Tiny Tapeout: PRESENT Block Cipher

This repository contains an implementation of the PRESENT block cipher designed for Tiny Tapeout.

• Read the full documentation for the project

Overview

PRESENT is an ultra-lightweight block cipher designed for power and area-constrained environments. This implementation operates on a 64-bit plaintext block and uses an 80-bit encryption key. To map the 64-bit datapath constraints onto the 8-bit Tiny Tapeout IO protocol, the top module features a Finite State Machine (FSM) wrapped around serial shift registers to sequentially load the data and key, then extract the ciphertext upon encryption completion.

Key Features

• Algorithm: PRESENT-80 (64-bit block, 80-bit key, 31 rounds).
• Target Platform: Tiny Tapeout (1x1 tile).
• Architecture: Nibble-serial datapath with a single shared S-Box for minimal area.
• IO Scheme: 8-bit parallel, sequenced over multiple clock cycles via uio_in control flags.

Testing

Comprehensive testing uses cocotb. Run the simulator tests locally by navigating to test/ and executing make.

Building

The ASIC design is automatically built and tested using GitHub Actions with LibreLane upon committing to this repository. See the Actions tab for logs and GDS artifacts.