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-rw-r--r--g10/sig-check.c280
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;
}
generated by cgit v1.2.3 (git 2.25.1) at 2025-05-05 17:44:13 +0000