From 2b4f5e5f0999459c0552a405a23c44f84eaa898b Mon Sep 17 00:00:00 2001
From: james-a-morris <jaamorris@cs.stonybrook.edu>
Date: Mon, 25 Sep 2023 14:51:03 -0400
Subject: [PATCH] improve: add custom encrypt/decrypt

---
 src/helpers/oshhhnap.ts | 64 +++++++++++++++++++++++++++++++++++++++++
 1 file changed, 64 insertions(+)
 create mode 100644 src/helpers/oshhhnap.ts

diff --git a/src/helpers/oshhhnap.ts b/src/helpers/oshhhnap.ts
new file mode 100644
index 00000000000..9585d8dd526
--- /dev/null
+++ b/src/helpers/oshhhnap.ts
@@ -0,0 +1,64 @@
+import { timelockDecrypt, timelockEncrypt } from 'tlock-js';
+import { HttpChainClient, HttpCachingChain } from 'drand-client';
+
+const testnetUnchainedUrl =
+  'https://pl-eu.testnet.drand.sh/7672797f548f3f4748ac4bf3352fc6c6b6468c9ad40ad456a397545c6e2df5bf';
+
+const getFastestNode = async () => {
+  const chain = new HttpCachingChain(testnetUnchainedUrl);
+  const client = new HttpChainClient(chain);
+
+  return client;
+};
+
+export async function timelockEncryption(message: string, duration: number) {
+  if (duration < 30)
+    throw new Error(
+      'Duration must be positive and greater or equal to 30 seconds'
+    );
+  const fastestNodeClient = await getFastestNode();
+  const latestRound = await fastestNodeClient.latest();
+  const chain = new HttpCachingChain(testnetUnchainedUrl);
+
+  const { period } = await chain.info();
+
+  const roundNumber = latestRound.round + Math.floor(duration / period);
+
+  const result = await timelockEncrypt(
+    latestRound.round + roundNumber,
+    Buffer.from(message),
+    fastestNodeClient
+  );
+
+  return result;
+}
+
+export async function timelockEncryptionForOshhhnap(
+  message: string,
+  proposalId: string,
+  duration: number
+) {
+  let result = await timelockEncryption(message, duration);
+
+  // We need to append the ID to the ciphertext, so we can decrypt it later
+  // and know which proposal it belongs to.
+  result = `${result}__ID__${proposalId}`;
+
+  return result;
+}
+
+export async function timelockDecryption(ciphertext: string) {
+  const fastestNodeClient = await getFastestNode();
+  const result = await timelockDecrypt(ciphertext, fastestNodeClient);
+  return result;
+}
+
+export async function timelockDecryptionForOshhhnap(ciphertext: string) {
+  // We need to remove the ID from the ciphertext, so we can decrypt it.
+  const [ciphertextWithoutId, proposalId] = ciphertext.split('__ID__');
+  const result = await timelockDecryption(ciphertextWithoutId);
+  return {
+    result,
+    proposalId
+  };
+}