--- gnupg-1.4.1/cipher/rsa.c.orig	2004-09-23 23:34:45 +0400

+++ gnupg-1.4.1/cipher/rsa.c	2005-03-17 16:47:44 +0300

@@ -193,19 +193,54 @@ generate( RSA_secret_key *sk, unsigned n

 /****************

- * Test wether the secret key is valid.

- * Returns: true if this is a valid key.

+ * Test whether the secret key is valid.

+ * Returns: nonzero if this is a valid key.

  */

 static int

 check_secret_key( RSA_secret_key *sk )

 {

-    int rc;

-    MPI temp = mpi_alloc( mpi_get_nlimbs(sk->p)*2 );

+    int rc = 0;

+    MPI temp    = mpi_alloc_secure ( mpi_get_nlimbs(sk->p) + mpi_get_nlimbs(sk->q) );

+    MPI p_1     = mpi_copy (sk->p); /* (p-1) */

+    MPI q_1     = mpi_copy (sk->p); /* (q-1) */

+    MPI p_1_q_1 = mpi_alloc_secure ( mpi_get_nlimbs(sk->p) + mpi_get_nlimbs(sk->q) ); /* (p-1)(q-1) */

+

+    /* Calculate (p-1)(q-1). */

+    mpi_sub_ui(p_1, p_1, 1);

+    mpi_sub_ui(q_1, q_1, 1);

+    mpi_mul(p_1_q_1, p_1, q_1);

+    /* Check pq = n. */

     mpi_mul(temp, sk->p, sk->q );

-    rc = mpi_cmp( temp, sk->n );

+    if( 0 != mpi_cmp(temp, sk->n ) )

+	goto end;

+	

+    /* Check gcd(e, (p-1)(q-1)) = 1. */

+    if( ! mpi_gcd(temp, sk->e, p_1_q_1) )

+	goto end;

+

+    /* Check de == 1 (mod (p-1)) and (mod (q-1)), i.e. d = e^-1. */

+    mpi_mulm(temp, sk->d, sk->e, p_1);

+    if( 0 != mpi_cmp_ui(temp, 1))

+	goto end;

+    mpi_mulm(temp, sk->d, sk->e, q_1);

+    if( 0 != mpi_cmp_ui(temp, 1))

+	goto end;

+

+    /* Check up == 1 (mod q). */

+    mpi_mulm(temp, sk->u, sk->p, sk->q);

+    if( 0 != mpi_cmp_ui(temp, 1))

+	goto end;

+

+    /* Success.  Fall through to deallocation code. */

+    rc = 1;

+

+ end:

     mpi_free(temp);

-    return !rc;

+    mpi_free(p_1);

+    mpi_free(q_1);

+    mpi_free(p_1_q_1);

+    return rc;

 }

@@ -419,6 +454,8 @@ int

 rsa_sign( int algo, MPI *resarr, MPI data, MPI *skey )

 {

     RSA_secret_key sk;

+    RSA_public_key pk;

+    MPI orig = mpi_alloc( mpi_get_nlimbs( data ) );

     if( algo != 1 && algo != 3 )

 	return G10ERR_PUBKEY_ALGO;

@@ -432,6 +469,13 @@ rsa_sign( int algo, MPI *resarr, MPI dat

     resarr[0] = mpi_alloc( mpi_get_nlimbs( sk.n ) );

     secret( resarr[0], data, &sk );

+    /* Check against wrong computation. */

+    pk.n = sk.n;

+    pk.e = sk.e;

+    public( orig, resarr[0], &pk);

+    if ( 0 != mpi_cmp( orig, data ) )

+	return G10ERR_BAD_SECKEY;

+

     return 0;

 }