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crypto: kdf - add SP800-108 counter key derivation function 

SP800-108 defines three KDFs - this patch provides the counter KDF
implementation.

The KDF is implemented as a service function where the caller has to
maintain the hash / HMAC state. Apart from this hash/HMAC state, no
additional state is required to be maintained by either the caller or
the KDF implementation.

The key for the KDF is set with the crypto_kdf108_setkey function which
is intended to be invoked before the caller requests a key derivation
operation via crypto_kdf108_ctr_generate.

SP800-108 allows the use of either a HMAC or a hash as crypto primitive
for the KDF. When a HMAC primtive is intended to be used,
crypto_kdf108_setkey must be used to set the HMAC key. Otherwise, for a
hash crypto primitve crypto_kdf108_ctr_generate can be used immediately
after allocating the hash handle.

Signed-off-by: Stephan Mueller <smueller@chronox.de>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
This commit is contained in:
Stephan Müller 2021-11-19 07:55:58 +01:00 committed by Herbert Xu
parent b808f32023
commit 026a733e66
4 changed files with 223 additions and 0 deletions
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4
crypto/Kconfig
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@ -1845,6 +1845,10 @@ config CRYPTO_JITTERENTROPY
random numbers. This Jitterentropy RNG registers with
the kernel crypto API and can be used by any caller.
config CRYPTO_KDF800108_CTR
tristate
select CRYPTO_HASH
config CRYPTO_USER_API
tristate

5
crypto/Makefile
View File

@ -200,3 +200,8 @@ obj-$(CONFIG_ASYMMETRIC_KEY_TYPE) += asymmetric_keys/
obj-$(CONFIG_CRYPTO_HASH_INFO) += hash_info.o
crypto_simd-y := simd.o
obj-$(CONFIG_CRYPTO_SIMD) += crypto_simd.o
#
# Key derivation function
#
obj-$(CONFIG_CRYPTO_KDF800108_CTR) += kdf_sp800108.o

153
crypto/kdf_sp800108.c Normal file
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@ -0,0 +1,153 @@
// SPDX-License-Identifier: GPL-2.0
/*
* SP800-108 Key-derivation function
*
* Copyright (C) 2021, Stephan Mueller <smueller@chronox.de>
*/
#include <linux/fips.h>
#include <linux/module.h>
#include <crypto/kdf_sp800108.h>
#include <crypto/internal/kdf_selftest.h>
/*
* SP800-108 CTR KDF implementation
*/
int crypto_kdf108_ctr_generate(struct crypto_shash *kmd,
const struct kvec *info, unsigned int info_nvec,
u8 *dst, unsigned int dlen)
{
SHASH_DESC_ON_STACK(desc, kmd);
__be32 counter = cpu_to_be32(1);
const unsigned int h = crypto_shash_digestsize(kmd), dlen_orig = dlen;
unsigned int i;
int err = 0;
u8 *dst_orig = dst;
desc->tfm = kmd;
while (dlen) {
err = crypto_shash_init(desc);
if (err)
goto out;
err = crypto_shash_update(desc, (u8 *)&counter, sizeof(__be32));
if (err)
goto out;
for (i = 0; i < info_nvec; i++) {
err = crypto_shash_update(desc, info[i].iov_base,
info[i].iov_len);
if (err)
goto out;
}
if (dlen < h) {
u8 tmpbuffer[HASH_MAX_DIGESTSIZE];
err = crypto_shash_final(desc, tmpbuffer);
if (err)
goto out;
memcpy(dst, tmpbuffer, dlen);
memzero_explicit(tmpbuffer, h);
goto out;
}
err = crypto_shash_final(desc, dst);
if (err)
goto out;
dlen -= h;
dst += h;
counter = cpu_to_be32(be32_to_cpu(counter) + 1);
}
out:
if (err)
memzero_explicit(dst_orig, dlen_orig);
shash_desc_zero(desc);
return err;
}
EXPORT_SYMBOL(crypto_kdf108_ctr_generate);
/*
* The seeding of the KDF
*/
int crypto_kdf108_setkey(struct crypto_shash *kmd,
const u8 *key, size_t keylen,
const u8 *ikm, size_t ikmlen)
{
unsigned int ds = crypto_shash_digestsize(kmd);
/* SP800-108 does not support IKM */
if (ikm || ikmlen)
return -EINVAL;
/* Check according to SP800-108 section 7.2 */
if (ds > keylen)
return -EINVAL;
/* Set the key for the MAC used for the KDF. */
return crypto_shash_setkey(kmd, key, keylen);
}
EXPORT_SYMBOL(crypto_kdf108_setkey);
/*
* Test vector obtained from
* http://csrc.nist.gov/groups/STM/cavp/documents/KBKDF800-108/CounterMode.zip
*/
static const struct kdf_testvec kdf_ctr_hmac_sha256_tv_template[] = {
{
.key = "\xdd\x1d\x91\xb7\xd9\x0b\x2b\xd3"
"\x13\x85\x33\xce\x92\xb2\x72\xfb"
"\xf8\xa3\x69\x31\x6a\xef\xe2\x42"
"\xe6\x59\xcc\x0a\xe2\x38\xaf\xe0",
.keylen = 32,
.ikm = NULL,
.ikmlen = 0,
.info = {
.iov_base = "\x01\x32\x2b\x96\xb3\x0a\xcd\x19"
"\x79\x79\x44\x4e\x46\x8e\x1c\x5c"
"\x68\x59\xbf\x1b\x1c\xf9\x51\xb7"
"\xe7\x25\x30\x3e\x23\x7e\x46\xb8"
"\x64\xa1\x45\xfa\xb2\x5e\x51\x7b"
"\x08\xf8\x68\x3d\x03\x15\xbb\x29"
"\x11\xd8\x0a\x0e\x8a\xba\x17\xf3"
"\xb4\x13\xfa\xac",
.iov_len = 60
},
.expected = "\x10\x62\x13\x42\xbf\xb0\xfd\x40"
"\x04\x6c\x0e\x29\xf2\xcf\xdb\xf0",
.expectedlen = 16
}
};
static int __init crypto_kdf108_init(void)
{
int ret = kdf_test(&kdf_ctr_hmac_sha256_tv_template[0], "hmac(sha256)",
crypto_kdf108_setkey, crypto_kdf108_ctr_generate);
if (ret) {
if (fips_enabled)
panic("alg: self-tests for CTR-KDF (hmac(sha256)) failed (rc=%d)\n",
ret);
WARN(1,
"alg: self-tests for CTR-KDF (hmac(sha256)) failed (rc=%d)\n",
ret);
} else {
pr_info("alg: self-tests for CTR-KDF (hmac(sha256)) passed\n");
}
return ret;
}
static void __exit crypto_kdf108_exit(void) { }
module_init(crypto_kdf108_init);
module_exit(crypto_kdf108_exit);
MODULE_LICENSE("GPL v2");
MODULE_AUTHOR("Stephan Mueller <smueller@chronox.de>");
MODULE_DESCRIPTION("Key Derivation Function conformant to SP800-108");

61
include/crypto/kdf_sp800108.h Normal file
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@ -0,0 +1,61 @@
/* SPDX-License-Identifier: GPL-2.0 */
/*
* Copyright (C) 2021, Stephan Mueller <smueller@chronox.de>
*/
#ifndef _CRYPTO_KDF108_H
#define _CRYPTO_KDF108_H
#include <crypto/hash.h>
#include <linux/uio.h>
/**
* Counter KDF generate operation according to SP800-108 section 5.1
* as well as SP800-56A section 5.8.1 (Single-step KDF).
*
* @kmd Keyed message digest whose key was set with crypto_kdf108_setkey or
* unkeyed message digest
* @info optional context and application specific information - this may be
* NULL
* @info_vec number of optional context/application specific information entries
* @dst destination buffer that the caller already allocated
* @dlen length of the destination buffer - the KDF derives that amount of
* bytes.
*
* To comply with SP800-108, the caller must provide Label || 0x00 || Context
* in the info parameter.
*
* @return 0 on success, < 0 on error
*/
int crypto_kdf108_ctr_generate(struct crypto_shash *kmd,
const struct kvec *info, unsigned int info_nvec,
u8 *dst, unsigned int dlen);
/**
* Counter KDF setkey operation
*
* @kmd Keyed message digest allocated by the caller. The key should not have
* been set.
* @key Seed key to be used to initialize the keyed message digest context.
* @keylen This length of the key buffer.
* @ikm The SP800-108 KDF does not support IKM - this parameter must be NULL
* @ikmlen This parameter must be 0.
*
* According to SP800-108 section 7.2, the seed key must be at least as large as
* the message digest size of the used keyed message digest. This limitation
* is enforced by the implementation.
*
* SP800-108 allows the use of either a HMAC or a hash primitive. When
* the caller intends to use a hash primitive, the call to
* crypto_kdf108_setkey is not required and the key derivation operation can
* immediately performed using crypto_kdf108_ctr_generate after allocating
* a handle.
*
* @return 0 on success, < 0 on error
*/
int crypto_kdf108_setkey(struct crypto_shash *kmd,
const u8 *key, size_t keylen,
const u8 *ikm, size_t ikmlen);
#endif /* _CRYPTO_KDF108_H */