gen_pkcs3: add comment explaining rationale
[exim.git] / src / util / cramtest.pl
1 #!/usr/bin/perl
2
3 # This script is contributed by Vadim Vygonets to aid in debugging CRAM-MD5
4 # authentication.
5
6 # A patch was contributed by Jon Warbrick to upgrade it to use the Digest::MD5
7 # module instead of the deprecated MD5 module.
8
9 # The script prompts for three data values: a user name, a password, and the
10 # challenge as sent out by an SMTP server. The challenge is a base-64 string.
11 # It should be copied (cut-and-pasted) literally as the third data item. The
12 # output of the program is the base-64 string that is to be returned as the
13 # response to the challenge. Using the example in RFC 2195:
14 #
15 # User: tim
16 # Password: tanstaaftanstaaf
17 # Challenge: PDE4OTYuNjk3MTcwOTUyQHBvc3RvZmZpY2UucmVzdG9uLm1jaS5uZXQ+
18 # dGltIGI5MTNhNjAyYzdlZGE3YTQ5NWI0ZTZlNzMzNGQzODkw
19 #
20 # The last line is what you you would send back to the server.
21
22
23 # Copyright (c) 2002
24 # Vadim Vygonets <vadik-exim@vygo.net>. All rights reserved.
25 # Public domain is OK with me.
26
27 use MIME::Base64;
28 use Digest::MD5;
29
30 print "User: ";
31 chop($user = <>);
32 print "Password: ";
33 chop($passwd = <>);
34 print "Challenge: ";
35 chop($chal = <>);
36 $chal =~ s/^334 //;
37
38 $context = new Digest::MD5;
39 if (length($passwd) > 64) {
40 $context->add($passwd);
41 $passwd = $context->digest();
42 $context->reset();
43 }
44
45 @passwd = unpack("C*", pack("a64", $passwd));
46 for ($i = 0; $i < 64; $i++) {
47 $pass_ipad[$i] = $passwd[$i] ^ 0x36;
48 $pass_opad[$i] = $passwd[$i] ^ 0x5C;
49 }
50 $context->add(pack("C64", @pass_ipad), decode_base64($chal));
51 $digest = $context->digest();
52 $context->reset();
53 $context->add(pack("C64", @pass_opad), $digest);
54 $digest = $context->digest();
55
56 print encode_base64($user . " " . unpack("H*", $digest));
57
58 # End