From 6b4220a2ce74fbfce0048dc4f18f3be4d504423d Mon Sep 17 00:00:00 2001
From: Martin Schanzenbach <schanzen@gnunet.org>
Date: Wed, 4 Dec 2024 08:58:18 +0100
Subject: [PATCH] add RELIC_ARITH CLI option that defaults to `easy`; making
 gmp an optional dependency. Fixes #12

---
 CMakeLists.txt     | 3 ++-
 README.md          | 5 +++--
 src/CMakeLists.txt | 8 +++++---
 3 files changed, 10 insertions(+), 6 deletions(-)

diff --git a/CMakeLists.txt b/CMakeLists.txt
index 1ab5947..db53469 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -29,6 +29,7 @@ else()
   message(STATUS "-finline-small-functions not supported.")
 endif()
 
+SET(RELIC_ARITH "easy" CACHE STRING "The ARITH value for RELIC build")
 
 message(STATUS "Relic CFLAGS: ${RELIC_CFLAGS}")
 include(ExternalProject)
@@ -48,7 +49,7 @@ ExternalProject_Add(
              -DTIMER=
              -DCHECK=off
              -DVERBS=off
-             -DARITH=gmp
+	     -DARITH=${RELIC_ARITH}
              -DFP_PRIME=381
              "-DFP_METHD=BASIC^^COMBA^^COMBA^^MONTY^^MONTY^^JMPDS^^SLIDE"
              "-DCFLAGS=${RELIC_CFLAGS}"
diff --git a/README.md b/README.md
index b4d6cd6..fd71976 100644
--- a/README.md
+++ b/README.md
@@ -10,13 +10,14 @@ Provides a library `libbbs` implementing the `BLS12381-SHA-256` and `BLS12-381-S
 
 Dependencies:
 
-- `gmp`
 - `cmake` (build only)
+- `gmp` (optional)
 
 ```zsh
 mkdir build
 cd build
-cmake ..
+cmake .. # Without GMP or
+cmake -DRELIC_ARITH="gmp" .. # (if you have gmp)
 ```
 
 ### Installation
diff --git a/src/CMakeLists.txt b/src/CMakeLists.txt
index dce5eb7..3695102 100644
--- a/src/CMakeLists.txt
+++ b/src/CMakeLists.txt
@@ -1,6 +1,8 @@
-find_library(GMP_LIB gmp REQUIRED)
-find_path(GMP_PATH gmp.h REQUIRED)
-message(STATUS "GMP_PATH: ${GMP_PATH}")
+if(RELIC_ARITH STREQUAL "gmp")
+	find_library(GMP_LIB gmp REQUIRED)
+	find_path(GMP_PATH gmp.h REQUIRED)
+	message(STATUS "GMP_PATH: ${GMP_PATH}")
+endif()
 
 add_library(bbs SHARED
 	bbs.c