Add check for EVP AES-CTR mode when openssl is enabled. Update README to include --enable-openssl option.
diff --git a/configure b/configure
index a1c07ab..ef3cb25 100755
--- a/configure
+++ b/configure
@@ -4874,7 +4874,57 @@
else
{ { $as_echo "$as_me:${as_lineno-$LINENO}: error: in \`$ac_pwd':" >&5
$as_echo "$as_me: error: in \`$ac_pwd':" >&2;}
-as_fn_error $? "can't find openssl crypto lib
+as_fn_error $? "can't find openssl >1.0.1 crypto lib
+See \`config.log' for more details" "$LINENO" 5; }
+fi
+
+ { $as_echo "$as_me:${as_lineno-$LINENO}: checking for EVP_aes_128_ctr in -lcrypto" >&5
+$as_echo_n "checking for EVP_aes_128_ctr in -lcrypto... " >&6; }
+if ${ac_cv_lib_crypto_EVP_aes_128_ctr+:} false; then :
+ $as_echo_n "(cached) " >&6
+else
+ ac_check_lib_save_LIBS=$LIBS
+LIBS="-lcrypto $LIBS"
+cat confdefs.h - <<_ACEOF >conftest.$ac_ext
+/* end confdefs.h. */
+
+/* Override any GCC internal prototype to avoid an error.
+ Use char because int might match the return type of a GCC
+ builtin and then its argument prototype would still apply. */
+#ifdef __cplusplus
+extern "C"
+#endif
+char EVP_aes_128_ctr ();
+int
+main ()
+{
+return EVP_aes_128_ctr ();
+ ;
+ return 0;
+}
+_ACEOF
+if ac_fn_c_try_link "$LINENO"; then :
+ ac_cv_lib_crypto_EVP_aes_128_ctr=yes
+else
+ ac_cv_lib_crypto_EVP_aes_128_ctr=no
+fi
+rm -f core conftest.err conftest.$ac_objext \
+ conftest$ac_exeext conftest.$ac_ext
+LIBS=$ac_check_lib_save_LIBS
+fi
+{ $as_echo "$as_me:${as_lineno-$LINENO}: result: $ac_cv_lib_crypto_EVP_aes_128_ctr" >&5
+$as_echo "$ac_cv_lib_crypto_EVP_aes_128_ctr" >&6; }
+if test "x$ac_cv_lib_crypto_EVP_aes_128_ctr" = xyes; then :
+ cat >>confdefs.h <<_ACEOF
+#define HAVE_LIBCRYPTO 1
+_ACEOF
+
+ LIBS="-lcrypto $LIBS"
+
+else
+ { { $as_echo "$as_me:${as_lineno-$LINENO}: error: in \`$ac_pwd':" >&5
+$as_echo "$as_me: error: in \`$ac_pwd':" >&2;}
+as_fn_error $? "can't find openssl >1.0.1 crypto lib
See \`config.log' for more details" "$LINENO" 5; }
fi