sizeof *pkc );
skc->timestamp = pkc->timestamp = make_timestamp();
skc->valid_days = pkc->valid_days = 0; /* fixme: make it configurable*/
skc->pubkey_algo = pkc->pubkey_algo = PUBKEY_ALGO_RSA;
memset(&pkc->mfx, 0, sizeof pkc->mfx);
pkc->d.rsa.rsa_n = pk.n;
pkc->d.rsa.rsa_e = pk.e;
skc->d.rsa.rsa_n = sk.n;
skc->d.rsa.rsa_e = sk.e;
skc->d.rsa.rsa_d = sk.d;
skc->d.rsa.rsa_p = sk.p;
skc->d.rsa.rsa_q = sk.q;
skc->d.rsa.rsa_u = sk.u;
skc->d.rsa.csum = checksum_mpi( skc->d.rsa.rsa_d );
skc->d.rsa.csum += checksum_mpi( skc->d.rsa.rsa_p );
skc->d.rsa.csum += checksum_mpi( skc->d.rsa.rsa_q );
skc->d.rsa.csum += checksum_mpi( skc->d.rsa.rsa_u );
if( !dek ) {
skc->d.rsa.is_protected = 0;
skc->d.rsa.protect_algo = 0;
}
else {
skc->d.rsa.is_protected = 1;
skc->d.rsa.protect_algo = CIPHER_ALGO_BLOWFISH;
randomize_buffer( skc->d.rsa.protect.blowfish.iv, 8, 1);
skc->d.rsa.csum += checksum( skc->d.rsa.protect.blowfish.iv, 8 );
rc = protect_secret_key( skc, dek );
if( rc ) {
log_error("protect_secret_key failed: %s\n", g10_errstr(rc) );
goto leave;
}
}
pkt1.pkttype = PKT_PUBLIC_CERT;
pkt1.pkt.public_cert = pkc;
pkt2.pkttype = PKT_SECRET_CERT;
pkt2.pkt.secret_cert = skc;
if( (rc = build_packet( pub_io, &pkt1 )) ) {
log_error("build public_cert packet failed: %s\n", g10_errstr(rc) );
goto leave;
}
if( (rc = build_packet( sec_io, &pkt2 )) ) {
log_error("build secret_cert packet failed: %s\n", g10_errstr(rc) );
goto leave;
}
*ret_pkc = pkt1.pkt.public_cert;
pkt1.pkt.public_cert = NULL;
*ret_skc = pkt1.pkt.secret_cert;
pkt1.pkt.secret_cert = NULL;
leave:
free_packet(&pkt1);
free_packet(&pkt2);
return rc;
}
#endif /*ENABLE_RSA_KEYGEN*/
static int
gen_dsa(unsigned nbits, KBNODE pub_root, KBNODE sec_root, DEK *dek,
PKT_secret_cert **ret_skc )
{
return G10ERR_GENERAL;
}
/****************
* Generate a keypair
*/
void
generate_keypair()
{
char *answer;
unsigned nbits;
char *pub_fname = NULL;
char *sec_fname = NULL;
char *uid = NULL;
IOBUF pub_io = NULL;
IOBUF sec_io = NULL;
KBNODE pub_root = NULL;
KBNODE sec_root = NULL;
PKT_secret_cert *skc = NULL;
DEK *dek = NULL;
int rc;
int algo;
const char *algo_name;
#ifndef TEST_ALGO
if( opt.batch || opt.answer_yes || opt.answer_no )
log_fatal("Key generation can only be used in interactive mode\n");
tty_printf("Please select the algorithm to use:\n"
" (1) ElGamal is the suggested one.\n"
" (2) DSA can only be used for signatures.\n"
#ifdef ENABLE_RSA_KEYGEN
" (3) RSA cannot be used in the U.S.\n"
#endif
);
#endif
for(;;) {
#ifdef TEST_ALGO
algo = TEST_ALGO;
#else
answer = tty_get("Your selection? (1,2"
#ifdef ENABLE_RSA_KEYGEN
",3"
#endif
") ");
tty_kill_prompt();
algo = *answer? atoi(answer): 1;
m_free(answer);
#endif
if( algo == 1 ) {
algo = PUBKEY_ALGO_ELGAMAL;
algo_name = "ElGamal";
break;
}
else if( algo == 2 ) {
algo = PUBKEY_ALGO_DSA;
algo_name = "DSA";
tty_printf("Sorry; DSA is not yet supported.\n");
}
#ifdef ENABLE_RSA_KEYGEN
else if( algo == 3 ) {
algo = PUBKEY_ALGO_RSA;
algo_name = "RSA";
break;
}
#endif
}
tty_printf("About to generate a new %s keypair.\n"
#ifndef TEST_NBITS
" minimum keysize is 768 bits\n"
" default keysize is 1024 bits\n"
" highest suggested keysize is 2048 bits\n"
#endif
, algo_name );
for(;;) {
#ifdef TEST_NBITS
nbits = TEST_NBITS;
#else
answer = tty_get("What keysize do you want? (1024) ");
tty_kill_prompt();
nbits = *answer? atoi(answer): 1024;
m_free(answer);
#endif
if( algo == PUBKEY_ALGO_DSA && (nbits < 512 || nbits > 1024) )
tty_printf("DSA does only allow keysizes from 512 to 1024\n");
else if( nbits < 768 )
tty_printf("keysize too small; 768 is smallest value allowed.\n");
else if( nbits > 2048 ) {
tty_printf("Keysizes larger than 2048 are not suggested, because "
"computations take REALLY long!\n");
answer = tty_get("Are you sure, that you want this keysize? ");
tty_kill_prompt();
if( answer_is_yes(answer) ) {
m_free(answer);
tty_printf("Okay, but keep in mind that your monitor "
"and keyboard radiation is also very vulnerable "
"to attacks!\n");
break;
}
m_free(answer);
}
else
break;
}
tty_printf("Requested keysize is %u bits\n", nbits );
if( algo == PUBKEY_ALGO_DSA && (nbits % 64) ) {
nbits = ((nbits + 63) / 64) * 64;
tty_printf("rounded up to %u bits\n", nbits );
}
else if( (nbits % 32) ) {
nbits = ((nbits + 31) / 32) * 32;
tty_printf("rounded up to %u bits\n", nbits );
}
#ifdef TEST_UID
uid = m_alloc(strlen(TEST_UID)+1);
strcpy(uid, TEST_UID);
#else
tty_printf( "\nYou need a User-ID to identify your key; please use your name and your\n"
"email address in this suggested format:\n"
" \"Heinrich Heine <heinrichh@uni-duesseldorf.de>\n" );
uid = NULL;
for(;;) {
m_free(uid);
tty_printf("\n");
uid = tty_get("Your User-ID: ");
tty_kill_prompt();
if( strlen(uid) < 5 )
tty_printf("Please enter a string of at least 5 characters\n");
else {
tty_printf("You selected this USER-ID:\n \"%s\"\n\n", uid);
answer = tty_get("Is this correct? ");
tty_kill_prompt();
if( answer_is_yes(answer) ) {
m_free(answer);
break;
}
m_free(answer);
}
}
#endif
tty_printf( "You need a Passphrase to protect your secret key.\n\n" );
dek = m_alloc_secure( sizeof *dek );
for(;;) {
dek->algo = CIPHER_ALGO_BLOWFISH;
rc = make_dek_from_passphrase( dek , 2 );
if( rc == -1 ) {
m_free(dek); dek = NULL;
tty_printf(
"You don't what a passphrase - this is probably a *bad* idea!\n"
"I will do it anyway. You can change your passphrase at anytime,\n"
"using this program with the option \"--change-passphrase\"\n\n" );
break;
}
else if( rc == G10ERR_PASSPHRASE ) {
tty_printf("passphrase not correctly repeated; try again.\n");
}
else if( rc ) {
m_free(dek); dek = NULL;
m_free(uid);
log_error("Error getting the passphrase: %s\n", g10_errstr(rc) );
return;
}
else
break; /* okay */
}
/* now check wether we a are allowed to write to the keyrings */
pub_fname = make_filename("~/.g10", "pubring.g10", NULL );
sec_fname = make_filename("~/.g10", "secring.g10", NULL );
if( opt.verbose ) {
tty_printf("writing public certificate to '%s'\n", pub_fname );
tty_printf("writing secret certificate to '%s'\n", sec_fname );
}
/* we create the packets as a tree of kbnodes. Because the structure
* we create is known in advance we simply generate a linked list
* The first packet is a comment packet, followed by the userid and
* the self signature.
*/
pub_root = make_comment_node("#created by G10 pre-release " VERSION );
sec_root = make_comment_node("#created by G10 pre-release " VERSION );
tty_printf(
"We need to generate a lot of random bytes. It is a good idea to perform\n"
"some other action (work in another window, move the mouse, utilize the\n"
"network and the disks) during the prime generation; this gives the random\n"
"number generator a better chance to gain enough entropy.\n" );
if( algo == PUBKEY_ALGO_ELGAMAL )
rc = gen_elg(nbits, pub_root, sec_root, dek, &skc );
#ifdef ENABLE_RSA_KEYGEN
else if( algo == PUBKEY_ALGO_RSA )
rc = gen_rsa(nbits, pub_io, sec_io, dek, &skc );
#endif
else if( algo == PUBKEY_ALGO_DSA )
rc = gen_dsa(nbits, pub_root, sec_root, dek, &skc );
else
log_bug(NULL);
if( !rc )
write_uid(pub_root, uid );
if( !rc )
write_uid(sec_root, uid );
if( !rc )
rc = write_selfsig(pub_root, pub_root, skc);
if( !rc )
rc = write_selfsig(sec_root, pub_root, skc);
if( !rc ) {
KBPOS pub_kbpos;
KBPOS sec_kbpos;
int rc1 = -1;
int rc2 = -1;
/* we can now write the certificates */
/* FIXME: should we check wether the user-id already exists? */
if( get_keyblock_handle( pub_fname, &pub_kbpos ) ) {
if( add_keyblock_resource( pub_fname, 1 ) ) {
log_error("can add keyblock file '%s'\n", pub_fname );
rc = G10ERR_CREATE_FILE;
}
else if( get_keyblock_handle( pub_fname, &pub_kbpos ) ) {
log_error("can get keyblock handle for '%s'\n", pub_fname );
rc = G10ERR_CREATE_FILE;
}
}
if( rc )
;
else if( get_keyblock_handle( sec_fname, &sec_kbpos ) ) {
if( add_keyblock_resource( sec_fname, 1 ) ) {
log_error("can add keyblock file '%s'\n", sec_fname );
rc = G10ERR_CREATE_FILE;
}
else if( get_keyblock_handle( sec_fname, &sec_kbpos ) ) {
log_error("can get keyblock handle for '%s'\n", sec_fname );
rc = G10ERR_CREATE_FILE;
}
}
if( rc )
;
else if( (rc=rc1=lock_keyblock( &pub_kbpos )) )
log_error("can't lock public keyring: %s\n", g10_errstr(rc) );
else if( (rc=rc2=lock_keyblock( &sec_kbpos )) )
log_error("can't lock secret keyring: %s\n", g10_errstr(rc) );
else if( (rc=insert_keyblock( &pub_kbpos, pub_root )) )
log_error("can't write public key: %s\n", g10_errstr(rc) );
else if( (rc=insert_keyblock( &sec_kbpos, sec_root )) )
log_error("can't write secret key: %s\n", g10_errstr(rc) );
else {
tty_printf("public and secret key created and signed.\n" );
}
if( !rc1 )
unlock_keyblock( &pub_kbpos );
if( !rc2 )
unlock_keyblock( &sec_kbpos );
}
if( rc )
tty_printf("Key generation failed: %s\n", g10_errstr(rc) );
release_kbnode( pub_root );
release_kbnode( sec_root );
if( skc ) /* the unprotected secret certificate */
free_secret_cert(skc);
m_free(uid);
m_free(dek);
m_free(pub_fname);
m_free(sec_fname);
}
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