Commit ee772cb6 authored by Ard Biesheuvel's avatar Ard Biesheuvel Committed by Herbert Xu
Browse files

crypto: curve25519 - implement generic KPP driver 



Expose the generic Curve25519 library via the crypto API KPP interface.

Signed-off-by: default avatarArd Biesheuvel <ardb@kernel.org>
Signed-off-by: default avatarHerbert Xu <herbert@gondor.apana.org.au>
parent f613457a

crypto/Kconfig

+5 −0
Original line number Diff line number Diff line
@@ -264,6 +264,11 @@ config CRYPTO_ECRDSA 
	  standard algorithms (called GOST algorithms). Only signature verification

	  is implemented.



config CRYPTO_CURVE25519

	tristate "Curve25519 algorithm"

	select CRYPTO_KPP

	select CRYPTO_LIB_CURVE25519_GENERIC



comment "Authenticated Encryption with Associated Data"



config CRYPTO_CCM

crypto/Makefile

+1 −0
Original line number Diff line number Diff line
@@ -168,6 +168,7 @@ obj-$(CONFIG_CRYPTO_ZSTD) += zstd.o 
obj-$(CONFIG_CRYPTO_OFB) += ofb.o

obj-$(CONFIG_CRYPTO_ECC) += ecc.o

obj-$(CONFIG_CRYPTO_ESSIV) += essiv.o

obj-$(CONFIG_CRYPTO_CURVE25519) += curve25519-generic.o



ecdh_generic-y += ecdh.o

ecdh_generic-y += ecdh_helper.o

crypto/curve25519-generic.c

0 → 100644
+90 −0
Original line number Diff line number Diff line 
// SPDX-License-Identifier: GPL-2.0-or-later



#include <crypto/curve25519.h>

#include <crypto/internal/kpp.h>

#include <crypto/kpp.h>

#include <linux/module.h>

#include <linux/scatterlist.h>



static int curve25519_set_secret(struct crypto_kpp *tfm, const void *buf,

				 unsigned int len)

{

	u8 *secret = kpp_tfm_ctx(tfm);



	if (!len)

		curve25519_generate_secret(secret);

	else if (len == CURVE25519_KEY_SIZE &&

		 crypto_memneq(buf, curve25519_null_point, CURVE25519_KEY_SIZE))

		memcpy(secret, buf, CURVE25519_KEY_SIZE);

	else

		return -EINVAL;

	return 0;

}



static int curve25519_compute_value(struct kpp_request *req)

{

	struct crypto_kpp *tfm = crypto_kpp_reqtfm(req);

	const u8 *secret = kpp_tfm_ctx(tfm);

	u8 public_key[CURVE25519_KEY_SIZE];

	u8 buf[CURVE25519_KEY_SIZE];

	int copied, nbytes;

	u8 const *bp;



	if (req->src) {

		copied = sg_copy_to_buffer(req->src,

					   sg_nents_for_len(req->src,

							    CURVE25519_KEY_SIZE),

					   public_key, CURVE25519_KEY_SIZE);

		if (copied != CURVE25519_KEY_SIZE)

			return -EINVAL;

		bp = public_key;

	} else {

		bp = curve25519_base_point;

	}



	curve25519_generic(buf, secret, bp);



	/* might want less than we've got */

	nbytes = min_t(size_t, CURVE25519_KEY_SIZE, req->dst_len);

	copied = sg_copy_from_buffer(req->dst, sg_nents_for_len(req->dst,

								nbytes),

				     buf, nbytes);

	if (copied != nbytes)

		return -EINVAL;

	return 0;

}



static unsigned int curve25519_max_size(struct crypto_kpp *tfm)

{

	return CURVE25519_KEY_SIZE;

}



static struct kpp_alg curve25519_alg = {

	.base.cra_name		= "curve25519",

	.base.cra_driver_name	= "curve25519-generic",

	.base.cra_priority	= 100,

	.base.cra_module	= THIS_MODULE,

	.base.cra_ctxsize	= CURVE25519_KEY_SIZE,



	.set_secret		= curve25519_set_secret,

	.generate_public_key	= curve25519_compute_value,

	.compute_shared_secret	= curve25519_compute_value,

	.max_size		= curve25519_max_size,

};



static int curve25519_init(void)

{

	return crypto_register_kpp(&curve25519_alg);

}



static void curve25519_exit(void)

{

	crypto_unregister_kpp(&curve25519_alg);

}



subsys_initcall(curve25519_init);

module_exit(curve25519_exit);



MODULE_ALIAS_CRYPTO("curve25519");

MODULE_ALIAS_CRYPTO("curve25519-generic");

MODULE_LICENSE("GPL");