pushEx abstract method

SecretExStream<SecretStreamCipherMessage> pushEx({ required Stream<SecretStreamPlainMessage> messageStream, required SecureKey key, })

Provides crypto_secretstream_xchacha20poly1305_(init_)push.

Transforms the messageStream of plaintext messages to an encrypted stream using crypto_secretstream_xchacha20poly1305_push with the given key.

Unlike the C API, which requires manual state management etc., this API combines all the required parts into a single, simple dart stream. As a first step, crypto_secretstream_xchacha20poly1305_init_push is used to generate the stream state from the key and the created header is sent as the first message of the returned SecretExStream. After that, any plain message (optionally with additional data and a tag) that is passed in via messageStream is encrypted with crypto_secretstream_xchacha20poly1305_push.

The stream also handles it's internal state gracefully and can react to tags and problems with the encryption, if the occur. It is also possible to explicitly rekey the stream via SecretExStream.rekey.

Note: If you want to gracefully end a push stream, the last message needs to have the SecretStreamMessageTag.finalPush tag. After that, you must not send any other messages and close the messageStream. If you close the stream without the tag, an empty message is automatically created and sent before the returned stream gets closed.

This method is basically a shortcut for createPushEx.bind(). Check the documentation of createPushEx if you need a transformer instead of a stream.

See https://libsodium.gitbook.io/doc/secret-key_cryptography/secretstream#encryption

Implementation

SecretExStream<SecretStreamCipherMessage> pushEx({
  required Stream<SecretStreamPlainMessage> messageStream,
  required SecureKey key,
});