diff --git a/keyDumper/encrypt_bundles.py b/keyDumper/encrypt_bundles.py
new file mode 100644
index 0000000..70242b4
--- /dev/null
+++ b/keyDumper/encrypt_bundles.py
@@ -0,0 +1,132 @@
+#!/usr/bin/env python3
+
+import os, sys, struct, argparse
+from Crypto.Cipher import AES
+
+KEY_DEFAULT = b"rK7CcATuZk7LAmhqqU4iBLNmAq8QbK3s"
+KEY_ALTERNATE = b"x4DZmD6D2HhkzT6qD8HpKeZdgM9HCmXP"
+
+
+def xor_crypt(data, key):
+    cipher = AES.new(key, AES.MODE_ECB)
+    out = bytearray(len(data))
+    for off in range(0, len(data), 16):
+        ctr = off // 16 + 1
+        ks = cipher.encrypt(struct.pack('<q', ctr) + b'\x00' * 8)
+        for j, b in enumerate(data[off:off+16]):
+            out[off+j] = b ^ ks[j]
+    return bytes(out)
+
+
+def process_file(inpath, outpath, key, dry_run=False):
+    try:
+        with open(inpath, 'rb') as f:
+            data = f.read()
+        if data[:7] != b'UnityFS':
+            print(f"  Warning: '{os.path.basename(inpath)}' does not start with UnityFS magic")
+        if dry_run:
+            print(f"  Would encrypt: {os.path.basename(inpath)} -> {os.path.basename(outpath)}")
+            return True
+        encrypted = xor_crypt(data, key)
+        os.makedirs(os.path.dirname(outpath) or '.', exist_ok=True)
+        with open(outpath, 'wb') as f:
+            f.write(encrypted)
+        print(f"  {os.path.basename(inpath)} -> {os.path.basename(outpath)}  ({len(data)} bytes)")
+        return True
+    except Exception as e:
+        print(f"  ERROR {os.path.basename(inpath)}: {e}", file=sys.stderr)
+        return False
+
+
+def main():
+    parser = argparse.ArgumentParser(
+        description="Re-encrypt decrypted Unity bundles for Holo's Hanafuda")
+    parser.add_argument('input', help='Input .unity3d file or directory of .unity3d files')
+    parser.add_argument('-o', '--output', help='Output file or directory')
+    parser.add_argument('--key-alternate', action='store_true',
+                        help='Use alternate bundle key candidate (x4DZmD6D2HhkzT6qD8HpKeZdgM9HCmXP)')
+    parser.add_argument('--key-hex', metavar='HEX',
+                        help='64-char hex AES-256 key (overrides defaults)')
+    parser.add_argument('--in-place', action='store_true',
+                        help='Write output next to the original .bundle in StandaloneWindows64/')
+    parser.add_argument('--dry-run', action='store_true',
+                        help='List what would be encrypted without writing')
+    args = parser.parse_args()
+
+    if args.key_hex:
+        key = bytes.fromhex(args.key_hex)
+        if len(key) != 32:
+            print("Error: --key-hex must be exactly 64 hex chars (32 bytes)", file=sys.stderr)
+            sys.exit(1)
+    elif args.key_alternate:
+        key = KEY_ALTERNATE
+    else:
+        key = KEY_DEFAULT
+
+    inpath = args.input
+
+    if os.path.isdir(inpath):
+        files = sorted(f for f in os.listdir(inpath) if f.endswith('.unity3d'))
+        if not files:
+            print(f"No .unity3d files found in '{inpath}'")
+            return
+
+        if args.output:
+            outdir = args.output
+        elif args.in_place:
+            outdir = os.path.normpath(os.path.join(inpath, '..', '..', 'StandaloneWindows64'))
+        else:
+            outdir = os.path.normpath(os.path.join(inpath, '..', 'reencrypted'))
+
+        if not args.dry_run:
+            os.makedirs(outdir, exist_ok=True)
+
+        ok = errs = 0
+        for fname in files:
+            fpath = os.path.join(inpath, fname)
+            base = fname.removesuffix('.unity3d')
+            outpath = os.path.join(outdir, base + '.bundle')
+            if process_file(fpath, outpath, key, args.dry_run):
+                ok += 1
+            else:
+                errs += 1
+
+        total = len(files)
+        print(f"\n{ok} OK, {errs} errors of {total}")
+        if not args.dry_run:
+            print(f"Output directory: {outdir}/")
+
+    else:
+        if not os.path.exists(inpath):
+            print(f"Error: '{inpath}' not found", file=sys.stderr)
+            sys.exit(1)
+
+        if args.output:
+            outpath = args.output
+        elif args.in_place:
+            base = os.path.splitext(os.path.basename(inpath))[0]
+            bundle_name = base + '.bundle'
+            candidates = [
+                os.path.join(os.path.dirname(inpath), bundle_name),
+                os.path.normpath(os.path.join(
+                    os.path.dirname(inpath), '..', '..', 'StandaloneWindows64', bundle_name)),
+            ]
+            outpath = None
+            for c in candidates:
+                if os.path.exists(c):
+                    outpath = c
+                    break
+            if not outpath:
+                print(f"Error: --in-place but no existing .bundle found for '{inpath}'",
+                      file=sys.stderr)
+                sys.exit(1)
+        else:
+            basedir = os.path.dirname(inpath) or '.'
+            basename = os.path.splitext(os.path.basename(inpath))[0] + '.bundle'
+            outpath = os.path.join(basedir, basename)
+
+        process_file(inpath, outpath, key, args.dry_run)
+
+
+if __name__ == '__main__':
+    main()