Update build for OpenEMV common crypto submodule

* Allow parent project to provide crypto submodule
* Allow crypto submodule to provide CMake config file dependencies
* Allow crypto submodule to provide pkgconfig file dependencies
* Remove CMake modules used to download and find MbedTLS. These are
  provided by the crypto submodule.
* Remove MbedTLS and OpenSSL checks, configs and linking. The crypto
  submodule will download/build/use an underlying crypto implementation.
* Remove crypto implementation definitions from generated config header

CMakeLists.txt

@@ -14,6 +14,17 @@ project(tr31
 	LANGUAGES C
 )
 
+# Determine whether this project is the top-level project
+if(${CMAKE_VERSION} VERSION_LESS "3.21")
+	get_directory_property(TR31_HAS_PARENT PARENT_DIRECTORY)
+	if(NOT TR31_HAS_PARENT)
+		set(TR31_IS_TOP_LEVEL True)
+	endif()
+else()
+	# CMake >=3.21 provides <PROJECT-NAME>_IS_TOP_LEVEL
+	set(TR31_IS_TOP_LEVEL ${tr31_IS_TOP_LEVEL})
+endif()
+
 set(CMAKE_C_STANDARD 11)
 set(CMAKE_C_EXTENSIONS OFF)
 if (CMAKE_COMPILER_IS_GNUCC OR CMAKE_COMPILER_IS_GNUCXX)
@@ -26,7 +37,17 @@ set(CMAKE_MODULE_PATH ${CMAKE_MODULE_PATH} "${CMAKE_CURRENT_SOURCE_DIR}/cmake/Mo
 
 include(CTest)
 
-add_subdirectory(crypto)
+# Allow parent scope to provide crypto targets when not building shared libs
+if(TR31_IS_TOP_LEVEL OR BUILD_SHARED_LIBS)
+	add_subdirectory(crypto EXCLUDE_FROM_ALL)
+	add_subdirectory(crypto/test)
+elseif (NOT TARGET crypto_tdes OR
+	NOT TARGET crypto_aes OR
+	NOT TARGET crypto_mem OR
+	NOT TARGET crypto_rand)
+	message(FATAL_ERROR "Parent project must provide crypto libraries for static builds")
+endif()
+
 add_subdirectory(src)
 add_subdirectory(test)
 
@@ -42,7 +63,8 @@ install(FILES
 
 # generate and install basic CMake config files
 include(CMakePackageConfigHelpers) # provides CMake config generator macros
-foreach(pkg IN LISTS TR31_PACKAGE_DEPENDENCIES)
+# NOTE: crypto subdirectory provides CRYPTO_PACKAGE_DEPENDENCIES
+foreach(pkg IN LISTS CRYPTO_PACKAGE_DEPENDENCIES)
 	# build dependency string for use in CMake config file
 	string(APPEND TR31_CONFIG_PACKAGE_DEPENDENCIES "find_dependency(${pkg})\n")
 endforeach()
@@ -77,7 +99,9 @@ export(EXPORT tr31Targets
 set(TR31_INSTALL_PKGCONFIG_DIR ${CMAKE_INSTALL_LIBDIR}/pkgconfig CACHE STRING "Installation location for tr31 pkgconfig files")
 message(STATUS "Using pkgconfig install location \"${TR31_INSTALL_PKGCONFIG_DIR}\"")
 set(TR31_PKGCONFIG_LIB_NAME ${CMAKE_PROJECT_NAME})
-# NOTE: subdirectories will provide TR31_PKGCONFIG_REQ_PRIV and TR31_PKGCONFIG_LIBS_PRIV
+# NOTE: crypto subdirectory provides CRYPTO_PKGCONFIG_REQ_PRIV and CRYPTO_PKGCONFIG_LIBS_PRIV
+set(TR31_PKGCONFIG_REQ_PRIV ${CRYPTO_PKGCONFIG_REQ_PRIV})
+set(TR31_PKGCONFIG_LIBS_PRIV ${CRYPTO_PKGCONFIG_LIBS_PRIV})
 configure_file(pkgconfig/libtr31.pc.in
 	"${CMAKE_CURRENT_BINARY_DIR}/pkgconfig/libtr31.pc"
 	@ONLY

src/CMakeLists.txt

@@ -7,35 +7,6 @@
 
 cmake_minimum_required(VERSION 3.16)
 
-find_package(MbedTLS 2.16) # Latest version available on Ubuntu 20.04 and Fedora 34
-option(FETCH_MBEDTLS "Download and build MbedTLS")
-if(NOT MbedTLS_FOUND AND FETCH_MBEDTLS)
-	include(FetchMbedTLS)
-endif()
-
-find_package(OpenSSL 1.1 COMPONENTS Crypto)
-
-# choose crypto implementation and inform parent scope
-if(NOT MbedTLS_FOUND AND NOT OpenSSL_FOUND)
-	message(FATAL_ERROR "Either MbedTLS or OpenSSL is required")
-endif()
-if(MbedTLS_FOUND)
-	# prefer MbedTLS
-	message(STATUS "Using MbedTLS")
-	set(USE_MBEDTLS TRUE)
-	list(APPEND TR31_PACKAGE_DEPENDENCIES "MbedTLS 2.16")
-	set(TR31_PACKAGE_DEPENDENCIES ${TR31_PACKAGE_DEPENDENCIES} PARENT_SCOPE)
-	# NOTE: MbedTLS has no pkgconfig file so TR31_PKGCONFIG_REQ_PRIV cannot be set
-	set(TR31_PKGCONFIG_LIBS_PRIV "-lmbedcrypto" PARENT_SCOPE)
-else()
-	message(STATUS "Using OpenSSL")
-	set(USE_OPENSSL TRUE)
-	list(APPEND TR31_PACKAGE_DEPENDENCIES "OpenSSL 1.1 COMPONENTS Crypto")
-	set(TR31_PACKAGE_DEPENDENCIES ${TR31_PACKAGE_DEPENDENCIES} PARENT_SCOPE)
-	set(TR31_PKGCONFIG_REQ_PRIV "libcrypto" PARENT_SCOPE)
-	set(TR31_PKGCONFIG_LIBS_PRIV "-lcrypto" PARENT_SCOPE)
-endif()
-
 include(CheckFunctionExists)
 check_function_exists("argp_parse" argp_FOUND)
 option(FETCH_ARGP "Download and build argp-standalone")
@@ -71,11 +42,6 @@ target_include_directories(tr31 INTERFACE
 	$<INSTALL_INTERFACE:include/${PROJECT_NAME}>
 )
 target_link_libraries(tr31 PRIVATE crypto_tdes crypto_aes crypto_mem crypto_rand)
-if(MbedTLS_FOUND)
-	target_link_libraries(tr31 PRIVATE MbedTLS::mbedcrypto)
-elseif(OpenSSL_FOUND)
-	target_link_libraries(tr31 PRIVATE OpenSSL::Crypto)
-endif()
 
 # TR-31 command line tool
 add_executable(tr31-tool tr31-tool.c)

src/tr31_config.h.in

@@ -22,7 +22,5 @@
 #define TR31_CONFIG_H
 
 #define TR31_LIB_VERSION_STRING "@CMAKE_PROJECT_VERSION@"
-#cmakedefine USE_MBEDTLS
-#cmakedefine USE_OPENSSL
 
 #endif

src/tr31_crypto.c

@@ -19,13 +19,13 @@
  */
 
 #include "tr31_crypto.h"
-#include "tr31_config.h"
 #include "tr31.h"
 
 #include "crypto_tdes.h"
 #include "crypto_aes.h"
 #include "crypto_mem.h"
 
+#include <stdint.h>
 #include <string.h>
 
 #define TR31_KBEK_VARIANT_XOR (0x45)