RFR: 8297878: KEM: Implementation

[Xue-Lei Andrew Fan]

On Wed, 12 Apr 2023 18:32:30 GMT, Weijun Wang <weijun at openjdk.org> wrote:

>> src/java.base/share/classes/javax/crypto/KEMSpi.java line 107:
>> 
>>> 105:      * @see KEM.Encapsulator
>>> 106:      */
>>> 107:     interface EncapsulatorSpi {
>> 
>> Is it really necessary to define a EncapsulatorSpi?  It looks like an internal implementation for KEMSpi service, rather than a public individual interface that EncapsulatorSpi.getInstance() could be used.
>
> Not exactly sure what you want. Security providers need to implement it and the `KEM` class uses it. Unlike other `AbcSpi` classes, it will not be created with a `getInstance` method.

If I get it right, SPI means "service provider interface", which is normally for public service access by searching the registers.  In the provider implementation, a SPI implementation is normally registered so that it can be accessed.  I did not find the registration in the provider implementation.  I know it is right because it is not expected to be registered as it is not expected to be accessed directly.

> Security providers need to implement it and the KEM class uses it.
I know, but it is not necessarily designed as an SPI (it could be a normal interface that a provider need to implement and KEM class uses).  You can code like this, but I'm not sure if it is the common way.

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PR Review Comment: https://git.openjdk.org/jdk/pull/13256#discussion_r1164684415