private static SecretSharedKey secretFromPrivateKey(ToolInvocation invocation, String inputArg, String outputArg, SealedSharedKey sealedSharedKey) throws IOException {
        var privateKey = ToolUtils.resolvePrivateKeyFromInvocation(invocation, sealedSharedKey.keyId(),
                                                                   !CliUtils.useStdIo(inputArg) && !CliUtils.useStdIo(outputArg));
        return SharedKeyGenerator.fromSealedKey(sealedSharedKey, privateKey);
    }
Tooling for decrypting a file using a private key that corresponds to the public key used
to originally encrypt the file.

Uses the opaque token abstraction from {@link SharedKeyGenerator}.

@author vekterli
vespaclient-java/src/main/java/com/yahoo/vespa/security/tool/crypto/DecryptTool.java