Import initial code for the SM2 cipher

This adds the SM2 algorithm defined in the Chinese standards
GB/T 32918.1-2016, GB/T 32918.2-2016, GB/T 32918.3-2016,
GB/T 32918.4-2016 and GB/T 32918.5-2017.

This is an ISC licensed implementation contributed by Ribose.inc, based
on the same code that was contributed to OpenSSL by Jack Lloyd. The port
to LibreSSL was done by Ronald Tse and Nickolay Olshevsky.

Github PR #105

I made quite a few cleanup passes on this, but more is needed, some
of which will happen in-tree before this is linked to the build.

ok deraadt inoguchi (a long time ago), jsing

1 files changed, 632 insertions, 0 deletions

diff --git a/src/lib/libcrypto/sm2/sm2_crypt.c b/src/lib/libcrypto/sm2/sm2_crypt.c
new file mode 100644
index 0000000000..2bb3b8ff63
--- /dev/null
+++ b/src/lib/libcrypto/sm2/sm2_crypt.c
@@ -0,0 +1,632 @@
+/*      $OpenBSD: sm2_crypt.c,v 1.1.1.1 2021/08/18 16:04:32 tb Exp $ */
+/*
+ * Copyright (c) 2017, 2019 Ribose Inc
+ *
+ * Permission to use, copy, modify, and/or distribute this software for any
+ * purpose with or without fee is hereby granted, provided that the above
+ * copyright notice and this permission notice appear in all copies.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
+ * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
+ * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
+ * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
+ * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
+ * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
+ * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
+ */
+
+#ifndef OPENSSL_NO_SM2
+
+#include <string.h>
+
+#include <openssl/asn1.h>
+#include <openssl/asn1t.h>
+#include <openssl/bn.h>
+#include <openssl/err.h>
+#include <openssl/evp.h>
+#include <openssl/sm2.h>
+
+#include "sm2_locl.h"
+
+typedef struct SM2_Ciphertext_st SM2_Ciphertext;
+
+SM2_Ciphertext *SM2_Ciphertext_new(void);
+void SM2_Ciphertext_free(SM2_Ciphertext *a);
+SM2_Ciphertext *d2i_SM2_Ciphertext(SM2_Ciphertext **a, const unsigned char **in,
+    long len);
+int i2d_SM2_Ciphertext(SM2_Ciphertext *a, unsigned char **out);
+
+struct SM2_Ciphertext_st {
+        BIGNUM *C1x;
+        BIGNUM *C1y;
+        ASN1_OCTET_STRING *C3;
+        ASN1_OCTET_STRING *C2;
+};
+
+static const ASN1_TEMPLATE SM2_Ciphertext_seq_tt[] = {
+        {
+                .flags = 0,
+                .tag = 0,
+                .offset = offsetof(SM2_Ciphertext, C1x),
+                .field_name = "C1x",
+                .item = &BIGNUM_it,
+        },
+        {
+                .flags = 0,
+                .tag = 0,
+                .offset = offsetof(SM2_Ciphertext, C1y),
+                .field_name = "C1y",
+                .item = &BIGNUM_it,
+        },
+        {
+                .flags = 0,
+                .tag = 0,
+                .offset = offsetof(SM2_Ciphertext, C3),
+                .field_name = "C3",
+                .item = &ASN1_OCTET_STRING_it,
+        },
+        {
+                .flags = 0,
+                .tag = 0,
+                .offset = offsetof(SM2_Ciphertext, C2),
+                .field_name = "C2",
+                .item = &ASN1_OCTET_STRING_it,
+        },
+};
+
+const ASN1_ITEM SM2_Ciphertext_it = {
+        .itype = ASN1_ITYPE_SEQUENCE,
+        .utype = V_ASN1_SEQUENCE,
+        .templates = SM2_Ciphertext_seq_tt,
+        .tcount = sizeof(SM2_Ciphertext_seq_tt) / sizeof(ASN1_TEMPLATE),
+        .funcs = NULL,
+        .size = sizeof(SM2_Ciphertext),
+        .sname = "SM2_Ciphertext",
+};
+
+SM2_Ciphertext *
+d2i_SM2_Ciphertext(SM2_Ciphertext **a, const unsigned char **in, long len)
+{
+        return (SM2_Ciphertext *) ASN1_item_d2i((ASN1_VALUE **)a, in, len,
+            &SM2_Ciphertext_it);
+}
+
+int
+i2d_SM2_Ciphertext(SM2_Ciphertext *a, unsigned char **out)
+{
+        return ASN1_item_i2d((ASN1_VALUE *)a, out, &SM2_Ciphertext_it);
+}
+
+SM2_Ciphertext *
+SM2_Ciphertext_new(void)
+{
+        return (SM2_Ciphertext *)ASN1_item_new(&SM2_Ciphertext_it);
+}
+
+void
+SM2_Ciphertext_free(SM2_Ciphertext *a)
+{
+        ASN1_item_free((ASN1_VALUE *)a, &SM2_Ciphertext_it);
+}
+
+static size_t
+ec_field_size(const EC_GROUP *group)
+{
+        /* Is there some simpler way to do this? */
+        BIGNUM *p;
+        size_t field_size = 0;
+
+        if ((p = BN_new()) == NULL)
+                goto err;
+        if (!EC_GROUP_get_curve(group, p, NULL, NULL, NULL))
+                goto err;
+        field_size = BN_num_bytes(p);
+ err:
+        BN_free(p);
+        return field_size;
+}
+
+int
+SM2_plaintext_size(const EC_KEY *key, const EVP_MD *digest, size_t msg_len,
+    size_t *pl_size)
+{
+        size_t field_size, overhead;
+        int md_size;
+
+        if ((field_size = ec_field_size(EC_KEY_get0_group(key))) == 0) {
+                SM2error(SM2_R_INVALID_FIELD);
+                return 0;
+        }
+
+        if ((md_size = EVP_MD_size(digest)) < 0) {
+                SM2error(SM2_R_INVALID_DIGEST);
+                return 0;
+        }
+
+        overhead = 10 + 2 * field_size + md_size;
+        if (msg_len <= overhead) {
+                SM2error(SM2_R_INVALID_ARGUMENT);
+                return 0;
+        }
+
+        *pl_size = msg_len - overhead;
+        return 1;
+}
+
+int
+SM2_ciphertext_size(const EC_KEY *key, const EVP_MD *digest, size_t msg_len,
+    size_t *c_size)
+{
+        size_t asn_size, field_size;
+        int md_size;
+
+        if ((field_size = ec_field_size(EC_KEY_get0_group(key))) == 0) {
+                SM2error(SM2_R_INVALID_FIELD);
+                return 0;
+        }
+
+        if ((md_size = EVP_MD_size(digest)) < 0) {
+                SM2error(SM2_R_INVALID_DIGEST);
+                return 0;
+        }
+
+        asn_size = 2 * ASN1_object_size(0, field_size + 1, V_ASN1_INTEGER) +
+            ASN1_object_size(0, md_size, V_ASN1_OCTET_STRING) +
+            ASN1_object_size(0, msg_len, V_ASN1_OCTET_STRING);
+
+        *c_size = ASN1_object_size(1, asn_size, V_ASN1_SEQUENCE);
+        return 1;
+}
+
+int
+sm2_kdf(uint8_t *key, size_t key_len, uint8_t *secret, size_t secret_len,
+    const EVP_MD *digest)
+{
+        EVP_MD_CTX *hash;
+        uint8_t *hash_buf = NULL;
+        uint32_t ctr = 1;
+        uint8_t ctr_buf[4] = {0};
+        size_t hadd, hlen;
+        int rc = 0;
+
+        if ((hash = EVP_MD_CTX_new()) == NULL) {
+                SM2error(ERR_R_MALLOC_FAILURE);
+                goto err;
+        }
+
+        if ((hlen = EVP_MD_size(digest)) < 0) {
+                SM2error(SM2_R_INVALID_DIGEST);
+                goto err;
+        }
+        if ((hash_buf = malloc(hlen)) == NULL) {
+                SM2error(ERR_R_MALLOC_FAILURE);
+                goto err;
+        }
+
+        EVP_MD_CTX_init(hash);
+        while ((key_len > 0) && (ctr != 0)) {
+                if (!EVP_DigestInit_ex(hash, digest, NULL)) {
+                        SM2error(ERR_R_EVP_LIB);
+                        goto err;
+                }
+                if (!EVP_DigestUpdate(hash, secret, secret_len)) {
+                        SM2error(ERR_R_EVP_LIB);
+                        goto err;
+                }
+
+                /* big-endian counter representation */
+                ctr_buf[0] = (ctr >> 24) & 0xff;
+                ctr_buf[1] = (ctr >> 16) & 0xff;
+                ctr_buf[2] = (ctr >> 8) & 0xff;
+                ctr_buf[3] = ctr & 0xff;
+                ctr++;
+
+                if (!EVP_DigestUpdate(hash, ctr_buf, 4)) {
+                        SM2error(ERR_R_EVP_LIB);
+                        goto err;
+                }
+                if (!EVP_DigestFinal(hash, hash_buf, NULL)) {
+                        SM2error(ERR_R_EVP_LIB);
+                        goto err;
+                }
+
+                hadd = key_len > hlen ? hlen : key_len;
+                memcpy(key, hash_buf, hadd);
+                memset(hash_buf, 0, hlen);
+                key_len -= hadd;
+                key += hadd;
+        }
+
+        rc = 1;
+ err:
+        free(hash_buf);
+        EVP_MD_CTX_free(hash);
+        return rc;
+}
+
+int
+SM2_encrypt(const EC_KEY *key, const EVP_MD *digest, const uint8_t *msg,
+    size_t msg_len, uint8_t *ciphertext_buf, size_t *ciphertext_len)
+{
+        SM2_Ciphertext ctext_struct;
+        EVP_MD_CTX *hash = NULL;
+        BN_CTX *ctx = NULL;
+        BIGNUM *order = NULL;
+        BIGNUM *k, *x1, *y1, *x2, *y2;
+        const EC_GROUP *group;
+        const EC_POINT *P;
+        EC_POINT *kG = NULL, *kP = NULL;
+        uint8_t *msg_mask = NULL, *x2y2 = NULL, *C3 = NULL;
+        size_t C3_size, field_size, i, x2size, y2size;
+        int rc = 0;
+        int clen;
+
+        ctext_struct.C2 = NULL;
+        ctext_struct.C3 = NULL;
+
+        if ((hash = EVP_MD_CTX_new()) == NULL) {
+                SM2error(ERR_R_MALLOC_FAILURE);
+                goto err;
+        }
+
+        if ((group = EC_KEY_get0_group(key)) == NULL) {
+                SM2error(SM2_R_INVALID_KEY);
+                goto err;
+        }
+
+        if ((order = BN_new()) == NULL) {
+                SM2error(ERR_R_MALLOC_FAILURE);
+                goto err;
+        }
+
+        if (!EC_GROUP_get_order(group, order, NULL)) {
+                SM2error(SM2_R_INVALID_GROUP_ORDER);
+                goto err;
+        }
+
+        if ((P = EC_KEY_get0_public_key(key)) == NULL) {
+                SM2error(SM2_R_INVALID_KEY);
+                goto err;
+        }
+
+        if ((field_size = ec_field_size(group)) == 0) {
+                SM2error(SM2_R_INVALID_FIELD);
+                goto err;
+        }
+
+        if ((C3_size = EVP_MD_size(digest)) < 0) {
+                SM2error(SM2_R_INVALID_DIGEST);
+                goto err;
+        }
+
+        if ((kG = EC_POINT_new(group)) == NULL) {
+                SM2error(ERR_R_MALLOC_FAILURE);
+                goto err;
+        }
+        if ((kP = EC_POINT_new(group)) == NULL) {
+                SM2error(ERR_R_MALLOC_FAILURE);
+                goto err;
+        }
+
+        if ((ctx = BN_CTX_new()) == NULL) {
+                SM2error(ERR_R_MALLOC_FAILURE);
+                goto err;
+        }
+
+        BN_CTX_start(ctx);
+        if ((k = BN_CTX_get(ctx)) == NULL) {
+                SM2error(ERR_R_BN_LIB);
+                goto err;
+        }
+        if ((x1 = BN_CTX_get(ctx)) == NULL) {
+                SM2error(ERR_R_BN_LIB);
+                goto err;
+        }
+        if ((x2 = BN_CTX_get(ctx)) == NULL) {
+                SM2error(ERR_R_BN_LIB);
+                goto err;
+        }
+        if ((y1 = BN_CTX_get(ctx)) == NULL) {
+                SM2error(ERR_R_BN_LIB);
+                goto err;
+        }
+        if ((y2 = BN_CTX_get(ctx)) == NULL) {
+                SM2error(ERR_R_BN_LIB);
+                goto err;
+        }
+
+        if ((x2y2 = calloc(2, field_size)) == NULL) {
+                SM2error(ERR_R_MALLOC_FAILURE);
+                goto err;
+        }
+
+        if ((C3 = calloc(1, C3_size)) == NULL) {
+                SM2error(ERR_R_MALLOC_FAILURE);
+                goto err;
+        }
+
+        memset(ciphertext_buf, 0, *ciphertext_len);
+
+        if (!BN_rand_range(k, order)) {
+                SM2error(SM2_R_RANDOM_NUMBER_GENERATION_FAILED);
+                goto err;
+        }
+
+        if (!EC_POINT_mul(group, kG, k, NULL, NULL, ctx)) {
+                SM2error(ERR_R_EC_LIB);
+                goto err;
+        }
+
+        if (!EC_POINT_get_affine_coordinates(group, kG, x1, y1, ctx)) {
+                SM2error(ERR_R_EC_LIB);
+                goto err;
+        }
+
+        if (!EC_POINT_mul(group, kP, NULL, P, k, ctx)) {
+                SM2error(ERR_R_EC_LIB);
+                goto err;
+        }
+
+        if (!EC_POINT_get_affine_coordinates(group, kP, x2, y2, ctx)) {
+                SM2error(ERR_R_EC_LIB);
+                goto err;
+        }
+
+        if ((x2size = BN_num_bytes(x2)) > field_size ||
+            (y2size = BN_num_bytes(y2)) > field_size) {
+                SM2error(SM2_R_BIGNUM_OUT_OF_RANGE);
+                goto err;
+        }
+
+        BN_bn2bin(x2, x2y2 + field_size - x2size);
+        BN_bn2bin(y2, x2y2 + 2 * field_size - y2size);
+
+        if ((msg_mask = calloc(1, msg_len)) == NULL) {
+                SM2error(ERR_R_MALLOC_FAILURE);
+                goto err;
+        }
+
+        if (!sm2_kdf(msg_mask, msg_len, x2y2, 2 * field_size, digest)) {
+                SM2error(SM2_R_KDF_FAILURE);
+                goto err;
+        }
+
+        for (i = 0; i != msg_len; i++)
+                msg_mask[i] ^= msg[i];
+
+        if (!EVP_DigestInit(hash, digest)) {
+                SM2error(ERR_R_EVP_LIB);
+                goto err;
+        }
+
+        if (!EVP_DigestUpdate(hash, x2y2, field_size)) {
+                SM2error(ERR_R_EVP_LIB);
+                goto err;
+        }
+
+        if (!EVP_DigestUpdate(hash, msg, msg_len)) {
+                SM2error(ERR_R_EVP_LIB);
+                goto err;
+        }
+
+        if (!EVP_DigestUpdate(hash, x2y2 + field_size, field_size)) {
+                SM2error(ERR_R_EVP_LIB);
+                goto err;
+        }
+
+        if (!EVP_DigestFinal(hash, C3, NULL)) {
+                SM2error(ERR_R_EVP_LIB);
+                goto err;
+        }
+
+        ctext_struct.C1x = x1;
+        ctext_struct.C1y = y1;
+        if ((ctext_struct.C3 = ASN1_OCTET_STRING_new()) == NULL) {
+                SM2error(ERR_R_MALLOC_FAILURE);
+                goto err;
+        }
+        if ((ctext_struct.C2 = ASN1_OCTET_STRING_new()) == NULL) {
+                SM2error(ERR_R_MALLOC_FAILURE);
+                goto err;
+        }
+        if (!ASN1_OCTET_STRING_set(ctext_struct.C3, C3, C3_size)) {
+                SM2error(ERR_R_INTERNAL_ERROR);
+                goto err;
+        }
+        if (!ASN1_OCTET_STRING_set(ctext_struct.C2, msg_mask, msg_len)) {
+                SM2error(ERR_R_INTERNAL_ERROR);
+                goto err;
+        }
+
+        if ((clen = i2d_SM2_Ciphertext(&ctext_struct, &ciphertext_buf)) < 0) {
+                SM2error(ERR_R_INTERNAL_ERROR);
+                goto err;
+        }
+
+        *ciphertext_len = clen;
+        rc = 1;
+
+ err:
+        ASN1_OCTET_STRING_free(ctext_struct.C2);
+        ASN1_OCTET_STRING_free(ctext_struct.C3);
+        free(msg_mask);
+        free(x2y2);
+        free(C3);
+        EVP_MD_CTX_free(hash);
+        BN_CTX_end(ctx);
+        BN_CTX_free(ctx);
+        EC_POINT_free(kG);
+        EC_POINT_free(kP);
+        BN_free(order);
+        return rc;
+}
+
+int
+SM2_decrypt(const EC_KEY *key, const EVP_MD *digest, const uint8_t *ciphertext,
+    size_t ciphertext_len, uint8_t *ptext_buf, size_t *ptext_len)
+{
+        SM2_Ciphertext *sm2_ctext = NULL;
+        EVP_MD_CTX *hash = NULL;
+        BN_CTX *ctx = NULL;
+        BIGNUM *x2, *y2;
+        const EC_GROUP *group;
+        EC_POINT *C1 = NULL;
+        const uint8_t *C2, *C3;
+        uint8_t *computed_C3 = NULL, *msg_mask = NULL, *x2y2 = NULL;
+        size_t field_size, x2size, y2size;
+        int msg_len = 0, rc = 0;
+        int hash_size, i;
+
+        if ((group = EC_KEY_get0_group(key)) == NULL) {
+                SM2error(SM2_R_INVALID_KEY);
+                goto err;
+        }
+
+        if ((field_size = ec_field_size(group)) == 0) {
+                SM2error(SM2_R_INVALID_FIELD);
+                goto err;
+        }
+
+        if ((hash_size = EVP_MD_size(digest)) < 0) {
+                SM2error(SM2_R_INVALID_DIGEST);
+                goto err;
+        }
+
+        memset(ptext_buf, 0xFF, *ptext_len);
+
+        if ((sm2_ctext = d2i_SM2_Ciphertext(NULL, &ciphertext,
+            ciphertext_len)) == NULL) {
+                SM2error(SM2_R_ASN1_ERROR);
+                goto err;
+        }
+
+        if (sm2_ctext->C3->length != hash_size) {
+                SM2error(SM2_R_INVALID_ENCODING);
+                goto err;
+        }
+
+        C2 = sm2_ctext->C2->data;
+        C3 = sm2_ctext->C3->data;
+        msg_len = sm2_ctext->C2->length;
+
+        if ((ctx = BN_CTX_new()) == NULL) {
+                SM2error(ERR_R_MALLOC_FAILURE);
+                goto err;
+        }
+
+        BN_CTX_start(ctx);
+        if ((x2 = BN_CTX_get(ctx)) == NULL) {
+                SM2error(ERR_R_BN_LIB);
+                goto err;
+        }
+        if ((y2 = BN_CTX_get(ctx)) == NULL) {
+                SM2error(ERR_R_BN_LIB);
+                goto err;
+        }
+
+        if ((msg_mask = calloc(1, msg_len)) == NULL) {
+                SM2error(ERR_R_MALLOC_FAILURE);
+                goto err;
+        }
+        if ((x2y2 = calloc(2, field_size)) == NULL) {
+                SM2error(ERR_R_MALLOC_FAILURE);
+                goto err;
+        }
+        if ((computed_C3 = calloc(1, hash_size)) == NULL) {
+                SM2error(ERR_R_MALLOC_FAILURE);
+                goto err;
+        }
+
+        if ((C1 = EC_POINT_new(group)) == NULL) {
+                SM2error(ERR_R_MALLOC_FAILURE);
+                goto err;
+        }
+
+        if (!EC_POINT_set_affine_coordinates(group, C1, sm2_ctext->C1x,
+            sm2_ctext->C1y, ctx))
+        {
+                SM2error(ERR_R_EC_LIB);
+                goto err;
+        }
+
+        if (!EC_POINT_mul(group, C1, NULL, C1, EC_KEY_get0_private_key(key),
+            ctx)) {
+                SM2error(ERR_R_EC_LIB);
+                goto err;
+        }
+
+        if (!EC_POINT_get_affine_coordinates(group, C1, x2, y2, ctx)) {
+                SM2error(ERR_R_EC_LIB);
+                goto err;
+        }
+
+        if ((x2size = BN_num_bytes(x2)) > field_size ||
+            (y2size = BN_num_bytes(y2)) > field_size) {
+                SM2error(SM2_R_BIGNUM_OUT_OF_RANGE);
+                goto err;
+        }
+
+        BN_bn2bin(x2, x2y2 + field_size - x2size);
+        BN_bn2bin(y2, x2y2 + 2 * field_size - y2size);
+
+        if (!sm2_kdf(msg_mask, msg_len, x2y2, 2 * field_size, digest)) {
+                SM2error(SM2_R_KDF_FAILURE);
+                goto err;
+        }
+
+        for (i = 0; i != msg_len; ++i)
+                ptext_buf[i] = C2[i] ^ msg_mask[i];
+
+        if ((hash = EVP_MD_CTX_new()) == NULL) {
+                SM2error(ERR_R_EVP_LIB);
+                goto err;
+        }
+
+        if (!EVP_DigestInit(hash, digest)) {
+                SM2error(ERR_R_EVP_LIB);
+                goto err;
+        }
+
+        if (!EVP_DigestUpdate(hash, x2y2, field_size)) {
+                SM2error(ERR_R_EVP_LIB);
+                goto err;
+        }
+
+        if (!EVP_DigestUpdate(hash, ptext_buf, msg_len)) {
+                SM2error(ERR_R_EVP_LIB);
+                goto err;
+        }
+
+        if (!EVP_DigestUpdate(hash, x2y2 + field_size, field_size)) {
+                SM2error(ERR_R_EVP_LIB);
+                goto err;
+        }
+
+        if (!EVP_DigestFinal(hash, computed_C3, NULL)) {
+                SM2error(ERR_R_EVP_LIB);
+                goto err;
+        }
+
+        if (memcmp(computed_C3, C3, hash_size) != 0)
+                goto err;
+
+        rc = 1;
+        *ptext_len = msg_len;
+
+ err:
+        if (rc == 0)
+                memset(ptext_buf, 0, *ptext_len);
+
+        free(msg_mask);
+        free(x2y2);
+        free(computed_C3);
+        EC_POINT_free(C1);
+        BN_CTX_end(ctx);
+        BN_CTX_free(ctx);
+        SM2_Ciphertext_free(sm2_ctext);
+        EVP_MD_CTX_free(hash);
+
+        return rc;
+}
+
+#endif /* OPENSSL_NO_SM2 */