/src/openssl36/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>

int ossl_sm2_compute_z_digest(uint8_t *out,
    const EVP_MD *digest,
    const uint8_t *id,
    const 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_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: 2026-10-28 06:28

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