src/Slim.php
public function createSealedResponse(
        int $status,
        string $body,
        SealingPublicKey $key,
        array $headers = [],
        string $version = '1.1'
    ): ResponseInterface {
        return new Response(
            $status,
            new Headers($headers),
            $this->stringToStream(
                Base64UrlSafe::encode(Simple::seal($body, $key))
            )
        );
    }
public function createSealedResponse(
        int $status,
        string $body,
        SealingPublicKey $key,
        array $headers = [],
        string $version = '1.1'
    ): ResponseInterface {
        return new Response(
            $status,
            new Headers($headers),
            $this->stringToStream(
                Base64UrlSafe::encode(Simple::seal($body, $key))
            )
        );
    }
Encrypt your HTTP response with the client's public key, so that only
the client can decrypt the message.

@param int $status
@param string $body
@param SealingPublicKey $key
@param array $headers
@param string $version
@return ResponseInterface