From 6ff8a84ed8fb062dd7e08149d7b5a2a7d5cd7e36 Mon Sep 17 00:00:00 2001
From: Derrick Hammer <derrick@derrickhammer.com>
Date: Fri, 17 Nov 2023 08:04:01 -0500
Subject: [PATCH] feat: add encrypted_cid.ts

---
 src/encrypted_cid.ts | 67 ++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 67 insertions(+)
 create mode 100644 src/encrypted_cid.ts

diff --git a/src/encrypted_cid.ts b/src/encrypted_cid.ts
new file mode 100644
index 0000000..d37f630
--- /dev/null
+++ b/src/encrypted_cid.ts
@@ -0,0 +1,67 @@
+import Multibase from "#multibase.js";
+import { Multihash } from "#multihash.js";
+import CID from "#cid.js";
+import { CID_TYPES } from "#constants.js";
+import { decodeEndian, encodeEndian } from "#util.js";
+
+export default class EncryptedCID extends Multibase {
+  encryptedBlobHash: Multihash;
+  originalCID: CID;
+  encryptionAlgorithm: number;
+  padding: number;
+  chunkSizeAsPowerOf2: number;
+  encryptionKey: Uint8Array;
+
+  constructor(
+    encryptedBlobHash: Multihash,
+    originalCID: CID,
+    encryptionKey: Uint8Array,
+    padding: number,
+    chunkSizeAsPowerOf2: number,
+    encryptionAlgorithm: number,
+  ) {
+    super();
+    this.encryptedBlobHash = encryptedBlobHash;
+    this.originalCID = originalCID;
+    this.encryptionKey = encryptionKey;
+    this.padding = padding;
+    this.chunkSizeAsPowerOf2 = chunkSizeAsPowerOf2;
+    this.encryptionAlgorithm = encryptionAlgorithm;
+  }
+
+  static decode(cid: string): EncryptedCID {
+    return EncryptedCID.fromBytes(Multibase.decodeString(cid));
+  }
+
+  static fromBytes(bytes: Uint8Array): EncryptedCID {
+    if (bytes[0] !== CID_TYPES.ENCRYPTED_DYNAMIC) {
+      throw new Error(`Invalid CID type (${bytes[0]})`);
+    }
+
+    return new EncryptedCID(
+      new Multihash(bytes.slice(3, 36)),
+      CID.fromBytes(bytes.slice(72)),
+      bytes.slice(36, 68),
+      decodeEndian(bytes.slice(68, 72)),
+      bytes[2],
+      bytes[1],
+    );
+  }
+
+  get chunkSize(): number {
+    return Math.pow(2, this.chunkSizeAsPowerOf2);
+  }
+
+  toBytes(): Uint8Array {
+    const data = [
+      CID_TYPES.ENCRYPTED_STATIC,
+      this.encryptionAlgorithm,
+      this.chunkSizeAsPowerOf2,
+      ...this.encryptedBlobHash.fullBytes,
+      ...this.encryptionKey,
+      ...encodeEndian(this.padding, 4),
+      ...this.originalCID.toBytes(),
+    ];
+    return new Uint8Array(data);
+  }
+}