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ElGamal funktioniert und ist default
This commit is contained in:
Werner Koch
parent
a51cca90b6
commit
46900fbd43
31 changed files with 1273 additions and 409 deletions
302
g10/sig-check.c
302
g10/sig-check.c
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@ -29,6 +29,7 @@
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#include "mpi.h"
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#include "keydb.h"
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#include "cipher.h"
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#include "main.h"
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/****************
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@ -40,7 +41,7 @@ int
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signature_check( PKT_signature *sig, MD_HANDLE digest )
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{
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PKT_pubkey_cert *pkc = m_alloc_clear( sizeof *pkc );
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MPI result = mpi_alloc(35);
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MPI result = NULL;
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int rc=0, i, j, c, old_enc;
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byte *dp;
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@ -50,11 +51,168 @@ signature_check( PKT_signature *sig, MD_HANDLE digest )
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goto leave;
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}
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if( pkc->pubkey_algo == PUBKEY_ALGO_RSA ) {
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if( pkc->pubkey_algo == PUBKEY_ALGO_ELGAMAL ) {
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ELG_public_key pkey;
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if( sig->d.elg.digest_algo == DIGEST_ALGO_RMD160 ) {
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/* complete the digest */
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rmd160_putchar( digest.u.rmd, sig->sig_class );
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{ u32 a = sig->timestamp;
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rmd160_putchar( digest.u.rmd, (a >> 24) & 0xff );
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rmd160_putchar( digest.u.rmd, (a >> 16) & 0xff );
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rmd160_putchar( digest.u.rmd, (a >> 8) & 0xff );
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rmd160_putchar( digest.u.rmd, a & 0xff );
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}
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dp = rmd160_final( digest.u.rmd );
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result = encode_rmd160_value( dp, 20, mpi_get_nbits(pkc->d.elg.p));
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}
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else if( sig->d.rsa.digest_algo == DIGEST_ALGO_MD5 ) {
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md5_putchar( digest.u.md5, sig->sig_class );
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{ u32 a = sig->timestamp;
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md5_putchar( digest.u.md5, (a >> 24) & 0xff );
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md5_putchar( digest.u.md5, (a >> 16) & 0xff );
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md5_putchar( digest.u.md5, (a >> 8) & 0xff );
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md5_putchar( digest.u.md5, a & 0xff );
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}
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md5_final( digest.u.md5 );
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dp = md5_read( digest.u.md5 );
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result = encode_md5_value( dp, 16, mpi_get_nbits(pkc->d.elg.p));
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}
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else {
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rc = G10ERR_DIGEST_ALGO;
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goto leave;
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}
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pkey.p = pkc->d.elg.p;
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pkey.g = pkc->d.elg.g;
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pkey.y = pkc->d.elg.y;
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if( !elg_verify( sig->d.elg.a, sig->d.elg.b, result, &pkey ) )
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rc = G10ERR_BAD_SIGN;
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}
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else if( pkc->pubkey_algo == PUBKEY_ALGO_RSA ) {
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RSA_public_key pkey;
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result = mpi_alloc(40);
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pkey.n = pkc->d.rsa.rsa_n;
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pkey.e = pkc->d.rsa.rsa_e;
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rsa_public( result, sig->d.rsa.rsa_integer, &pkey );
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old_enc = 0;
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for(i=j=0; (c=mpi_getbyte(result, i)) != -1; i++ ) {
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if( !j ) {
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if( !i && c != 1 )
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break;
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else if( i && c == 0xff )
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; /* skip the padding */
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else if( i && !c )
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j++;
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else
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break;
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}
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else if( ++j == 18 && c != 1 )
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break;
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else if( j == 19 && c == 0 ) {
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old_enc++;
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break;
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}
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}
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if( old_enc ) {
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log_error("old encoding scheme is not supported\n");
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rc = G10ERR_GENERAL;
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goto leave;
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}
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if( sig->d.rsa.digest_algo == DIGEST_ALGO_RMD160 ) {
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static byte asn[18] = /* stored reverse FIXME: need other values*/
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{ 0x10, 0x04, 0x00, 0x05, 0x05, 0x02, 0x0d, 0xf7, 0x86,
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0x48, 0x86, 0x2a, 0x08, 0x06, 0x0c, 0x30, 0x20, 0x30 };
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for(i=20,j=0; (c=mpi_getbyte(result, i)) != -1 && j < 18; i++, j++ )
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if( asn[j] != c )
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break;
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if( j != 18 || c ) { /* ASN is wrong */
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rc = G10ERR_BAD_PUBKEY;
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goto leave;
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}
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for(i++; (c=mpi_getbyte(result, i)) != -1; i++ )
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if( c != 0xff )
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break;
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i++;
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if( c != DIGEST_ALGO_RMD160 || mpi_getbyte(result, i) ) {
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/* Padding or leading bytes in signature is wrong */
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rc = G10ERR_BAD_PUBKEY;
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goto leave;
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}
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if( mpi_getbyte(result, 19) != sig->d.rsa.digest_start[0]
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|| mpi_getbyte(result, 18) != sig->d.rsa.digest_start[1] ) {
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/* Wrong key used to check the signature */
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rc = G10ERR_BAD_PUBKEY;
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goto leave;
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}
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/* complete the digest */
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rmd160_putchar( digest.u.rmd, sig->sig_class );
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{ u32 a = sig->timestamp;
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rmd160_putchar( digest.u.rmd, (a >> 24) & 0xff );
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rmd160_putchar( digest.u.rmd, (a >> 16) & 0xff );
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rmd160_putchar( digest.u.rmd, (a >> 8) & 0xff );
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rmd160_putchar( digest.u.rmd, a & 0xff );
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}
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dp = rmd160_final( digest.u.rmd );
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for(i=19; i >= 0; i--, dp++ )
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if( mpi_getbyte( result, i ) != *dp ) {
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rc = G10ERR_BAD_SIGN;
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goto leave;
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}
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}
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else if( sig->d.rsa.digest_algo == DIGEST_ALGO_MD5 ) {
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static byte asn[18] = /* stored reverse */
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{ 0x10, 0x04, 0x00, 0x05, 0x05, 0x02, 0x0d, 0xf7, 0x86,
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0x48, 0x86, 0x2a, 0x08, 0x06, 0x0c, 0x30, 0x20, 0x30 };
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for(i=16,j=0; j < 18 && (c=mpi_getbyte(result, i)) != -1; i++, j++ )
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if( asn[j] != c )
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break;
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if( j != 18 || c ) { /* ASN is wrong */
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rc = G10ERR_BAD_PUBKEY;
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goto leave;
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}
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for(i++; (c=mpi_getbyte(result, i)) != -1; i++ )
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if( c != 0xff )
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break;
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i++;
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if( c != DIGEST_ALGO_MD5 || mpi_getbyte(result, i) ) {
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/* Padding or leading bytes in signature is wrong */
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rc = G10ERR_BAD_PUBKEY;
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goto leave;
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}
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if( mpi_getbyte(result, 15) != sig->d.rsa.digest_start[0]
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|| mpi_getbyte(result, 14) != sig->d.rsa.digest_start[1] ) {
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/* Wrong key used to check the signature */
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rc = G10ERR_BAD_PUBKEY;
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goto leave;
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}
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/* complete the digest */
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md5_putchar( digest.u.md5, sig->sig_class );
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{ u32 a = sig->timestamp;
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md5_putchar( digest.u.md5, (a >> 24) & 0xff );
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md5_putchar( digest.u.md5, (a >> 16) & 0xff );
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md5_putchar( digest.u.md5, (a >> 8) & 0xff );
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md5_putchar( digest.u.md5, a & 0xff );
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}
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md5_final( digest.u.md5 );
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dp = md5_read( digest.u.md5 );
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for(i=15; i >= 0; i--, dp++ )
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if( mpi_getbyte( result, i ) != *dp ) {
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rc = G10ERR_BAD_SIGN;
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goto leave;
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}
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}
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else {
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rc = G10ERR_DIGEST_ALGO;
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goto leave;
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}
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}
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else {
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log_debug("signature_check: unsupported pubkey algo %d\n",
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@ -64,148 +222,10 @@ signature_check( PKT_signature *sig, MD_HANDLE digest )
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}
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/* Now RESULT contains the deciphered session key.
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*
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* The session key is stored in different ways:
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*
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* Old versions encodes the digest in in this format (msb is left):
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*
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* 0 1 MD5(16 bytes) 0 PAD(n bytes) 1
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*
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* Later versions encodes the digest like this:
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*
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* 0 1 PAD(n bytes) 0 ASN(18 bytes) MD(16 bytes)
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*
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* RIPE MD 160 digests are encoded like this:
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*
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* 0 42 PAD(n bytes) 0 ASN(18 bytes) MD(20 bytes)
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*
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* FIXME: we should use another ASN!
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*
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* PAD consists of FF bytes.
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* ASN is here the constant: 3020300c06082a864886f70d020505000410
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*/
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old_enc = 0;
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for(i=j=0; (c=mpi_getbyte(result, i)) != -1; i++ ) {
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if( !j ) {
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if( !i && c != 1 )
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break;
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else if( i && c == 0xff )
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; /* skip the padding */
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else if( i && !c )
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j++;
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else
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break;
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}
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else if( ++j == 18 && c != 1 )
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break;
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else if( j == 19 && c == 0 ) {
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old_enc++;
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break;
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}
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}
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if( old_enc ) {
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log_error("old encoding scheme is not supported\n");
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rc = G10ERR_GENERAL;
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goto leave;
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}
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if( sig->d.rsa.digest_algo == DIGEST_ALGO_RMD160 ) {
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static byte asn[18] = /* stored reverse FIXME: need other values*/
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{ 0x10, 0x04, 0x00, 0x05, 0x05, 0x02, 0x0d, 0xf7, 0x86,
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0x48, 0x86, 0x2a, 0x08, 0x06, 0x0c, 0x30, 0x20, 0x30 };
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for(i=20,j=0; (c=mpi_getbyte(result, i)) != -1 && j < 18; i++, j++ )
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if( asn[j] != c )
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break;
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if( j != 18 || c ) { /* ASN is wrong */
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rc = G10ERR_BAD_PUBKEY;
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goto leave;
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}
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for(i++; (c=mpi_getbyte(result, i)) != -1; i++ )
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if( c != 0xff )
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break;
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i++;
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if( c != DIGEST_ALGO_RMD160 || mpi_getbyte(result, i) ) {
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/* Padding or leading bytes in signature is wrong */
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rc = G10ERR_BAD_PUBKEY;
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goto leave;
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}
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if( mpi_getbyte(result, 19) != sig->d.rsa.digest_start[0]
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|| mpi_getbyte(result, 18) != sig->d.rsa.digest_start[1] ) {
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/* Wrong key used to check the signature */
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rc = G10ERR_BAD_PUBKEY;
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goto leave;
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}
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/* complete the digest */
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rmd160_putchar( digest.u.rmd, sig->sig_class );
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{ u32 a = sig->timestamp;
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rmd160_putchar( digest.u.rmd, (a >> 24) & 0xff );
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rmd160_putchar( digest.u.rmd, (a >> 16) & 0xff );
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rmd160_putchar( digest.u.rmd, (a >> 8) & 0xff );
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rmd160_putchar( digest.u.rmd, a & 0xff );
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}
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dp = rmd160_final( digest.u.rmd );
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for(i=19; i >= 0; i--, dp++ )
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if( mpi_getbyte( result, i ) != *dp ) {
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rc = G10ERR_BAD_SIGN;
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goto leave;
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}
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}
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else if( sig->d.rsa.digest_algo == DIGEST_ALGO_MD5 ) {
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static byte asn[18] = /* stored reverse */
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{ 0x10, 0x04, 0x00, 0x05, 0x05, 0x02, 0x0d, 0xf7, 0x86,
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0x48, 0x86, 0x2a, 0x08, 0x06, 0x0c, 0x30, 0x20, 0x30 };
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for(i=16,j=0; j < 18 && (c=mpi_getbyte(result, i)) != -1; i++, j++ )
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if( asn[j] != c )
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break;
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if( j != 18 || c ) { /* ASN is wrong */
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rc = G10ERR_BAD_PUBKEY;
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goto leave;
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}
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for(i++; (c=mpi_getbyte(result, i)) != -1; i++ )
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if( c != 0xff )
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break;
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i++;
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if( c != DIGEST_ALGO_MD5 || mpi_getbyte(result, i) ) {
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/* Padding or leading bytes in signature is wrong */
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rc = G10ERR_BAD_PUBKEY;
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goto leave;
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}
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if( mpi_getbyte(result, 15) != sig->d.rsa.digest_start[0]
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|| mpi_getbyte(result, 14) != sig->d.rsa.digest_start[1] ) {
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/* Wrong key used to check the signature */
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rc = G10ERR_BAD_PUBKEY;
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goto leave;
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}
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/* complete the digest */
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md5_putchar( digest.u.md5, sig->sig_class );
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{ u32 a = sig->timestamp;
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md5_putchar( digest.u.md5, (a >> 24) & 0xff );
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md5_putchar( digest.u.md5, (a >> 16) & 0xff );
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md5_putchar( digest.u.md5, (a >> 8) & 0xff );
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md5_putchar( digest.u.md5, a & 0xff );
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}
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md5_final( digest.u.md5 );
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dp = md5_read( digest.u.md5 );
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for(i=15; i >= 0; i--, dp++ )
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if( mpi_getbyte( result, i ) != *dp ) {
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rc = G10ERR_BAD_SIGN;
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goto leave;
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}
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}
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else {
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rc = G10ERR_DIGEST_ALGO;
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goto leave;
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}
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leave:
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mpi_free( result );
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if( pkc )
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free_pubkey_cert( pkc );
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mpi_free( result );
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return rc;
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}
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