Rapport is an end-to-end encrypted messaging app written in TypeScript. It uses a combination of AES-256 and ECDH to ensure perfect secrecy, as long as the key is secret.
- Simple interface
- Password-protected account
- Recovery phrase to recover account
- Password is NEVER stored on the database, not even hashed
- Several layers of encryption for each message
- Basic markdown supported (headings, bold, italics, lists and blockquotes)
It is hard to explain how it works, in a simple manner, so here's all the layers of decryption to get to a message:
$$
password \xrightarrow[\times97965,\ AUTH\_SALT]{pbkdf2-sha256} PAK\ {(password\ auth\ key)}
$$
$$
phrasestore\ \xrightarrow[PAK]{AES\ decrypt}\ passphrase'
$$
$$
passphrase'\ ==\ passphrase\ ?\ Verified
$$
$$
keystore\ \xrightarrow[PAK]{AES\ decrypt}\ user\_secret
$$
$$
privatestore\ \xrightarrow[user\_secret]{AES\ decrypt}\ private\_key
$$
$$
chatstore\ \xrightarrow[private\_key]{ECIES\ decrypt}\ chat\_secret
$$
$$
recipient\_public\_key\ \xrightarrow[private\_key]{ECDH\ compute}\ shared\_secret
$$
$$
shared\_secret\ \xrightarrow[]{sha256}\ K_{-2}
$$
$$
msgstore\ \xrightarrow[K_{-2}]{AES\ decrypt}\ res_{-1}
$$
$$
msg\_id\ +\ chat\_secret\ \xrightarrow[\times230903,\ MSG\_SALT]{pbkdf2-sha256}\ K_{-1}
$$
$$
res_{-1}\ \xrightarrow[K_{-1}]{AES\ decrypt}\ message
$$