Ingo Franzki 1fb05038cd libseckey: RSA signature: Support OSSL_PKEY_RSA_PSS_SALT_LEN_AUTO_DIGEST_MAX ...

Since OpenSSL 3.1 a new RSA-PSS salt length constant exists to select
the maximum possible salt length based on the RSA-PSS parameters and the
digest used: OSSL_PKEY_RSA_PSS_SALT_LEN_AUTO_DIGEST_MAX
This is the default salt length when no other salt length is set by
the caller.

In contrast to OSSL_PKEY_RSA_PSS_SALT_LEN_MAX, OSSL_PKEY_RSA_PSS_SALT_LEN_AUTO_DIGEST_MAX
also ensures that the resulting salt length is not larger than the used
digest size. The salt length calculated with OSSL_PKEY_RSA_PSS_SALT_LEN_MAX
may be larger than the digest size, dependent on the RSA-PSS parameters.

FIPS 186-4 section 5 "The RSA Digital Signature Algorithm", subsection
5.5 "PKCS #1" says: "For RSASSA-PSS […] the length (in bytes) of the
salt (sLen) shall satisfy 0 <= sLen <= hLen, where hLen is the length of
the hash function output block (in bytes)."

See OpenSSL commit https://github.com/openssl/openssl/commit/6c73ca4a2f4ea71f4a880670624e7b2fdb6f32da

Signed-off-by: Ingo Franzki <ifranzki@linux.ibm.com>
Signed-off-by: Steffen Eiden <seiden@linux.ibm.com>

2023-01-27 14:12:38 +01:00

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