Djam/u-boot
1
0
Fork 0
mirror of https://github.com/u-boot/u-boot.git synced 2025-04-11 07:24:46 +00:00
Code Issues Projects Releases Packages Wiki Activity Actions

lib: rsa: Set conventional salt length RSA-PSS parameter

Browse source 
RFC 3447 says that Typical salt length are either 0 or the length
of the output of the digest algorithm, RFC 4055 also recommends
hash value length as the salt length. Moreover, By convention,
most of the signing infrastructures/libraries use the length of
the digest algorithm (such as google cloud kms:
                      https://cloud.google.com/kms/docs/algorithms).

If the salt-length parameter is not set, openssl default to the
maximum allowed value, which is a openssl 'specificity', so this
works well for local signing, but restricts compatibility with
other engines (e.g pkcs11/libkmsp11):

```
returning 0x71 from C_SignInit due to status INVALID_ARGUMENT:
    at rsassa_pss.cc:53: expected salt length for key XX is 32,
    but 478 was supplied in the parameters
Could not obtain signature: error:41000070:PKCS#11 module::Mechanism invalid
```

To improve compatibility, we set the default RSA-PSS salt-length
value to the conventional one. A further improvement could consist
in making it configurable as signature FIT node attribute.

rfc3447: https://datatracker.ietf.org/doc/html/rfc3447
rfc4055: https://datatracker.ietf.org/doc/html/rfc4055

Signed-off-by: Loic Poulain <loic.poulain@linaro.org>
This commit is contained in:
Loic Poulain 2024-10-31 10:15:31 +01:00 • committed by Tom Rini
parent 356011f7ac
commit 1b99c15d73
1 changed files with 9 additions and 0 deletions
Show stats Download patch file Download diff file Expand all files Collapse all files

9
lib/rsa/rsa-sign.c
View file

@ -428,6 +428,15 @@ static int rsa_sign_with_key(EVP_PKEY *pkey, struct padding_algo *padding_algo,
ret = rsa_err("Signer padding setup failed");
goto err_sign;
}
/* Per RFC 3447 (and convention) the Typical salt length is the
* length of the output of the digest algorithm.
*/
if (EVP_PKEY_CTX_set_rsa_pss_saltlen(ckey,
checksum_algo->checksum_len) <= 0) {
ret = rsa_err("Signer salt length setup failed");
goto err_sign;
}
}
for (i = 0; i < region_count; i++) {