E2E example in PHP and Python

examples/publish-php/publish-encrypted.php

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+<?php
+
+$message = [
+    "message" => "Secret!",
+    "priority" => 5
+];
+$plaintext = json_encode($message);
+$key = deriveKey("secr3t password", "https://ntfy.sh/mysecret");
+$ciphertext = encrypt($plaintext, $key);
+
+file_get_contents('https://ntfy.sh/mysecret', false, stream_context_create([
+    'http' => [
+        'method' => 'POST', // PUT also works
+        'header' =>
+            "Content-Type: text/plain\r\n" .
+            "Encryption: jwe",
+        'content' => $ciphertext
+    ]
+]));
+
+function deriveKey($password, $topicUrl)
+{
+    $salt = hex2bin(hash("sha256", $topicUrl));
+    return openssl_pbkdf2($password, $salt, 32, 50000, "sha256");
+}
+
+function encrypt(string $plaintext, string $key): string
+{
+    $encodedHeader = base64url_encode(json_encode(["alg" => "dir", "enc" => "A256GCM"]));
+    $iv = openssl_random_pseudo_bytes(12); // GCM is used with a 96-bit IV
+    $aad = $encodedHeader;
+    $tag = null;
+    $content = openssl_encrypt($plaintext, "aes-256-gcm", $key, OPENSSL_RAW_DATA, $iv, $tag, $aad);
+    return
+        $encodedHeader . "." .
+        "." . // No content encryption key (CEK) in "dir" mode
+        base64url_encode($iv) . "." .
+        base64url_encode($content) . "." .
+        base64url_encode($tag);
+}
+
+function base64url_encode($input)
+{
+    return str_replace('=', '', strtr(base64_encode($input), '+/', '-_'));
+}
+

examples/publish-python/publish-encrypted.py

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+#!/usr/bin/env python3
+
+import requests
+
+import json
+from base64 import b64encode, urlsafe_b64encode, b64decode
+from Crypto.Cipher import AES
+from Crypto.Random import get_random_bytes
+from Crypto.Protocol.KDF import PBKDF2
+from Crypto.Hash import SHA256
+from Crypto.Random import get_random_bytes
+
+def derive_key(password, topic_url):
+    salt = SHA256.new(data=topic_url.encode('utf-8')).digest()
+    return PBKDF2(password, salt, 32, count=50000, hmac_hash_module=SHA256)
+
+def encrypt(plaintext, key):
+    encoded_header = b64urlencode('{"alg":"dir","enc":"A256GCM"}'.encode('utf-8'))
+    iv = get_random_bytes(12) # GCM is used with a 96-bit IV
+    aad = encoded_header
+    cipher = AES.new(key, AES.MODE_GCM, nonce=iv)
+    cipher.update(aad.encode('utf-8'))
+    ciphertext, tag = cipher.encrypt_and_digest(plaintext.encode('utf-8'))
+    return "{header}..{iv}.{ciphertext}.{tag}".format(
+        header = encoded_header,
+        iv = b64urlencode(iv),
+        ciphertext = b64urlencode(ciphertext),
+        tag = b64urlencode(tag)
+    )
+
+def b64urlencode(b):
+    return urlsafe_b64encode(b).decode('utf-8').replace("=", "")
+
+key = derive_key("secr3t password", "https://ntfy.sh/mysecret")
+ciphertext = encrypt('{"message":"Python says hi","tags":["secret"]}', key)
+
+resp = requests.post("https://ntfy.sh/mysecret",
+    data=ciphertext,
+    headers={
+        "Encryption": "jwe"
+    })
+resp.raise_for_status()

examples/publish-python/requirements.txt

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+requests
+pycryptodome