NAME

PGP - perl module to work with PGP messages

SYNOPSIS

use PGP;

$message = new PGP $pgppath;

DESCRIPTION

The PGP module allow a perl script to work with PGP related files.

• PGP::new

  $pgp = new PGP [$pgppath], [$pgpexec];

  Create the PGP encapsulation object. The standard location for the PGP executable is /usr/local/bin/pgp.

• PGP::Exec

  $pid = Exec $pgp $args, $in, $out, $err, $nobatchmode;

  Execute the PGP command and attach the $in, $out, $err file handles. This should be fine for the moment, but need to look into making sure that data is not written to a temporary file anywhere. The $nobatchmode parameter causes the PGP command to be executed without the +batchmode parameter. This seems to only be necessary when a key is being signed.

  The $args variable can have several substituted strings:

  %p	PGP path variable
  %r	Path to PGP keyring
  %k	Specified user

  Note: The above substitutions may change at any time. It is not advised that you write applications with substitutions. Almost certainly, the next release will not include substitutions.

  The file handle variables--$in, $out and $err--are send as normal filehandle names, but they reside in the PGP package. For example, the following procedure call is made:

  PGP->Exec ($args, FIN, FOUT, FERR);

  Even though the file handles were specified as FIN, FOUT and FERR; they must be referred to as PGP::FIN, PGP::FOUT and PGP::FERR in the orignal procedure that made the call.

• PGP::Sign

  $signed_document = Sign $pgp %args;

  The Sign procedure will take a file or data and sign with a PGP secret key. The default behavior is to sign the data with the last secret key added to the keyring, but that can be overridden with the Key argument. This method always returns the signed document.

  The %args consist of a series of keys and values. Since there are several variations in the way data can be signed, not all the following options must be specified. This approach also makes it much easier to scale to new versions of PGP with more options.

  Armor		The output should be ASCII armored
  Clear		Produce a "clear" signature
  Encrypt		Encrypt the resulting signed document with
  		the given keyobj
  Detach		Create a detached signature
  File		Sign the specified file
  Key		Sign with the specified key object
  Nosave		Do not allow user to save message
  Password	The password to use for signing
  Signfile	The filename of the signed document
  Text		Data to be signed.
  Wipe		Remove the orignal file

  The only absolute argument that is always required is the Password.

  Examples

  Sign $pgp Password => 'xyz', File => '/etc/motd', Clear => 1, Armor => 1;

  This would return a signed copy of the /etc/motd file. In this case, we use a file as the input, but the output is returned at the method's termination. The orignal file remains in the clear, and the signature is ASCII armored (Base64).

  Sign $pgp Password => 'abc', Text => 'Important info', Armor => 1,
            Signfile => 'signed.asc', Key => $keyobj;

  This is sort of the reverse of the first example. It takes what is in the Text field and signs it. It then puts the result in the file signed.asc and returns it to the caller. In this case, the entire message is ASCII armored including the orignal text (i.e. Text). We also specify another secret key to produce the signature. For more information on the the key objects, please see "PGP::Key" section.

• PGP::Encrypt

  $encrypted_document = Encrypt $pgp %args;

  The Encrypt method produces an encrypted document with the given public keys specified by Key. The Encrypt method follow the same conventions as the Sign method. The data to be encrypted can be sent to the method or can reside in a file. The resulting encrypted data can also reside in a file or be sent back to the caller.

  In addition to encrypting a document, the document can also be signed by using the Sign key in the %args array. If the document is to be signed by the default secret key (last key added to the secret keyring), then Sign can be left undefined or contain something other than a reference to a key object. Otherwise the Sign key should contain a reference to a specific key object (see "PGP::Key").

  Armor		The output should be ASCII armored
  Encryptfile	The filename of the encrypted document
  File		Encrypt the specified file
  Key		Encrypt with the specified key object
  Nosave		Do not allow user to save message
  Password	The password to use for signing
  Sign		In addition to encrypting, sign the document
  Text		Data to be encrypted
  Wipe		Remove orignal file

• PGP::Decrypt

  \%stats = Decrypt $pgp %args;

  Decrypt will use a PGP secret key to decrypt a message. The secret key must reside on the secret keyring. The Decrypt method follows the same conventions for data transfer that Sign and Encrypt follow. The resulting associative array that is sent back contains three fields:

  Text		The decrypted document
  Signature	PGP::Key object of the signer (if any)
  Time		Time document was signed (if any)
  Key		PGP::Key object used to decrypt document 

  The following are the accepted arguments:

  Password	Password to use for decrypting
  File		File to decrypt
  Keyring		Needed to return info about document
  Plainfile	File to put the data in
  Text		Document to decrypt
  Wipe		Remove original file

  The Password argument is required to perform the decryption of the document. The Keyring argument is also required if any document information is to be returned.

• PGP::Info

  \%doc = Info $pgp %args;

  Info returns an associative array or a reference to an associative array to the caller. This returned structure contains information about the document that is sent to the Info method. The returned structure is fairly straight forward:

  Text		The decrypted document
  Signature	PGP::Key object of the signer (if any)
  Time		Time document was signed (if any)
  Key		PGP::Key object used to decrypt document

  The Info method currently accepts the following arguments:

  File		File to decrypt
  Text		Document to decrypt

  At this point, we cheat with the Info method. Basically we send the document through the Decrypt method and grab the results.

PGP::Keyring

The PGP::Keyring object is used to perform key management functions.

• PGP::Keyring::new

  $Keyring = new PGP::Keyring $pgpkeyring;

• PGP::Keyring::Add_Key

  Add_Key $Keyring %args;

  Add a signature to the keyring. At this point, there is no error checking or verification that the key has been added.

  The %args associative array may contain the following:

  Text		The value is the public key
  File		File where the public key is stored

• PGP::Keyring::Remove_Key

  Remove_Key $Keyring $key;

  Remove a signature from a keyring.

• PGP::Keyring::Extract_Key

  $key = Extract_Key $Keyring $keyobj;

  Extract a key from the specified keyring. A real simple dirty way of extracting the key.

• PGP::Keyring::Sign_Key

  Sign_Key $Keyring %args;

  This method will sign a designated key with the

• PGP::Keyring::Generate_Key

  Generate_Key $Keyring;

  Generate a new secret and public key set. This routine will not be present in the first rev of code. It is also subject to change.

• PGP::Keyring::Revoke_Key

  $certificate = Revoke_Key $Keyring $Keyobj;

  Produce a revocation certificate for the given key. Revocation is actually a two step process. We must first mark the key as revoked. This is the same as the Remove_Key method. After flaging the key, the key must be extracted to produce a revocation certificate.

• PGP::Keyring::List_Keys

  @{$keyobj} = List_Keys $Keyring;

  List the keys on a given keyring. This routine simply captures the output of the command pgp -kc $keyring and does a quick parse on it. It takes the lines that it parses, and constructs PGP::Key objects. In the near future, this function will also pass the trust factors to the PGP::Key object. We got it in the output, so why not use it.

• PGP::Keyring::Find

  @keys = Find $keyring %criteria;
  \@keys = Find $keyring %criteria;
  $key = Find $keyring %criteria; (Single match)

  Function to locate a keys matching some criteria. This is not implemented as nicely as it should be (read kludge). The %criteria array is used to specify what keys are to be selected. The keys for the %criteria array are as follows:

  Keyid		Key with specifed keyid
  Owner		Name of the owner of the key
  Email		Email address of owner
  Bits		Size of the key in bits
  Date		Date that the key was generated
  Desc		Owner and Email keys combined

  The values for each specifed key (assocative array) are compared using a case-insensitive regular expression. This means that only a portion of the key data needs to be specified to have it selected. This also means that specifing too little criteria can cause several keys to be selected.

PGP::Key

The PGP::Key object is used to store the individual key information. It is primarily used by the PGP::Keyring object and for passing to the various methods that accept key parameters to encrypt and sign documents.

Future revisions will provide actual methods to do key comparison for the trust and validity factors. These methods will provide a standardized way to determine which keys can be trusted and which keys should not be used at all.

• PGP::Key::new

  $key = new PGP::Key $keyline;

  This is the constructor for the PGP::Key object. This is primarily used by the PGP::Keyring methods. The PGP::Keyring methods keep track of the keys and maintain the Trust and Validity components. About the only useful method is the PGP::Key::Fingerprint, which will return a string that is the finger print of the given key.

• + PGP::Key::Add_ID

  Add_ID $key $desc;

  The Add_ID method will add identification information to the owner and email portions of the given PGP::Key object. This is to support keys that multiple identification packets associated with them.

• PGP::Key::Add_Sig

• PGP::Key::Trust

  This will set and/or retrieve the trust factor. Currently, this routine will just store what is sent to it. Need to define some "trust" variables and provide useful routines to use them.

• PGP::Key::Validity

  This function will set and/or return the validity factor. This subroutine is very much like PGP::Key::Trust. It also needs to be worked on quite a bit.

• PGP::Key::Fingerprint

  $fingerprint = Fingerprint $key;

• PGP::Key::Format

  $formatted_text = Format $key %args;

  This method will return a formatted text string for a key. It is essentially the same as do a 'pgp -kv' or 'pgp -kvv' for a key object. Currently the only argument that Format will recognize is the Verbose argument. The Verbose parameter will list the signatures that have certified the current key object.

Known Bugs and Limitations

+ Hopefully none, proabably many!

Author

Gerard Hickey
RR 2  Box 409
Lower Main St.
North Berwick, ME   03906
hickey@ctron.com

Copyrights

Copyleft (l) 1996, by Gerard Hickey

What this means is that this program may be copied freely given that there is no payment in exchange for this program, and that all the source is left intact with all comments and documentation. If you wish to modify this program to correct bugs or to extend it's usefullness, please coordinate such actions with the author.