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Message-ID: <20240418152445.2773042-3-stefanb@linux.ibm.com>
Date: Thu, 18 Apr 2024 11:24:45 -0400
From: Stefan Berger <stefanb@...ux.ibm.com>
To: linux-crypto@...r.kernel.org, herbert@...dor.apana.org.au,
davem@...emloft.net
Cc: linux-kernel@...r.kernel.org, jarkko@...nel.org, ardb@...nel.org,
git@...sn.com, hkario@...hat.com, simo@...hat.com,
Stefan Berger <stefanb@...ux.ibm.com>,
Salvatore Benedetto <salvatore.benedetto@...el.com>
Subject: [PATCH v3 2/2] crypto: ecdh & ecc - Initialize ctx->private_key in proper byte order
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@...el.com>
Signed-off-by: Stefan Berger <stefanb@...ux.ibm.com>
Acked-by: Jarkko Sakkinen <jarkko@...nel.org>
---
crypto/ecc.c | 29 ++++++++++-------------------
crypto/ecdh.c | 8 +++-----
include/crypto/internal/ecc.h | 3 ++-
3 files changed, 15 insertions(+), 25 deletions(-)
diff --git a/crypto/ecc.c b/crypto/ecc.c
index 2e05387b9499..c1d2e884be1e 100644
--- a/crypto/ecc.c
+++ b/crypto/ecc.c
@@ -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:
diff --git a/crypto/ecdh.c b/crypto/ecdh.c
index c02c9a2b9682..72cfd1590156 100644
--- a/crypto/ecdh.c
+++ b/crypto/ecdh.c
@@ -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;
}
diff --git a/include/crypto/internal/ecc.h b/include/crypto/internal/ecc.h
index 4e2f5f938e91..7ca1f463d1ec 100644
--- a/include/crypto/internal/ecc.h
+++ b/include/crypto/internal/ecc.h
@@ -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
--
2.43.0
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