RFR: 8271566: DSA signature length value is not accurate in P11Signature

[Valerie Peng]

On Mon, 2 Aug 2021 19:31:54 GMT, Martin Balao <mbalao at openjdk.org> wrote:

> As described in JDK-8271566 [1], this patch proposal is intended to fix a problem that arises when using DSA keys that have a 256-bits (or larger) G parameter for signatures (either signing or verifying). There were some incorrect assumptions and hard-coded length values in the code before. Please note that, for example, the tuple (2048, 256) for DSA is valid according to FIPS PUB 186-4.
> 
> Beyond the specific issues in signatures, I decided to provide a broader solution and enable key parameter retrieval for other key types (EC, DH) when possible. This is, when the key is not sensitive. One thing that I should note here is that token keys (those that have the CKA_TOKEN attribute equal to 'true') are considered sensitive in this regard, at least by the NSS Software Token implementation. I don't have access to other vendor implementations but if there is any concern, we can adjust the constraint to NSS-only. However, I'm not sure which use-case would require to get private keys out of a real token, weakening its security. I'd be more conservative here and not query the values if not sure that it will succeed.
> 
> No regressions found in jdk/sun/security/pkcs11. A new test added: LargerDSAKey.
> 
> --
> [1] - https://bugs.openjdk.java.net/browse/JDK-8271566

test/jdk/sun/security/pkcs11/Signature/LargeDSAKey.java line 52:

> 50:             "Known text known text known text";
> 51: 
> 52:     public void main(Provider p) throws Exception {

nit: add @Override

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PR: https://git.openjdk.java.net/jdk/pull/4961