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linux/crypto/aes_ti.c
Ard Biesheuvel e59c1c9874 crypto: aes - create AES library based on the fixed time AES code
Take the existing small footprint and mostly time invariant C code
and turn it into a AES library that can be used for non-performance
critical, casual use of AES, 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 (e.g., in hard interrupts taken from kernel
context)

Signed-off-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
2019-07-26 14:55:33 +10:00

84 lines
2.0 KiB
C

// SPDX-License-Identifier: GPL-2.0-only
/*
* Scalar fixed time AES core transform
*
* Copyright (C) 2017 Linaro Ltd <ard.biesheuvel@linaro.org>
*/
#include <crypto/aes.h>
#include <linux/crypto.h>
#include <linux/module.h>
static int aesti_set_key(struct crypto_tfm *tfm, const u8 *in_key,
unsigned int key_len)
{
struct crypto_aes_ctx *ctx = crypto_tfm_ctx(tfm);
return aes_expandkey(ctx, in_key, key_len);
}
static void aesti_encrypt(struct crypto_tfm *tfm, u8 *out, const u8 *in)
{
const struct crypto_aes_ctx *ctx = crypto_tfm_ctx(tfm);
unsigned long flags;
/*
* Temporarily disable interrupts to avoid races where cachelines are
* evicted when the CPU is interrupted to do something else.
*/
local_irq_save(flags);
aes_encrypt(ctx, out, in);
local_irq_restore(flags);
}
static void aesti_decrypt(struct crypto_tfm *tfm, u8 *out, const u8 *in)
{
const struct crypto_aes_ctx *ctx = crypto_tfm_ctx(tfm);
unsigned long flags;
/*
* Temporarily disable interrupts to avoid races where cachelines are
* evicted when the CPU is interrupted to do something else.
*/
local_irq_save(flags);
aes_decrypt(ctx, out, in);
local_irq_restore(flags);
}
static struct crypto_alg aes_alg = {
.cra_name = "aes",
.cra_driver_name = "aes-fixed-time",
.cra_priority = 100 + 1,
.cra_flags = CRYPTO_ALG_TYPE_CIPHER,
.cra_blocksize = AES_BLOCK_SIZE,
.cra_ctxsize = sizeof(struct crypto_aes_ctx),
.cra_module = THIS_MODULE,
.cra_cipher.cia_min_keysize = AES_MIN_KEY_SIZE,
.cra_cipher.cia_max_keysize = AES_MAX_KEY_SIZE,
.cra_cipher.cia_setkey = aesti_set_key,
.cra_cipher.cia_encrypt = aesti_encrypt,
.cra_cipher.cia_decrypt = aesti_decrypt
};
static int __init aes_init(void)
{
return crypto_register_alg(&aes_alg);
}
static void __exit aes_fini(void)
{
crypto_unregister_alg(&aes_alg);
}
module_init(aes_init);
module_exit(aes_fini);
MODULE_DESCRIPTION("Generic fixed time AES");
MODULE_AUTHOR("Ard Biesheuvel <ard.biesheuvel@linaro.org>");
MODULE_LICENSE("GPL v2");