i2c-stub-toy/ext/libtomcrypt/README.md

# libtomcrypt

See `doc/crypt.pdf` for a detailed documentation

## Project Status

master: [![Build Status](https://api.travis-ci.org/libtom/libtomcrypt.png?branch=master)](https://travis-ci.org/libtom/libtomcrypt) [![Coverage Status](https://coveralls.io/repos/libtom/libtomcrypt/badge.png?branch=master)](https://coveralls.io/r/libtom/libtomcrypt)

develop: [![Build Status](https://api.travis-ci.org/libtom/libtomcrypt.png?branch=develop)](https://travis-ci.org/libtom/libtomcrypt) [![Coverage Status](https://coveralls.io/repos/libtom/libtomcrypt/badge.png?branch=develop)](https://coveralls.io/r/libtom/libtomcrypt)

[![Coverity Scan Build Status](https://scan.coverity.com/projects/487/badge.svg)](https://scan.coverity.com/projects/487)

## Submitting patches

Please branch off from develop if you want to submit a patch.

Patch integration will be faster if tests and documentation are included.

Please update the makefiles in a separate commit. To update them simply run the `updatemakes.sh` script.

## Branches

Please be aware, that all branches besides _master_ and _develop_ __can__ and __will be__ force-pushed, rebased and/or removed!

If you want to rely on such an _unstable_ branch, create your own fork of this repository to make sure nothing breaks for you.

## Configuration options

By default the library builds its entire feature set (besides `katja`) in a (depending on your needs more or less) optimal way.

There are numerous configuration options available if you want to trim down the functionality of the library.

Please have a look at `src/headers/tomcrypt_custom.h` for all available configuration options.

The following list is a small part of the available, but the most often required, configuration switches.

| Flag | Behavior |
| ---- | -------- |
| `LTC_NO_TEST` | Remove all algorithm self-tests from the library |
| `LTC_NO_FILE` | Remove all API functions requiring a pre-defined `FILE` data-type (mostly useful for embedded targets) |
| `MAX_RSA_SIZE` | Per default set to `4096`, if you need support for importing or generating bigger RSA keys, change this at compile-time. |
| `GMP_DESC` | enable [gmp](https://gmplib.org/) as MPI provider *\*1* |
| `LTM_DESC` | enable [libtommath](http://www.libtom.net/) as MPI provider *\*1* |
| `TFM_DESC` | enable [tomsfastmath](http://www.libtom.net/) as MPI provider *\*1* *\*2* |
| `USE_GMP` | use `gmp` as MPI provider when building the binaries *\*3* |
| `USE_LTM` | use `libtommath` as MPI provider when building the binaries *\*3* |
| `USE_TFM` | use `tomsfastmath` as MPI provider when building the binaries *\*3* |

*\*1* It is possible to build the library against all MPI providers in parallel and choose at startup-time which math library should be used.

*\*2* Please be aware that `tomsfastmath` has the limitation of a fixed max size of MPI's.

*\*3* Only one is supported at the time & this is only required when building the binaries, not when building the library itself.

## Building the library

There are several `makefile`s provided. Please choose the one that fits best for you.

| makefile | use-case |
| -------- | -------- |
| `makefile` | builds a static library (GNU Make required, broken on Mac OSX - use `makefile.unix` instead) |
| `makefile.shared` | builds a shared (and static) library (GNU Make required) |
| `makefile.unix` | for unusual UNIX platforms, or if you do not have GNU Make |
| `makefile.mingw` | for usage with the mingw compiler on MS Windows |
| `makefile.msvc` | for usage with the MSVC compiler on MS Windows |
| `libtomcrypt_VS2008.sln` | A VisualStudio 2008 project for MS Windows |

### Make targets

The `makefile`s provide several targets to build (VS project excluded).
The following list does not claim to be complete resp. to be available across all `makefile` variants.

| target | application |
| ------ | ----------- |
| *empty target*/none given | c.f. `library`
| `library` | builds only the library |
| `hashsum` | builds the `hashsum` binary, similar to [`shasum`](https://linux.die.net/man/1/shasum), but with support for all hash-algorithms included in the library *\*4* |
| `ltcrypt` | builds the `ltcrypt` binary, implementing something similar to [`crypt`](https://linux.die.net/man/3/crypt) *\*4* |
| `sizes` | builds the `sizes` binary, printing all internal data sizes on invocation *\*4* |
| `constants` | builds the `constants` binary, printing all internal constants on invocation *\*4* |
| `openssl-enc` | builds the `openssl-enc` binary, which is more or less compatible to [`openssl enc`](https://linux.die.net/man/1/enc) *\*4* *\*5* |
| `test` | builds the `test` binary, which runs all algorithm self-tests + some extended tests *\*4* *\*6* |
| `timing` | builds the `timing` binary, which can be used to measure timings for algorithms and modes *\*4* *\*6* |
| `bins` | builds `hashsum` *\*4* |
| `all_test` | builds `test`, `hashsum`, `ltcrypt`, `small`, `tv_gen`, `sizes` & `constants` *\*4* |

*\*4* also builds `library`

*\*5* broken build in some configurations, therefore not built by default

*\*6* requires define of one of `USE_GMP`, `USE_LTM` or `USE_TFM` (+ the appropriate MPI provider)

### Examples

You want to build the library as static library

    make

You want to build the library as shared library

    make -f makefile.shared

You have `libtommath` installed on your system and want to build a static library and the `test` binary to run the self-tests.

    make CFLAGS="-DUSE_LTM -DLTM_DESC" EXTRALIBS="-ltommath" test

You have `tomsfastmath` installed on your system and want to build a shared library and all binaries

    make -f makefile.shared CFLAGS="-DUSE_TFM -DTFM_DESC" EXTRALIBS="-ltfm" all demos

You have `gmp`, `libtommath` and `tomsfastmath` installed on your system and want to build a static library and the `timing` binary to measure timings against `gmp`.

    make CFLAGS="-DUSE_GMP -DGMP_DESC -DLTM_DESC -DTFM_DESC" EXTRALIBS="-lgmp" timing

If you have `libtommath` in a non-standard location:

    make CFLAGS="-DUSE_LTM -DLTM_DESC -I/opt/devel/ltm" EXTRALIBS="/opt/devel/ltm/libtommath.a" all