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experiments/gpu

GPU compute experiments using CUDA and Numba.

encrypt.cu — GPU File Encryptor

An industrial-strength file encryption tool using the GPU to accelerate the ChaCha20 keystream generation, with Argon2id key derivation and Poly1305 authentication.

Security model

Component Primitive Standard
Key derivation Argon2id RFC 9106
Encryption ChaCha20 stream cipher (GPU-parallelised) RFC 8439
Authentication Poly1305 MAC (CPU-side) RFC 8439
AAD Full 41-byte header authenticated RFC 8439 §2.8
Nonce 96-bit, OS CSPRNG —
Salt 128-bit, OS CSPRNG —
  • Passphrase read from /dev/tty (echo off) — never via argv
  • Key material zeroed after use via volatile loop (secure_zero)
  • Decrypted output written to .tmp file; renamed to final destination only after MAC verification passes — partial plaintext never persists on failure
  • Constant-time MAC comparison prevents timing side-channels
  • orig_size serialized as explicit little-endian — portable across architectures
  • OS CSPRNG used directly: getrandom() (Linux), BCryptGenRandom (Windows)

File format

[4 bytes magic 'VBCR'] [1 byte version=0x02] [16 bytes salt] [12 bytes nonce]
[8 bytes orig_size LE] [ciphertext chunks...]  [16 bytes Poly1305 tag]

The full 41-byte header is fed to Poly1305 as AAD, binding all header fields to the tag.

Dependencies

Build

Linux (sm_75+):

nvcc -O3 -use_fast_math -arch=sm_75 -std=c++17 \
     --ptxas-options=-v encrypt.cu -o vibecoder -largon2

Windows (MSVC + vcpkg argon2):

nvcc -allow-unsupported-compiler -O3 -use_fast_math -std=c++17 ^
  -I "C:\vcpkg\installed\x64-windows\include" ^
  -L "C:\vcpkg\installed\x64-windows\lib" ^
  encrypt.cu -o vibecoder.exe -largon2

Usage

vibecoder encrypt  [-r] [--chunk <MB>] <file|dir>
vibecoder decrypt  [-r] [--chunk <MB>] <file.enc|dir>
vibecoder verify        [--chunk <MB>] <file.enc>
Option Description
-r Recurse into directory
--chunk <MB> Streaming window size (default: 256 MB, min: 16 MB). Auto-clamped to 40% of free VRAM.

Passphrase: read interactively from /dev/tty (echo disabled), or set VIBECODER_PASSPHRASE env var for scripted/CI use.

Examples

# Encrypt a single file
vibecoder encrypt secret.tar.gz

# Decrypt
vibecoder decrypt secret.tar.gz.enc

# Verify MAC without writing plaintext
vibecoder verify secret.tar.gz.enc

# Recursively encrypt a directory
vibecoder encrypt -r ./documents

# Use a smaller chunk on a GPU with limited VRAM
vibecoder encrypt --chunk 64 large_file.iso

TRON 3d (main.cu, mainpy)

Implemented in CUDA and Python.