feat: add crypto impl for kgm/kwm (#16, #17)

src/decrypt-worker/crypto/kwm/kwm.ts

@@ -0,0 +1,17 @@
+import { transformBlob } from '~/decrypt-worker/util/transformBlob';
+import type { CryptoBase } from '../CryptoBase';
+import { KWM_KEY } from './kwm.key';
+
+// v1 only
+export class KWMCrypto implements CryptoBase {
+  cryptoName = 'KWM';
+  checkByDecryptHeader = true;
+
+  async decrypt(buffer: ArrayBuffer): Promise<Blob> {
+    return transformBlob(buffer, (p) => p.make.KuwoKWM(KWM_KEY));
+  }
+
+  public static make() {
+    return new KWMCrypto();
+  }
+}