gen-auth(1) generate various authentication strings


gen-auth [--help|--version] | <type> ...


gen-auth is tool to assist in all kinds of authentication / encoding / decoding / encrypting tasks. It began life as an smtp-specific tool, but has drifted in functionality over time.

The program actions are broken down into types of encoding to generate. Each <type> then takes its own specific args. The arguments are expected in a specific order on the command line. Every argument that isn't available on the command line will be prompted for. One benefit to this is arguments corresponding to passwords will not be echoed to the terminal when prompted for.


The program action is controlled by the first argument. The meaning of the following arguments is specified by this type
PLAIN <username> <password>
This type generates a PLAIN (RFC 2595) authentication string. It accepts supplemental arguments of username and password. It generates a Base64 encoded string ``\0<username>\0<password>''.
LOGIN <username> <password>
This method accepts username and password as supplemental args. It simply returns each string Base64 encoded. This provides only minimal advantages over using ENCODE twice. One advantage is hiding the password if you provide it on STDIN
CRAM-MD5 <username> <password> <challenge>
CRAM-MD5 (RFC 2195) accepts three supplemental arguments. The first is the username and the second is the password. The third is the challenge string provided by the server. This string can be either Base64 encoded or not. The RFC states that all (unencoded) challenge strings must start w/ '<'. This is used to whether the string is Base64 encoded or not.

CRAM-MD5 uses the challenge and the supplied password to generate a digest. it then returns the Base64 encoded version of the string md5(``<username> <challenge>'')

This authentication method requires the Digest::MD5 perl module to be installed.

CRAM-SHA1 <username> <password> <challenge>
This behaves the same as CRAM-MD5 but uses SHA1 digesting rather than MD5.

This authentication method requires the Digest::SHA1 perl module to be installed.

NTLM/SPA/MSN <username> <password> <domain> <challenge>
Although it may be advertised as one of the above types, this method of authentication if refered to singularly as NTLM. This is a multi-step authentication type. The first 3 arguments must be supplied up front. They are username, password, and domain, in that order. These three strings are used to generate an ``Auth Request'' string. This string should be passed verbatim to the server. The server will then respond with a challenge. This challenge is the fourth argument. After receiving the server challenge, gen-auth will produce an ``Auth Response''. Posting this response to the server completes the NTLM authentication transaction.

This authentication method requires the Authen::NTLM perl module to be installed. See EXAMPLES for an example of this transaction. Note also that 'domain' is often blank from client or ignored by server.

HTTP-BASIC <username> <password>
Returns the value base64(``<username>:<password>''). Used for HTTP Basic authentication (RFC 2617). Used by adding a header ``Authorization: Basic <string>'' to a HTTP request where <string> is the output of this command.
APOP <challenge> <password>
This implements the APOP authentication for the POP3 protocol as described in RFC 1939. <challenge> is the challenge string presented by the POP3 server in the greeting banner. <password> is the ``secret'' (usually a password) used to authenticate the user. This method returns a digest md5(``<challenge><password>''). This can be used to authenticate to a POP3 server in a string like ``APOP <user> <digest>'' where <digest> is the string generated by this command.

APOP required the Digest::MD5 perl module.

ENCODE <string>
Simply Base64 encodes a plaintext string. Provided as a convenience function.
DECODE <string>
Decodes a Base64 encoded string. Provided as a convenience function.
MD5/MD5-HEX <string>
Provides an MD5 digest of the supplied string in hex.
MD5-BASE64 <string>
Provides an MD5 digest of the supplied string in Base64.
ENCRYPT <string>
Returns a crypt(3) string generated from the input string.
SALTENCRYPT <string> <salt>
Same as ENCRYPT but you provide the salt as the second argument. See crypt(3) man page for details.
ROT13 <string>
This performs a rot13 action on <string>. This implementation only performs the action on ASCII 65-90,97-123. Any other character value is left untouched. Therefore this method is primarily for LOCALE=C, ASCII only. Feel free to send patches if you care to have it work in another setting.
ATBASH <string>
This performs an atbash action on <string>. Atbash mirrors a string such that 'a'=='z', 'b'=='y', etc. See the comments on locale and character set under ROT13.


Supresses echo on all input fields read from standard input. If this option is not used, echo is suppressed on fields which are known to be password fields but this may not be secure enough.
this screen.
version info.


generate a PLAIN AUTH string for user 'tim', password 'tanstaaftanstaaf'
  > gen-auth plain tim tanstaaftanstaaf
  Auth String: AHRpbQB0YW5zdGFhZnRhbnN0YWFm
generate a CRAM-MD5 string for user 'tim', password 'tanstaaftanstaaf', challenge '<[email protected]>', using prompt to hide password
  > gen-auth cram-md5                  
  username: tim
  challenge: PDE4OTYuNjk3MTcwOTUyQHBvc3RvZmZpY2UucmVzdG9uLm1jaS5uZXQ+
use the DECODE method to ensure we provided the correct output in our last example
  > gen-auth decode dGltIGI5MTNhNjAyYzdlZGE3YTQ5NWI0ZTZlNzMzNGQzODkw
  tim b913a602c7eda7a495b4e6e7334d3890
use the NTLM (MSN) method to authenticate to a mail server using user 'tim', password 'tanstaaftanstaaf', and domain MAIL. Both the gen-auth transaction and SMTP transaction are shown to demonstrate the interaction between the two.
  334 NTLM supported
  235 Authentication succeeded
  > gen-auth spa
  username: tim
  domain: MAIL


Required for all functionality
Required for MD5, MD5-BASE64, CRAM-MD5, APOP
Required for CRAM-SHA1
Required for NTLM/MSN/SPA


0 - no errors occurred
1 - unrecognized type specified