[thirdparty/openssl.git] / crypto / ec / ecdsa_ossl.c

/*
 * Copyright 2002-2018 The OpenSSL Project Authors. All Rights Reserved.
 *
 * Licensed under the OpenSSL license (the "License").  You may not use
 * this file except in compliance with the License.  You can obtain a copy
 * in the file LICENSE in the source distribution or at
 * https://www.openssl.org/source/license.html
 */

#include <string.h>
#include <openssl/err.h>
#include <openssl/obj_mac.h>
#include <openssl/bn.h>
#include <openssl/rand.h>
#include <openssl/ec.h>
#include "ec_lcl.h"

int ossl_ecdsa_sign(int type, const unsigned char *dgst, int dlen,
                    unsigned char *sig, unsigned int *siglen,
                    const BIGNUM *kinv, const BIGNUM *r, EC_KEY *eckey)
{
    ECDSA_SIG *s;

    s = ECDSA_do_sign_ex(dgst, dlen, kinv, r, eckey);
    if (s == NULL) {
        *siglen = 0;
        return 0;
    }
    *siglen = i2d_ECDSA_SIG(s, &sig);
    ECDSA_SIG_free(s);
    return 1;
}

static int ecdsa_sign_setup(EC_KEY *eckey, BN_CTX *ctx_in,
                            BIGNUM **kinvp, BIGNUM **rp,
                            const unsigned char *dgst, int dlen)
{
    BN_CTX *ctx = NULL;
    BIGNUM *k = NULL, *r = NULL, *X = NULL;
    const BIGNUM *order;
    EC_POINT *tmp_point = NULL;
    const EC_GROUP *group;
    int ret = 0;
    int order_bits;

    if (eckey == NULL || (group = EC_KEY_get0_group(eckey)) == NULL) {
        ECerr(EC_F_ECDSA_SIGN_SETUP, ERR_R_PASSED_NULL_PARAMETER);
        return 0;
    }

    if (!EC_KEY_can_sign(eckey)) {
        ECerr(EC_F_ECDSA_SIGN_SETUP, EC_R_CURVE_DOES_NOT_SUPPORT_SIGNING);
        return 0;
    }

    if (ctx_in == NULL) {
        if ((ctx = BN_CTX_new()) == NULL) {
            ECerr(EC_F_ECDSA_SIGN_SETUP, ERR_R_MALLOC_FAILURE);
            return 0;
        }
    } else
        ctx = ctx_in;

    k = BN_new();               /* this value is later returned in *kinvp */
    r = BN_new();               /* this value is later returned in *rp */
    X = BN_new();
    if (k == NULL || r == NULL || X == NULL) {
        ECerr(EC_F_ECDSA_SIGN_SETUP, ERR_R_MALLOC_FAILURE);
        goto err;
    }
    if ((tmp_point = EC_POINT_new(group)) == NULL) {
        ECerr(EC_F_ECDSA_SIGN_SETUP, ERR_R_EC_LIB);
        goto err;
    }
    order = EC_GROUP_get0_order(group);
    if (order == NULL) {
        ECerr(EC_F_ECDSA_SIGN_SETUP, ERR_R_EC_LIB);
        goto err;
    }

    /* Preallocate space */
    order_bits = BN_num_bits(order);
    if (!BN_set_bit(k, order_bits)
        || !BN_set_bit(r, order_bits)
        || !BN_set_bit(X, order_bits))
        goto err;

    do {
        /* get random k */
        do
            if (dgst != NULL) {
                if (!BN_generate_dsa_nonce
                    (k, order, EC_KEY_get0_private_key(eckey), dgst, dlen,
                     ctx)) {
                    ECerr(EC_F_ECDSA_SIGN_SETUP,
                             EC_R_RANDOM_NUMBER_GENERATION_FAILED);
                    goto err;
                }
            } else {
                if (!BN_priv_rand_range(k, order)) {
                    ECerr(EC_F_ECDSA_SIGN_SETUP,
                             EC_R_RANDOM_NUMBER_GENERATION_FAILED);
                    goto err;
                }
            }
        while (BN_is_zero(k));

        /* compute r the x-coordinate of generator * k */
        if (!EC_POINT_mul(group, tmp_point, k, NULL, NULL, ctx)) {
            ECerr(EC_F_ECDSA_SIGN_SETUP, ERR_R_EC_LIB);
            goto err;
        }
        if (EC_METHOD_get_field_type(EC_GROUP_method_of(group)) ==
            NID_X9_62_prime_field) {
            if (!EC_POINT_get_affine_coordinates_GFp
                (group, tmp_point, X, NULL, ctx)) {
                ECerr(EC_F_ECDSA_SIGN_SETUP, ERR_R_EC_LIB);
                goto err;
            }
        }
#ifndef OPENSSL_NO_EC2M
        else {                  /* NID_X9_62_characteristic_two_field */

            if (!EC_POINT_get_affine_coordinates_GF2m(group,
                                                      tmp_point, X, NULL,
                                                      ctx)) {
                ECerr(EC_F_ECDSA_SIGN_SETUP, ERR_R_EC_LIB);
                goto err;
            }
        }
#endif
        if (!BN_nnmod(r, X, order, ctx)) {
            ECerr(EC_F_ECDSA_SIGN_SETUP, ERR_R_BN_LIB);
            goto err;
        }
    }
    while (BN_is_zero(r));

    /* Check if optimized inverse is implemented */
    if (EC_GROUP_do_inverse_ord(group, k, k, ctx) == 0) {
        /* compute the inverse of k */
        if (group->mont_data != NULL) {
            /*
             * We want inverse in constant time, therefore we utilize the fact
             * order must be prime and use Fermats Little Theorem instead.
             */
            if (!BN_set_word(X, 2)) {
                ECerr(EC_F_ECDSA_SIGN_SETUP, ERR_R_BN_LIB);
                goto err;
            }
            if (!BN_mod_sub(X, order, X, order, ctx)) {
                ECerr(EC_F_ECDSA_SIGN_SETUP, ERR_R_BN_LIB);
                goto err;
            }
            BN_set_flags(X, BN_FLG_CONSTTIME);
            if (!BN_mod_exp_mont_consttime(k, k, X, order, ctx,
                                           group->mont_data)) {
                ECerr(EC_F_ECDSA_SIGN_SETUP, ERR_R_BN_LIB);
                goto err;
            }
        } else {
            if (!BN_mod_inverse(k, k, order, ctx)) {
                ECerr(EC_F_ECDSA_SIGN_SETUP, ERR_R_BN_LIB);
                goto err;
            }
        }
    }

    /* clear old values if necessary */
    BN_clear_free(*rp);
    BN_clear_free(*kinvp);
    /* save the pre-computed values  */
    *rp = r;
    *kinvp = k;
    ret = 1;
 err:
    if (!ret) {
        BN_clear_free(k);
        BN_clear_free(r);
    }
    if (ctx != ctx_in)
        BN_CTX_free(ctx);
    EC_POINT_free(tmp_point);
    BN_clear_free(X);
    return ret;
}

int ossl_ecdsa_sign_setup(EC_KEY *eckey, BN_CTX *ctx_in, BIGNUM **kinvp,
                          BIGNUM **rp)
{
    return ecdsa_sign_setup(eckey, ctx_in, kinvp, rp, NULL, 0);
}

ECDSA_SIG *ossl_ecdsa_sign_sig(const unsigned char *dgst, int dgst_len,
                               const BIGNUM *in_kinv, const BIGNUM *in_r,
                               EC_KEY *eckey)
{
    int ok = 0, i;
    BIGNUM *kinv = NULL, *s, *m = NULL, *tmp = NULL, *blind = NULL;
    BIGNUM *blindm = NULL;
    const BIGNUM *order, *ckinv;
    BN_CTX *ctx = NULL;
    const EC_GROUP *group;
    ECDSA_SIG *ret;
    const BIGNUM *priv_key;

    group = EC_KEY_get0_group(eckey);
    priv_key = EC_KEY_get0_private_key(eckey);

    if (group == NULL || priv_key == NULL) {
        ECerr(EC_F_OSSL_ECDSA_SIGN_SIG, ERR_R_PASSED_NULL_PARAMETER);
        return NULL;
    }

    if (!EC_KEY_can_sign(eckey)) {
        ECerr(EC_F_OSSL_ECDSA_SIGN_SIG, EC_R_CURVE_DOES_NOT_SUPPORT_SIGNING);
        return NULL;
    }

    ret = ECDSA_SIG_new();
    if (ret == NULL) {
        ECerr(EC_F_OSSL_ECDSA_SIGN_SIG, ERR_R_MALLOC_FAILURE);
        return NULL;
    }
    ret->r = BN_new();
    ret->s = BN_new();
    if (ret->r == NULL || ret->s == NULL) {
        ECerr(EC_F_OSSL_ECDSA_SIGN_SIG, ERR_R_MALLOC_FAILURE);
        goto err;
    }
    s = ret->s;

    ctx = BN_CTX_secure_new();
    if (ctx == NULL) {
        ECerr(EC_F_OSSL_ECDSA_SIGN_SIG, ERR_R_MALLOC_FAILURE);
        goto err;
    }

    BN_CTX_start(ctx);
    tmp = BN_CTX_get(ctx);
    m = BN_CTX_get(ctx);
    blind = BN_CTX_get(ctx);
    blindm = BN_CTX_get(ctx);
    if (blindm == NULL) {
        ECerr(EC_F_OSSL_ECDSA_SIGN_SIG, ERR_R_MALLOC_FAILURE);
        goto err;
    }

    order = EC_GROUP_get0_order(group);
    if (order == NULL) {
        ECerr(EC_F_OSSL_ECDSA_SIGN_SIG, ERR_R_EC_LIB);
        goto err;
    }
    i = BN_num_bits(order);
    /*
     * Need to truncate digest if it is too long: first truncate whole bytes.
     */
    if (8 * dgst_len > i)
        dgst_len = (i + 7) / 8;
    if (!BN_bin2bn(dgst, dgst_len, m)) {
        ECerr(EC_F_OSSL_ECDSA_SIGN_SIG, ERR_R_BN_LIB);
        goto err;
    }
    /* If still too long truncate remaining bits with a shift */
    if ((8 * dgst_len > i) && !BN_rshift(m, m, 8 - (i & 0x7))) {
        ECerr(EC_F_OSSL_ECDSA_SIGN_SIG, ERR_R_BN_LIB);
        goto err;
    }
    do {
        if (in_kinv == NULL || in_r == NULL) {
            if (!ecdsa_sign_setup(eckey, ctx, &kinv, &ret->r, dgst, dgst_len)) {
                ECerr(EC_F_OSSL_ECDSA_SIGN_SIG, ERR_R_ECDSA_LIB);
                goto err;
            }
            ckinv = kinv;
        } else {
            ckinv = in_kinv;
            if (BN_copy(ret->r, in_r) == NULL) {
                ECerr(EC_F_OSSL_ECDSA_SIGN_SIG, ERR_R_MALLOC_FAILURE);
                goto err;
            }
        }

        /*
         * The normal signature calculation is:
         *
         *   s := k^-1 * (m + r * priv_key) mod order
         *
         * We will blind this to protect against side channel attacks
         *
         *   s := blind^-1 * k^-1 * (blind * m + blind * r * priv_key) mod order
         */

        /* Generate a blinding value */
        do {
            if (!BN_priv_rand(blind, BN_num_bits(order) - 1,
                              BN_RAND_TOP_ANY, BN_RAND_BOTTOM_ANY))
                goto err;
        } while (BN_is_zero(blind));
        BN_set_flags(blind, BN_FLG_CONSTTIME);
        BN_set_flags(blindm, BN_FLG_CONSTTIME);
        BN_set_flags(tmp, BN_FLG_CONSTTIME);

        /* tmp := blind * priv_key * r mod order */
        if (!BN_mod_mul(tmp, blind, priv_key, order, ctx)) {
            ECerr(EC_F_OSSL_ECDSA_SIGN_SIG, ERR_R_BN_LIB);
            goto err;
        }
        if (!BN_mod_mul(tmp, tmp, ret->r, order, ctx)) {
            ECerr(EC_F_OSSL_ECDSA_SIGN_SIG, ERR_R_BN_LIB);
            goto err;
        }

        /* blindm := blind * m mod order */
        if (!BN_mod_mul(blindm, blind, m, order, ctx)) {
            ECerr(EC_F_OSSL_ECDSA_SIGN_SIG, ERR_R_BN_LIB);
            goto err;
        }

        /* s : = (blind * priv_key * r) + (blind * m) mod order */
        if (!BN_mod_add_quick(s, tmp, blindm, order)) {
            ECerr(EC_F_OSSL_ECDSA_SIGN_SIG, ERR_R_BN_LIB);
            goto err;
        }

        /* s := s * k^-1 mod order */
        if (!BN_mod_mul(s, s, ckinv, order, ctx)) {
            ECerr(EC_F_OSSL_ECDSA_SIGN_SIG, ERR_R_BN_LIB);
            goto err;
        }

        /* s:= s * blind^-1 mod order */
        if (BN_mod_inverse(blind, blind, order, ctx) == NULL) {
            ECerr(EC_F_OSSL_ECDSA_SIGN_SIG, ERR_R_BN_LIB);
            goto err;
        }
        if (!BN_mod_mul(s, s, blind, order, ctx)) {
            ECerr(EC_F_OSSL_ECDSA_SIGN_SIG, ERR_R_BN_LIB);
            goto err;
        }

        if (BN_is_zero(s)) {
            /*
             * if kinv and r have been supplied by the caller, don't
             * generate new kinv and r values
             */
            if (in_kinv != NULL && in_r != NULL) {
                ECerr(EC_F_OSSL_ECDSA_SIGN_SIG, EC_R_NEED_NEW_SETUP_VALUES);
                goto err;
            }
        } else
            /* s != 0 => we have a valid signature */
            break;
    }
    while (1);

    ok = 1;
 err:
    if (!ok) {
        ECDSA_SIG_free(ret);
        ret = NULL;
    }
    BN_CTX_end(ctx);
    BN_CTX_free(ctx);
    BN_clear_free(kinv);
    return ret;
}

/*-
 * returns
 *      1: correct signature
 *      0: incorrect signature
 *     -1: error
 */
int ossl_ecdsa_verify(int type, const unsigned char *dgst, int dgst_len,
                      const unsigned char *sigbuf, int sig_len, EC_KEY *eckey)
{
    ECDSA_SIG *s;
    const unsigned char *p = sigbuf;
    unsigned char *der = NULL;
    int derlen = -1;
    int ret = -1;

    s = ECDSA_SIG_new();
    if (s == NULL)
        return ret;
    if (d2i_ECDSA_SIG(&s, &p, sig_len) == NULL)
        goto err;
    /* Ensure signature uses DER and doesn't have trailing garbage */
    derlen = i2d_ECDSA_SIG(s, &der);
    if (derlen != sig_len || memcmp(sigbuf, der, derlen) != 0)
        goto err;
    ret = ECDSA_do_verify(dgst, dgst_len, s, eckey);
 err:
    OPENSSL_clear_free(der, derlen);
    ECDSA_SIG_free(s);
    return ret;
}

int ossl_ecdsa_verify_sig(const unsigned char *dgst, int dgst_len,
                          const ECDSA_SIG *sig, EC_KEY *eckey)
{
    int ret = -1, i;
    BN_CTX *ctx;
    const BIGNUM *order;
    BIGNUM *u1, *u2, *m, *X;
    EC_POINT *point = NULL;
    const EC_GROUP *group;
    const EC_POINT *pub_key;

    /* check input values */
    if (eckey == NULL || (group = EC_KEY_get0_group(eckey)) == NULL ||
        (pub_key = EC_KEY_get0_public_key(eckey)) == NULL || sig == NULL) {
        ECerr(EC_F_OSSL_ECDSA_VERIFY_SIG, EC_R_MISSING_PARAMETERS);
        return -1;
    }

    if (!EC_KEY_can_sign(eckey)) {
        ECerr(EC_F_OSSL_ECDSA_VERIFY_SIG, EC_R_CURVE_DOES_NOT_SUPPORT_SIGNING);
        return -1;
    }

    ctx = BN_CTX_new();
    if (ctx == NULL) {
        ECerr(EC_F_OSSL_ECDSA_VERIFY_SIG, ERR_R_MALLOC_FAILURE);
        return -1;
    }
    BN_CTX_start(ctx);
    u1 = BN_CTX_get(ctx);
    u2 = BN_CTX_get(ctx);
    m = BN_CTX_get(ctx);
    X = BN_CTX_get(ctx);
    if (X == NULL) {
        ECerr(EC_F_OSSL_ECDSA_VERIFY_SIG, ERR_R_BN_LIB);
        goto err;
    }

    order = EC_GROUP_get0_order(group);
    if (order == NULL) {
        ECerr(EC_F_OSSL_ECDSA_VERIFY_SIG, ERR_R_EC_LIB);
        goto err;
    }

    if (BN_is_zero(sig->r) || BN_is_negative(sig->r) ||
        BN_ucmp(sig->r, order) >= 0 || BN_is_zero(sig->s) ||
        BN_is_negative(sig->s) || BN_ucmp(sig->s, order) >= 0) {
        ECerr(EC_F_OSSL_ECDSA_VERIFY_SIG, EC_R_BAD_SIGNATURE);
        ret = 0;                /* signature is invalid */
        goto err;
    }
    /* calculate tmp1 = inv(S) mod order */
    /* Check if optimized inverse is implemented */
    if (EC_GROUP_do_inverse_ord(group, u2, sig->s, ctx) == 0) {
        if (!BN_mod_inverse(u2, sig->s, order, ctx)) {
            ECerr(EC_F_OSSL_ECDSA_VERIFY_SIG, ERR_R_BN_LIB);
            goto err;
        }
    }
    /* digest -> m */
    i = BN_num_bits(order);
    /*
     * Need to truncate digest if it is too long: first truncate whole bytes.
     */
    if (8 * dgst_len > i)
        dgst_len = (i + 7) / 8;
    if (!BN_bin2bn(dgst, dgst_len, m)) {
        ECerr(EC_F_OSSL_ECDSA_VERIFY_SIG, ERR_R_BN_LIB);
        goto err;
    }
    /* If still too long truncate remaining bits with a shift */
    if ((8 * dgst_len > i) && !BN_rshift(m, m, 8 - (i & 0x7))) {
        ECerr(EC_F_OSSL_ECDSA_VERIFY_SIG, ERR_R_BN_LIB);
        goto err;
    }
    /* u1 = m * tmp mod order */
    if (!BN_mod_mul(u1, m, u2, order, ctx)) {
        ECerr(EC_F_OSSL_ECDSA_VERIFY_SIG, ERR_R_BN_LIB);
        goto err;
    }
    /* u2 = r * w mod q */
    if (!BN_mod_mul(u2, sig->r, u2, order, ctx)) {
        ECerr(EC_F_OSSL_ECDSA_VERIFY_SIG, ERR_R_BN_LIB);
        goto err;
    }

    if ((point = EC_POINT_new(group)) == NULL) {
        ECerr(EC_F_OSSL_ECDSA_VERIFY_SIG, ERR_R_MALLOC_FAILURE);
        goto err;
    }
    if (!EC_POINT_mul(group, point, u1, pub_key, u2, ctx)) {
        ECerr(EC_F_OSSL_ECDSA_VERIFY_SIG, ERR_R_EC_LIB);
        goto err;
    }
    if (EC_METHOD_get_field_type(EC_GROUP_method_of(group)) ==
        NID_X9_62_prime_field) {
        if (!EC_POINT_get_affine_coordinates_GFp(group, point, X, NULL, ctx)) {
            ECerr(EC_F_OSSL_ECDSA_VERIFY_SIG, ERR_R_EC_LIB);
            goto err;
        }
    }
#ifndef OPENSSL_NO_EC2M
    else {                      /* NID_X9_62_characteristic_two_field */

        if (!EC_POINT_get_affine_coordinates_GF2m(group, point, X, NULL, ctx)) {
            ECerr(EC_F_OSSL_ECDSA_VERIFY_SIG, ERR_R_EC_LIB);
            goto err;
        }
    }
#endif
    if (!BN_nnmod(u1, X, order, ctx)) {
        ECerr(EC_F_OSSL_ECDSA_VERIFY_SIG, ERR_R_BN_LIB);
        goto err;
    }
    /*  if the signature is correct u1 is equal to sig->r */
    ret = (BN_ucmp(u1, sig->r) == 0);
 err:
    BN_CTX_end(ctx);
    BN_CTX_free(ctx);
    EC_POINT_free(point);
    return ret;
}
Commit	Line	Data
c6700d27	1	/*
3c7d0945	2	* Copyright 2002-2018 The OpenSSL Project Authors. All Rights Reserved.
4d94ae00	3	*
aa6bb135 RS	4	* Licensed under the OpenSSL license (the "License"). You may not use
	5	* this file except in compliance with the License. You can obtain a copy
	6	* in the file LICENSE in the source distribution or at
	7	* https://www.openssl.org/source/license.html
4d94ae00	8	*/
0bee0e62	9
a200a817	10	#include <string.h>
0bee0e62	11	#include <openssl/err.h>
14a7cfb3	12	#include <openssl/obj_mac.h>
0f814687	13	#include <openssl/bn.h>
8a99cb29	14	#include <openssl/rand.h>
6a47db45 DSH	15	#include <openssl/ec.h>
6a47db45 DSH	16	#include "ec_lcl.h"
190c615d	17
a200a817 DSH	18	int ossl_ecdsa_sign(int type, const unsigned char *dgst, int dlen,
	19	unsigned char sig, unsigned int siglen,
	20	const BIGNUM kinv, const BIGNUM r, EC_KEY *eckey)
	21	{
	22	ECDSA_SIG *s;
75e2c877	23
a200a817 DSH	24	s = ECDSA_do_sign_ex(dgst, dlen, kinv, r, eckey);
	25	if (s == NULL) {
	26	*siglen = 0;
	27	return 0;
	28	}
	29	*siglen = i2d_ECDSA_SIG(s, &sig);
	30	ECDSA_SIG_free(s);
	31	return 1;
	32	}
	33
8d6a75dc	34	static int ecdsa_sign_setup(EC_KEY eckey, BN_CTX ctx_in,
0f113f3e MC	35	BIGNUM kinvp, BIGNUM rp,
0f113f3e MC	36	const unsigned char *dgst, int dlen)
4d94ae00	37	{
0f113f3e	38	BN_CTX *ctx = NULL;
be2e334f DSH	39	BIGNUM k = NULL, r = NULL, *X = NULL;
be2e334f DSH	40	const BIGNUM *order;
0f113f3e MC	41	EC_POINT *tmp_point = NULL;
	42	const EC_GROUP *group;
	43	int ret = 0;
4a089bbd	44	int order_bits;
9dd84053	45
0f113f3e	46	if (eckey == NULL \|\| (group = EC_KEY_get0_group(eckey)) == NULL) {
6a47db45	47	ECerr(EC_F_ECDSA_SIGN_SETUP, ERR_R_PASSED_NULL_PARAMETER);
0f113f3e MC	48	return 0;
0f113f3e MC	49	}
a74333f9	50
4b0555ec DSH	51	if (!EC_KEY_can_sign(eckey)) {
	52	ECerr(EC_F_ECDSA_SIGN_SETUP, EC_R_CURVE_DOES_NOT_SUPPORT_SIGNING);
	53	return 0;
	54	}
	55
0f113f3e MC	56	if (ctx_in == NULL) {
0f113f3e MC	57	if ((ctx = BN_CTX_new()) == NULL) {
6a47db45	58	ECerr(EC_F_ECDSA_SIGN_SETUP, ERR_R_MALLOC_FAILURE);
0f113f3e MC	59	return 0;
	60	}
	61	} else
	62	ctx = ctx_in;
4d94ae00	63
0f113f3e MC	64	k = BN_new(); /* this value is later returned in kinvp /
0f113f3e MC	65	r = BN_new(); /* this value is later returned in rp /
0f113f3e	66	X = BN_new();
be2e334f	67	if (k == NULL \|\| r == NULL \|\| X == NULL) {
6a47db45	68	ECerr(EC_F_ECDSA_SIGN_SETUP, ERR_R_MALLOC_FAILURE);
0f113f3e MC	69	goto err;
	70	}
	71	if ((tmp_point = EC_POINT_new(group)) == NULL) {
6a47db45	72	ECerr(EC_F_ECDSA_SIGN_SETUP, ERR_R_EC_LIB);
0f113f3e MC	73	goto err;
0f113f3e MC	74	}
be2e334f DSH	75	order = EC_GROUP_get0_order(group);
be2e334f DSH	76	if (order == NULL) {
6a47db45	77	ECerr(EC_F_ECDSA_SIGN_SETUP, ERR_R_EC_LIB);
0f113f3e MC	78	goto err;
0f113f3e MC	79	}
cac4fb58	80
4a089bbd P	81	/* Preallocate space */
	82	order_bits = BN_num_bits(order);
	83	if (!BN_set_bit(k, order_bits)
	84	\|\| !BN_set_bit(r, order_bits)
	85	\|\| !BN_set_bit(X, order_bits))
	86	goto err;
	87
0f113f3e MC	88	do {
	89	/* get random k */
	90	do
0f113f3e MC	91	if (dgst != NULL) {
	92	if (!BN_generate_dsa_nonce
	93	(k, order, EC_KEY_get0_private_key(eckey), dgst, dlen,
	94	ctx)) {
6a47db45 DSH	95	ECerr(EC_F_ECDSA_SIGN_SETUP,
6a47db45 DSH	96	EC_R_RANDOM_NUMBER_GENERATION_FAILED);
0f113f3e MC	97	goto err;
0f113f3e MC	98	}
474e469b	99	} else {
ddc6a5c8	100	if (!BN_priv_rand_range(k, order)) {
6a47db45 DSH	101	ECerr(EC_F_ECDSA_SIGN_SETUP,
6a47db45 DSH	102	EC_R_RANDOM_NUMBER_GENERATION_FAILED);
0f113f3e MC	103	goto err;
	104	}
	105	}
	106	while (BN_is_zero(k));
4d94ae00	107
0f113f3e MC	108	/* compute r the x-coordinate of generator * k */
0f113f3e MC	109	if (!EC_POINT_mul(group, tmp_point, k, NULL, NULL, ctx)) {
6a47db45	110	ECerr(EC_F_ECDSA_SIGN_SETUP, ERR_R_EC_LIB);
0f113f3e MC	111	goto err;
	112	}
	113	if (EC_METHOD_get_field_type(EC_GROUP_method_of(group)) ==
	114	NID_X9_62_prime_field) {
	115	if (!EC_POINT_get_affine_coordinates_GFp
	116	(group, tmp_point, X, NULL, ctx)) {
6a47db45	117	ECerr(EC_F_ECDSA_SIGN_SETUP, ERR_R_EC_LIB);
0f113f3e MC	118	goto err;
	119	}
	120	}
b3310161	121	#ifndef OPENSSL_NO_EC2M
0f113f3e MC	122	else { /* NID_X9_62_characteristic_two_field */
	123
	124	if (!EC_POINT_get_affine_coordinates_GF2m(group,
	125	tmp_point, X, NULL,
	126	ctx)) {
6a47db45	127	ECerr(EC_F_ECDSA_SIGN_SETUP, ERR_R_EC_LIB);
0f113f3e MC	128	goto err;
	129	}
	130	}
b3310161	131	#endif
0f113f3e	132	if (!BN_nnmod(r, X, order, ctx)) {
6a47db45	133	ECerr(EC_F_ECDSA_SIGN_SETUP, ERR_R_BN_LIB);
0f113f3e MC	134	goto err;
	135	}
	136	}
	137	while (BN_is_zero(r));
4d94ae00	138
eb791696 AP	139	/* Check if optimized inverse is implemented */
	140	if (EC_GROUP_do_inverse_ord(group, k, k, ctx) == 0) {
	141	/* compute the inverse of k */
	142	if (group->mont_data != NULL) {
	143	/*
	144	* We want inverse in constant time, therefore we utilize the fact
	145	* order must be prime and use Fermats Little Theorem instead.
	146	*/
	147	if (!BN_set_word(X, 2)) {
	148	ECerr(EC_F_ECDSA_SIGN_SETUP, ERR_R_BN_LIB);
	149	goto err;
	150	}
	151	if (!BN_mod_sub(X, order, X, order, ctx)) {
	152	ECerr(EC_F_ECDSA_SIGN_SETUP, ERR_R_BN_LIB);
	153	goto err;
	154	}
	155	BN_set_flags(X, BN_FLG_CONSTTIME);
	156	if (!BN_mod_exp_mont_consttime(k, k, X, order, ctx,
	157	group->mont_data)) {
	158	ECerr(EC_F_ECDSA_SIGN_SETUP, ERR_R_BN_LIB);
	159	goto err;
	160	}
	161	} else {
	162	if (!BN_mod_inverse(k, k, order, ctx)) {
	163	ECerr(EC_F_ECDSA_SIGN_SETUP, ERR_R_BN_LIB);
	164	goto err;
	165	}
0f113f3e MC	166	}
0f113f3e MC	167	}
f54be179	168
0f113f3e	169	/* clear old values if necessary */
23a1d5e9 RS	170	BN_clear_free(*rp);
23a1d5e9 RS	171	BN_clear_free(*kinvp);
0f113f3e MC	172	/* save the pre-computed values */
	173	*rp = r;
	174	*kinvp = k;
	175	ret = 1;
	176	err:
	177	if (!ret) {
23a1d5e9 RS	178	BN_clear_free(k);
23a1d5e9 RS	179	BN_clear_free(r);
0f113f3e	180	}
23a1d5e9	181	if (ctx != ctx_in)
0f113f3e	182	BN_CTX_free(ctx);
8fdc3734	183	EC_POINT_free(tmp_point);
23a1d5e9	184	BN_clear_free(X);
26a7d938	185	return ret;
4d94ae00 BM	186	}
4d94ae00 BM	187
6a47db45 DSH	188	int ossl_ecdsa_sign_setup(EC_KEY eckey, BN_CTX ctx_in, BIGNUM **kinvp,
	189	BIGNUM **rp)
	190	{
	191	return ecdsa_sign_setup(eckey, ctx_in, kinvp, rp, NULL, 0);
	192	}
	193
	194	ECDSA_SIG ossl_ecdsa_sign_sig(const unsigned char dgst, int dgst_len,
	195	const BIGNUM in_kinv, const BIGNUM in_r,
	196	EC_KEY *eckey)
4d94ae00	197	{
0f113f3e	198	int ok = 0, i;
a3e9d5aa MC	199	BIGNUM kinv = NULL, s, m = NULL, tmp = NULL, *blind = NULL;
a3e9d5aa MC	200	BIGNUM *blindm = NULL;
be2e334f	201	const BIGNUM order, ckinv;
0f113f3e MC	202	BN_CTX *ctx = NULL;
	203	const EC_GROUP *group;
	204	ECDSA_SIG *ret;
0f113f3e MC	205	const BIGNUM *priv_key;
0f113f3e MC	206
0f113f3e MC	207	group = EC_KEY_get0_group(eckey);
0f113f3e MC	208	priv_key = EC_KEY_get0_private_key(eckey);
14a7cfb3	209
6a47db45 DSH	210	if (group == NULL \|\| priv_key == NULL) {
6a47db45 DSH	211	ECerr(EC_F_OSSL_ECDSA_SIGN_SIG, ERR_R_PASSED_NULL_PARAMETER);
0f113f3e MC	212	return NULL;
0f113f3e MC	213	}
4d94ae00	214
4b0555ec DSH	215	if (!EC_KEY_can_sign(eckey)) {
	216	ECerr(EC_F_OSSL_ECDSA_SIGN_SIG, EC_R_CURVE_DOES_NOT_SUPPORT_SIGNING);
	217	return NULL;
	218	}
	219
0f113f3e	220	ret = ECDSA_SIG_new();
90945fa3	221	if (ret == NULL) {
6a47db45	222	ECerr(EC_F_OSSL_ECDSA_SIGN_SIG, ERR_R_MALLOC_FAILURE);
0f113f3e MC	223	return NULL;
0f113f3e MC	224	}
8cc44d97 DSH	225	ret->r = BN_new();
	226	ret->s = BN_new();
	227	if (ret->r == NULL \|\| ret->s == NULL) {
	228	ECerr(EC_F_OSSL_ECDSA_SIGN_SIG, ERR_R_MALLOC_FAILURE);
	229	goto err;
	230	}
0f113f3e	231	s = ret->s;
c6700d27	232
a3e9d5aa MC	233	ctx = BN_CTX_secure_new();
	234	if (ctx == NULL) {
	235	ECerr(EC_F_OSSL_ECDSA_SIGN_SIG, ERR_R_MALLOC_FAILURE);
	236	goto err;
	237	}
	238
	239	BN_CTX_start(ctx);
	240	tmp = BN_CTX_get(ctx);
	241	m = BN_CTX_get(ctx);
	242	blind = BN_CTX_get(ctx);
	243	blindm = BN_CTX_get(ctx);
	244	if (blindm == NULL) {
6a47db45	245	ECerr(EC_F_OSSL_ECDSA_SIGN_SIG, ERR_R_MALLOC_FAILURE);
0f113f3e MC	246	goto err;
0f113f3e MC	247	}
4d94ae00	248
be2e334f DSH	249	order = EC_GROUP_get0_order(group);
be2e334f DSH	250	if (order == NULL) {
6a47db45	251	ECerr(EC_F_OSSL_ECDSA_SIGN_SIG, ERR_R_EC_LIB);
0f113f3e MC	252	goto err;
	253	}
	254	i = BN_num_bits(order);
	255	/*
	256	* Need to truncate digest if it is too long: first truncate whole bytes.
	257	*/
	258	if (8 * dgst_len > i)
	259	dgst_len = (i + 7) / 8;
	260	if (!BN_bin2bn(dgst, dgst_len, m)) {
6a47db45	261	ECerr(EC_F_OSSL_ECDSA_SIGN_SIG, ERR_R_BN_LIB);
0f113f3e MC	262	goto err;
	263	}
	264	/* If still too long truncate remaining bits with a shift */
	265	if ((8 * dgst_len > i) && !BN_rshift(m, m, 8 - (i & 0x7))) {
6a47db45	266	ECerr(EC_F_OSSL_ECDSA_SIGN_SIG, ERR_R_BN_LIB);
0f113f3e MC	267	goto err;
	268	}
	269	do {
	270	if (in_kinv == NULL \|\| in_r == NULL) {
	271	if (!ecdsa_sign_setup(eckey, ctx, &kinv, &ret->r, dgst, dgst_len)) {
6a47db45	272	ECerr(EC_F_OSSL_ECDSA_SIGN_SIG, ERR_R_ECDSA_LIB);
0f113f3e MC	273	goto err;
	274	}
	275	ckinv = kinv;
	276	} else {
	277	ckinv = in_kinv;
	278	if (BN_copy(ret->r, in_r) == NULL) {
6a47db45	279	ECerr(EC_F_OSSL_ECDSA_SIGN_SIG, ERR_R_MALLOC_FAILURE);
0f113f3e MC	280	goto err;
	281	}
	282	}
4d94ae00	283
a3e9d5aa MC	284	/*
	285	* The normal signature calculation is:
	286	*
	287	* s := k^-1 * (m + r * priv_key) mod order
	288	*
	289	* We will blind this to protect against side channel attacks
	290	*
7f9822a4	291	* s := blind^-1 * k^-1 * (blind * m + blind * r * priv_key) mod order
a3e9d5aa MC	292	*/
	293
	294	/* Generate a blinding value */
	295	do {
	296	if (!BN_priv_rand(blind, BN_num_bits(order) - 1,
	297	BN_RAND_TOP_ANY, BN_RAND_BOTTOM_ANY))
	298	goto err;
	299	} while (BN_is_zero(blind));
	300	BN_set_flags(blind, BN_FLG_CONSTTIME);
	301	BN_set_flags(blindm, BN_FLG_CONSTTIME);
	302	BN_set_flags(tmp, BN_FLG_CONSTTIME);
	303
	304	/* tmp := blind * priv_key * r mod order */
	305	if (!BN_mod_mul(tmp, blind, priv_key, order, ctx)) {
	306	ECerr(EC_F_OSSL_ECDSA_SIGN_SIG, ERR_R_BN_LIB);
	307	goto err;
	308	}
	309	if (!BN_mod_mul(tmp, tmp, ret->r, order, ctx)) {
	310	ECerr(EC_F_OSSL_ECDSA_SIGN_SIG, ERR_R_BN_LIB);
	311	goto err;
	312	}
	313
	314	/* blindm := blind * m mod order */
	315	if (!BN_mod_mul(blindm, blind, m, order, ctx)) {
	316	ECerr(EC_F_OSSL_ECDSA_SIGN_SIG, ERR_R_BN_LIB);
	317	goto err;
	318	}
	319
	320	/* s : = (blind * priv_key * r) + (blind * m) mod order */
	321	if (!BN_mod_add_quick(s, tmp, blindm, order)) {
6a47db45	322	ECerr(EC_F_OSSL_ECDSA_SIGN_SIG, ERR_R_BN_LIB);
0f113f3e MC	323	goto err;
0f113f3e MC	324	}
a3e9d5aa	325
7f9822a4 MC	326	/* s := s * k^-1 mod order */
7f9822a4 MC	327	if (!BN_mod_mul(s, s, ckinv, order, ctx)) {
a3e9d5aa MC	328	ECerr(EC_F_OSSL_ECDSA_SIGN_SIG, ERR_R_BN_LIB);
	329	goto err;
	330	}
7f9822a4 MC	331
	332	/* s:= s * blind^-1 mod order */
	333	if (BN_mod_inverse(blind, blind, order, ctx) == NULL) {
6a47db45	334	ECerr(EC_F_OSSL_ECDSA_SIGN_SIG, ERR_R_BN_LIB);
0f113f3e MC	335	goto err;
0f113f3e MC	336	}
7f9822a4	337	if (!BN_mod_mul(s, s, blind, order, ctx)) {
6a47db45	338	ECerr(EC_F_OSSL_ECDSA_SIGN_SIG, ERR_R_BN_LIB);
0f113f3e MC	339	goto err;
0f113f3e MC	340	}
a3e9d5aa	341
0f113f3e MC	342	if (BN_is_zero(s)) {
0f113f3e MC	343	/*
532b1183	344	* if kinv and r have been supplied by the caller, don't
0f113f3e MC	345	* generate new kinv and r values
	346	*/
	347	if (in_kinv != NULL && in_r != NULL) {
6a47db45	348	ECerr(EC_F_OSSL_ECDSA_SIGN_SIG, EC_R_NEED_NEW_SETUP_VALUES);
0f113f3e MC	349	goto err;
	350	}
	351	} else
	352	/* s != 0 => we have a valid signature */
	353	break;
	354	}
	355	while (1);
4d94ae00	356
0f113f3e MC	357	ok = 1;
	358	err:
	359	if (!ok) {
	360	ECDSA_SIG_free(ret);
	361	ret = NULL;
	362	}
a3e9d5aa	363	BN_CTX_end(ctx);
23a1d5e9	364	BN_CTX_free(ctx);
23a1d5e9	365	BN_clear_free(kinv);
0f113f3e	366	return ret;
4d94ae00 BM	367	}
4d94ae00 BM	368
a200a817 DSH	369	/*-
	370	* returns
	371	* 1: correct signature
	372	* 0: incorrect signature
	373	* -1: error
	374	*/
	375	int ossl_ecdsa_verify(int type, const unsigned char *dgst, int dgst_len,
	376	const unsigned char sigbuf, int sig_len, EC_KEY eckey)
	377	{
	378	ECDSA_SIG *s;
	379	const unsigned char *p = sigbuf;
	380	unsigned char *der = NULL;
	381	int derlen = -1;
	382	int ret = -1;
	383
	384	s = ECDSA_SIG_new();
	385	if (s == NULL)
26a7d938	386	return ret;
a200a817 DSH	387	if (d2i_ECDSA_SIG(&s, &p, sig_len) == NULL)
	388	goto err;
	389	/* Ensure signature uses DER and doesn't have trailing garbage */
	390	derlen = i2d_ECDSA_SIG(s, &der);
91e7bcc2	391	if (derlen != sig_len \|\| memcmp(sigbuf, der, derlen) != 0)
a200a817 DSH	392	goto err;
	393	ret = ECDSA_do_verify(dgst, dgst_len, s, eckey);
	394	err:
	395	OPENSSL_clear_free(der, derlen);
	396	ECDSA_SIG_free(s);
26a7d938	397	return ret;
a200a817 DSH	398	}
a200a817 DSH	399
6a47db45 DSH	400	int ossl_ecdsa_verify_sig(const unsigned char *dgst, int dgst_len,
6a47db45 DSH	401	const ECDSA_SIG sig, EC_KEY eckey)
4d94ae00	402	{
0f113f3e MC	403	int ret = -1, i;
0f113f3e MC	404	BN_CTX *ctx;
be2e334f DSH	405	const BIGNUM *order;
be2e334f DSH	406	BIGNUM u1, u2, m, X;
0f113f3e MC	407	EC_POINT *point = NULL;
	408	const EC_GROUP *group;
	409	const EC_POINT *pub_key;
9dd84053	410
0f113f3e MC	411	/* check input values */
	412	if (eckey == NULL \|\| (group = EC_KEY_get0_group(eckey)) == NULL \|\|
	413	(pub_key = EC_KEY_get0_public_key(eckey)) == NULL \|\| sig == NULL) {
6a47db45	414	ECerr(EC_F_OSSL_ECDSA_VERIFY_SIG, EC_R_MISSING_PARAMETERS);
0f113f3e MC	415	return -1;
0f113f3e MC	416	}
4d94ae00	417
4b0555ec DSH	418	if (!EC_KEY_can_sign(eckey)) {
	419	ECerr(EC_F_OSSL_ECDSA_VERIFY_SIG, EC_R_CURVE_DOES_NOT_SUPPORT_SIGNING);
	420	return -1;
	421	}
	422
0f113f3e	423	ctx = BN_CTX_new();
90945fa3	424	if (ctx == NULL) {
6a47db45	425	ECerr(EC_F_OSSL_ECDSA_VERIFY_SIG, ERR_R_MALLOC_FAILURE);
0f113f3e MC	426	return -1;
	427	}
	428	BN_CTX_start(ctx);
0f113f3e MC	429	u1 = BN_CTX_get(ctx);
	430	u2 = BN_CTX_get(ctx);
	431	m = BN_CTX_get(ctx);
	432	X = BN_CTX_get(ctx);
91e7bcc2	433	if (X == NULL) {
6a47db45	434	ECerr(EC_F_OSSL_ECDSA_VERIFY_SIG, ERR_R_BN_LIB);
0f113f3e MC	435	goto err;
0f113f3e MC	436	}
c6700d27	437
be2e334f DSH	438	order = EC_GROUP_get0_order(group);
be2e334f DSH	439	if (order == NULL) {
6a47db45	440	ECerr(EC_F_OSSL_ECDSA_VERIFY_SIG, ERR_R_EC_LIB);
0f113f3e MC	441	goto err;
0f113f3e MC	442	}
4d94ae00	443
0f113f3e MC	444	if (BN_is_zero(sig->r) \|\| BN_is_negative(sig->r) \|\|
	445	BN_ucmp(sig->r, order) >= 0 \|\| BN_is_zero(sig->s) \|\|
	446	BN_is_negative(sig->s) \|\| BN_ucmp(sig->s, order) >= 0) {
6a47db45	447	ECerr(EC_F_OSSL_ECDSA_VERIFY_SIG, EC_R_BAD_SIGNATURE);
0f113f3e MC	448	ret = 0; /* signature is invalid */
	449	goto err;
	450	}
	451	/* calculate tmp1 = inv(S) mod order */
eb791696 AP	452	/* Check if optimized inverse is implemented */
	453	if (EC_GROUP_do_inverse_ord(group, u2, sig->s, ctx) == 0) {
	454	if (!BN_mod_inverse(u2, sig->s, order, ctx)) {
	455	ECerr(EC_F_OSSL_ECDSA_VERIFY_SIG, ERR_R_BN_LIB);
	456	goto err;
	457	}
0f113f3e MC	458	}
	459	/* digest -> m */
	460	i = BN_num_bits(order);
	461	/*
	462	* Need to truncate digest if it is too long: first truncate whole bytes.
	463	*/
	464	if (8 * dgst_len > i)
	465	dgst_len = (i + 7) / 8;
	466	if (!BN_bin2bn(dgst, dgst_len, m)) {
6a47db45	467	ECerr(EC_F_OSSL_ECDSA_VERIFY_SIG, ERR_R_BN_LIB);
0f113f3e MC	468	goto err;
	469	}
	470	/* If still too long truncate remaining bits with a shift */
	471	if ((8 * dgst_len > i) && !BN_rshift(m, m, 8 - (i & 0x7))) {
6a47db45	472	ECerr(EC_F_OSSL_ECDSA_VERIFY_SIG, ERR_R_BN_LIB);
0f113f3e MC	473	goto err;
	474	}
	475	/* u1 = m * tmp mod order */
	476	if (!BN_mod_mul(u1, m, u2, order, ctx)) {
6a47db45	477	ECerr(EC_F_OSSL_ECDSA_VERIFY_SIG, ERR_R_BN_LIB);
0f113f3e MC	478	goto err;
	479	}
	480	/* u2 = r * w mod q */
	481	if (!BN_mod_mul(u2, sig->r, u2, order, ctx)) {
6a47db45	482	ECerr(EC_F_OSSL_ECDSA_VERIFY_SIG, ERR_R_BN_LIB);
0f113f3e MC	483	goto err;
	484	}
	485
	486	if ((point = EC_POINT_new(group)) == NULL) {
6a47db45	487	ECerr(EC_F_OSSL_ECDSA_VERIFY_SIG, ERR_R_MALLOC_FAILURE);
0f113f3e MC	488	goto err;
	489	}
	490	if (!EC_POINT_mul(group, point, u1, pub_key, u2, ctx)) {
6a47db45	491	ECerr(EC_F_OSSL_ECDSA_VERIFY_SIG, ERR_R_EC_LIB);
0f113f3e MC	492	goto err;
	493	}
	494	if (EC_METHOD_get_field_type(EC_GROUP_method_of(group)) ==
	495	NID_X9_62_prime_field) {
	496	if (!EC_POINT_get_affine_coordinates_GFp(group, point, X, NULL, ctx)) {
6a47db45	497	ECerr(EC_F_OSSL_ECDSA_VERIFY_SIG, ERR_R_EC_LIB);
0f113f3e MC	498	goto err;
	499	}
	500	}
b3310161	501	#ifndef OPENSSL_NO_EC2M
0f113f3e MC	502	else { /* NID_X9_62_characteristic_two_field */
	503
	504	if (!EC_POINT_get_affine_coordinates_GF2m(group, point, X, NULL, ctx)) {
6a47db45	505	ECerr(EC_F_OSSL_ECDSA_VERIFY_SIG, ERR_R_EC_LIB);
0f113f3e MC	506	goto err;
	507	}
	508	}
	509	#endif
	510	if (!BN_nnmod(u1, X, order, ctx)) {
6a47db45	511	ECerr(EC_F_OSSL_ECDSA_VERIFY_SIG, ERR_R_BN_LIB);
0f113f3e MC	512	goto err;
	513	}
	514	/* if the signature is correct u1 is equal to sig->r */
	515	ret = (BN_ucmp(u1, sig->r) == 0);
	516	err:
	517	BN_CTX_end(ctx);
	518	BN_CTX_free(ctx);
8fdc3734	519	EC_POINT_free(point);
0f113f3e	520	return ret;
4d94ae00	521	}