#include <stdio.h>
#include "cryptlib.h"
#include <openssl/bn.h>
#include <openssl/dsa.h>
#include <openssl/rand.h>
#include <openssl/asn1.h>
#ifndef OPENSSL_FIPS
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_do_verify(const unsigned char *dgst, int dgst_len, DSA_SIG *sig,
DSA *dsa);
static int dsa_init(DSA *dsa);
static int dsa_finish(DSA *dsa);
static DSA_METHOD openssl_dsa_meth = {
"OpenSSL DSA method",
dsa_do_sign,
dsa_sign_setup,
dsa_do_verify,
NULL,
NULL,
dsa_init,
dsa_finish,
0,
NULL,
NULL,
NULL
};
#define DSA_MOD_EXP(err_instr,dsa,rr,a1,p1,a2,p2,m,ctx,in_mont) \
do { \
int _tmp_res53; \
if((dsa)->meth->dsa_mod_exp) \
_tmp_res53 = (dsa)->meth->dsa_mod_exp((dsa), (rr), (a1), (p1), \
(a2), (p2), (m), (ctx), (in_mont)); \
else \
_tmp_res53 = BN_mod_exp2_mont((rr), (a1), (p1), (a2), (p2), \
(m), (ctx), (in_mont)); \
if(!_tmp_res53) err_instr; \
} while(0)
#define DSA_BN_MOD_EXP(err_instr,dsa,r,a,p,m,ctx,m_ctx) \
do { \
int _tmp_res53; \
if((dsa)->meth->bn_mod_exp) \
_tmp_res53 = (dsa)->meth->bn_mod_exp((dsa), (r), (a), (p), \
(m), (ctx), (m_ctx)); \
else \
_tmp_res53 = BN_mod_exp_mont((r), (a), (p), (m), (ctx), (m_ctx)); \
if(!_tmp_res53) err_instr; \
} while(0)
const DSA_METHOD *DSA_OpenSSL(void)
{
return &openssl_dsa_meth;
}
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;
BN_CTX *ctx=NULL;
int i,reason=ERR_R_BN_LIB;
DSA_SIG *ret=NULL;
BN_init(&m);
BN_init(&xr);
if (!dsa->p || !dsa->q || !dsa->g)
{
reason=DSA_R_MISSING_PARAMETERS;
goto err;
}
s=BN_new();
if (s == NULL) goto err;
i=BN_num_bytes(dsa->q);
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;
if ((dsa->kinv == NULL) || (dsa->r == NULL))
{
if (!DSA_sign_setup(dsa,ctx,&kinv,&r)) goto err;
}
else
{
kinv=dsa->kinv;
dsa->kinv=NULL;
r=dsa->r;
dsa->r=NULL;
}
if (BN_bin2bn(dgst,dlen,&m) == NULL) goto err;
if (!BN_mod_mul(&xr,dsa->priv_key,r,dsa->q,ctx)) goto err;
if (!BN_add(s, &xr, &m)) goto err;
if (BN_cmp(s,dsa->q) > 0)
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;
ret->r = r;
ret->s = s;
err:
if (!ret)
{
DSAerr(DSA_F_DSA_DO_SIGN,reason);
BN_free(r);
BN_free(s);
}
if (ctx != NULL) BN_CTX_free(ctx);
BN_clear_free(&m);
BN_clear_free(&xr);
if (kinv != NULL)
BN_clear_free(kinv);
return(ret);
}
static int dsa_sign_setup(DSA *dsa, BN_CTX *ctx_in, BIGNUM **kinvp, BIGNUM **rp)
{
BN_CTX *ctx;
BIGNUM k,kq,*K,*kinv=NULL,*r=NULL;
int ret=0;
if (!dsa->p || !dsa->q || !dsa->g)
{
DSAerr(DSA_F_DSA_SIGN_SETUP,DSA_R_MISSING_PARAMETERS);
return 0;
}
BN_init(&k);
BN_init(&kq);
if (ctx_in == NULL)
{
if ((ctx=BN_CTX_new()) == NULL) goto err;
}
else
ctx=ctx_in;
if ((r=BN_new()) == NULL) goto err;
do
if (!BN_rand_range(&k, dsa->q)) goto err;
while (BN_is_zero(&k));
if (dsa->flags & DSA_FLAG_CACHE_MONT_P)
{
if (!BN_MONT_CTX_set_locked(&dsa->method_mont_p,
CRYPTO_LOCK_DSA,
dsa->p, ctx))
goto err;
}
if ((dsa->flags & DSA_FLAG_NO_EXP_CONSTTIME) == 0)
{
if (!BN_copy(&kq, &k)) goto err;
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;
}
K = &kq;
}
else
{
K = &k;
}
if ((dsa->flags & DSA_FLAG_NO_EXP_CONSTTIME) == 0)
{
BN_set_flags(&k, BN_FLG_CONSTTIME);
}
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;
if ((kinv=BN_mod_inverse(NULL,&k,dsa->q,ctx)) == NULL) goto err;
if (*kinvp != NULL) BN_clear_free(*kinvp);
*kinvp=kinv;
kinv=NULL;
if (*rp != NULL) BN_clear_free(*rp);
*rp=r;
ret=1;
err:
if (!ret)
{
DSAerr(DSA_F_DSA_SIGN_SETUP,ERR_R_BN_LIB);
if (kinv != NULL) BN_clear_free(kinv);
if (r != NULL) BN_clear_free(r);
}
if (ctx_in == NULL) BN_CTX_free(ctx);
if (kinv != NULL) BN_clear_free(kinv);
BN_clear_free(&k);
BN_clear_free(&kq);
return(ret);
}
static int dsa_do_verify(const unsigned char *dgst, int dgst_len, DSA_SIG *sig,
DSA *dsa)
{
BN_CTX *ctx;
BIGNUM u1,u2,t1;
BN_MONT_CTX *mont=NULL;
int ret = -1;
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)
{
DSAerr(DSA_F_DSA_DO_VERIFY,DSA_R_BAD_Q_VALUE);
return -1;
}
if (BN_num_bits(dsa->p) > OPENSSL_DSA_MAX_MODULUS_BITS)
{
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;
if (BN_is_zero(sig->r) || BN_is_negative(sig->r) ||
BN_ucmp(sig->r, dsa->q) >= 0)
{
ret = 0;
goto err;
}
if (BN_is_zero(sig->s) || BN_is_negative(sig->s) ||
BN_ucmp(sig->s, dsa->q) >= 0)
{
ret = 0;
goto err;
}
if ((BN_mod_inverse(&u2,sig->s,dsa->q,ctx)) == NULL) goto err;
if (BN_bin2bn(dgst,dgst_len,&u1) == NULL) goto err;
if (!BN_mod_mul(&u1,&u1,&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)
{
mont = BN_MONT_CTX_set_locked(&dsa->method_mont_p,
CRYPTO_LOCK_DSA, dsa->p, ctx);
if (!mont)
goto err;
}
DSA_MOD_EXP(goto err, dsa, &t1, dsa->g, &u1, dsa->pub_key, &u2, dsa->p, ctx, mont);
if (!BN_mod(&u1,&t1,dsa->q,ctx)) goto err;
ret=(BN_ucmp(&u1, sig->r) == 0);
err:
if (ret != 1) 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);
return(ret);
}
static int dsa_init(DSA *dsa)
{
dsa->flags|=DSA_FLAG_CACHE_MONT_P;
return(1);
}
static int dsa_finish(DSA *dsa)
{
if(dsa->method_mont_p)
BN_MONT_CTX_free(dsa->method_mont_p);
return(1);
}
#endif