tird 0.6.0

A tool for encrypting file contents and hiding encrypted data among random data

tird

tird (an acronym for "this is random data") is a tool for encrypting file contents and hiding encrypted data among random data.

Goals

• Providing protection for individual files, including:
  • deniable encryption;
  • minimizing metadata leakage;
  • data hiding.
• Simplicity: refusal to implement features that are not directly related to primary security goals.
• Providing a stable encryption format with no cryptographic agility for long-term data storage.

Cryptographic primitives

• BLAKE2b:
  • salted and personalized BLAKE2b as part of a key derivation scheme;
  • keyed BLAKE2b for data authentication.
• Argon2 memory-hard function for key stretching and key derivation.
• ChaCha20-IETF cipher for data encryption.

Encryption format (cryptoblob structure)

                     512B          0+B
                 +----------+---------------+
                 | comments | file contents |
                 +----------+---------------+
  16B     0+B    |     plaintext/payload    | 64B     0+B     16B
+------+---------+--------------------------+-----+---------+------+
| salt | padding |        ciphertext        | MAC | padding | salt |
+------+---------+--------------------------+-----+---------+------+
|  random bytes  |      random-looking data       |  random bytes  |
+----------------+--------------------------------+----------------+

Tradeoffs and limitations

• tird does not support public-key cryptography.
• tird does not support file compression.
• tird does not support ASCII armored output.
• tird does not support Reed–Solomon error correction.
• tird does not support splitting the output into chunks.
• tird does not support low-level device reading and writing when used on MS Windows (devices cannot be used as keyfiles, cannot be overwritten, cannot be encrypted or hidden).
• tird does not provide a graphical user interface.
• tird does not provide a password generator.
• tird does not wipe sensitive data from the heap.
• tird can only encrypt one file per iteration. Encryption of directories and multiple files is not supported.
• tird does not fake file timestamps (atime, mtime, ctime).
• tird encryption speed is not very fast: up to 180 MiB/s (in my tests).

Warnings

• ⚠️ The author is not a cryptographer.
• ⚠️ tird has not been independently audited.
• ⚠️ tird probably won't help much when used in a compromised environment.
• ⚠️ tird probably won't help much when used with short and predictable keys.
• ⚠️ Keys may leak into the swap space.
• ⚠️ tird always releases unverified plaintext (violates The Cryptographic Doom Principle).
• ⚠️ tird does not sort digests of keyfiles and passphrases in constant time.
• ⚠️ Development is ongoing, there may be backward compatibility issues in the future.

Usage

Just run the script, select the option you want and then answer the questions.

Requirements

• Python >= 3.6
• PyNaCl >= 1.2.0 (provides Argon2 KDF)
• PyCryptodomex >= 3.6.2 (provides ChaCha20 cipher)

Install

Install python3 and python3-pip (or python-pip), then run

$ pip install tird

Binary builds (made with PyInstaller) are also available (see Releases).

TODO

Write documentation.

Feedback

Feel free to post any questions, feedback or criticisms to the Discussions.

License

This project is licensed under the terms of the Creative Commons Zero v1.0 Universal License (Public Domain Dedication).