sm4_generic.c

// SPDX-License-Identifier: GPL-2.0

/*
 * SM4 Cipher Algorithm.
 *
 * Copyright (C) 2018 ARM Limited or its affiliates.
 * All rights reserved.
 */

#include <crypto/sm4.h>
#include <linux/module.h>
#include <linux/init.h>
#include <linux/types.h>
#include <linux/errno.h>
#include <linux/crypto.h>
#include <asm/byteorder.h>
#include <asm/unaligned.h>

static const u32 fk[4] = {
	0xa3b1bac6, 0x56aa3350, 0x677d9197, 0xb27022dc
};

static const u8 sbox[256] = {
	0xd6, 0x90, 0xe9, 0xfe, 0xcc, 0xe1, 0x3d, 0xb7,
	0x16, 0xb6, 0x14, 0xc2, 0x28, 0xfb, 0x2c, 0x05,
	0x2b, 0x67, 0x9a, 0x76, 0x2a, 0xbe, 0x04, 0xc3,
	0xaa, 0x44, 0x13, 0x26, 0x49, 0x86, 0x06, 0x99,
	0x9c, 0x42, 0x50, 0xf4, 0x91, 0xef, 0x98, 0x7a,
	0x33, 0x54, 0x0b, 0x43, 0xed, 0xcf, 0xac, 0x62,
	0xe4, 0xb3, 0x1c, 0xa9, 0xc9, 0x08, 0xe8, 0x95,
	0x80, 0xdf, 0x94, 0xfa, 0x75, 0x8f, 0x3f, 0xa6,
	0x47, 0x07, 0xa7, 0xfc, 0xf3, 0x73, 0x17, 0xba,
	0x83, 0x59, 0x3c, 0x19, 0xe6, 0x85, 0x4f, 0xa8,
	0x68, 0x6b, 0x81, 0xb2, 0x71, 0x64, 0xda, 0x8b,
	0xf8, 0xeb, 0x0f, 0x4b, 0x70, 0x56, 0x9d, 0x35,
	0x1e, 0x24, 0x0e, 0x5e, 0x63, 0x58, 0xd1, 0xa2,
	0x25, 0x22, 0x7c, 0x3b, 0x01, 0x21, 0x78, 0x87,
	0xd4, 0x00, 0x46, 0x57, 0x9f, 0xd3, 0x27, 0x52,
	0x4c, 0x36, 0x02, 0xe7, 0xa0, 0xc4, 0xc8, 0x9e,
	0xea, 0xbf, 0x8a, 0xd2, 0x40, 0xc7, 0x38, 0xb5,
	0xa3, 0xf7, 0xf2, 0xce, 0xf9, 0x61, 0x15, 0xa1,
	0xe0, 0xae, 0x5d, 0xa4, 0x9b, 0x34, 0x1a, 0x55,
	0xad, 0x93, 0x32, 0x30, 0xf5, 0x8c, 0xb1, 0xe3,
	0x1d, 0xf6, 0xe2, 0x2e, 0x82, 0x66, 0xca, 0x60,
	0xc0, 0x29, 0x23, 0xab, 0x0d, 0x53, 0x4e, 0x6f,
	0xd5, 0xdb, 0x37, 0x45, 0xde, 0xfd, 0x8e, 0x2f,
	0x03, 0xff, 0x6a, 0x72, 0x6d, 0x6c, 0x5b, 0x51,
	0x8d, 0x1b, 0xaf, 0x92, 0xbb, 0xdd, 0xbc, 0x7f,
	0x11, 0xd9, 0x5c, 0x41, 0x1f, 0x10, 0x5a, 0xd8,
	0x0a, 0xc1, 0x31, 0x88, 0xa5, 0xcd, 0x7b, 0xbd,
	0x2d, 0x74, 0xd0, 0x12, 0xb8, 0xe5, 0xb4, 0xb0,
	0x89, 0x69, 0x97, 0x4a, 0x0c, 0x96, 0x77, 0x7e,
	0x65, 0xb9, 0xf1, 0x09, 0xc5, 0x6e, 0xc6, 0x84,
	0x18, 0xf0, 0x7d, 0xec, 0x3a, 0xdc, 0x4d, 0x20,
	0x79, 0xee, 0x5f, 0x3e, 0xd7, 0xcb, 0x39, 0x48
};

static const u32 ck[] = {
	0x00070e15, 0x1c232a31, 0x383f464d, 0x545b6269,
	0x70777e85, 0x8c939aa1, 0xa8afb6bd, 0xc4cbd2d9,
	0xe0e7eef5, 0xfc030a11, 0x181f262d, 0x343b4249,
	0x50575e65, 0x6c737a81, 0x888f969d, 0xa4abb2b9,
	0xc0c7ced5, 0xdce3eaf1, 0xf8ff060d, 0x141b2229,
	0x30373e45, 0x4c535a61, 0x686f767d, 0x848b9299,
	0xa0a7aeb5, 0xbcc3cad1, 0xd8dfe6ed, 0xf4fb0209,
	0x10171e25, 0x2c333a41, 0x484f565d, 0x646b7279
};

static u32 sm4_t_non_lin_sub(u32 x)
{
	int i;
	u8 *b = (u8 *)&x;

	for (i = 0; i < 4; ++i)
		b[i] = sbox[b[i]];

	return x;
}

static u32 sm4_key_lin_sub(u32 x)
{
	return x ^ rol32(x, 13) ^ rol32(x, 23);

}

static u32 sm4_enc_lin_sub(u32 x)
{
	return x ^ rol32(x, 2) ^ rol32(x, 10) ^ rol32(x, 18) ^ rol32(x, 24);
}

static u32 sm4_key_sub(u32 x)
{
	return sm4_key_lin_sub(sm4_t_non_lin_sub(x));
}

static u32 sm4_enc_sub(u32 x)
{
	return sm4_enc_lin_sub(sm4_t_non_lin_sub(x));
}

static u32 sm4_round(const u32 *x, const u32 rk)
{
	return x[0] ^ sm4_enc_sub(x[1] ^ x[2] ^ x[3] ^ rk);
}


/**
 * crypto_sm4_expand_key - Expands the SM4 key as described in GB/T 32907-2016
 * @ctx:	The location where the computed key will be stored.
 * @in_key:	The supplied key.
 * @key_len:	The length of the supplied key.
 *
 * Returns 0 on success. The function fails only if an invalid key size (or
 * pointer) is supplied.
 */
int crypto_sm4_expand_key(struct crypto_sm4_ctx *ctx, const u8 *in_key,
			  unsigned int key_len)
{
	u32 rk[4], t;
	const u32 *key = (u32 *)in_key;
	int i;

	if (key_len != SM4_KEY_SIZE)
		return -EINVAL;

	for (i = 0; i < 4; ++i)
		rk[i] = get_unaligned_be32(&key[i]) ^ fk[i];

	for (i = 0; i < 32; ++i) {
		t = rk[0] ^ sm4_key_sub(rk[1] ^ rk[2] ^ rk[3] ^ ck[i]);
		ctx->rkey_enc[i] = t;
		rk[0] = rk[1];
		rk[1] = rk[2];
		rk[2] = rk[3];
		rk[3] = t;
	}

	for (i = 0; i < 32; ++i)
		ctx->rkey_dec[i] = ctx->rkey_enc[31 - i];

	return 0;
}
EXPORT_SYMBOL_GPL(crypto_sm4_expand_key);

/**
 * crypto_sm4_set_key - Set the AES key.
 * @tfm:	The %crypto_tfm that is used in the context.
 * @in_key:	The input key.
 * @key_len:	The size of the key.
 *
 * Returns 0 on success, on failure the %CRYPTO_TFM_RES_BAD_KEY_LEN flag in tfm
 * is set. The function uses crypto_sm4_expand_key() to expand the key.
 * &crypto_sm4_ctx _must_ be the private data embedded in @tfm which is
 * retrieved with crypto_tfm_ctx().
 */
int crypto_sm4_set_key(struct crypto_tfm *tfm, const u8 *in_key,
		       unsigned int key_len)
{
	struct crypto_sm4_ctx *ctx = crypto_tfm_ctx(tfm);
	u32 *flags = &tfm->crt_flags;
	int ret;

	ret = crypto_sm4_expand_key(ctx, in_key, key_len);
	if (!ret)
		return 0;

	*flags |= CRYPTO_TFM_RES_BAD_KEY_LEN;
	return -EINVAL;
}
EXPORT_SYMBOL_GPL(crypto_sm4_set_key);

static void sm4_do_crypt(const u32 *rk, u32 *out, const u32 *in)
{
	u32 x[4], i, t;

	for (i = 0; i < 4; ++i)
		x[i] = get_unaligned_be32(&in[i]);

	for (i = 0; i < 32; ++i) {
		t = sm4_round(x, rk[i]);
		x[0] = x[1];
		x[1] = x[2];
		x[2] = x[3];
		x[3] = t;
	}

	for (i = 0; i < 4; ++i)
		put_unaligned_be32(x[3 - i], &out[i]);
}

/* encrypt a block of text */

void crypto_sm4_encrypt(struct crypto_tfm *tfm, u8 *out, const u8 *in)
{
	const struct crypto_sm4_ctx *ctx = crypto_tfm_ctx(tfm);

	sm4_do_crypt(ctx->rkey_enc, (u32 *)out, (u32 *)in);
}
EXPORT_SYMBOL_GPL(crypto_sm4_encrypt);

/* decrypt a block of text */

void crypto_sm4_decrypt(struct crypto_tfm *tfm, u8 *out, const u8 *in)
{
	const struct crypto_sm4_ctx *ctx = crypto_tfm_ctx(tfm);

	sm4_do_crypt(ctx->rkey_dec, (u32 *)out, (u32 *)in);
}
EXPORT_SYMBOL_GPL(crypto_sm4_decrypt);

static struct crypto_alg sm4_alg = {
	.cra_name		=	"sm4",
	.cra_driver_name	=	"sm4-generic",
	.cra_priority		=	100,
	.cra_flags		=	CRYPTO_ALG_TYPE_CIPHER,
	.cra_blocksize		=	SM4_BLOCK_SIZE,
	.cra_ctxsize		=	sizeof(struct crypto_sm4_ctx),
	.cra_module		=	THIS_MODULE,
	.cra_u			=	{
		.cipher = {
			.cia_min_keysize	=	SM4_KEY_SIZE,
			.cia_max_keysize	=	SM4_KEY_SIZE,
			.cia_setkey		=	crypto_sm4_set_key,
			.cia_encrypt		=	crypto_sm4_encrypt,
			.cia_decrypt		=	crypto_sm4_decrypt
		}
	}
};

static int __init sm4_init(void)
{
	return crypto_register_alg(&sm4_alg);
}

static void __exit sm4_fini(void)
{
	crypto_unregister_alg(&sm4_alg);
}

subsys_initcall(sm4_init);
module_exit(sm4_fini);

MODULE_DESCRIPTION("SM4 Cipher Algorithm");
MODULE_LICENSE("GPL v2");
MODULE_ALIAS_CRYPTO("sm4");
MODULE_ALIAS_CRYPTO("sm4-generic");