/src/openssl/crypto/sm2/sm2_sign.c

Source
/*
 * Copyright 2017-2026 The OpenSSL Project Authors. All Rights Reserved.
 * Copyright 2017 Ribose Inc. All Rights Reserved.
 * Ported from Ribose contributions from Botan.
 *
 * Licensed under the Apache License 2.0 (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 "internal/deprecated.h"

#include "crypto/sm2.h"
#include "crypto/sm2err.h"
#include "crypto/ec.h" /* ossl_ec_group_do_inverse_ord() */
#include "crypto/bn.h" /* fixed-top / Montgomery constant-time BN helpers */
#include "internal/numbers.h"
#include <openssl/err.h>
#include <openssl/evp.h>
#include <openssl/bn.h>
#include <string.h>

/*
 * [SM2 Signature Scheme]
 * (https://datatracker.ietf.org/doc/html/rfc8998#section-3.2.1)
 *
 * If either a client or a server needs to verify the peer's SM2 certificate
 * contained in the Certificate message, then the following ASCII string value
 * MUST be used as the SM2 identifier according to [GMT.0009-2012]:
 *
 * 1234567812345678
 */
static const uint8_t default_sm2_id[] = {
    0x31, 0x32, 0x33, 0x34, 0x35, 0x36, 0x37, 0x38,
    0x31, 0x32, 0x33, 0x34, 0x35, 0x36, 0x37, 0x38
};

int ossl_sm2_compute_z_digest(uint8_t *out,
    const EVP_MD *digest,
    const uint8_t *id,
    size_t id_len,
    const EC_KEY *key)
{
    int rc = 0;
    const EC_GROUP *group = EC_KEY_get0_group(key);
    const EC_POINT *pubkey = EC_KEY_get0_public_key(key);
    BN_CTX *ctx = NULL;
    EVP_MD_CTX *hash = NULL;
    BIGNUM *p = NULL;
    BIGNUM *a = NULL;
    BIGNUM *b = NULL;
    BIGNUM *xG = NULL;
    BIGNUM *yG = NULL;
    BIGNUM *xA = NULL;
    BIGNUM *yA = NULL;
    int p_bytes = 0;
    uint8_t *buf = NULL;
    uint16_t entl = 0;
    uint8_t e_byte = 0;

    /* SM2 Signatures require a public key, check for it */
    if (pubkey == NULL) {
        ERR_raise(ERR_LIB_SM2, ERR_R_PASSED_NULL_PARAMETER);
        goto done;
    }

    hash = EVP_MD_CTX_new();
    if (hash == NULL) {
        ERR_raise(ERR_LIB_SM2, ERR_R_EVP_LIB);
        goto done;
    }
    ctx = BN_CTX_new_ex(ossl_ec_key_get_libctx(key));
    if (ctx == NULL) {
        ERR_raise(ERR_LIB_SM2, ERR_R_BN_LIB);
        goto done;
    }

    BN_CTX_start(ctx);
    p = BN_CTX_get(ctx);
    a = BN_CTX_get(ctx);
    b = BN_CTX_get(ctx);
    xG = BN_CTX_get(ctx);
    yG = BN_CTX_get(ctx);
    xA = BN_CTX_get(ctx);
    yA = BN_CTX_get(ctx);

    if (yA == NULL) {
        ERR_raise(ERR_LIB_SM2, ERR_R_BN_LIB);
        goto done;
    }

    if (!EVP_DigestInit(hash, digest)) {
        ERR_raise(ERR_LIB_SM2, ERR_R_EVP_LIB);
        goto done;
    }

    /* Z = h(ENTL || ID || a || b || xG || yG || xA || yA) */

    if (id == NULL) {
        id = default_sm2_id;
        id_len = sizeof(default_sm2_id);
    }

    if (id_len >= (UINT16_MAX / 8)) {
        /* too large */
        ERR_raise(ERR_LIB_SM2, SM2_R_ID_TOO_LARGE);
        goto done;
    }

    entl = (uint16_t)(8 * id_len);

    e_byte = entl >> 8;
    if (!EVP_DigestUpdate(hash, &e_byte, 1)) {
        ERR_raise(ERR_LIB_SM2, ERR_R_EVP_LIB);
        goto done;
    }
    e_byte = entl & 0xFF;
    if (!EVP_DigestUpdate(hash, &e_byte, 1)) {
        ERR_raise(ERR_LIB_SM2, ERR_R_EVP_LIB);
        goto done;
    }

    if (id_len > 0 && !EVP_DigestUpdate(hash, id, id_len)) {
        ERR_raise(ERR_LIB_SM2, ERR_R_EVP_LIB);
        goto done;
    }

    if (!EC_GROUP_get_curve(group, p, a, b, ctx)) {
        ERR_raise(ERR_LIB_SM2, ERR_R_EC_LIB);
        goto done;
    }

    p_bytes = BN_num_bytes(p);
    buf = OPENSSL_zalloc(p_bytes);
    if (buf == NULL)
        goto done;

    if (BN_bn2binpad(a, buf, p_bytes) < 0
        || !EVP_DigestUpdate(hash, buf, p_bytes)
        || BN_bn2binpad(b, buf, p_bytes) < 0
        || !EVP_DigestUpdate(hash, buf, p_bytes)
        || !EC_POINT_get_affine_coordinates(group,
            EC_GROUP_get0_generator(group),
            xG, yG, ctx)
        || BN_bn2binpad(xG, buf, p_bytes) < 0
        || !EVP_DigestUpdate(hash, buf, p_bytes)
        || BN_bn2binpad(yG, buf, p_bytes) < 0
        || !EVP_DigestUpdate(hash, buf, p_bytes)
        || !EC_POINT_get_affine_coordinates(group,
            pubkey,
            xA, yA, ctx)
        || BN_bn2binpad(xA, buf, p_bytes) < 0
        || !EVP_DigestUpdate(hash, buf, p_bytes)
        || BN_bn2binpad(yA, buf, p_bytes) < 0
        || !EVP_DigestUpdate(hash, buf, p_bytes)
        || !EVP_DigestFinal(hash, out, NULL)) {
        ERR_raise(ERR_LIB_SM2, ERR_R_INTERNAL_ERROR);
        goto done;
    }

    rc = 1;

done:
    OPENSSL_free(buf);
    BN_CTX_end(ctx);
    BN_CTX_free(ctx);
    EVP_MD_CTX_free(hash);
    return rc;
}

static BIGNUM *sm2_compute_msg_hash(const EVP_MD *digest,
    const EC_KEY *key,
    const uint8_t *id,
    const size_t id_len,
    const uint8_t *msg, size_t msg_len)
{
    EVP_MD_CTX *hash = EVP_MD_CTX_new();
    const int md_size = EVP_MD_get_size(digest);
    uint8_t *z = NULL;
    BIGNUM *e = NULL;
    EVP_MD *fetched_digest = NULL;
    OSSL_LIB_CTX *libctx = ossl_ec_key_get_libctx(key);
    const char *propq = ossl_ec_key_get0_propq(key);

    if (md_size <= 0) {
        ERR_raise(ERR_LIB_SM2, SM2_R_INVALID_DIGEST);
        goto done;
    }
    if (hash == NULL) {
        ERR_raise(ERR_LIB_SM2, ERR_R_EVP_LIB);
        goto done;
    }

    z = OPENSSL_zalloc(md_size);
    if (z == NULL)
        goto done;

    fetched_digest = EVP_MD_fetch(libctx, EVP_MD_get0_name(digest), propq);
    if (fetched_digest == NULL) {
        ERR_raise(ERR_LIB_SM2, ERR_R_INTERNAL_ERROR);
        goto done;
    }

    if (!ossl_sm2_compute_z_digest(z, fetched_digest, id, id_len, key)) {
        /* SM2err already called */
        goto done;
    }

    if (!EVP_DigestInit(hash, fetched_digest)
        || !EVP_DigestUpdate(hash, z, md_size)
        || !EVP_DigestUpdate(hash, msg, msg_len)
        /* reuse z buffer to hold H(Z || M) */
        || !EVP_DigestFinal(hash, z, NULL)) {
        ERR_raise(ERR_LIB_SM2, ERR_R_EVP_LIB);
        goto done;
    }

    e = BN_bin2bn(z, md_size, NULL);
    if (e == NULL)
        ERR_raise(ERR_LIB_SM2, ERR_R_INTERNAL_ERROR);

done:
    EVP_MD_free(fetched_digest);
    OPENSSL_free(z);
    EVP_MD_CTX_free(hash);
    return e;
}

static ECDSA_SIG *sm2_sig_gen(const EC_KEY *key, const BIGNUM *e)
{
    const BIGNUM *dA = EC_KEY_get0_private_key(key);
    const EC_GROUP *group = EC_KEY_get0_group(key);
    const BIGNUM *order = EC_GROUP_get0_order(group);
    ECDSA_SIG *sig = NULL;
    EC_POINT *kG = NULL;
    BN_CTX *ctx = NULL;
    BIGNUM *k = NULL;
    BIGNUM *r = NULL;
    BIGNUM *s = NULL;
    BIGNUM *x1 = NULL;
    BIGNUM *tmp = NULL;
    BN_MONT_CTX *mont = EC_GROUP_get_mont_data(group);
    OSSL_LIB_CTX *libctx = ossl_ec_key_get_libctx(key);

    if (dA == NULL) {
        ERR_raise(ERR_LIB_SM2, SM2_R_INVALID_PRIVATE_KEY);
        goto done;
    }

    if (mont == NULL) {
        ERR_raise(ERR_LIB_SM2, ERR_R_EC_LIB);
        goto done;
    }
    kG = EC_POINT_new(group);
    if (kG == NULL) {
        ERR_raise(ERR_LIB_SM2, ERR_R_EC_LIB);
        goto done;
    }
    ctx = BN_CTX_new_ex(libctx);
    if (ctx == NULL) {
        ERR_raise(ERR_LIB_SM2, ERR_R_BN_LIB);
        goto done;
    }

    BN_CTX_start(ctx);
    k = BN_CTX_get(ctx);
    x1 = BN_CTX_get(ctx);
    tmp = BN_CTX_get(ctx);
    if (tmp == NULL) {
        ERR_raise(ERR_LIB_SM2, ERR_R_BN_LIB);
        goto done;
    }

    /*
     * These values are returned and so should not be allocated out of the
     * context
     */
    r = BN_new();
    s = BN_new();

    if (r == NULL || s == NULL) {
        ERR_raise(ERR_LIB_SM2, ERR_R_BN_LIB);
        goto done;
    }

    /*
     * A3: Generate a random number k in [1,n-1] using random number generators;
     * A4: Compute (x1,y1)=[k]G, and convert the type of data x1 to be integer
     *     as specified in clause 4.2.8 of GM/T 0003.1-2012;
     * A5: Compute r=(e+x1) mod n. If r=0 or r+k=n, then go to A3;
     * A6: Compute s=(1/(1+dA)*(k-r*dA)) mod n. If s=0, then go to A3;
     * A7: Convert the type of data (r,s) to be bit strings according to the details
     *     in clause 4.2.2 of GM/T 0003.1-2012. Then the signature of message M is (r,s).
     */
    for (;;) {
        if (!BN_priv_rand_range_ex(k, order, 0, ctx)) {
            ERR_raise(ERR_LIB_SM2, ERR_R_INTERNAL_ERROR);
            goto done;
        }
        /*
         * Pin the nonce to a fixed, value-independent width and flag it
         * BN_FLG_CONSTTIME, so its magnitude does not leak through operand
         * lengths in the scalar copy inside the ladder, or in the arithmetic
         * below.  BN_priv_rand_range_ex() is kept so the nonce value itself
         * is unchanged; only its representation is pinned.
         */
        BN_set_flags(k, BN_FLG_CONSTTIME);
        if (!bn_set_top_fixed(k, bn_get_top(order))) {
            ERR_raise(ERR_LIB_SM2, ERR_R_BN_LIB);
            goto done;
        }

        if (!EC_POINT_mul(group, kG, k, NULL, NULL, ctx)
            || !EC_POINT_get_affine_coordinates(group, kG, x1, NULL,
                ctx)
            || !BN_mod_add(r, e, x1, order, ctx)) {
            ERR_raise(ERR_LIB_SM2, ERR_R_INTERNAL_ERROR);
            goto done;
        }

        /* try again if r == 0 or r + k == n */
        if (BN_is_zero(r))
            continue;

        /*
         * Since 0 < r < n and 0 < k < n, r + k == n is the same as
         * k == n - r.  Both operands of the subtraction are public, so
         * compute it in the open and then compare against the nonce with a
         * fixed-width constant-time comparison.  A BN_cmp() on r + k would
         * branch on whether the sum carried into an extra word, which
         * depends on the value of k.
         */
        if (!BN_sub(tmp, order, r)
            || !bn_set_top_fixed(tmp, bn_get_top(order))) {
            ERR_raise(ERR_LIB_SM2, ERR_R_BN_LIB);
            goto done;
        }

        if (CRYPTO_memcmp(bn_get_words(k), bn_get_words(tmp),
                bn_get_top(order) * sizeof(BN_ULONG))
            == 0)
            continue;

        /*
         * s = ((1 + dA)^-1 * (k - r * dA)) mod order
         *
         * Computed with fixed-top / Montgomery constant-time primitives, so
         * that the running time does not depend on the secret k or dA (the
         * generic BN_mod_mul()/BN_sub() used previously reduce via BN_div(),
         * whose timing is value dependent).  This mirrors the ECDSA path.
         *
         * s holds (1 + dA)^-1 throughout; the (k - r * dA) term is built in
         * tmp.  bn_mul_mont_fixed_top() with one operand in the Montgomery
         * domain yields the plain product, and the final
         * BN_mod_mul_montgomery() returns the user-visible, normalised value.
         */
        if (!BN_add(s, dA, BN_value_one())
            || !ossl_ec_group_do_inverse_ord(group, s, s, ctx)
            || !bn_to_mont_fixed_top(tmp, r, mont, ctx)
            || !bn_mul_mont_fixed_top(tmp, tmp, dA, mont, ctx)
            || !bn_mod_sub_fixed_top(tmp, k, tmp, order)
            || !bn_to_mont_fixed_top(tmp, tmp, mont, ctx)
            || !BN_mod_mul_montgomery(s, tmp, s, mont, ctx)) {
            ERR_raise(ERR_LIB_SM2, ERR_R_BN_LIB);
            goto done;
        }

        /* try again if s == 0 */
        if (BN_is_zero(s))
            continue;

        sig = ECDSA_SIG_new();
        if (sig == NULL) {
            ERR_raise(ERR_LIB_SM2, ERR_R_ECDSA_LIB);
            goto done;
        }

        /* takes ownership of r and s */
        ECDSA_SIG_set0(sig, r, s);
        break;
    }

done:
    if (sig == NULL) {
        BN_free(r);
        BN_free(s);
    }

    BN_CTX_end(ctx);
    BN_CTX_free(ctx);
    EC_POINT_free(kG);
    return sig;
}

static int sm2_sig_verify(const EC_KEY *key, const ECDSA_SIG *sig,
    const BIGNUM *e)
{
    int ret = 0;
    const EC_GROUP *group = EC_KEY_get0_group(key);
    const BIGNUM *order = EC_GROUP_get0_order(group);
    BN_CTX *ctx = NULL;
    EC_POINT *pt = NULL;
    BIGNUM *t = NULL;
    BIGNUM *x1 = NULL;
    const BIGNUM *r = NULL;
    const BIGNUM *s = NULL;
    OSSL_LIB_CTX *libctx = ossl_ec_key_get_libctx(key);

    ctx = BN_CTX_new_ex(libctx);
    if (ctx == NULL) {
        ERR_raise(ERR_LIB_SM2, ERR_R_BN_LIB);
        goto done;
    }
    BN_CTX_start(ctx);
    t = BN_CTX_get(ctx);
    x1 = BN_CTX_get(ctx);
    if (x1 == NULL) {
        ERR_raise(ERR_LIB_SM2, ERR_R_BN_LIB);
        goto done;
    }

    pt = EC_POINT_new(group);
    if (pt == NULL) {
        ERR_raise(ERR_LIB_SM2, ERR_R_EC_LIB);
        goto done;
    }

    /*
     * B1: verify whether r' in [1,n-1], verification failed if not
     * B2: verify whether s' in [1,n-1], verification failed if not
     * B3: set M'~=ZA || M'
     * B4: calculate e'=Hv(M'~)
     * B5: calculate t = (r' + s') modn, verification failed if t=0
     * B6: calculate the point (x1', y1')=[s']G + [t]PA
     * B7: calculate R=(e'+x1') modn, verification pass if yes, otherwise failed
     */

    ECDSA_SIG_get0(sig, &r, &s);

    if (BN_cmp(r, BN_value_one()) < 0
        || BN_cmp(s, BN_value_one()) < 0
        || BN_cmp(order, r) <= 0
        || BN_cmp(order, s) <= 0) {
        ERR_raise(ERR_LIB_SM2, SM2_R_BAD_SIGNATURE);
        goto done;
    }

    if (!BN_mod_add(t, r, s, order, ctx)) {
        ERR_raise(ERR_LIB_SM2, ERR_R_BN_LIB);
        goto done;
    }

    if (BN_is_zero(t)) {
        ERR_raise(ERR_LIB_SM2, SM2_R_BAD_SIGNATURE);
        goto done;
    }

    if (!EC_POINT_mul(group, pt, s, EC_KEY_get0_public_key(key), t, ctx)
        || !EC_POINT_get_affine_coordinates(group, pt, x1, NULL, ctx)) {
        ERR_raise(ERR_LIB_SM2, ERR_R_EC_LIB);
        goto done;
    }

    if (!BN_mod_add(t, e, x1, order, ctx)) {
        ERR_raise(ERR_LIB_SM2, ERR_R_BN_LIB);
        goto done;
    }

    if (BN_cmp(r, t) == 0)
        ret = 1;

done:
    EC_POINT_free(pt);
    BN_CTX_end(ctx);
    BN_CTX_free(ctx);
    return ret;
}

ECDSA_SIG *ossl_sm2_do_sign(const EC_KEY *key,
    const EVP_MD *digest,
    const uint8_t *id,
    const size_t id_len,
    const uint8_t *msg, size_t msg_len)
{
    BIGNUM *e = NULL;
    ECDSA_SIG *sig = NULL;

    e = sm2_compute_msg_hash(digest, key, id, id_len, msg, msg_len);
    if (e == NULL) {
        /* SM2err already called */
        goto done;
    }

    sig = sm2_sig_gen(key, e);

done:
    BN_free(e);
    return sig;
}

int ossl_sm2_do_verify(const EC_KEY *key,
    const EVP_MD *digest,
    const ECDSA_SIG *sig,
    const uint8_t *id,
    const size_t id_len,
    const uint8_t *msg, size_t msg_len)
{
    BIGNUM *e = NULL;
    int ret = 0;

    e = sm2_compute_msg_hash(digest, key, id, id_len, msg, msg_len);
    if (e == NULL) {
        /* SM2err already called */
        goto done;
    }

    ret = sm2_sig_verify(key, sig, e);

done:
    BN_free(e);
    return ret;
}

int ossl_sm2_internal_sign(const unsigned char *dgst, int dgstlen,
    unsigned char *sig, unsigned int *siglen,
    EC_KEY *eckey)
{
    BIGNUM *e = NULL;
    ECDSA_SIG *s = NULL;
    int sigleni;
    int ret = -1;

    if (sig == NULL) {
        ERR_raise(ERR_LIB_SM2, ERR_R_PASSED_NULL_PARAMETER);
        goto done;
    }

    e = BN_bin2bn(dgst, dgstlen, NULL);
    if (e == NULL) {
        ERR_raise(ERR_LIB_SM2, ERR_R_BN_LIB);
        goto done;
    }

    s = sm2_sig_gen(eckey, e);
    if (s == NULL) {
        ERR_raise(ERR_LIB_SM2, ERR_R_INTERNAL_ERROR);
        goto done;
    }

    sigleni = i2d_ECDSA_SIG(s, &sig);
    if (sigleni < 0) {
        ERR_raise(ERR_LIB_SM2, ERR_R_INTERNAL_ERROR);
        goto done;
    }
    *siglen = (unsigned int)sigleni;

    ret = 1;

done:
    ECDSA_SIG_free(s);
    BN_free(e);
    return ret;
}

int ossl_sm2_internal_verify(const unsigned char *dgst, int dgstlen,
    const unsigned char *sig, int sig_len,
    EC_KEY *eckey)
{
    ECDSA_SIG *s = NULL;
    BIGNUM *e = NULL;
    const unsigned char *p = sig;
    unsigned char *der = NULL;
    int derlen = -1;
    int ret = -1;

    s = ECDSA_SIG_new();
    if (s == NULL) {
        ERR_raise(ERR_LIB_SM2, ERR_R_ECDSA_LIB);
        goto done;
    }
    if (d2i_ECDSA_SIG(&s, &p, sig_len) == NULL) {
        ERR_raise(ERR_LIB_SM2, SM2_R_INVALID_ENCODING);
        goto done;
    }
    /* Ensure signature uses DER and doesn't have trailing garbage */
    derlen = i2d_ECDSA_SIG(s, &der);
    if (derlen != sig_len || memcmp(sig, der, derlen) != 0) {
        ERR_raise(ERR_LIB_SM2, SM2_R_INVALID_ENCODING);
        goto done;
    }

    e = BN_bin2bn(dgst, dgstlen, NULL);
    if (e == NULL) {
        ERR_raise(ERR_LIB_SM2, ERR_R_BN_LIB);
        goto done;
    }

    ret = sm2_sig_verify(eckey, s, e);

done:
    OPENSSL_free(der);
    BN_free(e);
    ECDSA_SIG_free(s);
    return ret;
}

Coverage Report

Created: 2026-10-16 07:07

Line	Count	Source
1		/*
2		* Copyright 2017-2026 The OpenSSL Project Authors. All Rights Reserved.
3		* Copyright 2017 Ribose Inc. All Rights Reserved.
4		* Ported from Ribose contributions from Botan.
5		*
6		* Licensed under the Apache License 2.0 (the "License"). You may not use
7		* this file except in compliance with the License. You can obtain a copy
8		* in the file LICENSE in the source distribution or at
9		* https://www.openssl.org/source/license.html
10		*/
11
12		#include "internal/deprecated.h"
13
14		#include "crypto/sm2.h"
15		#include "crypto/sm2err.h"
16		#include "crypto/ec.h" /* ossl_ec_group_do_inverse_ord() */
17		#include "crypto/bn.h" /* fixed-top / Montgomery constant-time BN helpers */
18		#include "internal/numbers.h"
19		#include <openssl/err.h>
20		#include <openssl/evp.h>
21		#include <openssl/bn.h>
22		#include <string.h>
23
24		/*
25		* [SM2 Signature Scheme]
26		* (https://datatracker.ietf.org/doc/html/rfc8998#section-3.2.1)
27		*
28		* If either a client or a server needs to verify the peer's SM2 certificate
29		* contained in the Certificate message, then the following ASCII string value
30		* MUST be used as the SM2 identifier according to [GMT.0009-2012]:
31		*
32		* 1234567812345678
33		*/
34		static const uint8_t default_sm2_id[] = {
35		0x31, 0x32, 0x33, 0x34, 0x35, 0x36, 0x37, 0x38,
36		0x31, 0x32, 0x33, 0x34, 0x35, 0x36, 0x37, 0x38
37		};
38
39		int ossl_sm2_compute_z_digest(uint8_t *out,
40		const EVP_MD *digest,
41		const uint8_t *id,
42		size_t id_len,
43		const EC_KEY *key)
44	0	{
45	0	int rc = 0;
46	0	const EC_GROUP *group = EC_KEY_get0_group(key);
47	0	const EC_POINT *pubkey = EC_KEY_get0_public_key(key);
48	0	BN_CTX *ctx = NULL;
49	0	EVP_MD_CTX *hash = NULL;
50	0	BIGNUM *p = NULL;
51	0	BIGNUM *a = NULL;
52	0	BIGNUM *b = NULL;
53	0	BIGNUM *xG = NULL;
54	0	BIGNUM *yG = NULL;
55	0	BIGNUM *xA = NULL;
56	0	BIGNUM *yA = NULL;
57	0	int p_bytes = 0;
58	0	uint8_t *buf = NULL;
59	0	uint16_t entl = 0;
60	0	uint8_t e_byte = 0;
61
62		/* SM2 Signatures require a public key, check for it */
63	0	if (pubkey == NULL) {
64	0	ERR_raise(ERR_LIB_SM2, ERR_R_PASSED_NULL_PARAMETER);
65	0	goto done;
66	0	}
67
68	0	hash = EVP_MD_CTX_new();
69	0	if (hash == NULL) {
70	0	ERR_raise(ERR_LIB_SM2, ERR_R_EVP_LIB);
71	0	goto done;
72	0	}
73	0	ctx = BN_CTX_new_ex(ossl_ec_key_get_libctx(key));
74	0	if (ctx == NULL) {
75	0	ERR_raise(ERR_LIB_SM2, ERR_R_BN_LIB);
76	0	goto done;
77	0	}
78
79	0	BN_CTX_start(ctx);
80	0	p = BN_CTX_get(ctx);
81	0	a = BN_CTX_get(ctx);
82	0	b = BN_CTX_get(ctx);
83	0	xG = BN_CTX_get(ctx);
84	0	yG = BN_CTX_get(ctx);
85	0	xA = BN_CTX_get(ctx);
86	0	yA = BN_CTX_get(ctx);
87
88	0	if (yA == NULL) {
89	0	ERR_raise(ERR_LIB_SM2, ERR_R_BN_LIB);
90	0	goto done;
91	0	}
92
93	0	if (!EVP_DigestInit(hash, digest)) {
94	0	ERR_raise(ERR_LIB_SM2, ERR_R_EVP_LIB);
95	0	goto done;
96	0	}
97
98		/* Z = h(ENTL \|\| ID \|\| a \|\| b \|\| xG \|\| yG \|\| xA \|\| yA) */
99
100	0	if (id == NULL) {
101	0	id = default_sm2_id;
102	0	id_len = sizeof(default_sm2_id);
103	0	}
104
105	0	if (id_len >= (UINT16_MAX / 8)) {
106		/* too large */
107	0	ERR_raise(ERR_LIB_SM2, SM2_R_ID_TOO_LARGE);
108	0	goto done;
109	0	}
110
111	0	entl = (uint16_t)(8 * id_len);
112
113	0	e_byte = entl >> 8;
114	0	if (!EVP_DigestUpdate(hash, &e_byte, 1)) {
115	0	ERR_raise(ERR_LIB_SM2, ERR_R_EVP_LIB);
116	0	goto done;
117	0	}
118	0	e_byte = entl & 0xFF;
119	0	if (!EVP_DigestUpdate(hash, &e_byte, 1)) {
120	0	ERR_raise(ERR_LIB_SM2, ERR_R_EVP_LIB);
121	0	goto done;
122	0	}
123
124	0	if (id_len > 0 && !EVP_DigestUpdate(hash, id, id_len)) {
125	0	ERR_raise(ERR_LIB_SM2, ERR_R_EVP_LIB);
126	0	goto done;
127	0	}
128
129	0	if (!EC_GROUP_get_curve(group, p, a, b, ctx)) {
130	0	ERR_raise(ERR_LIB_SM2, ERR_R_EC_LIB);
131	0	goto done;
132	0	}
133
134	0	p_bytes = BN_num_bytes(p);
135	0	buf = OPENSSL_zalloc(p_bytes);
136	0	if (buf == NULL)
137	0	goto done;
138
139	0	if (BN_bn2binpad(a, buf, p_bytes) < 0
140	0	\|\| !EVP_DigestUpdate(hash, buf, p_bytes)
141	0	\|\| BN_bn2binpad(b, buf, p_bytes) < 0
142	0	\|\| !EVP_DigestUpdate(hash, buf, p_bytes)
143	0	\|\| !EC_POINT_get_affine_coordinates(group,
144	0	EC_GROUP_get0_generator(group),
145	0	xG, yG, ctx)
146	0	\|\| BN_bn2binpad(xG, buf, p_bytes) < 0
147	0	\|\| !EVP_DigestUpdate(hash, buf, p_bytes)
148	0	\|\| BN_bn2binpad(yG, buf, p_bytes) < 0
149	0	\|\| !EVP_DigestUpdate(hash, buf, p_bytes)
150	0	\|\| !EC_POINT_get_affine_coordinates(group,
151	0	pubkey,
152	0	xA, yA, ctx)
153	0	\|\| BN_bn2binpad(xA, buf, p_bytes) < 0
154	0	\|\| !EVP_DigestUpdate(hash, buf, p_bytes)
155	0	\|\| BN_bn2binpad(yA, buf, p_bytes) < 0
156	0	\|\| !EVP_DigestUpdate(hash, buf, p_bytes)
157	0	\|\| !EVP_DigestFinal(hash, out, NULL)) {
158	0	ERR_raise(ERR_LIB_SM2, ERR_R_INTERNAL_ERROR);
159	0	goto done;
160	0	}
161
162	0	rc = 1;
163
164	0	done:
165	0	OPENSSL_free(buf);
166	0	BN_CTX_end(ctx);
167	0	BN_CTX_free(ctx);
168	0	EVP_MD_CTX_free(hash);
169	0	return rc;
170	0	}
171
172		static BIGNUM sm2_compute_msg_hash(const EVP_MD digest,
173		const EC_KEY *key,
174		const uint8_t *id,
175		const size_t id_len,
176		const uint8_t *msg, size_t msg_len)
177	0	{
178	0	EVP_MD_CTX *hash = EVP_MD_CTX_new();
179	0	const int md_size = EVP_MD_get_size(digest);
180	0	uint8_t *z = NULL;
181	0	BIGNUM *e = NULL;
182	0	EVP_MD *fetched_digest = NULL;
183	0	OSSL_LIB_CTX *libctx = ossl_ec_key_get_libctx(key);
184	0	const char *propq = ossl_ec_key_get0_propq(key);
185
186	0	if (md_size <= 0) {
187	0	ERR_raise(ERR_LIB_SM2, SM2_R_INVALID_DIGEST);
188	0	goto done;
189	0	}
190	0	if (hash == NULL) {
191	0	ERR_raise(ERR_LIB_SM2, ERR_R_EVP_LIB);
192	0	goto done;
193	0	}
194
195	0	z = OPENSSL_zalloc(md_size);
196	0	if (z == NULL)
197	0	goto done;
198
199	0	fetched_digest = EVP_MD_fetch(libctx, EVP_MD_get0_name(digest), propq);
200	0	if (fetched_digest == NULL) {
201	0	ERR_raise(ERR_LIB_SM2, ERR_R_INTERNAL_ERROR);
202	0	goto done;
203	0	}
204
205	0	if (!ossl_sm2_compute_z_digest(z, fetched_digest, id, id_len, key)) {
206		/* SM2err already called */
207	0	goto done;
208	0	}
209
210	0	if (!EVP_DigestInit(hash, fetched_digest)
211	0	\|\| !EVP_DigestUpdate(hash, z, md_size)
212	0	\|\| !EVP_DigestUpdate(hash, msg, msg_len)
213		/* reuse z buffer to hold H(Z \|\| M) */
214	0	\|\| !EVP_DigestFinal(hash, z, NULL)) {
215	0	ERR_raise(ERR_LIB_SM2, ERR_R_EVP_LIB);
216	0	goto done;
217	0	}
218
219	0	e = BN_bin2bn(z, md_size, NULL);
220	0	if (e == NULL)
221	0	ERR_raise(ERR_LIB_SM2, ERR_R_INTERNAL_ERROR);
222
223	0	done:
224	0	EVP_MD_free(fetched_digest);
225	0	OPENSSL_free(z);
226	0	EVP_MD_CTX_free(hash);
227	0	return e;
228	0	}
229
230		static ECDSA_SIG sm2_sig_gen(const EC_KEY key, const BIGNUM *e)
231	0	{
232	0	const BIGNUM *dA = EC_KEY_get0_private_key(key);
233	0	const EC_GROUP *group = EC_KEY_get0_group(key);
234	0	const BIGNUM *order = EC_GROUP_get0_order(group);
235	0	ECDSA_SIG *sig = NULL;
236	0	EC_POINT *kG = NULL;
237	0	BN_CTX *ctx = NULL;
238	0	BIGNUM *k = NULL;
239	0	BIGNUM *r = NULL;
240	0	BIGNUM *s = NULL;
241	0	BIGNUM *x1 = NULL;
242	0	BIGNUM *tmp = NULL;
243	0	BN_MONT_CTX *mont = EC_GROUP_get_mont_data(group);
244	0	OSSL_LIB_CTX *libctx = ossl_ec_key_get_libctx(key);
245
246	0	if (dA == NULL) {
247	0	ERR_raise(ERR_LIB_SM2, SM2_R_INVALID_PRIVATE_KEY);
248	0	goto done;
249	0	}
250
251	0	if (mont == NULL) {
252	0	ERR_raise(ERR_LIB_SM2, ERR_R_EC_LIB);
253	0	goto done;
254	0	}
255	0	kG = EC_POINT_new(group);
256	0	if (kG == NULL) {
257	0	ERR_raise(ERR_LIB_SM2, ERR_R_EC_LIB);
258	0	goto done;
259	0	}
260	0	ctx = BN_CTX_new_ex(libctx);
261	0	if (ctx == NULL) {
262	0	ERR_raise(ERR_LIB_SM2, ERR_R_BN_LIB);
263	0	goto done;
264	0	}
265
266	0	BN_CTX_start(ctx);
267	0	k = BN_CTX_get(ctx);
268	0	x1 = BN_CTX_get(ctx);
269	0	tmp = BN_CTX_get(ctx);
270	0	if (tmp == NULL) {
271	0	ERR_raise(ERR_LIB_SM2, ERR_R_BN_LIB);
272	0	goto done;
273	0	}
274
275		/*
276		* These values are returned and so should not be allocated out of the
277		* context
278		*/
279	0	r = BN_new();
280	0	s = BN_new();
281
282	0	if (r == NULL \|\| s == NULL) {
283	0	ERR_raise(ERR_LIB_SM2, ERR_R_BN_LIB);
284	0	goto done;
285	0	}
286
287		/*
288		* A3: Generate a random number k in [1,n-1] using random number generators;
289		* A4: Compute (x1,y1)=[k]G, and convert the type of data x1 to be integer
290		* as specified in clause 4.2.8 of GM/T 0003.1-2012;
291		* A5: Compute r=(e+x1) mod n. If r=0 or r+k=n, then go to A3;
292		* A6: Compute s=(1/(1+dA)(k-rdA)) mod n. If s=0, then go to A3;
293		* A7: Convert the type of data (r,s) to be bit strings according to the details
294		* in clause 4.2.2 of GM/T 0003.1-2012. Then the signature of message M is (r,s).
295		*/
296	0	for (;;) {
297	0	if (!BN_priv_rand_range_ex(k, order, 0, ctx)) {
298	0	ERR_raise(ERR_LIB_SM2, ERR_R_INTERNAL_ERROR);
299	0	goto done;
300	0	}
301		/*
302		* Pin the nonce to a fixed, value-independent width and flag it
303		* BN_FLG_CONSTTIME, so its magnitude does not leak through operand
304		* lengths in the scalar copy inside the ladder, or in the arithmetic
305		* below. BN_priv_rand_range_ex() is kept so the nonce value itself
306		* is unchanged; only its representation is pinned.
307		*/
308	0	BN_set_flags(k, BN_FLG_CONSTTIME);
309	0	if (!bn_set_top_fixed(k, bn_get_top(order))) {
310	0	ERR_raise(ERR_LIB_SM2, ERR_R_BN_LIB);
311	0	goto done;
312	0	}
313
314	0	if (!EC_POINT_mul(group, kG, k, NULL, NULL, ctx)
315	0	\|\| !EC_POINT_get_affine_coordinates(group, kG, x1, NULL,
316	0	ctx)
317	0	\|\| !BN_mod_add(r, e, x1, order, ctx)) {
318	0	ERR_raise(ERR_LIB_SM2, ERR_R_INTERNAL_ERROR);
319	0	goto done;
320	0	}
321
322		/* try again if r == 0 or r + k == n */
323	0	if (BN_is_zero(r))
324	0	continue;
325
326		/*
327		* Since 0 < r < n and 0 < k < n, r + k == n is the same as
328		* k == n - r. Both operands of the subtraction are public, so
329		* compute it in the open and then compare against the nonce with a
330		* fixed-width constant-time comparison. A BN_cmp() on r + k would
331		* branch on whether the sum carried into an extra word, which
332		* depends on the value of k.
333		*/
334	0	if (!BN_sub(tmp, order, r)
335	0	\|\| !bn_set_top_fixed(tmp, bn_get_top(order))) {
336	0	ERR_raise(ERR_LIB_SM2, ERR_R_BN_LIB);
337	0	goto done;
338	0	}
339
340	0	if (CRYPTO_memcmp(bn_get_words(k), bn_get_words(tmp),
341	0	bn_get_top(order) * sizeof(BN_ULONG))
342	0	== 0)
343	0	continue;
344
345		/*
346		* s = ((1 + dA)^-1 * (k - r * dA)) mod order
347		*
348		* Computed with fixed-top / Montgomery constant-time primitives, so
349		* that the running time does not depend on the secret k or dA (the
350		* generic BN_mod_mul()/BN_sub() used previously reduce via BN_div(),
351		* whose timing is value dependent). This mirrors the ECDSA path.
352		*
353		* s holds (1 + dA)^-1 throughout; the (k - r * dA) term is built in
354		* tmp. bn_mul_mont_fixed_top() with one operand in the Montgomery
355		* domain yields the plain product, and the final
356		* BN_mod_mul_montgomery() returns the user-visible, normalised value.
357		*/
358	0	if (!BN_add(s, dA, BN_value_one())
359	0	\|\| !ossl_ec_group_do_inverse_ord(group, s, s, ctx)
360	0	\|\| !bn_to_mont_fixed_top(tmp, r, mont, ctx)
361	0	\|\| !bn_mul_mont_fixed_top(tmp, tmp, dA, mont, ctx)
362	0	\|\| !bn_mod_sub_fixed_top(tmp, k, tmp, order)
363	0	\|\| !bn_to_mont_fixed_top(tmp, tmp, mont, ctx)
364	0	\|\| !BN_mod_mul_montgomery(s, tmp, s, mont, ctx)) {
365	0	ERR_raise(ERR_LIB_SM2, ERR_R_BN_LIB);
366	0	goto done;
367	0	}
368
369		/* try again if s == 0 */
370	0	if (BN_is_zero(s))
371	0	continue;
372
373	0	sig = ECDSA_SIG_new();
374	0	if (sig == NULL) {
375	0	ERR_raise(ERR_LIB_SM2, ERR_R_ECDSA_LIB);
376	0	goto done;
377	0	}
378
379		/* takes ownership of r and s */
380	0	ECDSA_SIG_set0(sig, r, s);
381	0	break;
382	0	}
383
384	0	done:
385	0	if (sig == NULL) {
386	0	BN_free(r);
387	0	BN_free(s);
388	0	}
389
390	0	BN_CTX_end(ctx);
391	0	BN_CTX_free(ctx);
392	0	EC_POINT_free(kG);
393	0	return sig;
394	0	}
395
396		static int sm2_sig_verify(const EC_KEY key, const ECDSA_SIG sig,
397		const BIGNUM *e)
398	0	{
399	0	int ret = 0;
400	0	const EC_GROUP *group = EC_KEY_get0_group(key);
401	0	const BIGNUM *order = EC_GROUP_get0_order(group);
402	0	BN_CTX *ctx = NULL;
403	0	EC_POINT *pt = NULL;
404	0	BIGNUM *t = NULL;
405	0	BIGNUM *x1 = NULL;
406	0	const BIGNUM *r = NULL;
407	0	const BIGNUM *s = NULL;
408	0	OSSL_LIB_CTX *libctx = ossl_ec_key_get_libctx(key);
409
410	0	ctx = BN_CTX_new_ex(libctx);
411	0	if (ctx == NULL) {
412	0	ERR_raise(ERR_LIB_SM2, ERR_R_BN_LIB);
413	0	goto done;
414	0	}
415	0	BN_CTX_start(ctx);
416	0	t = BN_CTX_get(ctx);
417	0	x1 = BN_CTX_get(ctx);
418	0	if (x1 == NULL) {
419	0	ERR_raise(ERR_LIB_SM2, ERR_R_BN_LIB);
420	0	goto done;
421	0	}
422
423	0	pt = EC_POINT_new(group);
424	0	if (pt == NULL) {
425	0	ERR_raise(ERR_LIB_SM2, ERR_R_EC_LIB);
426	0	goto done;
427	0	}
428
429		/*
430		* B1: verify whether r' in [1,n-1], verification failed if not
431		* B2: verify whether s' in [1,n-1], verification failed if not
432		* B3: set M'~=ZA \|\| M'
433		* B4: calculate e'=Hv(M'~)
434		* B5: calculate t = (r' + s') modn, verification failed if t=0
435		* B6: calculate the point (x1', y1')=[s']G + [t]PA
436		* B7: calculate R=(e'+x1') modn, verification pass if yes, otherwise failed
437		*/
438
439	0	ECDSA_SIG_get0(sig, &r, &s);
440
441	0	if (BN_cmp(r, BN_value_one()) < 0
442	0	\|\| BN_cmp(s, BN_value_one()) < 0
443	0	\|\| BN_cmp(order, r) <= 0
444	0	\|\| BN_cmp(order, s) <= 0) {
445	0	ERR_raise(ERR_LIB_SM2, SM2_R_BAD_SIGNATURE);
446	0	goto done;
447	0	}
448
449	0	if (!BN_mod_add(t, r, s, order, ctx)) {
450	0	ERR_raise(ERR_LIB_SM2, ERR_R_BN_LIB);
451	0	goto done;
452	0	}
453
454	0	if (BN_is_zero(t)) {
455	0	ERR_raise(ERR_LIB_SM2, SM2_R_BAD_SIGNATURE);
456	0	goto done;
457	0	}
458
459	0	if (!EC_POINT_mul(group, pt, s, EC_KEY_get0_public_key(key), t, ctx)
460	0	\|\| !EC_POINT_get_affine_coordinates(group, pt, x1, NULL, ctx)) {
461	0	ERR_raise(ERR_LIB_SM2, ERR_R_EC_LIB);
462	0	goto done;
463	0	}
464
465	0	if (!BN_mod_add(t, e, x1, order, ctx)) {
466	0	ERR_raise(ERR_LIB_SM2, ERR_R_BN_LIB);
467	0	goto done;
468	0	}
469
470	0	if (BN_cmp(r, t) == 0)
471	0	ret = 1;
472
473	0	done:
474	0	EC_POINT_free(pt);
475	0	BN_CTX_end(ctx);
476	0	BN_CTX_free(ctx);
477	0	return ret;
478	0	}
479
480		ECDSA_SIG ossl_sm2_do_sign(const EC_KEY key,
481		const EVP_MD *digest,
482		const uint8_t *id,
483		const size_t id_len,
484		const uint8_t *msg, size_t msg_len)
485	0	{
486	0	BIGNUM *e = NULL;
487	0	ECDSA_SIG *sig = NULL;
488
489	0	e = sm2_compute_msg_hash(digest, key, id, id_len, msg, msg_len);
490	0	if (e == NULL) {
491		/* SM2err already called */
492	0	goto done;
493	0	}
494
495	0	sig = sm2_sig_gen(key, e);
496
497	0	done:
498	0	BN_free(e);
499	0	return sig;
500	0	}
501
502		int ossl_sm2_do_verify(const EC_KEY *key,
503		const EVP_MD *digest,
504		const ECDSA_SIG *sig,
505		const uint8_t *id,
506		const size_t id_len,
507		const uint8_t *msg, size_t msg_len)
508	0	{
509	0	BIGNUM *e = NULL;
510	0	int ret = 0;
511
512	0	e = sm2_compute_msg_hash(digest, key, id, id_len, msg, msg_len);
513	0	if (e == NULL) {
514		/* SM2err already called */
515	0	goto done;
516	0	}
517
518	0	ret = sm2_sig_verify(key, sig, e);
519
520	0	done:
521	0	BN_free(e);
522	0	return ret;
523	0	}
524
525		int ossl_sm2_internal_sign(const unsigned char *dgst, int dgstlen,
526		unsigned char sig, unsigned int siglen,
527		EC_KEY *eckey)
528	0	{
529	0	BIGNUM *e = NULL;
530	0	ECDSA_SIG *s = NULL;
531	0	int sigleni;
532	0	int ret = -1;
533
534	0	if (sig == NULL) {
535	0	ERR_raise(ERR_LIB_SM2, ERR_R_PASSED_NULL_PARAMETER);
536	0	goto done;
537	0	}
538
539	0	e = BN_bin2bn(dgst, dgstlen, NULL);
540	0	if (e == NULL) {
541	0	ERR_raise(ERR_LIB_SM2, ERR_R_BN_LIB);
542	0	goto done;
543	0	}
544
545	0	s = sm2_sig_gen(eckey, e);
546	0	if (s == NULL) {
547	0	ERR_raise(ERR_LIB_SM2, ERR_R_INTERNAL_ERROR);
548	0	goto done;
549	0	}
550
551	0	sigleni = i2d_ECDSA_SIG(s, &sig);
552	0	if (sigleni < 0) {
553	0	ERR_raise(ERR_LIB_SM2, ERR_R_INTERNAL_ERROR);
554	0	goto done;
555	0	}
556	0	*siglen = (unsigned int)sigleni;
557
558	0	ret = 1;
559
560	0	done:
561	0	ECDSA_SIG_free(s);
562	0	BN_free(e);
563	0	return ret;
564	0	}
565
566		int ossl_sm2_internal_verify(const unsigned char *dgst, int dgstlen,
567		const unsigned char *sig, int sig_len,
568		EC_KEY *eckey)
569	0	{
570	0	ECDSA_SIG *s = NULL;
571	0	BIGNUM *e = NULL;
572	0	const unsigned char *p = sig;
573	0	unsigned char *der = NULL;
574	0	int derlen = -1;
575	0	int ret = -1;
576
577	0	s = ECDSA_SIG_new();
578	0	if (s == NULL) {
579	0	ERR_raise(ERR_LIB_SM2, ERR_R_ECDSA_LIB);
580	0	goto done;
581	0	}
582	0	if (d2i_ECDSA_SIG(&s, &p, sig_len) == NULL) {
583	0	ERR_raise(ERR_LIB_SM2, SM2_R_INVALID_ENCODING);
584	0	goto done;
585	0	}
586		/* Ensure signature uses DER and doesn't have trailing garbage */
587	0	derlen = i2d_ECDSA_SIG(s, &der);
588	0	if (derlen != sig_len \|\| memcmp(sig, der, derlen) != 0) {
589	0	ERR_raise(ERR_LIB_SM2, SM2_R_INVALID_ENCODING);
590	0	goto done;
591	0	}
592
593	0	e = BN_bin2bn(dgst, dgstlen, NULL);
594	0	if (e == NULL) {
595	0	ERR_raise(ERR_LIB_SM2, ERR_R_BN_LIB);
596	0	goto done;
597	0	}
598
599	0	ret = sm2_sig_verify(eckey, s, e);
600
601	0	done:
602	0	OPENSSL_free(der);
603	0	BN_free(e);
604	0	ECDSA_SIG_free(s);
605	0	return ret;
606	0	}