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;
}
/* Calculate W = inv(S) mod Q
* save W in u2 */
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;
/* u1 = M * w mod q */
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 (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);
/* BN_copy(&u1,&t1); */
/* let u1 = u1 mod q */
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);
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 (ctx != NULL) BN_CTX_free(ctx);
BN_free(&u1);
BN_free(&u2);
BN_free(&t1);
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;
/* Get random k */
do
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_CONSTTIME);
}
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;
}
/* Compute r = (g^k mod p) mod q */
if ((dsa->flags & DSA_FLAG_NO_EXP_CONSTTIME) == 0)
{
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;
}
K = &kq;
}
else
{
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 (*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);
}
/*
* read packets, try to authenticate the user and
* return only if authentication is successful
*/
static void
do_authloop(Authctxt *authctxt)
{
int authenticated = 0;
u_int bits;
Key *client_host_key;
BIGNUM *n;
char *client_user, *password;
char info[1024];
u_int dlen;
u_int ulen;
int prev, type = 0;
struct passwd *pw = authctxt->pw;
debug("Attempting authentication for %s%.100s.",
authctxt->valid ? "" : "illegal user ", authctxt->user);
/* If the user has no password, accept authentication immediately. */
if (options.password_authentication &&
#ifdef KRB5
(!options.kerberos_authentication || options.kerberos_or_local_passwd) &&
#endif
PRIVSEP(auth_password(authctxt, ""))) {
auth_log(authctxt, 1, "without authentication", "");
return;
}
/* Indicate that authentication is needed. */
packet_start(SSH_SMSG_FAILURE);
packet_send();
packet_write_wait();
client_user = NULL;
for (;;) {
/* default to fail */
authenticated = 0;
info[0] = '\0';
/* Get a packet from the client. */
prev = type;
type = packet_read();
/*
* If we started challenge-response authentication but the
* next packet is not a response to our challenge, release
* the resources allocated by get_challenge() (which would
* normally have been released by verify_response() had we
* received such a response)
*/
if (prev == SSH_CMSG_AUTH_TIS &&
type != SSH_CMSG_AUTH_TIS_RESPONSE)
abandon_challenge_response(authctxt);
/* Process the packet. */
switch (type) {
case SSH_CMSG_AUTH_RHOSTS_RSA:
if (!options.rhosts_rsa_authentication) {
verbose("Rhosts with RSA authentication disabled.");
break;
}
/*
* Get client user name. Note that we just have to
* trust the client; root on the client machine can
* claim to be any user.
*/
client_user = packet_get_string(&ulen);
/* Get the client host key. */
client_host_key = key_new(KEY_RSA1);
bits = packet_get_int();
packet_get_bignum(client_host_key->rsa->e);
packet_get_bignum(client_host_key->rsa->n);
if (bits != BN_num_bits(client_host_key->rsa->n))
verbose("Warning: keysize mismatch for client_host_key: "
"actual %d, announced %d",
BN_num_bits(client_host_key->rsa->n), bits);
packet_check_eom();
authenticated = auth_rhosts_rsa(authctxt, client_user,
client_host_key);
key_free(client_host_key);
snprintf(info, sizeof info, " ruser %.100s", client_user);
break;
case SSH_CMSG_AUTH_RSA:
if (!options.rsa_authentication) {
verbose("RSA authentication disabled.");
break;
}
/* RSA authentication requested. */
if ((n = BN_new()) == NULL)
fatal("do_authloop: BN_new failed");
//.........这里部分代码省略.........
//.........这里部分代码省略.........
/* y := b^2 */
if (!BN_mod_sqr(y, b, p, ctx)) goto end;
/* t := (2*a)*b^2 - 1*/
if (!BN_mod_mul(t, t, y, p, ctx)) goto end;
if (!BN_sub_word(t, 1)) goto end;
/* x = a*b*t */
if (!BN_mod_mul(x, A, b, p, ctx)) goto end;
if (!BN_mod_mul(x, x, t, p, ctx)) goto end;
if (!BN_copy(ret, x)) goto end;
err = 0;
goto vrfy;
}
/* e > 2, so we really have to use the Tonelli/Shanks algorithm.
* First, find some y that is not a square. */
if (!BN_copy(q, p)) goto end; /* use 'q' as temp */
q->neg = 0;
i = 2;
do
{
/* For efficiency, try small numbers first;
* if this fails, try random numbers.
*/
if (i < 22)
{
if (!BN_set_word(y, i)) goto end;
}
else
{
if (!BN_pseudo_rand(y, BN_num_bits(p), 0, 0)) goto end;
if (BN_ucmp(y, p) >= 0)
{
if (!(p->neg ? BN_add : BN_sub)(y, y, p)) goto end;
}
/* now 0 <= y < |p| */
if (BN_is_zero(y))
if (!BN_set_word(y, i)) goto end;
}
r = BN_kronecker(y, q, ctx); /* here 'q' is |p| */
if (r < -1) goto end;
if (r == 0)
{
/* m divides p */
BNerr(BN_F_BN_MOD_SQRT, BN_R_P_IS_NOT_PRIME);
goto end;
}
}
while (r == 1 && ++i < 82);
if (r != -1)
{
/* Many rounds and still no non-square -- this is more likely
* a bug than just bad luck.
* Even if p is not prime, we should have found some y
* such that r == -1.
*/
BNerr(BN_F_BN_MOD_SQRT, BN_R_TOO_MANY_ITERATIONS);
goto end;
}
/* Here's our actual 'q': */
//.........这里部分代码省略.........
if (!BN_mod_mul(t, t, y, p, ctx) ||
!BN_sub_word(t, 1)) {
goto end;
}
// x = a*b*t
if (!BN_mod_mul(x, A, b, p, ctx) ||
!BN_mod_mul(x, x, t, p, ctx)) {
goto end;
}
if (!BN_copy(ret, x)) {
goto end;
}
err = 0;
goto vrfy;
}
// e > 2, so we really have to use the Tonelli/Shanks algorithm.
// First, find some y that is not a square.
if (!BN_copy(q, p)) {
goto end; // use 'q' as temp
}
q->neg = 0;
i = 2;
do {
// For efficiency, try small numbers first;
// if this fails, try random numbers.
if (i < 22) {
if (!BN_set_word(y, i)) {
goto end;
}
} else {
if (!BN_pseudo_rand(y, BN_num_bits(p), 0, 0)) {
goto end;
}
if (BN_ucmp(y, p) >= 0) {
if (!(p->neg ? BN_add : BN_sub)(y, y, p)) {
goto end;
}
}
// now 0 <= y < |p|
if (BN_is_zero(y)) {
if (!BN_set_word(y, i)) {
goto end;
}
}
}
r = bn_jacobi(y, q, ctx); // here 'q' is |p|
if (r < -1) {
goto end;
}
if (r == 0) {
// m divides p
OPENSSL_PUT_ERROR(BN, BN_R_P_IS_NOT_PRIME);
goto end;
}
} while (r == 1 && ++i < 82);
if (r != -1) {
// Many rounds and still no non-square -- this is more likely
// a bug than just bad luck.
// Even if p is not prime, we should have found some y
// such that r == -1.
OPENSSL_PUT_ERROR(BN, BN_R_TOO_MANY_ITERATIONS);
BIGNUM *
BN_mod_inverse(BIGNUM *in, const BIGNUM *a, const BIGNUM *n, BN_CTX *ctx)
{
BIGNUM *A, *B, *X, *Y, *M, *D, *T, *R = NULL;
BIGNUM *ret = NULL;
int sign;
if ((BN_get_flags(a, BN_FLG_CONSTTIME) != 0) ||
(BN_get_flags(n, BN_FLG_CONSTTIME) != 0)) {
return BN_mod_inverse_no_branch(in, a, n, ctx);
}
bn_check_top(a);
bn_check_top(n);
BN_CTX_start(ctx);
A = BN_CTX_get(ctx);
B = BN_CTX_get(ctx);
X = BN_CTX_get(ctx);
D = BN_CTX_get(ctx);
M = BN_CTX_get(ctx);
Y = BN_CTX_get(ctx);
T = BN_CTX_get(ctx);
if (T == NULL)
goto err;
if (in == NULL)
R = BN_new();
else
R = in;
if (R == NULL)
goto err;
BN_one(X);
BN_zero(Y);
if (BN_copy(B, a) == NULL)
goto err;
if (BN_copy(A, n) == NULL)
goto err;
A->neg = 0;
if (B->neg || (BN_ucmp(B, A) >= 0)) {
if (!BN_nnmod(B, B, A, ctx))
goto err;
}
sign = -1;
/* From B = a mod |n|, A = |n| it follows that
*
* 0 <= B < A,
* -sign*X*a == B (mod |n|),
* sign*Y*a == A (mod |n|).
*/
if (BN_is_odd(n) && (BN_num_bits(n) <= (BN_BITS <= 32 ? 450 : 2048))) {
/* Binary inversion algorithm; requires odd modulus.
* This is faster than the general algorithm if the modulus
* is sufficiently small (about 400 .. 500 bits on 32-bit
* sytems, but much more on 64-bit systems) */
int shift;
while (!BN_is_zero(B)) {
/*
* 0 < B < |n|,
* 0 < A <= |n|,
* (1) -sign*X*a == B (mod |n|),
* (2) sign*Y*a == A (mod |n|)
*/
/* Now divide B by the maximum possible power of two in the integers,
* and divide X by the same value mod |n|.
* When we're done, (1) still holds. */
shift = 0;
while (!BN_is_bit_set(B, shift)) /* note that 0 < B */
{
shift++;
if (BN_is_odd(X)) {
if (!BN_uadd(X, X, n))
goto err;
}
/* now X is even, so we can easily divide it by two */
if (!BN_rshift1(X, X))
goto err;
}
if (shift > 0) {
if (!BN_rshift(B, B, shift))
goto err;
}
/* Same for A and Y. Afterwards, (2) still holds. */
shift = 0;
while (!BN_is_bit_set(A, shift)) /* note that 0 < A */
{
shift++;
if (BN_is_odd(Y)) {
if (!BN_uadd(Y, Y, n))
goto err;
}
/* now Y is even */
//.........这里部分代码省略.........
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