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crypto: ecdh - Initialize ctx->private_key in proper byte order

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The private key in ctx->private_key is currently initialized in reverse
byte order in ecdh_set_secret and whenever the key is needed in proper
byte order the variable priv is introduced and the bytes from
ctx->private_key are copied into priv while being byte-swapped
(ecc_swap_digits). To get rid of the unnecessary byte swapping initialize
ctx->private_key in proper byte order and clean up all functions that were
previously using priv or were called with ctx->private_key:

- ecc_gen_privkey: Directly initialize the passed ctx->private_key with
  random bytes filling all the digits of the private key. Get rid of the
  priv variable. This function only has ecdh_set_secret as a caller to
  create NIST P192/256/384 private keys.

- crypto_ecdh_shared_secret: Called only from ecdh_compute_value with
  ctx->private_key. Get rid of the priv variable and work with the passed
  private_key directly.

- ecc_make_pub_key: Called only from ecdh_compute_value with
  ctx->private_key. Get rid of the priv variable and work with the passed
  private_key directly.

Cc: Salvatore Benedetto <salvatore.benedetto@intel.com>
Signed-off-by: Stefan Berger <stefanb@linux.ibm.com>
Acked-by: Jarkko Sakkinen <jarkko@kernel.org>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
This commit is contained in:
Stefan Berger 2024-04-18 11:24:45 -04:00 committed by Herbert Xu
parent bd955a4e92
commit 01474b70a7
3 changed files with 15 additions and 25 deletions
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29
crypto/ecc.c
View File

@ -1497,10 +1497,10 @@ EXPORT_SYMBOL(ecc_is_key_valid);
* This method generates a private key uniformly distributed in the range
* [2, n-3].
*/
int ecc_gen_privkey(unsigned int curve_id, unsigned int ndigits, u64 *privkey)
int ecc_gen_privkey(unsigned int curve_id, unsigned int ndigits,
u64 *private_key)
{
const struct ecc_curve *curve = ecc_get_curve(curve_id);
u64 priv[ECC_MAX_DIGITS];
unsigned int nbytes = ndigits << ECC_DIGITS_TO_BYTES_SHIFT;
unsigned int nbits = vli_num_bits(curve->n, ndigits);
int err;
@ -1509,7 +1509,7 @@ int ecc_gen_privkey(unsigned int curve_id, unsigned int ndigits, u64 *privkey)
* Step 1 & 2: check that N is included in Table 1 of FIPS 186-5,
* section 6.1.1.
*/
if (nbits < 224 || ndigits > ARRAY_SIZE(priv))
if (nbits < 224)
return -EINVAL;
/*
@ -1527,17 +1527,16 @@ int ecc_gen_privkey(unsigned int curve_id, unsigned int ndigits, u64 *privkey)
return -EFAULT;
/* Step 3: obtain N returned_bits from the DRBG. */
err = crypto_rng_get_bytes(crypto_default_rng, (u8 *)priv, nbytes);
err = crypto_rng_get_bytes(crypto_default_rng,
(u8 *)private_key, nbytes);
crypto_put_default_rng();
if (err)
return err;
/* Step 4: make sure the private key is in the valid range. */
if (__ecc_is_key_valid(curve, priv, ndigits))
if (__ecc_is_key_valid(curve, private_key, ndigits))
return -EINVAL;
ecc_swap_digits(priv, privkey, ndigits);
return 0;
}
EXPORT_SYMBOL(ecc_gen_privkey);
@ -1547,23 +1546,20 @@ int ecc_make_pub_key(unsigned int curve_id, unsigned int ndigits,
{
int ret = 0;
struct ecc_point *pk;
u64 priv[ECC_MAX_DIGITS];
const struct ecc_curve *curve = ecc_get_curve(curve_id);
if (!private_key || ndigits > ARRAY_SIZE(priv)) {
if (!private_key) {
ret = -EINVAL;
goto out;
}
ecc_swap_digits(private_key, priv, ndigits);
pk = ecc_alloc_point(ndigits);
if (!pk) {
ret = -ENOMEM;
goto out;
}
ecc_point_mult(pk, &curve->g, priv, NULL, curve, ndigits);
ecc_point_mult(pk, &curve->g, private_key, NULL, curve, ndigits);
/* SP800-56A rev 3 5.6.2.1.3 key check */
if (ecc_is_pubkey_valid_full(curve, pk)) {
@ -1647,13 +1643,11 @@ int crypto_ecdh_shared_secret(unsigned int curve_id, unsigned int ndigits,
{
int ret = 0;
struct ecc_point *product, *pk;
u64 priv[ECC_MAX_DIGITS];
u64 rand_z[ECC_MAX_DIGITS];
unsigned int nbytes;
const struct ecc_curve *curve = ecc_get_curve(curve_id);
if (!private_key || !public_key ||
ndigits > ARRAY_SIZE(priv) || ndigits > ARRAY_SIZE(rand_z)) {
if (!private_key || !public_key || ndigits > ARRAY_SIZE(rand_z)) {
ret = -EINVAL;
goto out;
}
@ -1674,15 +1668,13 @@ int crypto_ecdh_shared_secret(unsigned int curve_id, unsigned int ndigits,
if (ret)
goto err_alloc_product;
ecc_swap_digits(private_key, priv, ndigits);
product = ecc_alloc_point(ndigits);
if (!product) {
ret = -ENOMEM;
goto err_alloc_product;
}
ecc_point_mult(product, pk, priv, rand_z, curve, ndigits);
ecc_point_mult(product, pk, private_key, rand_z, curve, ndigits);
if (ecc_point_is_zero(product)) {
ret = -EFAULT;
@ -1692,7 +1684,6 @@ int crypto_ecdh_shared_secret(unsigned int curve_id, unsigned int ndigits,
ecc_swap_digits(product->x, secret, ndigits);
err_validity:
memzero_explicit(priv, sizeof(priv));
memzero_explicit(rand_z, sizeof(rand_z));
ecc_free_point(product);
err_alloc_product:

8
crypto/ecdh.c
View File

@ -27,7 +27,6 @@ static int ecdh_set_secret(struct crypto_kpp *tfm, const void *buf,
unsigned int len)
{
struct ecdh_ctx *ctx = ecdh_get_ctx(tfm);
u64 priv[ECC_MAX_DIGITS];
struct ecdh params;
int ret = 0;
@ -41,15 +40,14 @@ static int ecdh_set_secret(struct crypto_kpp *tfm, const void *buf,
return ecc_gen_privkey(ctx->curve_id, ctx->ndigits,
ctx->private_key);
memcpy(ctx->private_key, params.key, params.key_size);
ecc_swap_digits(ctx->private_key, priv, ctx->ndigits);
ecc_digits_from_bytes(params.key, params.key_size,
ctx->private_key, ctx->ndigits);
if (ecc_is_key_valid(ctx->curve_id, ctx->ndigits,
priv, params.key_size) < 0) {
ctx->private_key, params.key_size) < 0) {
memzero_explicit(ctx->private_key, params.key_size);
ret = -EINVAL;
}
memzero_explicit(priv, sizeof(priv));
return ret;
}

3
include/crypto/internal/ecc.h
View File

@ -103,7 +103,8 @@ int ecc_is_key_valid(unsigned int curve_id, unsigned int ndigits,
* Returns 0 if the private key was generated successfully, a negative value
* if an error occurred.
*/
int ecc_gen_privkey(unsigned int curve_id, unsigned int ndigits, u64 *privkey);
int ecc_gen_privkey(unsigned int curve_id, unsigned int ndigits,
u64 *private_key);
/**
* ecc_make_pub_key() - Compute an ECC public key