Feat: Add SPECK48/96 CTR cipher module

speck48_96ctr.js

@@ -0,0 +1,40 @@
+import speck from 'generic-speck';
+import { blake2bHex } from 'blakejs';
+
+const speck48_96 = speck({ bits: 24, rounds: 23, rightRotations: 8, leftRotations: 3 });
+
+export function getKey(kStr) {
+    const key96bit = blake2bHex(kStr, null, 12);
+    return [
+        parseInt(key96bit.slice(0, 6), 16),
+        parseInt(key96bit.slice(6, 12), 16),
+        parseInt(key96bit.slice(12, 18), 16),
+        parseInt(key96bit.slice(18, 24), 16)
+    ];
+}
+
+function deriveNonce(key) {
+    return speck48_96.encrypt(0, key) & 0xFFFFFF;
+}
+
+function ctrKeystream(key, index) {
+    const nonce = deriveNonce(key);
+    const ctrBlock = nonce * 16777216 + (index & 0xFFFFFF);
+    return speck48_96.encrypt(ctrBlock, key);
+}
+
+export function encrypt(ptStr, key) {
+    return Array.from(ptStr, (c, i) => {
+        const ks = ctrKeystream(key, i);
+        return (c.codePointAt(0) ^ ks) >>> 0;
+    });
+}
+
+export function decrypt(numArr, key) {
+    return numArr.map((ct, i) => {
+        const ks = ctrKeystream(key, i);
+        const cp = (ct ^ ks) >>> 0;
+        try { return String.fromCodePoint(cp); }
+        catch { return ''; }
+    }).join('');
+}