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

[Martin Balao]

On Tue, 3 Aug 2021 21:05:24 GMT, Valerie Peng <valeriep 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
>
> src/jdk.crypto.cryptoki/share/classes/sun/security/pkcs11/P11Key.java line 386:
> 
>> 384:                 (attributes[2].getBoolean() == false)) {
>> 385:             keySensitive = true;
>> 386:         }
> 
> nit: this block and line 377 can simply be:
> `boolean keySensitive  = (attributes[0].getBoolean() || attributes[1].getBoolean() || (!attributes[2].getBoolean()));`

Sure

> src/jdk.crypto.cryptoki/share/classes/sun/security/pkcs11/P11Signature.java line 123:
> 
>> 121: 
>> 122:     // signature length expected or 0 for unknown
>> 123:     private int signatureLength;
> 
> nit: use a shorter name, e.g. sigLen, so to fit in one line.

Ok

> src/jdk.crypto.cryptoki/share/classes/sun/security/pkcs11/P11Signature.java line 817:
> 
>> 815:     }
>> 816: 
>> 817:     private byte[] asn1ToDSA(byte[] sig) throws SignatureException {
> 
> Have you considered keeping this as a static method but add one more int argument, i.e. signature length? It seems that the method asn1ToECDSA() can be made static too.

Ok

> 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

Sure

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