From 5d3d23ca4a374be23efd794746d1b3db1ed4c3ea Mon Sep 17 00:00:00 2001
From: Pascal Perrenoud <pascal@pband.ch>
Date: Wed, 4 Sep 2024 21:10:10 +0200
Subject: [PATCH] pwd-wrap : Implement

---
 index.ts        |  1 +
 src/pwd-wrap.ts | 49 +++++++++++++++++++++++++++++++++++++++++++++++++
 2 files changed, 50 insertions(+)
 create mode 100644 src/pwd-wrap.ts

diff --git a/index.ts b/index.ts
index 1548fd3..2225b2d 100644
--- a/index.ts
+++ b/index.ts
@@ -6,3 +6,4 @@ export * as JWT from "./src/jwt"
 export {SecretBox} from './src/secret-box'
 export {PrivateWrap} from './src/private-wrap'
 export {SecretWrap} from './src/secret-wrap'
+export {PwdWrap} from './src/pwd-wrap'
diff --git a/src/pwd-wrap.ts b/src/pwd-wrap.ts
new file mode 100644
index 0000000..abd4c79
--- /dev/null
+++ b/src/pwd-wrap.ts
@@ -0,0 +1,49 @@
+import {hkdf, pbkdf, Usage} from './kdf'
+import {SecretWrap} from './secret-wrap'
+import logger from 'log'
+import {a2b64, b642a} from "misc";
+
+const log = logger('crypto:pwd-wrap')
+
+export class PwdWrap {
+    private constructor(private readonly box: SecretWrap, private readonly salt: Uint8Array) {}
+
+    private static async derive(pwd: string, salt: Uint8Array) : Promise<CryptoKey> {
+        const k = await pbkdf(salt, pwd)
+        return await hkdf(k, Usage.wrap) as CryptoKey
+    }
+
+    public static async encrypt(data: CryptoKey, pwd: string, salt?: Uint8Array) : Promise<PwdWrap> {
+        log.trace('encrypt')
+        salt = salt ?? crypto.getRandomValues(new Uint8Array(16))
+        const k = await PwdWrap.derive(pwd, salt)
+        const box = await SecretWrap.encrypt(data, k)
+        return new PwdWrap(box, salt)
+    }
+    public async decrypt(pwd: string) : Promise<CryptoKey> {
+        log.trace('decrypt')
+        const k = await PwdWrap.derive(pwd, this.salt)
+        return this.box.decrypt(k)
+    }
+
+    public toString(): String {
+        log.trace('toString')
+        const salt = a2b64(this.salt)
+        const box = this.box.toString()
+        return `${salt}.${box}`
+    }
+
+    public fromString(data: string): PwdWrap | null {
+        log.trace('fromString')
+
+        const parts = data.split('.', 2)
+        if (parts.length !== 2) return null
+
+        const salt = b642a(parts[0])
+        if (salt.is_err()) return null
+        const box = SecretWrap.fromString(parts[1])
+        if (box === null) return null
+
+        return new PwdWrap(box, salt.unwrap())
+    }
+}