fix(ffi): reject private JWKs in RSA public imports

[harrshita123]

Summary

• Reject RSA JWKs containing the private exponent when importing a public key through the native FFI backend.
• Add regression coverage for RSA-OAEP, RSA-PSS, and RSASSA-PKCS1-v1_5 public-key imports.

Root cause

The shared native RSA JWK importer required d for private-key imports but did not require it to be absent for public-key imports. Public-key import methods therefore accepted private JWKs and silently discarded their private parameters.

The new validation rejects the JWK before allocating or parsing the native RSA key.

Validation

• dart analyze
• dart test test/rsa_jwk_validation_test.dart -p vm
• dart test test/rsa_jwk_validation_test.dart -p chrome
• dart test -p vm

Fixes #332

[HamdaanAliQuatil]

This looks correct. An RSA JWK with d is a private key, so the public import APIs should reject it instead of silently using only n and e. Keeping the check in the shared RSA importer covers OAEP, PSS, and PKCS#1 and brings the native backend in line with Web Crypto.

I ran the focused test on VM and Chromium, the full VM suite, and dart analyze locally; all passed. Could you also add a short entry under 0.6.2-wip in the changelog?

[harrshita123]

This looks correct. An RSA JWK with d is a private key, so the public import APIs should reject it instead of silently using only n and e. Keeping the check in the shared RSA importer covers OAEP, PSS, and PKCS#1 and brings the native backend in line with Web Crypto.

I ran the focused test on VM and Chromium, the full VM suite, and dart analyze locally; all passed. Could you also add a short entry under 0.6.2-wip in the changelog?

I have added a short entry under 0.6.2-wip in the changelog to document the RSA public JWK import fix.

[HamdaanAliQuatil]

lgtm :)