Added a bignum library to abstract possible implementations.

2 files changed, 67 insertions, 0 deletions

diff --git a/libcmix-bignum/gmp/CMakeLists.txt b/libcmix-bignum/gmp/CMakeLists.txt
new file mode 100644
index 0000000..44b99ad
--- /dev/null
+++ b/libcmix-bignum/gmp/CMakeLists.txt
@@ -0,0 +1,18 @@
+include(get_target_name)
+
+get_target_name(target_name)
+
+find_package(gmp REQUIRED)
+
+add_library(${target_name} SHARED
+	gmp_bignum.c
+)
+
+target_compile_options(${target_name}
+	PRIVATE -std=c99
+)
+
+target_link_libraries(${target_name}
+	PRIVATE cmix-bignum-interface
+	PRIVATE gmp
+)
diff --git a/libcmix-bignum/gmp/gmp_bignum.c b/libcmix-bignum/gmp/gmp_bignum.c
new file mode 100644
index 0000000..cc40b48
--- /dev/null
+++ b/libcmix-bignum/gmp/gmp_bignum.c
@@ -0,0 +1,49 @@
+#include "bignum.h"
+
+#include "gmp.h"
+
+void from_bignum(mpz_t i, struct Bignum b) {	
+	mpz_import(i, b.len, -1, 1, 0, 0, b.data);
+}
+
+void to_bignum(struct Bignum* b, mpz_t i) {
+	mpz_export(b->data, &b->len, -1, 1, 0, 0, i);
+}
+
+enum bignum_error get_curve25519_mod(struct Bignum* result) {
+	mpz_t mod;
+	mpz_init(mod);
+	mpz_ui_pow_ui(mod, 2, 255);
+	mpz_sub_ui(mod, mod, 19);
+	
+	to_bignum(result, mod);
+	return NoError;
+}
+
+enum bignum_error multiply_mod(struct Bignum* result, struct Bignum const lh, struct Bignum const rh, struct Bignum const mod) {
+	mpz_t lh_;
+	mpz_init(lh_);
+	from_bignum(lh_, lh);
+	
+	mpz_t rh_;
+	mpz_init(rh_);
+	from_bignum(rh_, rh);
+	
+	mpz_t result_;
+	mpz_init(result_);
+	mpz_mul(result_, lh_, rh_);
+	
+	mpz_t mod_;
+	mpz_init(mod_);
+	from_bignum(mod_, mod);
+	mpz_mod(result_, result_, mod_);
+	
+	to_bignum(result, result_);
+	
+	mpz_clear(result_);
+	mpz_clear(lh_);
+	mpz_clear(rh_);
+	mpz_clear(mod_);
+	
+	return NoError;
+}