# Caravel User Project

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# SHA-1 engine

See a [https://github.com/konradwilk/sha1](https://github.com/konradwilk/sha1) for the full git history of this code. Branch name is submission-mpw-two.

This is an implementation of [https://www.rfc-editor.org/rfc/inline-errata/rfc3174.html](RFC 3174) of SHA-1 engine.

It is not the most secure one nowadays (it is still used for git commit ids and TPM PCR values), but
it looked like the easiest of the SHA engines to implement. The communication channel is via
WishBone commands to provide sixteen words after which the engine starts and computes the digest
in about 160 cycles. Then digest can be retrieved via the wishbone. There is a IRQ line so when
it has completed it will bring it high if that is enabled.

![SHA1](pics/sha1.png)

If you want to see this more interactively, I would recommend you clone
[https://github.com/konradwilk/sha1](https://github.com/konradwilk/sha1) and run

```
make test_wb_logic
```

which will use the various WishBone commands to program it.

### Documentation

To create the GDS files, there are macros that are being ingested. The best way to do is by
checking out the SHA-1 engine:

```
git clone https://github.com/konradwilk/sha1
```

And then there are some pre-requisities:

 - You need to have OpenLANE installed. The Makefile assumes that is all setup.
   Specifically that the docker container is installed.
 - And make sure to have TARGET_PATH set to this directory (caravel_user_project).
 - You have the `open_mpw_checker` installed as well (and the docker container).

From within the `sha1` directory execute:

```
make gds
```

which will generate the GDS, LEF, etc files. Copy them in the `gds` sub-directory.
After that, you need to copy them to `caravel_user_project`. To do that:

```
make caravel
```

which will copy the appropiate files, run the OpenLANE to jam the macros together, and
run the checkers.