From ede06757a3f8bf344b015f95eb835277e971d2b7 Mon Sep 17 00:00:00 2001
From: Pascal Perrenoud <pascal@pband.ch>
Date: Thu, 6 Jun 2024 01:50:10 +0200
Subject: [PATCH] Implement kdf

---
 src/kdf.ts | 90 ++++++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 90 insertions(+)
 create mode 100644 src/kdf.ts

diff --git a/src/kdf.ts b/src/kdf.ts
new file mode 100644
index 0000000..7d6a2c2
--- /dev/null
+++ b/src/kdf.ts
@@ -0,0 +1,90 @@
+import logger from 'log'
+const log = logger('crypto:kdf')
+
+export enum Usage {
+    sign,
+    wrap,
+}
+export async function hkdf(key: Uint8Array, usage: Usage) : Promise<CryptoKey | Uint8Array> {
+    log.trace("HKDF")
+    log.trace(`usage : ${usage === Usage.sign ? 'sign' : 'wrap'}`)
+
+    const material = await crypto.subtle.importKey(
+        "raw",
+        key,
+        "HKDF",
+        false,
+        ["deriveKey", "deriveBits"],
+    )
+
+    if (usage === Usage.wrap) {
+        return crypto.subtle.deriveKey(
+            {
+                name: "HKDF",
+                hash: "SHA-512",
+                salt: new Uint8Array(32),
+                info: new TextEncoder().encode("wrap"),
+            },
+            material,
+            {name: "AES-GCM", length: 256},
+            false,
+            ["wrapKey", "unwrapKey"],
+        )
+    } else if (usage === Usage.sign) {
+        const buffer = await crypto.subtle.deriveBits(
+            {
+                name: "HKDF",
+                hash: "SHA-512",
+                salt: new Uint8Array(32),
+                info: new TextEncoder().encode("sign"),
+            },
+            material,
+            256
+        )
+        return new Uint8Array(buffer)
+    } else {
+        log.warn(`Called HKDF with unknown enum value : ${usage}`)
+        throw "I don't even know what to say."
+    }
+}
+
+export async function pbkdf(salt: Uint8Array, password: string) : Promise<Uint8Array> {
+    log.trace("PBKDF")
+    const material = await crypto.subtle.importKey(
+        "raw",
+        new TextEncoder().encode(password),
+        "PBKDF2",
+        false,
+        ["deriveBits"],
+    )
+
+    const buffer = await crypto.subtle.deriveBits(
+        {
+            name: "PBKDF2",
+            salt,
+            iterations: 250_000,
+            hash: "SHA-512",
+        },
+        material,
+        256,
+    )
+
+    return new Uint8Array(buffer)
+}
+
+export function ecdh(privkey: CryptoKey, pubkey: CryptoKey) : Promise<CryptoKey> {
+    log.trace("ECDH")
+    return crypto.subtle.deriveKey(
+        {
+            name: "ECDH",
+            public: pubkey,
+        },
+        privkey,
+        {
+            name: "AES-GCM",
+            length: 256,
+        },
+        false,
+        ["wrapKey", "unwrapKey"],
+    )
+}