-authentication. You'll need to get Eric Young's libdes library in
-order to use my MS-CHAP extensions. You can find it in:
+authentication. You may need to get Eric Young's libdes library in
+order to use my MS-CHAP extensions. A lot of UNIX systems already
+have DES encryption available via the crypt(3), encrypt(3) and
+setkey(3) interfaces. Some may (such as that on Digital UNIX)
+provide only the encryption mechanism and will not perform
+decryption. This is okay. We only need to encrypt to perform
+MS-CHAP authentication.
+
+If you have encrypt/setkey available, then hopefully you need only
+define these two things in your Makefile: -DUSE_CRYPT and -DCHAPMS.
+Skip the paragraphs below about obtaining and building libdes. Do
+the "make clean" and "make" as described below. Linux users
+should not need to modify their Makefiles. Instead,
+just do "make CHAPMS=1 USE_CRYPT=1".
+
+If you don't have encrypt and setkey, you will need Eric Young's
+libdes library. You can find it in: