🔐 Secure Transform Utility

Encryptor / Decryptor

Encrypt or decrypt text and files with repeating-key byte transformation. Use your own key or apply a generated 512-bit key, then save results locally with clear file suffixes.

Suggested 512-bit key: 3449d8f2dab8d0e1031d242612801c5f58802055297400cf8bedfdec535d197db7eefa87afbfea0341d24e62edc8f82d00a9fc11cf1bc30f001614158df708fa
Overview

Encryptor / Decryptor - Browser-Based Repeating-Key Cipher Tool

This tool encrypts and decrypts text or files directly in your browser using a repeating-key byte transformation. Each byte of your input is shifted by the corresponding byte of your key (with the key cycling as needed), and the result is Base64-encoded for text mode or saved as a binary file for file mode. The scheme is simple and fast, making it convenient for obfuscating logs, scrambling config values, or sharing lightly protected data with a trusted party who knows the key.

Important: this is not AES or any standardized cipher. The repeating-key transform is a classical symmetric obfuscation technique. It is not suitable for protecting sensitive personal data, passwords, financial records, or anything that requires cryptographic security guarantees. For those use cases, use a proper AES-GCM or ChaCha20-Poly1305 implementation. Use this tool for casual obfuscation, learning about byte-level transforms, or situations where convenience matters more than security strength.

100% freeNo sign-up requiredRuns entirely in your browserSupports text and file mode
How to use it
  1. 1Choose Encrypt or Decrypt and select Text Mode or File Mode using the buttons at the top of the panel.
  2. 2Enter your key in the key field. You can type any passphrase, click Use Suggested Key to apply a freshly generated 512-bit random key, or Import Key from a saved .txt or .json file.
  3. 3In Text Mode, paste your plain text (to encrypt) or paste the Base64 ciphertext (to decrypt) into the input area. In File Mode, pick any file from your device.
  4. 4Click Encrypt Now or Decrypt Now and watch the progress bar. Text results appear in the output area; file results download automatically with a -enc or -dec suffix.
  5. 5After encrypting, click Export Key to save your key to a file. You will need the exact same key to decrypt later - there is no recovery mechanism.
Key features
  • Repeating-key byte transform with Base64 output - a fast, symmetric obfuscation scheme suitable for casual use and non-sensitive data.
  • Text mode and file mode in one tool - encrypt short messages or entire binary files with the same key workflow.
  • Random 512-bit key generator using the Web Crypto API's cryptographically random number source, with one-click refresh.
  • Key import and export - save your key as a plain text file and reload it later, or share it with a trusted recipient.
  • Chunked processing with a live progress bar so large files do not freeze the browser tab during the transform.
  • All operations run locally in your browser - no data is uploaded; files are read with the File API and results are downloaded directly.
  • Clear labeling of the scheme's limitations - the UI and documentation are transparent that this is obfuscation, not strong encryption.

Frequently asked questions

Is this tool safe for encrypting passwords or personal data?
No. This tool uses a repeating-key byte transformation, not AES or any peer-reviewed cipher. It is designed for casual obfuscation - hiding data from casual inspection, not protecting it against a determined adversary. For passwords, personal data, or anything sensitive, use a tool built on AES-GCM or an equivalent standard.
What happens if I lose my key?
There is no recovery option. The same key used to encrypt must be used to decrypt. If you lose it, the data cannot be recovered. Always export and back up your key immediately after encrypting anything you want to keep.
Does my file or text get uploaded anywhere?
No. The entire transform runs inside your browser using JavaScript. Files are read with the browser's File API and results are downloaded locally. Nothing is sent to a server.
Can I encrypt any file type?
Yes. File mode reads any file as raw bytes, transforms each byte with the key, and writes the result back as a binary download. The file type does not matter. The output file gets the original extension with -enc or -dec appended so it is easy to identify.
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Full guide

Encryptor & Decryptor Complete Guide

Understand AES encryption, Base64 encoding, hashing, and when to use each approach.

AES encryption & Base64 encodingHashing vs encryption explainedCommon questions answered

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