1 files changed, 55 insertions, 0 deletions
diff --git a/core/crypto/dh.js b/core/crypto/dh.js
new file mode 100644
index 0000000..bd705d9
--- /dev/null
+++ b/core/crypto/dh.js
@@ -0,0 +1,55 @@
+import { modPow, bigIntToU8Array, u8ArrayToBigInt } from "./bigint.js";
+
+class DHPublicKey {
+    constructor(key) {
+        this._key = key;
+    }
+
+    get algorithm() {
+        return { name: "DH" };
+    }
+
+    exportKey() {
+        return this._key;
+    }
+}
+
+export class DHCipher {
+    constructor() {
+        this._g = null;
+        this._p = null;
+        this._gBigInt = null;
+        this._pBigInt = null;
+        this._privateKey = null;
+    }
+
+    get algorithm() {
+        return { name: "DH" };
+    }
+
+    static generateKey(algorithm, _extractable) {
+        const cipher = new DHCipher;
+        cipher._generateKey(algorithm);
+        return { privateKey: cipher, publicKey: new DHPublicKey(cipher._publicKey) };
+    }
+
+    _generateKey(algorithm) {
+        const g = algorithm.g;
+        const p = algorithm.p;
+        this._keyBytes = p.length;
+        this._gBigInt = u8ArrayToBigInt(g);
+        this._pBigInt = u8ArrayToBigInt(p);
+        this._privateKey = window.crypto.getRandomValues(new Uint8Array(this._keyBytes));
+        this._privateKeyBigInt = u8ArrayToBigInt(this._privateKey);
+        this._publicKey = bigIntToU8Array(modPow(
+            this._gBigInt, this._privateKeyBigInt, this._pBigInt), this._keyBytes);
+    }
+
+    deriveBits(algorithm, length) {
+        const bytes = Math.ceil(length / 8);
+        const pkey = new Uint8Array(algorithm.public);
+        const len = bytes > this._keyBytes ? bytes : this._keyBytes;
+        const secret = modPow(u8ArrayToBigInt(pkey), this._privateKeyBigInt, this._pBigInt);
+        return bigIntToU8Array(secret, len).slice(0, len);
+    }
+}