482 lines
10 KiB
C
482 lines
10 KiB
C
/* SPDX-License-Identifier: GPL-2.0-or-later */
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/*
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* SM2 asymmetric public-key algorithm
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* as specified by OSCCA GM/T 0003.1-2012 -- 0003.5-2012 SM2 and
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* described at https://tools.ietf.org/html/draft-shen-sm2-ecdsa-02
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*
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* Copyright (c) 2020, Alibaba Group.
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* Authors: Tianjia Zhang <tianjia.zhang@linux.alibaba.com>
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*/
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#include <linux/module.h>
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#include <linux/mpi.h>
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#include <crypto/internal/akcipher.h>
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#include <crypto/akcipher.h>
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#include <crypto/hash.h>
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#include <crypto/sm3_base.h>
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#include <crypto/rng.h>
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#include <crypto/sm2.h>
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#include "sm2signature.asn1.h"
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#define MPI_NBYTES(m) ((mpi_get_nbits(m) + 7) / 8)
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struct ecc_domain_parms {
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const char *desc; /* Description of the curve. */
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unsigned int nbits; /* Number of bits. */
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unsigned int fips:1; /* True if this is a FIPS140-2 approved curve */
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/* The model describing this curve. This is mainly used to select
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* the group equation.
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*/
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enum gcry_mpi_ec_models model;
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/* The actual ECC dialect used. This is used for curve specific
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* optimizations and to select encodings etc.
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*/
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enum ecc_dialects dialect;
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const char *p; /* The prime defining the field. */
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const char *a, *b; /* The coefficients. For Twisted Edwards
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* Curves b is used for d. For Montgomery
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* Curves (a,b) has ((A-2)/4,B^-1).
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*/
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const char *n; /* The order of the base point. */
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const char *g_x, *g_y; /* Base point. */
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unsigned int h; /* Cofactor. */
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};
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static const struct ecc_domain_parms sm2_ecp = {
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.desc = "sm2p256v1",
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.nbits = 256,
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.fips = 0,
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.model = MPI_EC_WEIERSTRASS,
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.dialect = ECC_DIALECT_STANDARD,
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.p = "0xfffffffeffffffffffffffffffffffffffffffff00000000ffffffffffffffff",
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.a = "0xfffffffeffffffffffffffffffffffffffffffff00000000fffffffffffffffc",
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.b = "0x28e9fa9e9d9f5e344d5a9e4bcf6509a7f39789f515ab8f92ddbcbd414d940e93",
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.n = "0xfffffffeffffffffffffffffffffffff7203df6b21c6052b53bbf40939d54123",
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.g_x = "0x32c4ae2c1f1981195f9904466a39c9948fe30bbff2660be1715a4589334c74c7",
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.g_y = "0xbc3736a2f4f6779c59bdcee36b692153d0a9877cc62a474002df32e52139f0a0",
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.h = 1
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};
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static int sm2_ec_ctx_init(struct mpi_ec_ctx *ec)
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{
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const struct ecc_domain_parms *ecp = &sm2_ecp;
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MPI p, a, b;
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MPI x, y;
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int rc = -EINVAL;
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p = mpi_scanval(ecp->p);
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a = mpi_scanval(ecp->a);
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b = mpi_scanval(ecp->b);
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if (!p || !a || !b)
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goto free_p;
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x = mpi_scanval(ecp->g_x);
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y = mpi_scanval(ecp->g_y);
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if (!x || !y)
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goto free;
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rc = -ENOMEM;
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/* mpi_ec_setup_elliptic_curve */
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ec->G = mpi_point_new(0);
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if (!ec->G)
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goto free;
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mpi_set(ec->G->x, x);
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mpi_set(ec->G->y, y);
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mpi_set_ui(ec->G->z, 1);
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rc = -EINVAL;
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ec->n = mpi_scanval(ecp->n);
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if (!ec->n) {
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mpi_point_release(ec->G);
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goto free;
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}
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ec->h = ecp->h;
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ec->name = ecp->desc;
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mpi_ec_init(ec, ecp->model, ecp->dialect, 0, p, a, b);
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rc = 0;
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free:
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mpi_free(x);
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mpi_free(y);
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free_p:
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mpi_free(p);
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mpi_free(a);
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mpi_free(b);
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return rc;
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}
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static void sm2_ec_ctx_deinit(struct mpi_ec_ctx *ec)
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{
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mpi_ec_deinit(ec);
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memset(ec, 0, sizeof(*ec));
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}
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static int sm2_ec_ctx_reset(struct mpi_ec_ctx *ec)
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{
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sm2_ec_ctx_deinit(ec);
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return sm2_ec_ctx_init(ec);
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}
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/* RESULT must have been initialized and is set on success to the
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* point given by VALUE.
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*/
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static int sm2_ecc_os2ec(MPI_POINT result, MPI value)
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{
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int rc;
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size_t n;
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const unsigned char *buf;
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unsigned char *buf_memory;
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MPI x, y;
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n = (mpi_get_nbits(value)+7)/8;
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buf_memory = kmalloc(n, GFP_KERNEL);
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rc = mpi_print(GCRYMPI_FMT_USG, buf_memory, n, &n, value);
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if (rc) {
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kfree(buf_memory);
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return rc;
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}
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buf = buf_memory;
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if (n < 1) {
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kfree(buf_memory);
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return -EINVAL;
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}
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if (*buf != 4) {
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kfree(buf_memory);
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return -EINVAL; /* No support for point compression. */
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}
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if (((n-1)%2)) {
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kfree(buf_memory);
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return -EINVAL;
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}
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n = (n-1)/2;
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x = mpi_read_raw_data(buf + 1, n);
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if (!x) {
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kfree(buf_memory);
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return -ENOMEM;
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}
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y = mpi_read_raw_data(buf + 1 + n, n);
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kfree(buf_memory);
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if (!y) {
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mpi_free(x);
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return -ENOMEM;
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}
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mpi_normalize(x);
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mpi_normalize(y);
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mpi_set(result->x, x);
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mpi_set(result->y, y);
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mpi_set_ui(result->z, 1);
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mpi_free(x);
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mpi_free(y);
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return 0;
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}
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struct sm2_signature_ctx {
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MPI sig_r;
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MPI sig_s;
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};
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int sm2_get_signature_r(void *context, size_t hdrlen, unsigned char tag,
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const void *value, size_t vlen)
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{
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struct sm2_signature_ctx *sig = context;
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if (!value || !vlen)
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return -EINVAL;
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sig->sig_r = mpi_read_raw_data(value, vlen);
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if (!sig->sig_r)
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return -ENOMEM;
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return 0;
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}
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int sm2_get_signature_s(void *context, size_t hdrlen, unsigned char tag,
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const void *value, size_t vlen)
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{
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struct sm2_signature_ctx *sig = context;
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if (!value || !vlen)
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return -EINVAL;
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sig->sig_s = mpi_read_raw_data(value, vlen);
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if (!sig->sig_s)
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return -ENOMEM;
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return 0;
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}
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static int sm2_z_digest_update(struct shash_desc *desc,
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MPI m, unsigned int pbytes)
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{
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static const unsigned char zero[32];
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unsigned char *in;
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unsigned int inlen;
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in = mpi_get_buffer(m, &inlen, NULL);
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if (!in)
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return -EINVAL;
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if (inlen < pbytes) {
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/* padding with zero */
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crypto_sm3_update(desc, zero, pbytes - inlen);
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crypto_sm3_update(desc, in, inlen);
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} else if (inlen > pbytes) {
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/* skip the starting zero */
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crypto_sm3_update(desc, in + inlen - pbytes, pbytes);
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} else {
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crypto_sm3_update(desc, in, inlen);
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}
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kfree(in);
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return 0;
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}
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static int sm2_z_digest_update_point(struct shash_desc *desc,
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MPI_POINT point, struct mpi_ec_ctx *ec, unsigned int pbytes)
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{
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MPI x, y;
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int ret = -EINVAL;
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x = mpi_new(0);
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y = mpi_new(0);
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if (!mpi_ec_get_affine(x, y, point, ec) &&
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!sm2_z_digest_update(desc, x, pbytes) &&
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!sm2_z_digest_update(desc, y, pbytes))
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ret = 0;
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mpi_free(x);
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mpi_free(y);
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return ret;
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}
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int sm2_compute_z_digest(struct crypto_akcipher *tfm,
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const unsigned char *id, size_t id_len,
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unsigned char dgst[SM3_DIGEST_SIZE])
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{
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struct mpi_ec_ctx *ec = akcipher_tfm_ctx(tfm);
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uint16_t bits_len;
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unsigned char entl[2];
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SHASH_DESC_ON_STACK(desc, NULL);
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unsigned int pbytes;
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if (id_len > (USHRT_MAX / 8) || !ec->Q)
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return -EINVAL;
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bits_len = (uint16_t)(id_len * 8);
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entl[0] = bits_len >> 8;
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entl[1] = bits_len & 0xff;
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pbytes = MPI_NBYTES(ec->p);
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/* ZA = H256(ENTLA | IDA | a | b | xG | yG | xA | yA) */
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sm3_base_init(desc);
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crypto_sm3_update(desc, entl, 2);
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crypto_sm3_update(desc, id, id_len);
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if (sm2_z_digest_update(desc, ec->a, pbytes) ||
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sm2_z_digest_update(desc, ec->b, pbytes) ||
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sm2_z_digest_update_point(desc, ec->G, ec, pbytes) ||
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sm2_z_digest_update_point(desc, ec->Q, ec, pbytes))
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return -EINVAL;
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crypto_sm3_final(desc, dgst);
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return 0;
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}
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EXPORT_SYMBOL(sm2_compute_z_digest);
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static int _sm2_verify(struct mpi_ec_ctx *ec, MPI hash, MPI sig_r, MPI sig_s)
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{
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int rc = -EINVAL;
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struct gcry_mpi_point sG, tP;
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MPI t = NULL;
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MPI x1 = NULL, y1 = NULL;
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mpi_point_init(&sG);
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mpi_point_init(&tP);
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x1 = mpi_new(0);
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y1 = mpi_new(0);
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t = mpi_new(0);
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/* r, s in [1, n-1] */
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if (mpi_cmp_ui(sig_r, 1) < 0 || mpi_cmp(sig_r, ec->n) > 0 ||
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mpi_cmp_ui(sig_s, 1) < 0 || mpi_cmp(sig_s, ec->n) > 0) {
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goto leave;
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}
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/* t = (r + s) % n, t == 0 */
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mpi_addm(t, sig_r, sig_s, ec->n);
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if (mpi_cmp_ui(t, 0) == 0)
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goto leave;
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/* sG + tP = (x1, y1) */
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rc = -EBADMSG;
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mpi_ec_mul_point(&sG, sig_s, ec->G, ec);
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mpi_ec_mul_point(&tP, t, ec->Q, ec);
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mpi_ec_add_points(&sG, &sG, &tP, ec);
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if (mpi_ec_get_affine(x1, y1, &sG, ec))
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goto leave;
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/* R = (e + x1) % n */
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mpi_addm(t, hash, x1, ec->n);
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/* check R == r */
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rc = -EKEYREJECTED;
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if (mpi_cmp(t, sig_r))
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goto leave;
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rc = 0;
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leave:
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mpi_point_free_parts(&sG);
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mpi_point_free_parts(&tP);
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mpi_free(x1);
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mpi_free(y1);
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mpi_free(t);
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return rc;
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}
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static int sm2_verify(struct akcipher_request *req)
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{
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struct crypto_akcipher *tfm = crypto_akcipher_reqtfm(req);
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struct mpi_ec_ctx *ec = akcipher_tfm_ctx(tfm);
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unsigned char *buffer;
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struct sm2_signature_ctx sig;
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MPI hash;
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int ret;
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if (unlikely(!ec->Q))
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return -EINVAL;
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buffer = kmalloc(req->src_len + req->dst_len, GFP_KERNEL);
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if (!buffer)
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return -ENOMEM;
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sg_pcopy_to_buffer(req->src,
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sg_nents_for_len(req->src, req->src_len + req->dst_len),
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buffer, req->src_len + req->dst_len, 0);
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sig.sig_r = NULL;
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sig.sig_s = NULL;
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ret = asn1_ber_decoder(&sm2signature_decoder, &sig,
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buffer, req->src_len);
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if (ret)
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goto error;
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ret = -ENOMEM;
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hash = mpi_read_raw_data(buffer + req->src_len, req->dst_len);
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if (!hash)
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goto error;
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ret = _sm2_verify(ec, hash, sig.sig_r, sig.sig_s);
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mpi_free(hash);
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error:
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mpi_free(sig.sig_r);
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mpi_free(sig.sig_s);
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kfree(buffer);
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return ret;
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}
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static int sm2_set_pub_key(struct crypto_akcipher *tfm,
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const void *key, unsigned int keylen)
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{
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struct mpi_ec_ctx *ec = akcipher_tfm_ctx(tfm);
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MPI a;
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int rc;
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rc = sm2_ec_ctx_reset(ec);
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if (rc)
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return rc;
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ec->Q = mpi_point_new(0);
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if (!ec->Q)
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return -ENOMEM;
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/* include the uncompressed flag '0x04' */
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rc = -ENOMEM;
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a = mpi_read_raw_data(key, keylen);
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if (!a)
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goto error;
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mpi_normalize(a);
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rc = sm2_ecc_os2ec(ec->Q, a);
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mpi_free(a);
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if (rc)
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goto error;
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return 0;
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error:
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mpi_point_release(ec->Q);
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ec->Q = NULL;
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return rc;
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}
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static unsigned int sm2_max_size(struct crypto_akcipher *tfm)
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{
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/* Unlimited max size */
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return PAGE_SIZE;
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}
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static int sm2_init_tfm(struct crypto_akcipher *tfm)
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{
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struct mpi_ec_ctx *ec = akcipher_tfm_ctx(tfm);
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return sm2_ec_ctx_init(ec);
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}
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static void sm2_exit_tfm(struct crypto_akcipher *tfm)
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{
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struct mpi_ec_ctx *ec = akcipher_tfm_ctx(tfm);
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sm2_ec_ctx_deinit(ec);
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}
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static struct akcipher_alg sm2 = {
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.verify = sm2_verify,
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.set_pub_key = sm2_set_pub_key,
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.max_size = sm2_max_size,
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.init = sm2_init_tfm,
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.exit = sm2_exit_tfm,
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.base = {
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.cra_name = "sm2",
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.cra_driver_name = "sm2-generic",
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.cra_priority = 100,
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.cra_module = THIS_MODULE,
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.cra_ctxsize = sizeof(struct mpi_ec_ctx),
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},
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};
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static int sm2_init(void)
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{
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return crypto_register_akcipher(&sm2);
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}
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static void sm2_exit(void)
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{
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crypto_unregister_akcipher(&sm2);
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}
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subsys_initcall(sm2_init);
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module_exit(sm2_exit);
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MODULE_LICENSE("GPL");
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MODULE_AUTHOR("Tianjia Zhang <tianjia.zhang@linux.alibaba.com>");
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MODULE_DESCRIPTION("SM2 generic algorithm");
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MODULE_ALIAS_CRYPTO("sm2-generic");
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