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ElGamal funktioniert und ist default

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This commit is contained in:
Werner Koch 1997-11-24 22:24:04 +00:00
parent a51cca90b6
commit 46900fbd43
31 changed files with 1273 additions and 409 deletions
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47
g10/seskey.c
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@ -26,6 +26,7 @@
#include "util.h"
#include "cipher.h"
#include "mpi.h"
#include "main.h"
@ -73,7 +74,7 @@ encode_session_key( DEK *dek, unsigned nbits )
* 0 2 RND(n bytes) 0 A DEK(k bytes) CSUM(2 bytes)
*
* RND are non-zero random bytes.
* A is the cipher algorithm ( 42 for Blowfish )
* A is the cipher algorithm
* DEK is the encryption key (session key) length k depends on the
* cipher algorithm (20 is used with blowfish).
* CSUM is the 16 bit checksum over the DEK
@ -106,7 +107,7 @@ encode_session_key( DEK *dek, unsigned nbits )
MPI
encode_rmd160_value( byte *md, unsigned len, unsigned nbits )
{
static byte asn[18] = /* stored reverse FIXME: need other values*/
static byte asn[18] = /* FIXME: need other values*/
{ 0x30, 0x20, 0x30, 0x0c, 0x06, 0x08, 0x2a, 0x86,0x48,
0x86, 0xf7, 0x0d, 0x02, 0x05, 0x05, 0x00, 0x04, 0x10 };
int nframe = (nbits+7) / 8;
@ -119,7 +120,7 @@ encode_rmd160_value( byte *md, unsigned len, unsigned nbits )
/* We encode the MD in this way:
*
* 0 42 PAD(n bytes) 0 ASN(18 bytes) MD(20 bytes)
* 0 A PAD(n bytes) 0 ASN(18 bytes) MD(20 bytes)
*
* PAD consists of FF bytes.
*/
@ -138,3 +139,43 @@ encode_rmd160_value( byte *md, unsigned len, unsigned nbits )
return frame;
}
/****************
* Encode a md5 message digest of LEN bytes into NBITS.
* returns: A mpi with the session key (caller must free)
*/
MPI
encode_md5_value( byte *md, unsigned len, unsigned nbits )
{
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;
byte *p;
MPI frame;
int i,n,c;
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 = mpi_alloc_secure( 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;
}