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37d2adfe61
gnupg/cipher/pubkey.c
Werner Koch 37d2adfe61 a whole bunch of internal cleanups
1998-06-13 06:59:14 +00:00

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9.8 KiB
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/* pubkey.c - pubkey dispatcher
* Copyright (C) 1998 Free Software Foundation, Inc.
*
* This file is part of GNUPG.
*
* GNUPG 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.
*
* GNUPG 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 "errors.h"
#include "mpi.h"
#include "cipher.h"
#include "dynload.h"
/****************
* Return the number of public key material numbers
*/
int
pubkey_get_npkey( int algo )
{
if( is_ELGAMAL(algo) )
return 3;
if( is_RSA(algo) )
return 2;
if( algo == PUBKEY_ALGO_DSA )
return 4;
return 0;
}
/****************
* Return the number of secret key material numbers
*/
int
pubkey_get_nskey( int algo )
{
if( is_ELGAMAL(algo) )
return 4;
if( is_RSA(algo) )
return 6;
if( algo == PUBKEY_ALGO_DSA )
return 5;
return 0;
}
/****************
* Return the number of signature material numbers
*/
int
pubkey_get_nsig( int algo )
{
if( is_ELGAMAL(algo) )
return 2;
if( is_RSA(algo) )
return 1;
if( algo == PUBKEY_ALGO_DSA )
return 2;
return 0;
}
/****************
* Return the number of encryption material numbers
*/
int
pubkey_get_nenc( int algo )
{
if( is_ELGAMAL(algo) )
return 2;
if( is_RSA(algo) )
return 1;
return 0;
}
/****************
* Get the number of nbits from the public key
*/
unsigned
pubkey_nbits( int algo, MPI *pkey )
{
if( is_ELGAMAL( algo ) )
return mpi_get_nbits( pkey[0] );
if( algo == PUBKEY_ALGO_DSA )
return mpi_get_nbits( pkey[0] );
if( is_RSA( algo) )
return mpi_get_nbits( pkey[0] );
return 0;
}
int
pubkey_check_secret_key( int algo, MPI *skey )
{
int rc = 0;
if( is_ELGAMAL(algo) ) {
ELG_secret_key sk;
sk.p = skey[0];
sk.g = skey[1];
sk.y = skey[2];
sk.x = skey[3];
if( !elg_check_secret_key( &sk ) )
rc = G10ERR_BAD_SECKEY;
}
else if( algo == PUBKEY_ALGO_DSA ) {
DSA_secret_key sk;
sk.p = skey[0];
sk.q = skey[1];
sk.g = skey[2];
sk.y = skey[3];
sk.x = skey[4];
if( !dsa_check_secret_key( &sk ) )
rc = G10ERR_BAD_SECKEY;
}
#ifdef HAVE_RSA_CIPHER
else if( is_RSA(k->pubkey_algo) ) {
/* FIXME */
RSA_secret_key sk;
assert( ndata == 1 && nskey == 6 );
sk.n = skey[0];
sk.e = skey[1];
sk.d = skey[2];
sk.p = skey[3];
sk.q = skey[4];
sk.u = skey[5];
plain = mpi_alloc_secure( mpi_get_nlimbs(sk.n) );
rsa_secret( plain, data[0], &sk );
}
#endif
else
rc = G10ERR_PUBKEY_ALGO;
return rc;
}
/****************
* This is the interface to the public key encryption.
* Encrypt DATA with PKEY and put it into RESARR which
* should be an array of MPIs of size PUBKEY_MAX_NENC (or less if the
* algorithm allows this - check with pubkey_get_nenc() )
*/
int
pubkey_encrypt( int algo, MPI *resarr, MPI data, MPI *pkey )
{
if( DBG_CIPHER ) {
int i;
log_debug("pubkey_encrypt: algo=%d\n", algo );
for(i=0; i < pubkey_get_npkey(algo); i++ )
log_mpidump(" pkey:", pkey[i] );
log_mpidump(" data:", data );
}
/* FIXME: check that data fits into the key */
if( is_ELGAMAL(algo) ) {
ELG_public_key pk;
pk.p = pkey[0];
pk.g = pkey[1];
pk.y = pkey[2];
resarr[0] = mpi_alloc( mpi_get_nlimbs( pk.p ) );
resarr[1] = mpi_alloc( mpi_get_nlimbs( pk.p ) );
elg_encrypt( resarr[0], resarr[1], data, &pk );
}
#ifdef HAVE_RSA_CIPHER
else if( algo == PUBKEY_ALGO_RSA || algo == PUBKEY_ALGO_RSA_E ) {
RSA_public_key pk;
pk.n = pkey[0];
pk.e = pkey[1];
resarr[0] = mpi_alloc( mpi_get_nlimbs( pk.p ) );
rsa_public( resarr[0], data, &pk );
}
#endif
else
return G10ERR_PUBKEY_ALGO;
if( DBG_CIPHER ) {
int i;
for(i=0; i < pubkey_get_nenc(algo); i++ )
log_mpidump(" encr:", resarr[i] );
}
return 0;
}
/****************
* This is the interface to the public key decryption.
* ALGO gives the algorithm to use and this implicitly determines
* the size of the arrays.
* result is a pointer to a mpi variable which will receive a
* newly allocated mpi or NULL in case of an error.
*/
int
pubkey_decrypt( int algo, MPI *result, MPI *data, MPI *skey )
{
MPI plain = NULL;
*result = NULL; /* so the caller can always do an mpi_free */
if( DBG_CIPHER ) {
int i;
log_debug("pubkey_decrypt: algo=%d\n", algo );
for(i=0; i < pubkey_get_nskey(algo); i++ )
log_mpidump(" skey:", skey[i] );
for(i=0; i < pubkey_get_nenc(algo); i++ )
log_mpidump(" data:", data[i] );
}
if( is_ELGAMAL(algo) ) {
ELG_secret_key sk;
sk.p = skey[0];
sk.g = skey[1];
sk.y = skey[2];
sk.x = skey[3];
plain = mpi_alloc_secure( mpi_get_nlimbs( sk.p ) );
elg_decrypt( plain, data[0], data[1], &sk );
}
#ifdef HAVE_RSA_CIPHER
else if( algo == PUBKEY_ALGO_RSA || algo == PUBKEY_ALGO_RSA_E ) {
RSA_secret_key sk;
sk.n = skey[0];
sk.e = skey[1];
sk.d = skey[2];
sk.p = skey[3];
sk.q = skey[4];
sk.u = skey[5];
plain = mpi_alloc_secure( mpi_get_nlimbs(sk.n) );
rsa_secret( plain, data[0], &sk );
}
#endif
else
return G10ERR_PUBKEY_ALGO;
*result = plain;
return 0;
}
/****************
* This is the interface to the public key signing.
* Sign hash with skey and put the result into resarr which
* should be an array of MPIs of size PUBKEY_MAX_NSIG (or less if the
* algorithm allows this - check with pubkey_get_nsig() )
*/
int
pubkey_sign( int algo, MPI *resarr, MPI data, MPI *skey )
{
if( DBG_CIPHER ) {
int i;
log_debug("pubkey_sign: algo=%d\n", algo );
for(i=0; i < pubkey_get_nskey(algo); i++ )
log_mpidump(" skey:", skey[i] );
log_mpidump(" data:", data );
}
if( is_ELGAMAL(algo) ) {
ELG_secret_key sk;
sk.p = skey[0];
sk.g = skey[1];
sk.y = skey[2];
sk.x = skey[3];
resarr[0] = mpi_alloc( mpi_get_nlimbs( sk.p ) );
resarr[1] = mpi_alloc( mpi_get_nlimbs( sk.p ) );
elg_sign( resarr[0], resarr[1], data, &sk );
}
else if( algo == PUBKEY_ALGO_DSA ) {
DSA_secret_key sk;
sk.p = skey[0];
sk.q = skey[1];
sk.g = skey[2];
sk.y = skey[3];
sk.x = skey[4];
resarr[0] = mpi_alloc( mpi_get_nlimbs( sk.p ) );
resarr[1] = mpi_alloc( mpi_get_nlimbs( sk.p ) );
dsa_sign( resarr[0], resarr[1], data, &sk );
}
#ifdef HAVE_RSA_CIPHER
else if( algo == PUBKEY_ALGO_RSA || algo == PUBKEY_ALGO_RSA_S ) {
RSA_secret_key sk;
sk.n = skey[0];
sk.e = skey[1];
sk.d = skey[2];
sk.p = skey[3];
sk.q = skey[4];
sk.u = skey[5];
plain = mpi_alloc_secure( mpi_get_nlimbs(sk.n) );
rsa_sign( plain, data[0], &sk );
}
#endif
else
return G10ERR_PUBKEY_ALGO;
if( DBG_CIPHER ) {
int i;
for(i=0; i < pubkey_get_nsig(algo); i++ )
log_mpidump(" sig:", resarr[i] );
}
return 0;
}
/****************
* Verify a public key signature.
* Return 0 if the signature is good
*/
int
pubkey_verify( int algo, MPI hash, MPI *data, MPI *pkey )
{
int rc = 0;
if( is_ELGAMAL( algo ) ) {
ELG_public_key pk;
pk.p = pkey[0];
pk.g = pkey[1];
pk.y = pkey[2];
if( !elg_verify( data[0], data[1], hash, &pk ) )
rc = G10ERR_BAD_SIGN;
}
else if( algo == PUBKEY_ALGO_DSA ) {
DSA_public_key pk;
pk.p = pkey[0];
pk.q = pkey[1];
pk.g = pkey[2];
pk.y = pkey[3];
if( !dsa_verify( data[0], data[1], hash, &pk ) )
rc = G10ERR_BAD_SIGN;
}
#ifdef HAVE_RSA_CIPHER
else if( algo == PUBKEY_ALGO_RSA || algo == PUBKEY_ALGO_RSA_S ) {
RSA_public_key pk;
int i, j, c, old_enc;
byte *dp;
const byte *asn;
size_t mdlen, asnlen;
pk.e = pkey[0];
pk.n = pkey[1];
result = mpi_alloc(40);
rsa_public( result, data[0], &pk );
old_enc = 0;
for(i=j=0; (c=mpi_getbyte(result, i)) != -1; i++ ) {
if( !j ) {
if( !i && c != 1 )
break;
else if( i && c == 0xff )
; /* skip the padding */
else if( i && !c )
j++;
else
break;
}
else if( ++j == 18 && c != 1 )
break;
else if( j == 19 && c == 0 ) {
old_enc++;
break;
}
}
if( old_enc ) {
log_error("old encoding scheme is not supported\n");
rc = G10ERR_GENERAL;
goto leave;
}
if( (rc=check_digest_algo(sig->digest_algo)) )
goto leave; /* unsupported algo */
md_enable( digest, sig->digest_algo );
asn = md_asn_oid( sig->digest_algo, &asnlen, &mdlen );
for(i=mdlen,j=asnlen-1; (c=mpi_getbyte(result, i)) != -1 && j >= 0;
i++, j-- )
if( asn[j] != c )
break;
if( j != -1 || mpi_getbyte(result, i) ) { /* ASN is wrong */
rc = G10ERR_BAD_PUBKEY;
goto leave;
}
for(i++; (c=mpi_getbyte(result, i)) != -1; i++ )
if( c != 0xff )
break;
i++;
if( c != sig->digest_algo || mpi_getbyte(result, i) ) {
/* Padding or leading bytes in signature is wrong */
rc = G10ERR_BAD_PUBKEY;
goto leave;
}
if( mpi_getbyte(result, mdlen-1) != sig->digest_start[0]
|| mpi_getbyte(result, mdlen-2) != sig->digest_start[1] ) {
/* Wrong key used to check the signature */
rc = G10ERR_BAD_PUBKEY;
goto leave;
}
/* complete the digest */
md_putc( digest, sig->sig_class );
{ u32 a = sig->timestamp;
md_putc( digest, (a >> 24) & 0xff );
md_putc( digest, (a >> 16) & 0xff );
md_putc( digest, (a >> 8) & 0xff );
md_putc( digest, a & 0xff );
}
md_final( digest );
dp = md_read( digest, sig->digest_algo );
for(i=mdlen-1; i >= 0; i--, dp++ ) {
if( mpi_getbyte( result, i ) != *dp ) {
rc = G10ERR_BAD_SIGN;
break;
}
}
}
#endif
else
rc = G10ERR_PUBKEY_ALGO;
return rc;
}
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