/* Original version from Steven Schoch <schoch@sheba.arc.nasa.gov> */
+
+
#include <stdio.h>
#include "cryptlib.h"
#include <openssl/bn.h>
+#include <openssl/sha.h>
#include <openssl/dsa.h>
#include <openssl/rand.h>
#include <openssl/asn1.h>
static DSA_SIG *dsa_do_sign(const unsigned char *dgst, int dlen, DSA *dsa);
-static int dsa_sign_setup(DSA *dsa, BN_CTX *ctx_in, BIGNUM **kinvp, BIGNUM **rp);
+static int dsa_sign_setup_no_digest(DSA *dsa, BN_CTX *ctx_in, BIGNUM **kinvp, BIGNUM **rp);
+static int dsa_sign_setup(DSA *dsa, BN_CTX *ctx_in,
+ BIGNUM **kinvp, BIGNUM **rp,
+ const unsigned char *dgst, int dlen);
static int dsa_do_verify(const unsigned char *dgst, int dgst_len, DSA_SIG *sig,
DSA *dsa);
static int dsa_init(DSA *dsa);
static DSA_METHOD openssl_dsa_meth = {
"OpenSSL DSA method",
dsa_do_sign,
-dsa_sign_setup,
+dsa_sign_setup_no_digest,
dsa_do_verify,
NULL, /* dsa_mod_exp, */
NULL, /* dsa_bn_mod_exp, */
dsa_init,
dsa_finish,
-0,
+DSA_FLAG_FIPS_METHOD,
NULL,
NULL,
NULL
};
-/* These macro wrappers replace attempts to use the dsa_mod_exp() and
+/*-
+ * These macro wrappers replace attempts to use the dsa_mod_exp() and
* bn_mod_exp() handlers in the DSA_METHOD structure. We avoid the problem of
* having a the macro work as an expression by bundling an "err_instr". So;
*
static DSA_SIG *dsa_do_sign(const unsigned char *dgst, int dlen, DSA *dsa)
{
BIGNUM *kinv=NULL,*r=NULL,*s=NULL;
- BIGNUM m;
- BIGNUM xr;
+ BIGNUM *m;
+ BIGNUM *xr;
BN_CTX *ctx=NULL;
- int i,reason=ERR_R_BN_LIB;
+ int reason=ERR_R_BN_LIB;
DSA_SIG *ret=NULL;
+ int noredo = 0;
- BN_init(&m);
- BN_init(&xr);
+ m = BN_new();
+ xr = BN_new();
+ if(!m || !xr) goto err;
if (!dsa->p || !dsa->q || !dsa->g)
{
s=BN_new();
if (s == NULL) goto err;
-
- i=BN_num_bytes(dsa->q); /* should be 20 */
- if ((dlen > i) || (dlen > 50))
- {
- reason=DSA_R_DATA_TOO_LARGE_FOR_KEY_SIZE;
- goto err;
- }
-
ctx=BN_CTX_new();
if (ctx == NULL) goto err;
-
+redo:
if ((dsa->kinv == NULL) || (dsa->r == NULL))
{
- if (!DSA_sign_setup(dsa,ctx,&kinv,&r)) goto err;
+ if (!dsa_sign_setup(dsa,ctx,&kinv,&r,dgst,dlen))
+ goto err;
}
else
{
dsa->kinv=NULL;
r=dsa->r;
dsa->r=NULL;
+ noredo = 1;
}
- if (BN_bin2bn(dgst,dlen,&m) == NULL) goto err;
+
+ if (dlen > BN_num_bytes(dsa->q))
+ /* if the digest length is greater than the size of q use the
+ * BN_num_bits(dsa->q) leftmost bits of the digest, see
+ * fips 186-3, 4.2 */
+ dlen = BN_num_bytes(dsa->q);
+ if (BN_bin2bn(dgst,dlen,m) == NULL)
+ goto err;
/* Compute s = inv(k) (m + xr) mod q */
- if (!BN_mod_mul(&xr,dsa->priv_key,r,dsa->q,ctx)) goto err;/* s = xr */
- if (!BN_add(s, &xr, &m)) goto err; /* s = m + xr */
+ if (!BN_mod_mul(xr,dsa->priv_key,r,dsa->q,ctx)) goto err;/* s = xr */
+ if (!BN_add(s, xr, m)) goto err; /* s = m + xr */
if (BN_cmp(s,dsa->q) > 0)
- BN_sub(s,s,dsa->q);
+ if (!BN_sub(s,s,dsa->q)) goto err;
if (!BN_mod_mul(s,s,kinv,dsa->q,ctx)) goto err;
ret=DSA_SIG_new();
if (ret == NULL) goto err;
+ /* Redo if r or s is zero as required by FIPS 186-3: this is
+ * very unlikely.
+ */
+ if (BN_is_zero(r) || BN_is_zero(s))
+ {
+ if (noredo)
+ {
+ reason = DSA_R_NEED_NEW_SETUP_VALUES;
+ goto err;
+ }
+ goto redo;
+ }
ret->r = r;
ret->s = s;
BN_free(s);
}
if (ctx != NULL) BN_CTX_free(ctx);
- BN_clear_free(&m);
- BN_clear_free(&xr);
+ BN_clear_free(m);
+ BN_clear_free(xr);
if (kinv != NULL) /* dsa->kinv is NULL now if we used it */
BN_clear_free(kinv);
return(ret);
}
-static int dsa_sign_setup(DSA *dsa, BN_CTX *ctx_in, BIGNUM **kinvp, BIGNUM **rp)
+static int dsa_sign_setup_no_digest(DSA *dsa, BN_CTX *ctx_in,
+ BIGNUM **kinvp, BIGNUM **rp) {
+ return dsa_sign_setup(dsa, ctx_in, kinvp, rp, NULL, 0);
+}
+
+static int dsa_sign_setup(DSA *dsa, BN_CTX *ctx_in,
+ BIGNUM **kinvp, BIGNUM **rp,
+ const unsigned char *dgst, int dlen)
{
- BN_CTX *ctx;
- BIGNUM k,kq,*K,*kinv=NULL,*r=NULL;
+ BN_CTX *ctx = NULL;
+ BIGNUM *k,*kq,*K,*kinv=NULL,*r=NULL;
int ret=0;
if (!dsa->p || !dsa->q || !dsa->g)
return 0;
}
- BN_init(&k);
- BN_init(&kq);
+ k = BN_new();
+ kq = BN_new();
+ if(!k || !kq) goto err;
if (ctx_in == NULL)
{
/* Get random k */
do
- if (!BN_rand_range(&k, dsa->q)) goto err;
- while (BN_is_zero(&k));
+ {
+#ifndef OPENSSL_NO_SHA512
+ if (dgst != NULL)
+ {
+ /* We calculate k from SHA512(private_key + H(message)
+ * + random). This protects the private key from a weak
+ * PRNG. */
+ if (!BN_generate_dsa_nonce(k, dsa->q, dsa->priv_key, dgst,
+ dlen, ctx))
+ goto err;
+ }
+ else
+#endif
+ if (!BN_rand_range(k, dsa->q)) goto err;
+ } while (BN_is_zero(k));
+
if ((dsa->flags & DSA_FLAG_NO_EXP_CONSTTIME) == 0)
{
- BN_set_flags(&k, BN_FLG_EXP_CONSTTIME);
+ BN_set_flags(k, BN_FLG_CONSTTIME);
}
if (dsa->flags & DSA_FLAG_CACHE_MONT_P)
if ((dsa->flags & DSA_FLAG_NO_EXP_CONSTTIME) == 0)
{
- if (!BN_copy(&kq, &k)) goto err;
+ if (!BN_copy(kq, k)) goto err;
/* We do not want timing information to leak the length of k,
* so we compute g^k using an equivalent exponent of fixed length.
* (This is a kludge that we need because the BN_mod_exp_mont()
* does not let us specify the desired timing behaviour.) */
- if (!BN_add(&kq, &kq, dsa->q)) goto err;
- if (BN_num_bits(&kq) <= BN_num_bits(dsa->q))
+ if (!BN_add(kq, kq, dsa->q)) goto err;
+ if (BN_num_bits(kq) <= BN_num_bits(dsa->q))
{
- if (!BN_add(&kq, &kq, dsa->q)) goto err;
+ if (!BN_add(kq, kq, dsa->q)) goto err;
}
- K = &kq;
+ K = kq;
}
else
{
- K = &k;
+ K = k;
}
DSA_BN_MOD_EXP(goto err, dsa, r, dsa->g, K, dsa->p, ctx,
dsa->method_mont_p);
if (!BN_mod(r,r,dsa->q,ctx)) goto err;
/* Compute part of 's = inv(k) (m + xr) mod q' */
- if ((kinv=BN_mod_inverse(NULL,&k,dsa->q,ctx)) == NULL) goto err;
+ if ((kinv=BN_mod_inverse(NULL,k,dsa->q,ctx)) == NULL) goto err;
if (*kinvp != NULL) BN_clear_free(*kinvp);
*kinvp=kinv;
BN_clear_free(r);
}
if (ctx_in == NULL) BN_CTX_free(ctx);
- BN_clear_free(&k);
- BN_clear_free(&kq);
+ BN_clear_free(k);
+ BN_clear_free(kq);
return(ret);
}
DSA *dsa)
{
BN_CTX *ctx;
- BIGNUM u1,u2,t1;
+ BIGNUM *u1,*u2,*t1;
BN_MONT_CTX *mont=NULL;
- int ret = -1;
+ int ret = -1, i;
if (!dsa->p || !dsa->q || !dsa->g)
{
DSAerr(DSA_F_DSA_DO_VERIFY,DSA_R_MISSING_PARAMETERS);
return -1;
}
- if (BN_num_bits(dsa->q) != 160)
+ i = BN_num_bits(dsa->q);
+ /* fips 186-3 allows only different sizes for q */
+ if (i != 160 && i != 224 && i != 256)
{
DSAerr(DSA_F_DSA_DO_VERIFY,DSA_R_BAD_Q_VALUE);
return -1;
DSAerr(DSA_F_DSA_DO_VERIFY,DSA_R_MODULUS_TOO_LARGE);
return -1;
}
-
- BN_init(&u1);
- BN_init(&u2);
- BN_init(&t1);
-
- if ((ctx=BN_CTX_new()) == NULL) goto err;
+ u1 = BN_new();
+ u2 = BN_new();
+ t1 = BN_new();
+ ctx=BN_CTX_new();
+ if(!u1 || !u2 || !t1 || !ctx) goto err;
if (BN_is_zero(sig->r) || BN_is_negative(sig->r) ||
BN_ucmp(sig->r, dsa->q) >= 0)
/* Calculate W = inv(S) mod Q
* save W in u2 */
- if ((BN_mod_inverse(&u2,sig->s,dsa->q,ctx)) == NULL) goto err;
+ if ((BN_mod_inverse(u2,sig->s,dsa->q,ctx)) == NULL) goto err;
/* save M in u1 */
- if (BN_bin2bn(dgst,dgst_len,&u1) == NULL) goto err;
+ if (dgst_len > (i >> 3))
+ /* if the digest length is greater than the size of q use the
+ * BN_num_bits(dsa->q) leftmost bits of the digest, see
+ * fips 186-3, 4.2 */
+ dgst_len = (i >> 3);
+ if (BN_bin2bn(dgst,dgst_len,u1) == NULL) goto err;
/* u1 = M * w mod q */
- if (!BN_mod_mul(&u1,&u1,&u2,dsa->q,ctx)) goto err;
+ if (!BN_mod_mul(u1,u1,u2,dsa->q,ctx)) goto err;
/* u2 = r * w mod q */
- if (!BN_mod_mul(&u2,sig->r,&u2,dsa->q,ctx)) goto err;
+ if (!BN_mod_mul(u2,sig->r,u2,dsa->q,ctx)) goto err;
if (dsa->flags & DSA_FLAG_CACHE_MONT_P)
}
- DSA_MOD_EXP(goto err, dsa, &t1, dsa->g, &u1, dsa->pub_key, &u2, dsa->p, ctx, mont);
+ DSA_MOD_EXP(goto err, dsa, t1, dsa->g, u1, dsa->pub_key, u2, dsa->p, ctx, mont);
/* BN_copy(&u1,&t1); */
/* let u1 = u1 mod q */
- if (!BN_mod(&u1,&t1,dsa->q,ctx)) goto err;
+ if (!BN_mod(u1,t1,dsa->q,ctx)) goto err;
/* V is now in u1. If the signature is correct, it will be
* equal to R. */
- ret=(BN_ucmp(&u1, sig->r) == 0);
+ ret=(BN_ucmp(u1, sig->r) == 0);
err:
- /* XXX: surely this is wrong - if ret is 0, it just didn't verify;
- there is no error in BN. Test should be ret == -1 (Ben) */
- if (ret != 1) DSAerr(DSA_F_DSA_DO_VERIFY,ERR_R_BN_LIB);
+ if (ret < 0) DSAerr(DSA_F_DSA_DO_VERIFY,ERR_R_BN_LIB);
if (ctx != NULL) BN_CTX_free(ctx);
- BN_free(&u1);
- BN_free(&u2);
- BN_free(&t1);
+ if(u1) BN_free(u1);
+ if(u2) BN_free(u2);
+ if(t1) BN_free(t1);
return(ret);
}