Various

packages/system/src/encrypted.ts

@@ -0,0 +1,70 @@
+import { pbkdf2 } from "@noble/hashes/pbkdf2";
+import { sha256 } from '@noble/hashes/sha256';
+import {hmac} from "@noble/hashes/hmac";
+import { bytesToHex, hexToBytes, randomBytes } from "@noble/hashes/utils";
+import { base64 } from "@scure/base";
+import { streamXOR as xchacha20 } from "@stablelib/xchacha20";
+
+export class InvalidPinError extends Error {
+  constructor(){
+    super();
+  }
+}
+
+/**
+ * Pin protected data
+ */
+export class PinEncrypted {
+    static readonly #opts = {c: 32, dkLen: 32}
+    #decrypted?: Uint8Array
+    #encrypted: PinEncryptedPayload
+  
+    constructor(enc: PinEncryptedPayload) {
+      this.#encrypted = enc;
+    }
+  
+    get value() {
+      if(!this.#decrypted) throw new Error("Content has not been decrypted yet");
+      return bytesToHex(this.#decrypted);
+    }
+  
+    decrypt(pin: string) {
+      const key = pbkdf2(sha256, pin, base64.decode(this.#encrypted.salt), PinEncrypted.#opts);
+      const ciphertext = base64.decode(this.#encrypted.ciphertext);
+      const nonce = base64.decode(this.#encrypted.iv);
+      const plaintext = xchacha20(key, nonce, ciphertext, ciphertext);
+      if(plaintext.length !== 32) throw new InvalidPinError();
+      const mac = base64.encode(hmac(sha256, key, plaintext));
+      if(mac !== this.#encrypted.mac) throw new InvalidPinError();
+      this.#decrypted = plaintext;
+    }
+
+    toPayload() {
+      return this.#encrypted;
+    }
+  
+    static create(content: string, pin: string) {
+      const salt = randomBytes(24);
+      const nonce = randomBytes(24);
+      const plaintext = hexToBytes(content);
+      const key = pbkdf2(sha256, pin, salt, PinEncrypted.#opts);
+      const mac = base64.encode(hmac(sha256, key, plaintext));
+      const ciphertext = xchacha20(key, nonce, plaintext, plaintext);
+      const ret = new PinEncrypted({
+        salt: base64.encode(salt),
+        ciphertext: base64.encode(ciphertext),
+        iv: base64.encode(nonce),
+        mac
+      });
+      ret.#decrypted = plaintext;
+      return ret;
+    }
+  }
+  
+  export interface PinEncryptedPayload {
+    salt: string, // for KDF
+    ciphertext: string
+    iv: string,
+    mac: string
+  }
+