ElGamal funktioniert und ist default

1 files changed, 150 insertions, 130 deletions

diff --git a/g10/sig-check.c b/g10/sig-check.c
index 75e800693..ff212585c 100644
--- a/g10/sig-check.c
+++ b/g10/sig-check.c
@@ -29,6 +29,7 @@
 #include "mpi.h"
 #include "keydb.h"
 #include "cipher.h"
+#include "main.h"
 
 
 /****************
@@ -40,7 +41,7 @@ int
 signature_check( PKT_signature *sig, MD_HANDLE digest )
 {
     PKT_pubkey_cert *pkc = m_alloc_clear( sizeof *pkc );
-    MPI result = mpi_alloc(35);
+    MPI result = NULL;
     int rc=0, i, j, c, old_enc;
     byte *dp;
 
@@ -50,162 +51,181 @@ signature_check( PKT_signature *sig, MD_HANDLE digest )
 	goto leave;
     }
 
-    if( pkc->pubkey_algo == PUBKEY_ALGO_RSA ) {
-	RSA_public_key pkey;
-	pkey.n = pkc->d.rsa.rsa_n;
-	pkey.e = pkc->d.rsa.rsa_e;
-	rsa_public( result, sig->d.rsa.rsa_integer, &pkey );
-    }
-    else {
-	log_debug("signature_check: unsupported pubkey algo %d\n",
-			pkc->pubkey_algo );
-	rc = G10ERR_PUBKEY_ALGO;
-	goto leave;
-    }
-
+    if( pkc->pubkey_algo == PUBKEY_ALGO_ELGAMAL ) {
+	ELG_public_key pkey;
 
-    /* Now RESULT contains the deciphered session key.
-     *
-     * The session key is stored in different ways:
-     *
-     * Old versions encodes the digest in in this format (msb is left):
-     *
-     *	   0  1  MD5(16 bytes)	0  PAD(n bytes)  1
-     *
-     * Later versions encodes the digest like this:
-     *
-     *	   0  1  PAD(n bytes)	0  ASN(18 bytes)  MD(16 bytes)
-     *
-     * RIPE MD 160 digests are encoded like this:
-     *
-     *	   0  42 PAD(n bytes)	0  ASN(18 bytes)  MD(20 bytes)
-     *
-     * FIXME: we should use another ASN!
-     *
-     * PAD consists of FF bytes.
-     * ASN is here the constant: 3020300c06082a864886f70d020505000410
-     */
-    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;
+	if( sig->d.elg.digest_algo == DIGEST_ALGO_RMD160 ) {
+	    /* complete the digest */
+	    rmd160_putchar( digest.u.rmd, sig->sig_class );
+	    {	u32 a = sig->timestamp;
+		rmd160_putchar( digest.u.rmd, (a >> 24) & 0xff );
+		rmd160_putchar( digest.u.rmd, (a >> 16) & 0xff );
+		rmd160_putchar( digest.u.rmd, (a >>  8) & 0xff );
+		rmd160_putchar( digest.u.rmd,  a	& 0xff );
+	    }
+	    dp = rmd160_final( digest.u.rmd );
+	    result = encode_rmd160_value( dp, 20, mpi_get_nbits(pkc->d.elg.p));
 	}
-	else if( ++j == 18 && c != 1 )
-	    break;
-	else if( j == 19 && c == 0 ) {
-	    old_enc++;
-	    break;
+	else if( sig->d.rsa.digest_algo == DIGEST_ALGO_MD5 ) {
+	    md5_putchar( digest.u.md5, sig->sig_class );
+	    {	u32 a = sig->timestamp;
+		md5_putchar( digest.u.md5, (a >> 24) & 0xff );
+		md5_putchar( digest.u.md5, (a >> 16) & 0xff );
+		md5_putchar( digest.u.md5, (a >>  8) & 0xff );
+		md5_putchar( digest.u.md5,  a	     & 0xff );
+	    }
+	    md5_final( digest.u.md5 );
+	    dp = md5_read( digest.u.md5 );
+	    result = encode_md5_value( dp, 16, mpi_get_nbits(pkc->d.elg.p));
 	}
+	else {
+	    rc = G10ERR_DIGEST_ALGO;
+	    goto leave;
+	}
+
+	pkey.p = pkc->d.elg.p;
+	pkey.g = pkc->d.elg.g;
+	pkey.y = pkc->d.elg.y;
+	if( !elg_verify( sig->d.elg.a, sig->d.elg.b, result, &pkey ) )
+	    rc = G10ERR_BAD_SIGN;
     }
-    if( old_enc ) {
-	log_error("old encoding scheme is not supported\n");
-	rc = G10ERR_GENERAL;
-	goto leave;
-    }
+    else if( pkc->pubkey_algo == PUBKEY_ALGO_RSA ) {
+	RSA_public_key pkey;
 
-    if( sig->d.rsa.digest_algo == DIGEST_ALGO_RMD160 ) {
-	static byte asn[18] = /* stored reverse FIXME: need other values*/
-	      { 0x10, 0x04, 0x00, 0x05, 0x05, 0x02, 0x0d, 0xf7, 0x86,
-		0x48, 0x86, 0x2a, 0x08, 0x06, 0x0c, 0x30, 0x20, 0x30 };
+	result = mpi_alloc(40);
+	pkey.n = pkc->d.rsa.rsa_n;
+	pkey.e = pkc->d.rsa.rsa_e;
+	rsa_public( result, sig->d.rsa.rsa_integer, &pkey );
 
-	for(i=20,j=0; (c=mpi_getbyte(result, i)) != -1 && j < 18; i++, j++ )
-	    if( asn[j] != c )
+	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;
-	if( j != 18 || c ) { /* ASN is wrong */
-	    rc = G10ERR_BAD_PUBKEY;
-	    goto leave;
-	}
-	for(i++; (c=mpi_getbyte(result, i)) != -1; i++ )
-	    if( c != 0xff  )
+	    else if( j == 19 && c == 0 ) {
+		old_enc++;
 		break;
-	i++;
-	if( c != DIGEST_ALGO_RMD160 || mpi_getbyte(result, i) ) {
-	    /* Padding or leading bytes in signature is wrong */
-	    rc = G10ERR_BAD_PUBKEY;
-	    goto leave;
+	    }
 	}
-	if( mpi_getbyte(result, 19) != sig->d.rsa.digest_start[0]
-	    || mpi_getbyte(result, 18) != sig->d.rsa.digest_start[1] ) {
-	    /* Wrong key used to check the signature */
-	    rc = G10ERR_BAD_PUBKEY;
+	if( old_enc ) {
+	    log_error("old encoding scheme is not supported\n");
+	    rc = G10ERR_GENERAL;
 	    goto leave;
 	}
 
-	/* complete the digest */
-	rmd160_putchar( digest.u.rmd, sig->sig_class );
-	{   u32 a = sig->timestamp;
-	    rmd160_putchar( digest.u.rmd, (a >> 24) & 0xff );
-	    rmd160_putchar( digest.u.rmd, (a >> 16) & 0xff );
-	    rmd160_putchar( digest.u.rmd, (a >>  8) & 0xff );
-	    rmd160_putchar( digest.u.rmd,  a	    & 0xff );
-	}
-	dp = rmd160_final( digest.u.rmd );
-	for(i=19; i >= 0; i--, dp++ )
-	    if( mpi_getbyte( result, i ) != *dp ) {
-		rc = G10ERR_BAD_SIGN;
+	if( sig->d.rsa.digest_algo == DIGEST_ALGO_RMD160 ) {
+	    static byte asn[18] = /* stored reverse FIXME: need other values*/
+		  { 0x10, 0x04, 0x00, 0x05, 0x05, 0x02, 0x0d, 0xf7, 0x86,
+		    0x48, 0x86, 0x2a, 0x08, 0x06, 0x0c, 0x30, 0x20, 0x30 };
+
+	    for(i=20,j=0; (c=mpi_getbyte(result, i)) != -1 && j < 18; i++, j++ )
+		if( asn[j] != c )
+		    break;
+	    if( j != 18 || c ) { /* 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 != DIGEST_ALGO_RMD160 || mpi_getbyte(result, i) ) {
+		/* Padding or leading bytes in signature is wrong */
+		rc = G10ERR_BAD_PUBKEY;
+		goto leave;
+	    }
+	    if( mpi_getbyte(result, 19) != sig->d.rsa.digest_start[0]
+		|| mpi_getbyte(result, 18) != sig->d.rsa.digest_start[1] ) {
+		/* Wrong key used to check the signature */
+		rc = G10ERR_BAD_PUBKEY;
 		goto leave;
 	    }
-    }
-    else if( sig->d.rsa.digest_algo == DIGEST_ALGO_MD5 ) {
-	static byte asn[18] = /* stored reverse */
-	      { 0x10, 0x04, 0x00, 0x05, 0x05, 0x02, 0x0d, 0xf7, 0x86,
-		0x48, 0x86, 0x2a, 0x08, 0x06, 0x0c, 0x30, 0x20, 0x30 };
 
-	for(i=16,j=0; j < 18 && (c=mpi_getbyte(result, i)) != -1; i++, j++ )
-	    if( asn[j] != c )
-		break;
-	if( j != 18 || c ) { /* 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 != DIGEST_ALGO_MD5 || mpi_getbyte(result, i) ) {
-	    /* Padding or leading bytes in signature is wrong */
-	    rc = G10ERR_BAD_PUBKEY;
-	    goto leave;
-	}
-	if( mpi_getbyte(result, 15) != sig->d.rsa.digest_start[0]
-	    || mpi_getbyte(result, 14) != sig->d.rsa.digest_start[1] ) {
-	    /* Wrong key used to check the signature */
-	    rc = G10ERR_BAD_PUBKEY;
-	    goto leave;
+	    /* complete the digest */
+	    rmd160_putchar( digest.u.rmd, sig->sig_class );
+	    {	u32 a = sig->timestamp;
+		rmd160_putchar( digest.u.rmd, (a >> 24) & 0xff );
+		rmd160_putchar( digest.u.rmd, (a >> 16) & 0xff );
+		rmd160_putchar( digest.u.rmd, (a >>  8) & 0xff );
+		rmd160_putchar( digest.u.rmd,  a	& 0xff );
+	    }
+	    dp = rmd160_final( digest.u.rmd );
+	    for(i=19; i >= 0; i--, dp++ )
+		if( mpi_getbyte( result, i ) != *dp ) {
+		    rc = G10ERR_BAD_SIGN;
+		    goto leave;
+		}
 	}
+	else if( sig->d.rsa.digest_algo == DIGEST_ALGO_MD5 ) {
+	    static byte asn[18] = /* stored reverse */
+		  { 0x10, 0x04, 0x00, 0x05, 0x05, 0x02, 0x0d, 0xf7, 0x86,
+		    0x48, 0x86, 0x2a, 0x08, 0x06, 0x0c, 0x30, 0x20, 0x30 };
 
-	/* complete the digest */
-	md5_putchar( digest.u.md5, sig->sig_class );
-	{   u32 a = sig->timestamp;
-	    md5_putchar( digest.u.md5, (a >> 24) & 0xff );
-	    md5_putchar( digest.u.md5, (a >> 16) & 0xff );
-	    md5_putchar( digest.u.md5, (a >>  8) & 0xff );
-	    md5_putchar( digest.u.md5,	a	 & 0xff );
-	}
-	md5_final( digest.u.md5 );
-	dp = md5_read( digest.u.md5 );
-	for(i=15; i >= 0; i--, dp++ )
-	    if( mpi_getbyte( result, i ) != *dp ) {
-		rc = G10ERR_BAD_SIGN;
+	    for(i=16,j=0; j < 18 && (c=mpi_getbyte(result, i)) != -1; i++, j++ )
+		if( asn[j] != c )
+		    break;
+	    if( j != 18 || c ) { /* 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 != DIGEST_ALGO_MD5 || mpi_getbyte(result, i) ) {
+		/* Padding or leading bytes in signature is wrong */
+		rc = G10ERR_BAD_PUBKEY;
+		goto leave;
+	    }
+	    if( mpi_getbyte(result, 15) != sig->d.rsa.digest_start[0]
+		|| mpi_getbyte(result, 14) != sig->d.rsa.digest_start[1] ) {
+		/* Wrong key used to check the signature */
+		rc = G10ERR_BAD_PUBKEY;
+		goto leave;
+	    }
+
+	    /* complete the digest */
+	    md5_putchar( digest.u.md5, sig->sig_class );
+	    {	u32 a = sig->timestamp;
+		md5_putchar( digest.u.md5, (a >> 24) & 0xff );
+		md5_putchar( digest.u.md5, (a >> 16) & 0xff );
+		md5_putchar( digest.u.md5, (a >>  8) & 0xff );
+		md5_putchar( digest.u.md5,  a	     & 0xff );
+	    }
+	    md5_final( digest.u.md5 );
+	    dp = md5_read( digest.u.md5 );
+	    for(i=15; i >= 0; i--, dp++ )
+		if( mpi_getbyte( result, i ) != *dp ) {
+		    rc = G10ERR_BAD_SIGN;
+		    goto leave;
+		}
+	}
+	else {
+	    rc = G10ERR_DIGEST_ALGO;
+	    goto leave;
+	}
     }
     else {
-	rc = G10ERR_DIGEST_ALGO;
+	log_debug("signature_check: unsupported pubkey algo %d\n",
+			pkc->pubkey_algo );
+	rc = G10ERR_PUBKEY_ALGO;
 	goto leave;
     }
 
+
   leave:
-    mpi_free( result );
     if( pkc )
 	free_pubkey_cert( pkc );
+    mpi_free( result );
     return rc;
 }