src/Slim.php
public function createSealedRequest(
        string $method,
        string $uri,
        string $body,
        SealingPublicKey $key,
        array $headers = []
    ): RequestInterface {
        return new Request(
            $method,
            Uri::createFromString($uri),
            new Headers($headers),
            [],
            [],
            $this->stringToStream(
                Base64UrlSafe::encode(Simple::seal($body, $key))
            ),
            []
        );
    }
public function createSealedRequest(
        string $method,
        string $uri,
        string $body,
        SealingPublicKey $key,
        array $headers = []
    ): RequestInterface {
        return new Request(
            $method,
            Uri::createFromString($uri),
            new Headers($headers),
            [],
            [],
            $this->stringToStream(
                Base64UrlSafe::encode(Simple::seal($body, $key))
            ),
            []
        );
    }
Encrypt your HTTP request with the server's public key, so that only
the server can decrypt the message.

@param string $method
@param string $uri
@param string $body
@param SealingPublicKey $key
@param array $headers
@return RequestInterface