# I am the Watcher. I am your guide through this vast new twtiverse.
# 
# Usage:
#     https://watcher.sour.is/api/plain/users              View list of users and latest twt date.
#     https://watcher.sour.is/api/plain/twt                View all twts.
#     https://watcher.sour.is/api/plain/mentions?uri=:uri  View all mentions for uri.
#     https://watcher.sour.is/api/plain/conv/:hash         View all twts for a conversation subject.
# 
# Options:
#     uri     Filter to show a specific users twts.
#     offset  Start index for quey.
#     limit   Count of items to return (going back in time).
# 
# twt range = 1 2
# self = https://watcher.sour.is/conv/bjjnrsa
eapl.me
eapl.me
View Thread
trying to implement it quickly, I get the same questions than you

# https://www.php.net/manual/en/function.openssl-pbkdf2.php
    $password = $sharedKey;
    $salt = openssl_random_pseudo_bytes(16);  # What's the salt length ?
    $keyLength = 20;  # What's the key length here ?
    $iterations = 100000;
    $generatedKey = openssl_pbkdf2($password, $salt, $keyLength, $iterations, 'sha256');
    echo bin2hex($generatedKey)."\n";
    echo base64_encode($generatedKey)."\n";

    $iv = openssl_random_pseudo_bytes(16); // AES-256-CBC requires 16-byte IV
    $cipherText = openssl_encrypt($message, 'aes-256-cbc', $generatedKey, OPENSSL_RAW_DATA, $iv);
    return base64_encode($iv . $cipherText);

arne
uplegger.eu
View Thread
@eapl.me Here is what I've got so far: https://github.com/upputter/testing-twtxt-dm

There is a "00_well_known_message.enc" file, which I have the encryption paremters for (https://github.com/upputter/testing-twtxt-dm/blob/9fdf3be6aa8fe810a4cb275375dbb3d4a2a958ee/wellknown_test.php#L28).

According to my finding, I assume, that the saltsize in openssl is "8" and the PBKDF2 algo is "sha256".