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-rw-r--r--g10/seskey.c179
1 files changed, 48 insertions, 131 deletions
diff --git a/g10/seskey.c b/g10/seskey.c
index dd8ad13ab..1488620cd 100644
--- a/g10/seskey.c
+++ b/g10/seskey.c
@@ -29,7 +29,6 @@
#include "main.h"
-
/****************
* Make a session key and put it into DEK
*/
@@ -61,15 +60,16 @@ encode_session_key( DEK *dek, unsigned nbits )
{
int nframe = (nbits+7) / 8;
byte *p;
- MPI frame;
+ byte *frame;
int i,n,c;
u16 csum;
+ MPI a;
/* the current limitation is, that we can only use a session key
* which length is a multiple of BITS_PER_MPI_LIMB
* I think we can live with that.
*/
- if( dek->keylen + 7 > nframe || (nbits % BITS_PER_MPI_LIMB) || !nframe )
+ if( dek->keylen + 7 > nframe || !nframe )
log_bug("can't encode a %d bit key in a %d bits frame\n",
dek->keylen*8, nbits );
@@ -83,163 +83,80 @@ encode_session_key( DEK *dek, unsigned nbits )
* cipher algorithm (20 is used with blowfish).
* CSUM is the 16 bit checksum over the DEK
*/
- frame = mpi_alloc_secure( nframe / BYTES_PER_MPI_LIMB );
csum = 0;
for( p = dek->key, i=0; i < dek->keylen; i++ )
csum += *p++;
- mpi_putbyte(frame, 0, csum );
- mpi_putbyte(frame, 1, csum >> 8 );
- for(n=2,i=dek->keylen-1, p = dek->key; i >= 0; i--, n++ )
- mpi_putbyte(frame, n, p[i] );
- mpi_putbyte(frame, n++, dek->algo );
- mpi_putbyte(frame, n++, 0 );
- while( n < nframe-2 ) {
+
+ frame = m_alloc_secure( nframe );
+ n = 0;
+ frame[n++] = 0;
+ frame[n++] = 2;
+ i = nframe - 6 - dek->keylen;
+ assert( i > 0 );
+ for( ; i ; i-- ) {
while( !(c = get_random_byte(1)) )
;
- mpi_putbyte(frame, n++, c );
+ frame[n++] = c;
}
- mpi_putbyte(frame, n++, 2 );
- mpi_putbyte(frame, n++, 0 );
+ frame[n++] = 0;
+ frame[n++] = dek->algo;
+ memcpy( frame+n, dek->key, dek->keylen ); n += dek->keylen;
+ frame[n++] = csum >>8;
+ frame[n++] = csum;
assert( n == nframe );
- return frame;
+ a = mpi_alloc_secure( (nframe+BYTES_PER_MPI_LIMB-1) / BYTES_PER_MPI_LIMB );
+ mpi_set_buffer( a, frame, nframe, 0 );
+ m_free(frame);
+ return a;
}
-/****************
- * Encode a ripemd160 message digest of LEN bytes into NBITS.
- * returns: A mpi with the session key (caller must free)
- * RMD160 Object ID is 1.3.36.3.2.1
- */
-static MPI
-encode_rmd160_value( byte *md, unsigned len, unsigned nbits, int secure )
-{
- static byte asn[15] =
- { 0x30, 0x21, 0x30, 0x09, 0x06, 0x05, 0x2b, 0x24, 0x03,
- 0x02, 0x01, 0x05, 0x00, 0x04, 0x14 };
- int nframe = (nbits+7) / 8;
- MPI frame;
- int i,n;
-
- if( (nbits % BITS_PER_MPI_LIMB) || nframe < 42 || len != 20 )
- log_bug("can't encode a %d bit MD into a %d bits frame\n",len*8, nbits);
- /* We encode the MD in this way:
- *
- * 0 A PAD(n bytes) 0 ASN(15 bytes) MD(20 bytes)
- *
- * PAD consists of FF bytes.
- */
- frame = secure ? mpi_alloc_secure( nframe / BYTES_PER_MPI_LIMB )
- : mpi_alloc( nframe / BYTES_PER_MPI_LIMB );
- n = 0;
- for(i=20-1; i >= 0; i--, n++ )
- mpi_putbyte(frame, n, md[i] );
- for( i=15-1; i >= 0; i--, n++ )
- mpi_putbyte(frame, n, asn[i] );
- mpi_putbyte(frame, n++, 0 );
- while( n < nframe-2 )
- mpi_putbyte(frame, n++, 0xff );
- mpi_putbyte(frame, n++, DIGEST_ALGO_RMD160 );
- mpi_putbyte(frame, n++, 0 );
- assert( n == nframe );
- return frame;
-}
-
-/****************
- * Encode a sha-1 message digest of LEN bytes into NBITS.
- * returns: A mpi with the session key (caller must free)
- * SHA-1 Objet ID is 1.3.14.3.2.26
- */
static MPI
-encode_sha1_value( byte *md, unsigned len, unsigned nbits, int secure )
+do_encode_md( MD_HANDLE md, int algo, size_t len, unsigned nbits,
+ const byte *asn, size_t asnlen )
{
- static byte asn[15] =
- { 0x30, 0x21, 0x30, 0x09, 0x06, 0x05, 0x2b, 0x0e, 0x03,
- 0x02, 0x1a, 0x05, 0x00, 0x04, 0x14 };
int nframe = (nbits+7) / 8;
- MPI frame;
+ byte *frame;
int i,n;
+ MPI a;
- if( (nbits % BITS_PER_MPI_LIMB) || nframe < 42 || len != 20 )
+ if( len + asnlen + 4 > nframe )
log_bug("can't encode a %d bit MD into a %d bits frame\n",len*8, nbits);
/* We encode the MD in this way:
*
- * 0 A PAD(n bytes) 0 ASN(15 bytes) MD(20 bytes)
+ * 0 A PAD(n bytes) 0 ASN(asnlen bytes) MD(len bytes)
*
* PAD consists of FF bytes.
*/
- frame = secure ? mpi_alloc_secure( nframe / BYTES_PER_MPI_LIMB )
- : mpi_alloc( nframe / BYTES_PER_MPI_LIMB );
+ frame = md_is_secure(md)? m_alloc_secure( nframe ) : m_alloc( nframe );
n = 0;
- for(i=20-1; i >= 0; i--, n++ )
- mpi_putbyte(frame, n, md[i] );
- for( i=15-1; i >= 0; i--, n++ )
- mpi_putbyte(frame, n, asn[i] );
- mpi_putbyte(frame, n++, 0 );
- while( n < nframe-2 )
- mpi_putbyte(frame, n++, 0xff );
- mpi_putbyte(frame, n++, DIGEST_ALGO_RMD160 );
- mpi_putbyte(frame, n++, 0 );
+ frame[n++] = 0;
+ frame[n++] = algo;
+ i = nframe - len - asnlen -3 ;
+ assert( i > 1 );
+ memset( frame+n, 0xff, i ); n += i;
+ frame[n++] = 0;
+ memcpy( frame+n, asn, asnlen ); n += asnlen;
+ memcpy( frame+n, md_read(md, algo), len ); n += len;
assert( n == nframe );
- return frame;
+ a = md_is_secure(md)?
+ mpi_alloc_secure( (nframe+BYTES_PER_MPI_LIMB-1) / BYTES_PER_MPI_LIMB )
+ : mpi_alloc( (nframe+BYTES_PER_MPI_LIMB-1) / BYTES_PER_MPI_LIMB );
+ mpi_set_buffer( a, frame, nframe, 0 );
+ m_free(frame);
+ return a;
}
-/****************
- * Encode a md5 message digest of LEN bytes into NBITS.
- * returns: A mpi with the session key (caller must free)
- * MD5 Object ID is 1.2.840.113549.2.5
- */
-static MPI
-encode_md5_value( byte *md, unsigned len, unsigned nbits, int secure )
-{
- static byte asn[18] =
- { 0x30, 0x20, 0x30, 0x0c, 0x06, 0x08, 0x2a, 0x86,0x48,
- 0x86, 0xf7, 0x0d, 0x02, 0x05, 0x05, 0x00, 0x04, 0x10 };
- int nframe = (nbits+7) / 8;
- MPI frame;
- int i,n;
-
- if( (nbits % BITS_PER_MPI_LIMB) || nframe < 38 || len != 16 )
- log_bug("can't encode a %d bit MD into a %d bits frame\n",len*8, nbits);
-
- /* We encode the MD in this way:
- *
- * 0 A PAD(n bytes) 0 ASN(18 bytes) MD(16 bytes)
- *
- * PAD consists of FF bytes.
- */
- frame = secure ? mpi_alloc_secure( nframe / BYTES_PER_MPI_LIMB )
- : mpi_alloc( nframe / BYTES_PER_MPI_LIMB );
- n = 0;
- for(i=16-1; i >= 0; i--, n++ )
- mpi_putbyte(frame, n, md[i] );
- for( i=18-1; i >= 0; i--, n++ )
- mpi_putbyte(frame, n, asn[i] );
- mpi_putbyte(frame, n++, 0 );
- while( n < nframe-2 )
- mpi_putbyte(frame, n++, 0xff );
- mpi_putbyte(frame, n++, DIGEST_ALGO_MD5 );
- mpi_putbyte(frame, n++, 0 );
- assert( n == nframe );
- return frame;
-}
-
MPI
encode_md_value( MD_HANDLE md, unsigned nbits )
{
- switch( md_get_algo( md ) ) {
- case DIGEST_ALGO_MD5:
- return encode_md5_value( md_read(md, DIGEST_ALGO_MD5),
- 16, nbits, md_is_secure(md) );
- case DIGEST_ALGO_RMD160:
- return encode_rmd160_value( md_read(md, DIGEST_ALGO_RMD160),
- 20, nbits, md_is_secure(md) );
- case DIGEST_ALGO_SHA1:
- return encode_sha1_value( md_read(md, DIGEST_ALGO_SHA1),
- 20, nbits, md_is_secure(md) );
- default:
- BUG();
- }
+ int algo = md_get_algo(md);
+ const byte *asn;
+ size_t asnlen, mdlen;
+
+ asn = md_asn_oid( algo, &asnlen, &mdlen );
+ return do_encode_md( md, algo, mdlen, nbits, asn, asnlen );
}
generated by cgit v1.2.3 (git 2.25.1) at 2025-05-04 11:49:40 +0000