sha1

Implementation status

The core has been completed and been used in several designs. It is considered mature and ready to use.. Minor changes are non-functional cleanups of code.

Introduction

Verilog implementation of the SHA-1 cryptgraphic hash function. The functionality follows the specification in NIST FIPS 180-4.

The implementation is iterative with one cycle/round. The initialization takes one cycle. The W memory is based around a sliding window of 16 32-bit registers that are updated in sync with the round processing. The total latency/message block is 82 cycles.

There are top level wrappers that provides interface for easy integration into a System on Chip (SoC). This interface contains mesage block and digest registers to allow a host to load the next block while the current block is being processed.

The implementation also includes a functional model written in Python.

Implementation details

The sha1 design is divided into the following sections.

• src/rtl - RTL source files
• src/tb - Testbenches for the RTL files
• src/model/python - Functional model written in python
• doc - documentation (currently not done.)
• toolruns - Where tools are supposed to be run. Includes a Makefile for building and simulating the design using Icarus Verilog

The actual core consists of the following files:

• sha1_core.v - The core itself with wide interfaces.
• sha1_w_mem.v - W message block memort and expansion logic.

The top level entity is called sha1_core. This entity has wide interfaces (512 bit block input, 160 bit digest). In order to make it usable you probably want to wrap the core with a bus interface.

Unless you want to provide your own interface you therefore also need to use a top level wrapper. There is one wrapper provided:

• sha1.v - A wrapper with a 32-bit memory like interface.

The core (sha1_core) will sample all data inputs when given the init or next signal. the wrappers provided contains additional data registers. This allows you to load a new block while the core is processing the previous block.

FuseSoC

This core is supported by the FuseSoC core package manager and build system. Some quick FuseSoC instructions:

Install FuseSoC

pip install fusesoc

Create and enter a new workspace

mkdir workspace && cd workspace

Register sha1 as a library in the workspace

fusesoc library add sha1 /path/to/sha1

...if repo is available locally or... ...to get the upstream repo

fusesoc library add sha1 https://github.com/secworks/sha1

Run tb_sha1 testbench

fusesoc run --target=tb_sha1 secworks:crypto:sha1

Run with modelsim instead of default tool (icarus)

fusesoc run --target=tb_sha1 --tool=modelsim secworks:crypto:sha1

FPGA-results

Altera Cyclone FPGAs

Implementation results using Altera Quartus-II 13.1.

Altera Cyclone IV E

• EP4CE6F17C6
• 2913 LEs
• 1527 regs
• 107 MHz

Altera Cyclone IV GX

• EP4CGX22CF19C6
• 2814 LEs
• 1527 regs
• 105 MHz

Altera Cyclone V

• 5CGXFC7C7F23C8
• 1124 ALMs
• 1527 regs
• 104 MHz

Xilinx FPGAs

Implementation results using ISE 14.7.

Xilinx Spartan-6

• xc6slx45-3csg324
• 1589 LUTs
• 564 Slices
• 1592 regs
• 100 MHz