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[v2,02/14] crypto: ecdsa - Adjust tests on length of key parameters

Message ID 20240215231414.3857320-3-stefanb@linux.ibm.com
State Superseded
Headers show
Series Add support for NIST P521 to ecdsa and ecdh | expand

Commit Message

Stefan Berger Feb. 15, 2024, 11:14 p.m. UTC 
In preparation for support of NIST P521, adjust the basic tests on the
length of the provided key parameters to only ensure that the length of the
x plus y coordinates parameter array is not an odd number and that each
coordinate fits into an array of 'ndigits' digits. Mathematical tests on
the key's parameters are then done in ecc_is_pubkey_valid_full rejecting
invalid keys.

The change is necessary since NIST P521 keys do not have keys with
coordinates that each fully require 'full' digits (= u64), unlike
NIST P192/256/384 that all require multiple 'full' digits.

Signed-off-by: Stefan Berger <stefanb@linux.ibm.com>
---
 crypto/ecdsa.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)
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Patch

diff --git a/crypto/ecdsa.c b/crypto/ecdsa.c
index ba8fb76fd165..64e1e69d53ba 100644
--- a/crypto/ecdsa.c
+++ b/crypto/ecdsa.c
@@ -230,7 +230,7 @@  static int ecdsa_set_pub_key(struct crypto_akcipher *tfm, const void *key, unsig
 	if (ret < 0)
 		return ret;
 
-	if (keylen < 1 || (((keylen - 1) >> 1) % sizeof(u64)) != 0)
+	if (keylen < 1 || ((keylen - 1) & 1) != 0)
 		return -EINVAL;
 	/* we only accept uncompressed format indicated by '4' */
 	if (d[0] != 4)
@@ -239,7 +239,7 @@  static int ecdsa_set_pub_key(struct crypto_akcipher *tfm, const void *key, unsig
 	keylen--;
 	digitlen = keylen >> 1;
 
-	ndigits = digitlen / sizeof(u64);
+	ndigits = DIV_ROUND_UP(digitlen, sizeof(u64));
 	if (ndigits != ctx->curve->g.ndigits)
 		return -EINVAL;