1. Quick Start (without marketing nonsense)

1. Select the text or file you want to encrypt.
2. Choose a binary key file that meets the basic requirements (see section 4).
3. Click Encode (for text) or Generate (for files).
4. You’ll get either a Base64 block or a file with the extension .adt.
5. To decode, just reverse the process using the exact same key file.

No accounts, no tracking, no uploads. Everything happens locally in your browser.

3. How It Works (and Why It’s Cool)

For every byte in the input (text or file), the encoder picks a random index into the key file. From that index, it searches backwards until it finds a position where the key file contains the same byte value.

That found position is stored as a 3-byte offset (24 bits) in the output.

• Each input byte becomes exactly 3 output bytes.
• The search wraps around the key file if needed (modulo arithmetic).
• No actual data is stored — only the location of matching values in the key.
• The result contains no structure, no markers, and no signature.

Decryption requires the exact same key file. Without it, there is no way to reconstruct the original data. The key file must be at least 64 kB in size. It must contain each byte value (0–255) at least twice somewhere in the file to ensure successful encoding and decoding.

4. Key File Rules

• The key file must be at least 64 kB in size.
• To ensure correct encoding and decoding, it must contain each possible byte value (0–255) at least twice anywhere in the file.
• Random files, images, ZIPs or executables usually meet this condition.

For example: two people meet and exchange a vacation photo via USB flash drive. That file becomes the key. Later, it can be used to encrypt a message. No password. No internet. Just a shared file that only they possess.

Think of your key file like a toothbrush: don’t share it, and replace it regularly.

5. Safety Principles

• Use a new key file at least once a month. Don't let it become part of your backups or cloud history.
• Delete old key files. If they’re no longer needed, erase them securely.
• Delete the encrypted message after sending it. No point keeping it around if it’s already delivered.
• Delete the decrypted message right after reading. If you want to keep it, store it encrypted again.
• Never store key and message together. Not on the same disk, not in the same ZIP, not in the same email.

ADT offers no password, no login, no recovery. If something leaks, it's because you left it lying around.

6. Algorithm Overview

ADT encoding is based on position matching in a binary key file. Each input byte is replaced with a 24-bit offset pointing to a matching value in the key.

• A random index is selected into the key file.
• The algorithm moves backward (modulo) until it finds the first occurrence of the same byte value.
• The found index is stored as three bytes (big-endian offset).

This means:

• Each input byte becomes exactly 3 output bytes.
• The output has no structure, no delimiter, no metadata.
• Decryption requires the exact same key file to reverse the lookup.
• If the key file is lost, corrupted, or doesn’t contain matching values for the original data, the encrypted message becomes permanently unreadable — by design.

7. Even a moron could code this

The algorithm is deliberately simple. There are no hidden layers, no encryption libraries, no clever obfuscation. Anyone with basic programming knowledge can recreate it in a weekend.

That’s not a weakness. That’s the point. If you want to understand how it works, just read the source. It’s short, clean, and brutally transparent.

If that’s too much to ask — maybe encryption isn't your field.