crypto: sm4 - create SM4 library based on sm4 generic code

Take the existing small footprint and mostly time invariant C code
and turn it into a SM4 library that can be used for non-performance
critical, casual use of SM4, and as a fallback for, e.g., SIMD code
that needs a secondary path that can be taken in contexts where the
SIMD unit is off limits.

Secondly, some codes have been optimized, such as unrolling small
times loop, removing unnecessary memory shifts, exporting sbox, fk,
ck arrays, and basic encryption and decryption functions.

Signed-off-by: Tianjia Zhang <[e-mail]>
Signed-off-by: Herbert Xu <[e-mail]>

crypto/Kconfig

···
 config CRYPTO_SM4
 	tristate "SM4 cipher algorithm"
 	select CRYPTO_ALGAPI
+	select CRYPTO_LIB_SM4
 	help
 	  SM4 cipher algorithms (OSCCA GB/T 32907-2016).
 

crypto/sm4_generic.c

···
 #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 SM4 key.
  * @tfm:	The %crypto_tfm that is used in the context.
  * @in_key:	The input key.
  * @key_len:	The size of the key.
  *
- * This function uses crypto_sm4_expand_key() to expand the key.
+ * This function uses sm4_expandkey() to expand the key.
  * &crypto_sm4_ctx _must_ be the private data embedded in @tfm which is
  * retrieved with crypto_tfm_ctx().
  *
···
 {
 	struct crypto_sm4_ctx *ctx = crypto_tfm_ctx(tfm);
 
-	return crypto_sm4_expand_key(ctx, in_key, key_len);
+	return sm4_expandkey(ctx, in_key, key_len);
 }
 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 */
 
···
 {
 	const struct crypto_sm4_ctx *ctx = crypto_tfm_ctx(tfm);
 
-	sm4_do_crypt(ctx->rkey_enc, (u32 *)out, (u32 *)in);
+	sm4_crypt_block(ctx->rkey_enc, out, in);
 }
 EXPORT_SYMBOL_GPL(crypto_sm4_encrypt);
 
···
 {
 	const struct crypto_sm4_ctx *ctx = crypto_tfm_ctx(tfm);
 
-	sm4_do_crypt(ctx->rkey_dec, (u32 *)out, (u32 *)in);
+	sm4_crypt_block(ctx->rkey_dec, out, in);
 }
 EXPORT_SYMBOL_GPL(crypto_sm4_decrypt);
 

include/crypto/sm4.h

···
 /*
  * Common values for the SM4 algorithm
  * Copyright (C) 2018 ARM Limited or its affiliates.
+ * Copyright (c) 2021 Tianjia Zhang <[e-mail]>
  */
 
 #ifndef _CRYPTO_SM4_H
···
 	u32 rkey_dec[SM4_RKEY_WORDS];
 };
 
-int crypto_sm4_set_key(struct crypto_tfm *tfm, const u8 *in_key,
-		       unsigned int key_len);
-int crypto_sm4_expand_key(struct crypto_sm4_ctx *ctx, const u8 *in_key,
+/**
+ * sm4_expandkey - 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 sm4_expandkey(struct crypto_sm4_ctx *ctx, const u8 *in_key,
 			  unsigned int key_len);
 
+/**
+ * sm4_crypt_block - Encrypt or decrypt a single SM4 block
+ * @rk:		The rkey_enc for encrypt or rkey_dec for decrypt
+ * @out:	Buffer to store output data
+ * @in: 	Buffer containing the input data
+ */
+void sm4_crypt_block(const u32 *rk, u8 *out, const u8 *in);
+
+int crypto_sm4_set_key(struct crypto_tfm *tfm, const u8 *in_key,
+		       unsigned int key_len);
 void crypto_sm4_encrypt(struct crypto_tfm *tfm, u8 *out, const u8 *in);
 void crypto_sm4_decrypt(struct crypto_tfm *tfm, u8 *out, const u8 *in);
 

lib/crypto/Kconfig

···
 
 config CRYPTO_LIB_SHA256
 	tristate
+
+config CRYPTO_LIB_SM4
+	tristate

lib/crypto/Makefile

···
 obj-$(CONFIG_CRYPTO_LIB_SHA256)			+= libsha256.o
 libsha256-y					:= sha256.o
 
+obj-$(CONFIG_CRYPTO_LIB_SM4)			+= libsm4.o
+libsm4-y					:= sm4.o
+
 ifneq ($(CONFIG_CRYPTO_MANAGER_DISABLE_TESTS),y)
 libblake2s-y					+= blake2s-selftest.o
 libchacha20poly1305-y				+= chacha20poly1305-selftest.o

lib/crypto/sm4.c

···
+/* SPDX-License-Identifier: GPL-2.0-or-later */
+/*
+ * SM4, as specified in
+ * https://tools.ietf.org/id/draft-ribose-cfrg-sm4-10.html
+ *
+ * Copyright (C) 2018 ARM Limited or its affiliates.
+ * Copyright (c) 2021 Tianjia Zhang <[e-mail]>
+ */
+
+#include <linux/module.h>
+#include <asm/unaligned.h>
+#include <crypto/sm4.h>
+
+static const u32 fk[4] = {
+	0xa3b1bac6, 0x56aa3350, 0x677d9197, 0xb27022dc
+};
+
+static const u32 __cacheline_aligned ck[32] = {
+	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 const u8 __cacheline_aligned 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 inline u32 sm4_t_non_lin_sub(u32 x)
+{
+	u32 out;
+
+	out  = (u32)sbox[x & 0xff];
+	out |= (u32)sbox[(x >> 8) & 0xff] << 8;
+	out |= (u32)sbox[(x >> 16) & 0xff] << 16;
+	out |= (u32)sbox[(x >> 24) & 0xff] << 24;
+
+	return out;
+}
+
+static inline u32 sm4_key_lin_sub(u32 x)
+{
+	return x ^ rol32(x, 13) ^ rol32(x, 23);
+}
+
+static inline u32 sm4_enc_lin_sub(u32 x)
+{
+	return x ^ rol32(x, 2) ^ rol32(x, 10) ^ rol32(x, 18) ^ rol32(x, 24);
+}
+
+static inline u32 sm4_key_sub(u32 x)
+{
+	return sm4_key_lin_sub(sm4_t_non_lin_sub(x));
+}
+
+static inline u32 sm4_enc_sub(u32 x)
+{
+	return sm4_enc_lin_sub(sm4_t_non_lin_sub(x));
+}
+
+static inline u32 sm4_round(u32 x0, u32 x1, u32 x2, u32 x3, u32 rk)
+{
+	return x0 ^ sm4_enc_sub(x1 ^ x2 ^ x3 ^ rk);
+}
+
+
+/**
+ * sm4_expandkey - 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 sm4_expandkey(struct crypto_sm4_ctx *ctx, const u8 *in_key,
+			  unsigned int key_len)
+{
+	u32 rk[4];
+	const u32 *key = (u32 *)in_key;
+	int i;
+
+	if (key_len != SM4_KEY_SIZE)
+		return -EINVAL;
+
+	rk[0] = get_unaligned_be32(&key[0]) ^ fk[0];
+	rk[1] = get_unaligned_be32(&key[1]) ^ fk[1];
+	rk[2] = get_unaligned_be32(&key[2]) ^ fk[2];
+	rk[3] = get_unaligned_be32(&key[3]) ^ fk[3];
+
+	for (i = 0; i < 32; i += 4) {
+		rk[0] ^= sm4_key_sub(rk[1] ^ rk[2] ^ rk[3] ^ ck[i + 0]);
+		rk[1] ^= sm4_key_sub(rk[2] ^ rk[3] ^ rk[0] ^ ck[i + 1]);
+		rk[2] ^= sm4_key_sub(rk[3] ^ rk[0] ^ rk[1] ^ ck[i + 2]);
+		rk[3] ^= sm4_key_sub(rk[0] ^ rk[1] ^ rk[2] ^ ck[i + 3]);
+
+		ctx->rkey_enc[i + 0] = rk[0];
+		ctx->rkey_enc[i + 1] = rk[1];
+		ctx->rkey_enc[i + 2] = rk[2];
+		ctx->rkey_enc[i + 3] = rk[3];
+		ctx->rkey_dec[31 - 0 - i] = rk[0];
+		ctx->rkey_dec[31 - 1 - i] = rk[1];
+		ctx->rkey_dec[31 - 2 - i] = rk[2];
+		ctx->rkey_dec[31 - 3 - i] = rk[3];
+	}
+
+	return 0;
+}
+EXPORT_SYMBOL_GPL(sm4_expandkey);
+
+/**
+ * sm4_crypt_block - Encrypt or decrypt a single SM4 block
+ * @rk:		The rkey_enc for encrypt or rkey_dec for decrypt
+ * @out:	Buffer to store output data
+ * @in: 	Buffer containing the input data
+ */
+void sm4_crypt_block(const u32 *rk, u8 *out, const u8 *in)
+{
+	u32 x[4], i;
+
+	x[0] = get_unaligned_be32(in + 0 * 4);
+	x[1] = get_unaligned_be32(in + 1 * 4);
+	x[2] = get_unaligned_be32(in + 2 * 4);
+	x[3] = get_unaligned_be32(in + 3 * 4);
+
+	for (i = 0; i < 32; i += 4) {
+		x[0] = sm4_round(x[0], x[1], x[2], x[3], rk[i + 0]);
+		x[1] = sm4_round(x[1], x[2], x[3], x[0], rk[i + 1]);
+		x[2] = sm4_round(x[2], x[3], x[0], x[1], rk[i + 2]);
+		x[3] = sm4_round(x[3], x[0], x[1], x[2], rk[i + 3]);
+	}
+
+	put_unaligned_be32(x[3 - 0], out + 0 * 4);
+	put_unaligned_be32(x[3 - 1], out + 1 * 4);
+	put_unaligned_be32(x[3 - 2], out + 2 * 4);
+	put_unaligned_be32(x[3 - 3], out + 3 * 4);
+}
+EXPORT_SYMBOL_GPL(sm4_crypt_block);
+
+MODULE_DESCRIPTION("Generic SM4 library");
+MODULE_LICENSE("GPL v2");