Useful hard fork

[developergames2d]

Can you make a Monero hard fork so that for each transaction you can add an encrypted message (~80-160 Bytes) that only the recipient can read?

[vtnerd]

You can do that now with tx_extra. Use the existing ECDH+hash as the shared-key, and then encrypt and stash into tx_extra.

[developergames2d]

You can do that now with tx_extra. Use the existing ECDH+hash as the shared-key, and then encrypt and stash into tx_extra.

How can I do it in monero-gui?

[vtnerd]

You can do that now with tx_extra. Use the existing ECDH+hash as the shared-key, and then encrypt and stash into tx_extra.

How can I do it in monero-gui?

You can't, this something that would require custom tools to be written.

[moneromooo-monero]

There is a monero fork that implements exactly this:
https://git.townforge.net/townforge/townforge/commit/7c70d0ef6e4900434e54cb7cf071074d3d4da66b