tinc/m4/openssl.m4
Guus Sliepen edc1efed3c Use AES256 and SHA256 by default for the legacy protocol.
At the start of the decade, there were still distributions that shipped
with versions of OpenSSL that did not support these algorithms. By now
everyone should support them. The old defaults were Blowfish and SHA1,
both of which are not considered secure anymore.

The meta-protocol now always uses AES in CFB mode, but the key length
will adapt to the one specified by the Cipher option. The digest for the
meta-protocol is hardcoded to SHA256.
2016-10-30 15:17:52 +01:00

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dnl Check to find the LibreSSL/OpenSSL headers/libraries
AC_DEFUN([tinc_OPENSSL],
[
case $host_os in
*mingw*)
;;
*)
AC_CHECK_FUNC(dlopen,
[],
[AC_CHECK_LIB(dl, dlopen,
[LIBS="$LIBS -ldl"],
[AC_MSG_ERROR([LibreSSL/OpenSSL depends on libdl.]); break]
)]
)
;;
esac
AC_ARG_WITH(openssl,
AS_HELP_STRING([--with-openssl=DIR], [LibreSSL/OpenSSL base directory, or:]),
[openssl="$withval"
CPPFLAGS="$CPPFLAGS -I$withval/include"
LDFLAGS="$LDFLAGS -L$withval/lib"]
)
AC_ARG_WITH(openssl-include,
AS_HELP_STRING([--with-openssl-include=DIR], [LibreSSL/OpenSSL headers directory (without trailing /openssl)]),
[openssl_include="$withval"
CPPFLAGS="$CPPFLAGS -I$withval"]
)
AC_ARG_WITH(openssl-lib,
AS_HELP_STRING([--with-openssl-lib=DIR], [LibreSSL/OpenSSL library directory]),
[openssl_lib="$withval"
LDFLAGS="$LDFLAGS -L$withval"]
)
AC_CHECK_HEADERS([openssl/evp.h openssl/rsa.h openssl/rand.h openssl/err.h openssl/sha.h openssl/pem.h openssl/engine.h],
[],
[AC_MSG_ERROR([LibreSSL/OpenSSL header files not found.]); break]
)
AC_CHECK_LIB(crypto, EVP_EncryptInit_ex,
[LIBS="-lcrypto $LIBS"],
[AC_MSG_ERROR([LibreSSL/OpenSSL libraries not found.])]
)
AC_CHECK_FUNCS([RAND_bytes EVP_EncryptInit_ex EVP_CIPHER_CTX_new], ,
[AC_MSG_ERROR([Missing LibreSSL/OpenSSL functionality, make sure you have installed the latest version.]); break],
)
AC_CHECK_DECLS([OpenSSL_add_all_algorithms EVP_aes_256_cfb], ,
[AC_MSG_ERROR([Missing LibreSSL/OpenSSL functionality, make sure you have installed the latest version.]); break],
[#include <openssl/evp.h>]
)
AC_CHECK_FUNCS([BN_GENCB_new ERR_remove_state RSA_set0_key], , , [#include <openssl/rsa.h>])
])