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-rw-r--r--cipher/elgamal.c164
1 files changed, 3 insertions, 161 deletions
diff --git a/cipher/elgamal.c b/cipher/elgamal.c
index 2ca784017..eb69a655c 100644
--- a/cipher/elgamal.c
+++ b/cipher/elgamal.c
@@ -1,5 +1,6 @@
/* elgamal.c - elgamal Public Key encryption
- * Copyright (C) 1998, 2000, 2001, 2003 Free Software Foundation, Inc.
+ * Copyright (C) 1998, 2000, 2001, 2003,
+ * 2004 Free Software Foundation, Inc.
*
* For a description of the algorithm, see:
* Bruce Schneier: Applied Cryptography. John Wiley & Sons, 1996.
@@ -52,8 +53,6 @@ static void generate( ELG_secret_key *sk, unsigned nbits, MPI **factors );
static int check_secret_key( ELG_secret_key *sk );
static void do_encrypt(MPI a, MPI b, MPI input, ELG_public_key *pkey );
static void decrypt(MPI output, MPI a, MPI b, ELG_secret_key *skey );
-static void sign(MPI a, MPI b, MPI input, ELG_secret_key *skey);
-static int verify(MPI a, MPI b, MPI input, ELG_public_key *pkey);
static void (*progress_cb) ( void *, int );
@@ -141,10 +140,6 @@ test_keys( ELG_secret_key *sk, unsigned nbits )
if( mpi_cmp( test, out2 ) )
log_fatal("Elgamal operation: encrypt, decrypt failed\n");
- sign( out1_a, out1_b, test, sk );
- if( !verify( out1_a, out1_b, test, &pk ) )
- log_fatal("Elgamal operation: sign, verify failed\n");
-
mpi_free( test );
mpi_free( out1_a );
mpi_free( out1_b );
@@ -375,8 +370,6 @@ do_encrypt(MPI a, MPI b, MPI input, ELG_public_key *pkey )
}
-
-
static void
decrypt(MPI output, MPI a, MPI b, ELG_secret_key *skey )
{
@@ -399,111 +392,6 @@ decrypt(MPI output, MPI a, MPI b, ELG_secret_key *skey )
}
-/****************
- * Make an Elgamal signature out of INPUT
- */
-
-static void
-sign(MPI a, MPI b, MPI input, ELG_secret_key *skey )
-{
- MPI k;
- MPI t = mpi_alloc( mpi_get_nlimbs(a) );
- MPI inv = mpi_alloc( mpi_get_nlimbs(a) );
- MPI p_1 = mpi_copy(skey->p);
-
- /*
- * b = (t * inv) mod (p-1)
- * b = (t * inv(k,(p-1),(p-1)) mod (p-1)
- * b = (((M-x*a) mod (p-1)) * inv(k,(p-1),(p-1))) mod (p-1)
- *
- */
- mpi_sub_ui(p_1, p_1, 1);
- k = gen_k( skey->p, 0 /* no small K ! */ );
- mpi_powm( a, skey->g, k, skey->p );
- mpi_mul(t, skey->x, a );
- mpi_subm(t, input, t, p_1 );
- while( mpi_is_neg(t) ) {
- BUG(); /* That is nonsense code - left over from a very early test?*/
- mpi_add(t, t, p_1);
- }
- mpi_invm(inv, k, p_1 );
- mpi_mulm(b, t, inv, p_1 );
-
-#if 0
- if( DBG_CIPHER ) {
- log_mpidump("elg sign p= ", skey->p);
- log_mpidump("elg sign g= ", skey->g);
- log_mpidump("elg sign y= ", skey->y);
- log_mpidump("elg sign x= ", skey->x);
- log_mpidump("elg sign k= ", k);
- log_mpidump("elg sign M= ", input);
- log_mpidump("elg sign a= ", a);
- log_mpidump("elg sign b= ", b);
- }
-#endif
- mpi_free(k);
- mpi_free(t);
- mpi_free(inv);
- mpi_free(p_1);
-}
-
-
-/****************
- * Returns true if the signature composed of A and B is valid.
- */
-static int
-verify(MPI a, MPI b, MPI input, ELG_public_key *pkey )
-{
- int rc;
- MPI t1;
- MPI t2;
- MPI base[4];
- MPI exp[4];
-
- if( !(mpi_cmp_ui( a, 0 ) > 0 && mpi_cmp( a, pkey->p ) < 0) )
- return 0; /* assertion 0 < a < p failed */
-
- t1 = mpi_alloc( mpi_get_nlimbs(a) );
- t2 = mpi_alloc( mpi_get_nlimbs(a) );
-
-#if 0
- /* t1 = (y^a mod p) * (a^b mod p) mod p */
- mpi_powm( t1, pkey->y, a, pkey->p );
- mpi_powm( t2, a, b, pkey->p );
- mpi_mulm( t1, t1, t2, pkey->p );
-
- /* t2 = g ^ input mod p */
- mpi_powm( t2, pkey->g, input, pkey->p );
-
- rc = !mpi_cmp( t1, t2 );
-#elif 0
- /* t1 = (y^a mod p) * (a^b mod p) mod p */
- base[0] = pkey->y; exp[0] = a;
- base[1] = a; exp[1] = b;
- base[2] = NULL; exp[2] = NULL;
- mpi_mulpowm( t1, base, exp, pkey->p );
-
- /* t2 = g ^ input mod p */
- mpi_powm( t2, pkey->g, input, pkey->p );
-
- rc = !mpi_cmp( t1, t2 );
-#else
- /* t1 = g ^ - input * y ^ a * a ^ b mod p */
- mpi_invm(t2, pkey->g, pkey->p );
- base[0] = t2 ; exp[0] = input;
- base[1] = pkey->y; exp[1] = a;
- base[2] = a; exp[2] = b;
- base[3] = NULL; exp[3] = NULL;
- mpi_mulpowm( t1, base, exp, pkey->p );
- rc = !mpi_cmp_ui( t1, 1 );
-
-#endif
-
- mpi_free(t1);
- mpi_free(t2);
- return rc;
-}
-
/*********************************************
************** interface ******************
*********************************************/
@@ -546,7 +434,6 @@ elg_check_secret_key( int algo, MPI *skey )
}
-
int
elg_encrypt( int algo, MPI *resarr, MPI data, MPI *pkey )
{
@@ -586,45 +473,6 @@ elg_decrypt( int algo, MPI *result, MPI *data, MPI *skey )
return 0;
}
-int
-elg_sign( int algo, MPI *resarr, MPI data, MPI *skey )
-{
- ELG_secret_key sk;
-
- if( !is_ELGAMAL(algo) )
- return G10ERR_PUBKEY_ALGO;
- if( !data || !skey[0] || !skey[1] || !skey[2] || !skey[3] )
- return G10ERR_BAD_MPI;
-
- sk.p = skey[0];
- sk.g = skey[1];
- sk.y = skey[2];
- sk.x = skey[3];
- resarr[0] = mpi_alloc( mpi_get_nlimbs( sk.p ) );
- resarr[1] = mpi_alloc( mpi_get_nlimbs( sk.p ) );
- sign( resarr[0], resarr[1], data, &sk );
- return 0;
-}
-
-int
-elg_verify( int algo, MPI hash, MPI *data, MPI *pkey )
-{
- ELG_public_key pk;
-
- if( !is_ELGAMAL(algo) )
- return G10ERR_PUBKEY_ALGO;
- if( !data[0] || !data[1] || !hash
- || !pkey[0] || !pkey[1] || !pkey[2] )
- return G10ERR_BAD_MPI;
-
- pk.p = pkey[0];
- pk.g = pkey[1];
- pk.y = pkey[2];
- if( !verify( data[0], data[1], hash, &pk ) )
- return G10ERR_BAD_SIGN;
- return 0;
-}
-
unsigned int
elg_get_nbits( int algo, MPI *pkey )
@@ -642,9 +490,6 @@ elg_get_nbits( int algo, MPI *pkey )
* the ALGO is invalid.
* Usage: Bit 0 set : allows signing
* 1 set : allows encryption
- * NOTE: This function allows signing also for ELG-E, which is not
- * okay but a bad hack to allow to work with old gpg keys. The real check
- * is done in the gnupg ocde depending on the packet version.
*/
const char *
elg_get_info( int algo, int *npkey, int *nskey, int *nenc, int *nsig,
@@ -656,11 +501,8 @@ elg_get_info( int algo, int *npkey, int *nskey, int *nenc, int *nsig,
*nsig = 2;
switch( algo ) {
- case PUBKEY_ALGO_ELGAMAL:
- *use = PUBKEY_USAGE_SIG|PUBKEY_USAGE_ENC;
- return "ELG";
case PUBKEY_ALGO_ELGAMAL_E:
- *use = PUBKEY_USAGE_SIG|PUBKEY_USAGE_ENC;
+ *use = PUBKEY_USAGE_ENC;
return "ELG-E";
default: *use = 0; return NULL;
}
generated by cgit v1.2.3 (git 2.25.1) at 2025-05-22 16:38:24 +0000