From 094ca96844842928810f14844413109fc6cdd890 Mon Sep 17 00:00:00 2001 From: Eduardo Chappa Date: Sun, 3 Feb 2013 00:59:38 -0700 Subject: Initial Alpine Version --- imap/docs/md5.txt | 91 +++++++++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 91 insertions(+) create mode 100644 imap/docs/md5.txt (limited to 'imap/docs/md5.txt') diff --git a/imap/docs/md5.txt b/imap/docs/md5.txt new file mode 100644 index 00000000..c43f1023 --- /dev/null +++ b/imap/docs/md5.txt @@ -0,0 +1,91 @@ +/* ======================================================================== + * Copyright 1988-2006 University of Washington + * + * Licensed under the Apache License, Version 2.0 (the "License"); + * you may not use this file except in compliance with the License. + * You may obtain a copy of the License at + * + * http://www.apache.org/licenses/LICENSE-2.0 + * + * + * ======================================================================== + */ + + MD5 Based Authentication + Mark Crispin + 1 November 1999 + + + The IMAP toolkit makes available two MD5 based authentication +mechanisms, CRAM-MD5 and APOP. CRAM-MD5 is described in RFC 2195, and +is a SASL (RFC 2222) authentication mechanism. APOP is described in +RFC 1939, the standard document for the POP3 protocol. + + These mechanisms use the same general idea. The server issues a +challenge; the client responds with an MD5 checksum of the challenge +plus the password; the server in compares the client's response with +its own calculated value of the checksum. If the client's response +matches the server's calulated value, the client is authenticated. + + Unlike plaintext passwords, this form of authentication is +believed to be secure against the session being monitored; "sniffing" +the session will not disclose the password nor will it provide usable +information to authenticate in another session without knowing the +password. + + The key disadvantage with this form of authentication is that the +server must know a plaintext form of the password. In traditional +UNIX authentication, the server only knows an encrypted form of the +password. Consequently, the authentication database for this form of +authentication must be kept strictly confidential; a bad guy who +acquires access to this database can access any account in the +database. + + CRAM-MD5 client support is implemented unconditionally; any +client application built with the IMAP toolkit will use CRAM-MD5 with +any server which advertises CRAM-MD5 SASL support. + + CRAM-MD5 and APOP server support is implemented if, and only if, +the CRAM-MD5 authentication database exists. By default, the CRAM-MD5 +authentication database is in a UNIX file called + /etc/cram-md5.pwd +It is recommended that this file be protected 0400. + + NOTE: FAILURE TO PROTECT THIS FILE AGAINST UNAUTHORIZED + ACCESS WILL COMPROMSE CRAM-MD5 AND APOP AUTHENTICATION + FOR ALL USERS LISTED IN THIS DATABASE. + + If the CRAM-MD5 authentication database exists, then plaintext +password authentication (e.g. the LOGIN command) will also use the +CRAM-MD5 passwords instead of UNIX passwords. Alternatively, it is +possible to build the IMAP toolkit so that plaintext password +authentication is disabled entirely, by using PASSWDTYPE=nul, e.g. + make aix PASSWDTYPE=nul + + + The CRAM-MD5 authentication database file consists of a series of +text lines, consisting of a UNIX user name, a single tab, and the +password. A line starting with a "#" character is ignored, as are any +lines which are not in valid format. For example: + +------------------------------Sample------------------------------ +# CRAM-MD5 authentication database +# Entries are in form +# Lines starting with "#" are comments + +bill hubba-hubba +hillary nysenator +monica beret +tripp wired +kenstarr inquisitor +reno waco +jessie thebody +billgates ruleworld +------------------------------Sample------------------------------ + + Every entry in the CRAM-MD5 authentication database must have a +corresponding entry in the /etc/passwd file. It is STRONGLY +RECOMMENDED that the CRAM-MD5 password NOT be the same as the +/etc/passwd password. It is permitted for the /etc/passwd password to +be disabled; /etc/passwd is just used to get the UID, GID, and home +directory information. -- cgit v1.2.3-54-g00ecf