RFR: 8325513: Export method for Cipher [v3]

[Weijun Wang]

On Fri, 10 May 2024 14:00:55 GMT, Weijun Wang <weijun at openjdk.org> wrote:

>> Add `Cipher::export` API.
>
> Weijun Wang has updated the pull request incrementally with one additional commit since the last revision:
> 
>   change new method to non final

I don't know if any AES cipher defines an export function. As I said earlier the reason I introduce this method is for HPHE. In HPKE, the cipher algorithm name is "HPKE" and the keys used in initialization are asymmetric keys. While the 3rd step in HPKE is an AEAD cipher, I cannot guarantee the export function would only generate a key for this AEAD algorithm. The fact that a length is needed for the function means the output could be anything. Also, there is an export-only mode that does not require an AEAD cipher at all.

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PR Comment: https://git.openjdk.org/jdk/pull/18409#issuecomment-2105951017