perl-Crypt-OpenPGP / Crypt-OpenPGP

Pure-Perl OpenPGP implementation
https://metacpan.org/pod/Crypt::OpenPGP
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NAME Crypt::OpenPGP - Pure-Perl OpenPGP implementation

SYNOPSIS my $pgp = Crypt::OpenPGP->new;

    # Given an input stream (could be a signature, ciphertext, etc),
    # do the "right thing" to it.
    my $message_body; $message_body .= $_ while <STDIN>;
    my $result = $pgp->handle( Data => $message_body );

    # Create a detached, ASCII-armoured signature of $file using the
    # secret key $key_id, protected with the passphrase $pass. 
    my $file = 'really-from-me.txt';
    my $key_id = '...';
    my $pass = 'foo bar';
    my $signature = $pgp->sign(
        Filename   => $file,
        KeyID      => $key_id,
        Passphrase => $pass,
        Detach     => 1,
        Armour     => 1,
    );

    # Verify the detached signature $signature, which should be of the
    # source file $file.
    my $is_valid = $pgp->verify(
        Signature  => $signature,
        Files      => [ $file ],
    );

    # Using the public key associated with $key_id, encrypt the contents
    # of the file $file, and ASCII-armour the ciphertext.
    my $ciphertext = $pgp->encrypt(
        Filename   => $file,
        Recipients => $key_id,
        Armour     => 1,
    );

    # Decrypt $ciphertext using the secret key used to encrypt it,
    # which key is protected with the passphrase $pass.
    my $plaintext = $pgp->decrypt(
        Data       => $ciphertext,
        Passphrase => $pass,
    );

DESCRIPTION Crypt::OpenPGP is a pure-Perl implementation of the OpenPGP standard[1]. In addition to support for the standard itself, Crypt::OpenPGP claims compatibility with many other PGP implementations, both those that support the standard and those that preceded it.

*Crypt::OpenPGP* provides signing/verification, encryption/decryption,
keyring management, and key-pair generation; in short it should provide
you with everything you need to PGP-enable yourself. Alternatively it
can be used as part of a larger system; for example, perhaps you have a
web-form-to-email generator written in Perl, and you'd like to encrypt
outgoing messages, because they contain sensitive information.
*Crypt::OpenPGP* can be plugged into such a scenario, given your public
key, and told to encrypt all messages; they will then be readable only
by you.

This module currently supports "RSA" and "DSA" for digital signatures,
and "RSA" and "ElGamal" for encryption/decryption. It supports the
symmetric ciphers "3DES", "Blowfish", "IDEA", "Twofish", "CAST5", and
"Rijndael" ("AES"). "Rijndael" is supported for key sizes of 128, 192,
and 256 bits. *Crypt::OpenPGP* supports the digest algorithms "MD5",
"SHA-1", and "RIPE-MD/160". And it supports "ZIP" and "Zlib"
compression.

COMPATIBILITY One of the highest priorities for Crypt::OpenPGP is compatibility with other PGP implementations, including PGP implementations that existed before the OpenPGP standard.

As a means towards that end, some of the high-level *Crypt::OpenPGP*
methods can be used in compatibility mode; given an argument *Compat*
and a PGP implementation with which they should be compatible, these
method will do their best to choose ciphers, digest algorithms, etc.
that are compatible with that implementation. For example, PGP2 only
supports "IDEA" encryption, "MD5" digests, and version 3 signature
formats; if you tell *Crypt::OpenPGP* that it must be compatible with
PGP2, it will only use these algorithms/formats when encrypting and
signing data.

To use this feature, supply either *sign* or *encrypt* with the *Compat*
parameter, giving it one of the values from the list below. For example:

    my $ct = $pgp->encrypt(
                  Compat     => 'PGP2',
                  Filename   => 'foo.pl',
                  Recipients => $key_id,
             );

Because *PGP2* was specified, the data will automatically be encrypted
using the "IDEA" cipher, and will be compressed using "ZIP".

Here is a list of the current compatibility sets and the algorithms and
formats they support.

*   PGP2

    Encryption: symmetric cipher = "IDEA", compression = "ZIP",
    modification detection code (MDC) = 0

    Signing: digest = "MD5", packet format = version 3

*   PGP5

    Encryption: symmetric cipher = "3DES", compression = "ZIP",
    modification detection code (MDC) = 0

    Signing: digest = "SHA-1", packet format = version 3

*   GnuPG

    Encryption: symmetric cipher = "Rijndael", compression = "Zlib",
    modification detection code (MDC) = 1

    Signing: digest = "RIPE-MD/160", packet format = version 4

If the compatibility setting is unspecified (that is, if no *Compat*
argument is supplied), the settings (ciphers, digests, etc.) fall back
to their default settings.

USAGE Crypt::OpenPGP has the following high-level interface. On failure, all methods will return "undef" and set the errstr for the object; look below at the ERROR HANDLING section for more information.

Crypt::OpenPGP->new( %args ) Constructs a new Crypt::OpenPGP instance and returns that object. Returns "undef" on failure.

*%args* can contain:

*   Compat

    The compatibility mode for this *Crypt::OpenPGP* object. This value
    will propagate down into method calls upon this object, meaning that
    it will be applied for all method calls invoked on this object. For
    example, if you set *Compat* here, you do not have to set it again
    when calling *encrypt* or *sign* (below), unless, of course, you
    want to set *Compat* to a different value for those methods.

    *Compat* influences several factors upon object creation, unless
    otherwise overridden in the constructor arguments: if you have a
    configuration file for this compatibility mode (eg. ~/.gnupg/options
    for GnuPG), it will be automatically read in, and *Crypt::OpenPGP*
    will set any options relevant to its execution (symmetric cipher
    algorithm, etc.); *PubRing* and *SecRing* (below) are set according
    to the default values for this compatibility mode (eg.
    ~/.gnupg/pubring.gpg for the GnuPG public keyring).

*   SecRing

    Path to your secret keyring. If unspecified, *Crypt::OpenPGP* will
    look for your keyring in a number of default places.

    As an alternative to passing in a path to the keyring file, you can
    pass in a *Crypt::OpenPGP::KeyRing* object representing a secret
    keyring.

*   PubRing

    Path to your public keyring. If unspecified, *Crypt::OpenPGP* will
    look for your keyring in a number of default places.

    As an alternative to passing in a path to the keyring file, you can
    pass in a *Crypt::OpenPGP::KeyRing* object representing a public
    keyring.

*   ConfigFile

    Path to a PGP/GnuPG config file. If specified, you must also pass in
    a value for the *Compat* parameter, stating what format config file
    you are passing in. For example, if you are passing in the path to a
    GnuPG config file, you should give a value of "GnuPG" for the
    *Compat* flag.

    If you leave *ConfigFile* unspecified, but you have specified a
    value for *Compat*, *Crypt::OpenPGP* will try to find your config
    file, based on the value of *Compat* that you pass in (eg.
    ~/.gnupg/options if *Compat* is "GnuPG").

    NOTE: if you do not specify a *Compat* flag, *Crypt::OpenPGP* cannot
    read any configuration files, even if you *have* specified a value
    for the *ConfigFile* parameter, because it will not be able to
    determine the proper config file format.

*   KeyServer

    The hostname of the HKP keyserver. This is a required argument.
    There are a number of keyservers including:

        keyserver.ubuntu.com
        keys.openpgp.org

    If *AutoKeyRetrieve* is set to a true value, keys will be
    automatically retrieved from the keyserver if they are not found in
    your local keyring.

*   AutoKeyRetrieve

    If set to a true value, and if *KeyServer* is set to a keyserver
    name, *encrypt* and *verify* will automatically try to fetch public
    keys from the keyserver if they are not found in your local keyring.

$pgp->handle( %args ) A do-what-I-mean wrapper around decrypt and verify. Given either a filename or a block of data--for example, data from an incoming email message--handle "handles" it as appropriate for whatever encryption or signing the message contains. For example, if the data is encrypted, handle will return the decrypted data (after prompting you for the passphrase). If the data is signed, handle will check the validity of the signature and return indication of the validity of the signature.

The return value is a reference to a hash, which may contain the
following keys, depending on the data passed to the method:

*   Plaintext

    If the data is encrypted, the decrypted message.

*   Validity

    If the data is signed, a true value if the signature is valid, a
    false value otherwise. The true value will be either the signer's
    email address, if available, or 1, if not.

*   Signature

    If the data is signed, the *Crypt::OpenPGP::Signature* object
    representing the signature.

If an error occurs, the return value will be "undef", and the error
message can be obtained by calling *errstr* on the *Crypt::OpenPGP*
object.

*%args* can contain:

*   Data

    The data to be "handled". This should be a simple scalar containing
    an arbitrary amount of data.

    *Data* is optional; if unspecified, you should specify a filename
    (see *Filename*, below).

*   Filename

    The path to a file to "handle".

    *Filename* is optional; if unspecified, you should specify the data
    in *Data*, above. If both *Data* and *Filename* are specified, the
    data in *Data* overrides that in *Filename*.

*   PassphraseCallback

    If the data is encrypted, you will need to supply *handle* with the
    proper passphrase to unlock the private key, or the password to
    decrypt the symmetrically-encrypted data (depending on the method of
    encryption used). If you do not specify this parameter, this default
    passphrase callback will be used:

        sub _default_passphrase_cb {
            my($cert) = @_;
            my $prompt;
            if ($cert) {
                $prompt = sprintf qq(
        You need a passphrase to unlock the secret key for
        user "%s".
        %d-bit %s key, ID %s

        Enter passphrase: ), $cert->uid,
                             $cert->key->size,
                             $cert->key->alg,
                             substr($cert->key_id_hex, -8, 8);
            } else {
                $prompt = "Enter passphrase: ";
            }
            _prompt($prompt, '', 1);
        }

    If you do specify this parameter, make sure that your callback
    function can handle both asymmetric and symmetric encryption.

    See the *PassphraseCallback* parameter for *decrypt*, below.

$pgp->encrypt( %args ) Encrypts a block of data. The encryption is actually done with a symmetric cipher; the key for the symmetric cipher is then encrypted with either the public key of the recipient or using a passphrase that you enter. The former case is using public-key cryptography, the latter, standard symmetric ciphers. In the first case, the session key can only be unlocked by someone with the corresponding secret key; in the second, it can only be unlocked by someone who knows the passphrase.

Given the parameter *SignKeyID* (see below), *encrypt* will first sign
the message before encrypting it, adding a Signature packet to the
encrypted plaintext.

Returns a block of data containing two PGP packets: the encrypted
symmetric key and the encrypted data.

On failure returns "undef".

*%args* can contain:

*   Compat

    Specifies the PGP compatibility setting. See *COMPATIBILITY*, above.

*   Data

    The plaintext to be encrypted. This should be a simple scalar
    containing an arbitrary amount of data.

    *Data* is optional; if unspecified, you should specify a filename
    (see *Filename*, below).

*   Filename

    The path to a file to encrypt.

    *Filename* is optional; if unspecified, you should specify the data
    in *Data*, above. If both *Data* and *Filename* are specified, the
    data in *Data* overrides that in *Filename*.

*   Recipients

    The intended recipients of the encrypted message. In other words,
    either the key IDs or user IDs of the public keys that should be
    used to encrypt the message. Each recipient specified should be
    either a key ID--an 8-digit or 16-digit hexadecimal number--or part
    of a user ID that can be used to look up the user's public key in
    your keyring. Examples:

        8-digit hex key ID: 123ABC45
        16-digit hex key ID: 678DEF90123ABC45
        (Part of) User ID: foo@bar

    Note that the 8-digit hex key ID is the last 8 digits of the (long)
    16-digit hex key ID.

    If you wish to encrypt the message for multiple recipients, the
    value of *Recipients* should be a reference to a list of recipients
    (as defined above). For each recipient in the list, the public key
    will be looked up in your public keyring, and an encrypted session
    key packet will be added to the encrypted message.

    This argument is optional; if not provided you should provide the
    *Passphrase* option (below) to perform symmetric-key encryption when
    encrypting the session key.

*   KeyID

    A deprecated alias for *Recipients* (above). There is no need to use
    *KeyID*, as its functionality has been completely subsumed into the
    *Recipients* parameter.

*   Passphrase

    The mechanism to use symmetric-key, or "conventional", encryption,
    when encrypting the session key. In other words, this allows you to
    use *Crypt::OpenPGP* for encryption/decryption without using
    public-key cryptography; this can be useful in certain circumstances
    (for example, when encrypting data locally on disk).

    This argument is optional; if not provided you should provide the
    *Recipients* option (above) to perform public-key encryption when
    encrypting the session key.

*   RecipientsCallback

    After the list of recipients for a message (as given in
    *Recipients*, above) has been mapped into a set of keys from your
    public keyring, you can use *RecipientsCallback* to review/modify
    that list of keys. The value of *RecipientsCallback* should be a
    reference to a subroutine; when invoked that routine will be handed
    a reference to an array of *Crypt::OpenPGP::Certificate* objects. It
    should then return a reference to a list of such objects.

    This can be useful particularly when supplying user IDs in the list
    of *Recipients* for an encrypted message. Since user IDs are looked
    up using partial matches (eg. *b* could match *b*, *abc*, *bar*,
    etc.), one intended recipient may actually turn up multiple keys.
    You can use *RecipientsCallback* to audit that list before actually
    encrypting the message:

        my %BAD_KEYS = (
            ABCDEF1234567890 => 1,
            1234567890ABCDEF => 1,
        );
        my $cb = sub {
            my $keys = shift;
            my @return;
            for my $cert (@$keys) {
                push @return, $cert unless $BAD_KEYS{ $cert->key_id_hex };
            }
            \@returns;
        };
        my $ct = $pgp->encrypt( ..., RecipientsCallback => $cb, ... );

*   Cipher

    The name of a symmetric cipher with which the plaintext will be
    encrypted. Valid arguments are "DES3", "CAST5", "Blowfish", "IDEA",
    "Twofish", "Rijndael", "Rijndael192", and "Rijndael256" (the last
    two are "Rijndael" with key sizes of 192 and 256 bits,
    respectively).

    This argument is optional; if you have provided a *Compat*
    parameter, *Crypt::OpenPGP* will use the appropriate cipher for the
    supplied compatibility mode. Otherwise, *Crypt::OpenPGP* currently
    defaults to "DES3"; this could change in the future.

*   Compress

    The name of a compression algorithm with which the plaintext will be
    compressed before it is encrypted. Valid values are "ZIP" and
    "Zlib".

    By default text is not compressed.

*   Armour

    If true, the data returned from *encrypt* will be ASCII-armoured.
    This can be useful when you need to send data through email, for
    example.

    By default the returned data is not armoured.

*   SignKeyID

    If you wish to sign the plaintext message before encrypting it,
    provide *encrypt* with the *SignKeyID* parameter and give it a key
    ID with which the message can be signed. This allows recipients of
    your message to verify its validity.

    By default messages not signed.

*   SignPassphrase

    The passphrase to unlock the secret key to be used when signing the
    message.

    If you are signing the message--that is, if you have provided the
    *SignKeyID* parameter--either this argument or
    *SignPassphraseCallback* is required.

*   SignPassphraseCallback

    The callback routine to enable the passphrase being passed in
    through some user-defined routine. See the *PassphraseCallback*
    parameter for *sign*, below.

    If you are signing the message--that is, if you have provided the
    *SignKeyID* parameter--either this argument or *SignPassphrase* is
    required.

*   MDC

    When set to a true value, instructs *encrypt* to use encrypted MDC
    (modification detection code) packets instead of standard encrypted
    data packets. These are a newer form of encrypted data packets that
    are followed by a "SHA-1" hash of the plaintext data. This prevents
    attacks that modify the encrypted text by using a message digest to
    detect changes.

    By default *MDC* is set to 0, and *encrypt* generates standard
    encrypted data packets. Set it to a true value to turn on MDC
    packets. Note that *MDC* will automatically be turned on if you are
    using a *Compat* mode that is known to support it.

$pgp->decrypt( %args ) Decrypts a block of ciphertext. The ciphertext should be of the sort returned from encrypt, in either armoured or non-armoured form. This is compatible with all other implementations of PGP: the output of their encryption should serves as the input to this method.

When called in scalar context, returns the plaintext (that is, the
decrypted ciphertext), or "undef" on failure. When called in list
context, returns a three-element list containing the plaintext and the
result of signature verification (see next paragraph), or the empty list
on failure. Either of the failure conditions listed here indicates that
decryption failed.

If *decrypt* is called in list context, and the encrypted text contains
a signature over the plaintext, *decrypt* will attempt to verify the
signature and will return the result of that verification as the second
element in the return list, and the actual *Crypt::OpenPGP::Signature*
object as the third element in the return list. If you call *decrypt* in
list context and the ciphertext does *not* contain a signature, that
second element will be "undef", and the *errstr* will be set to the
string "No Signature\n". The second element in the return list can have
one of three possible values: "undef", meaning that either an error
occurred in verifying the signature, *or* the ciphertext did not contain
a signature; 0, meaning that the signature is invalid; or a true value
of either the signer's user ID or 1, if the user ID cannot be
determined. Note that these are the same values returned from *verify*
(below).

For example, to decrypt a message that may contain a signature that you
want verified, you might use code like this:

    my($pt, $valid, $sig) = $pgp->decrypt( ... );
    die "Decryption failed: ", $pgp->errstr unless $pt;
    die "Signature verification failed: ", $pgp->errstr
        unless defined $valid || $pgp->errstr !~ /^No Signature/;
    print "Signature created at ", $sig->timestamp, "\n";

This checks for errors in decryption, as well as errors in signature
verification, excluding the error denoting that the plaintext was not
signed.

*%args* can contain:

*   Data

    The ciphertext to be decrypted. This should be a simple scalar
    containing an arbitrary amount of data.

    *Data* is optional; if unspecified, you should specify a filename
    (see *Filename*, below).

*   Filename

    The path to a file to decrypt.

    *Filename* is optional; if unspecified, you should specify the data
    in *Data*, above. If both *Data* and *Filename* are specified, the
    data in *Data* overrides that in *Filename*.

*   Passphrase

    The passphrase to unlock your secret key, or to decrypt a
    symmetrically-encrypted message; the usage depends on how the
    message is encrypted.

    This argument is optional if your secret key is protected; if not
    provided you should supply the *PassphraseCallback* parameter
    (below).

*   PassphraseCallback

    A callback routine to allow interactive users (for example) to enter
    the passphrase for the specific key being used to decrypt the
    ciphertext, or the passphrase used to encrypt a
    symmetrically-encrypted message. This is useful when your ciphertext
    is encrypted to several recipients, if you do not necessarily know
    ahead of time the secret key that will be used to decrypt it. It is
    also useful when you wish to provide an interactive user with some
    feedback about the key being used to decrypt the message, or when
    you don't know what type of encryption (symmetric or public-key)
    will be used to encrypt a message.

    The value of this parameter should be a reference to a subroutine.
    This routine will be called when a passphrase is needed from the
    user, and it will be given either zero arguments or one argument,
    depending on whether the message is encrypted symmetrically (zero
    arguments) or using public-key encryption (one argument). If the
    latter, the one argument is a *Crypt::OpenPGP::Certificate* object
    representing the secret key. You can use the information in this
    object to present details about the key to the user.

    In either case, the callback routine should return the passphrase, a
    scalar string.

    Your callback routine can use the number of arguments to determine
    how to prompt the user for a passphrase; for example:

        sub passphrase_cb {
            if (my $cert = $_[0]) {
                printf "Enter passphrase for secret key %s: ",
                    $cert->key_id_hex;
            } else {
                print "Enter passphrase: ";
            }
        }

    This argument is optional if your secret key is protected; if not
    provided you should supply the *Passphrase* parameter (above).

$pgp->sign( %args ) Creates and returns a digital signature on a block of data.

On failure returns "undef".

*%args* can contain:

*   Compat

    Specifies the PGP compatibility setting. See *COMPATIBILITY*, above.

*   Data

    The text to be signed. This should be a simple scalar containing an
    arbitrary amount of data.

    *Data* is optional; if unspecified, you should specify a filename
    (see *Filename*, below).

*   Filename

    The path to a file to sign.

    *Filename* is optional; if unspecified, you should specify the data
    in *Data*, above. If both *Data* and *Filename* are specified, the
    data in *Data* overrides that in *Filename*.

*   Detach

    If set to a true value the signature created will be a detached
    signature; that is, a signature that does not contain the original
    text. This assumes that the person who will be verifying the
    signature can somehow obtain the original text (for example, if you
    sign the text of an email message, the original text is the
    message).

    By default signatures are not detached.

*   Armour

    If true, the data returned from *sign* will be ASCII-armoured. This
    can be useful when you need to send data through email, for example.

    By default the returned signature is not armoured.

*   Clearsign

    If true, the signature created on the data is a clear-text
    signature. This form of signature displays the clear text of the
    signed data, followed by the ASCII-armoured signature on that data.
    Such a format is desirable when sending signed messages to groups of
    users who may or may not have PGP, because it allows the text of the
    message to be readable without special software.

    When *Clearsign* is set to true, *Armour* and *Detach* are
    automatically turned on, because the signature created is a
    detached, armoured signature.

    By default *Clearsign* is false.

*   KeyID

    The ID of the secret key that should be used to sign the message.
    The value of the key ID should be specified as a 16-digit
    hexadecimal number.

    This argument is mandatory.

*   Passphrase

    The passphrase to unlock your secret key.

    This argument is optional if your secret key is protected; if not
    provided you should supply the *PassphraseCallback* parameter
    (below).

*   PassphraseCallback

    A callback routine to allow interactive users (for example) to enter
    the passphrase for the specific key being used to sign the message.
    This is useful when you wish to provide an interactive user with
    some feedback about the key being used to sign the message.

    The value of this parameter should be a reference to a subroutine.
    This routine will be called when a passphrase is needed from the
    user, and it will be given one argument: a
    *Crypt::OpenPGP::Certificate* object representing the secret key.
    You can use the information in this object to present details about
    the key to the user. The callback routine should return the
    passphrase, a scalar string.

    This argument is optional if your secret key is protected; if not
    provided you should supply the *Passphrase* parameter (above).

*   Digest

    The digest algorithm to use when creating the signature; the data to
    be signed is hashed by a message digest algorithm, then signed.
    Possible values are "MD5", "SHA1", and "RIPEMD160".

    This argument is optional; if not provided, the digest algorithm
    will be set based on the *Compat* setting provided to *sign* or
    *new*. If you have not provided a *Compat* setting, *SHA1* will be
    used.

*   Version

    The format version of the created signature. The two possible values
    are 3 and 4; version 4 signatures will not be compatible with older
    PGP implementations.

    The default value is 4, although this could change in the future.

$pgp->verify( %args ) Verifies a digital signature. Returns true for a valid signature, 0 for an invalid signature, and "undef" if an error occurs (in which case you should call errstr to determine the source of the error). The 'true' value returned for a successful signature will be, if available, the PGP User ID of the person who created the signature. If that value is unavailable, the return value will be 1.

If called in list context, the second element returned in the return
list will be the *Crypt::OpenPGP::Signature* object representing the
actual signature.

*%args* can contain:

*   Signature

    The signature data, as returned from *sign*. This data can be either
    a detached signature or a non-detached signature. If the former, you
    will need to specify the list of files comprising the original
    signed data (see *Data* or *Files*, below).

    Either this argument or *SigFile* is required.

*   SigFile

    The path to a file containing the signature data. This data can be
    either a detached signature or a non-detached signature. If the
    former, you will need to specify the list of files comprising the
    original signed data (see *Data* or *Files*, below).

    Either this argument or *SigFile* is required.

*   Data

    Specifies the original signed data.

    If the signature (in either *Signature* or *SigFile*) is a detached
    signature, either *Data* or *Files* is a mandatory argument.

*   Files

    Specifies a list of files comprising the original signed data. The
    value should be a reference to a list of file paths; if there is
    only one file, the value can be specified as a scalar string, rather
    than a reference to a list.

    If the signature (in either *Signature* or *SigFile*) is a detached
    signature, either *Data* or *Files* is a mandatory argument.

$pgp->keygen( %args ) NOTE: this interface is alpha and could change in future releases!

Generates a public/secret PGP keypair. Returns two keyblocks (objects of
type *Crypt::OpenPGP::KeyBlock*), a public and a secret keyblock,
respectively. A keyblock is essentially a block of keys, subkeys,
signatures, and user ID PGP packets.

*%args* can contain:

*   Type

    The type of key to generate. Currently there are two valid values:
    "RSA" and "DSA". "ElGamal" key generation is not supported at the
    moment.

    This is a required argument.

*   Size

    Bitsize of the key to be generated. This should be an even integer;
    there is no low end currently implemented in *Crypt::OpenPGP*, but
    for the sake of security *Size* should be at least 1024 bits.

    This is a required argument.

*   Identity

    A string that identifies the owner of the key. Typically this is the
    combination of the user's name and an email address; for example,

        Foo Bar <foo@bar.com>

    The *Identity* is used to build a User ID packet that is stored in
    each of the returned keyblocks.

    This is a required argument.

*   Passphrase

    String with which the secret key will be encrypted. When read in
    from disk, the key can then only be unlocked using this string.

    This is a required argument.

*   Version

    Specifies the key version; defaults to version 4 keys. You should
    only set this to version 3 if you know why you are doing so (for
    backwards compatibility, most likely). Version 3 keys only support
    RSA.

*   Verbosity

    Set to a true value to enable a status display during key
    generation; since key generation is a relatively lengthy process, it
    is helpful to have an indication that some action is occurring.

    *Verbosity* is 0 by default.

ERROR HANDLING If an error occurs in any of the above methods, the method will return "undef". You should then call the method errstr to determine the source of the error:

    $pgp->errstr

In the case that you do not yet have a *Crypt::OpenPGP* object (that is,
if an error occurs while creating a *Crypt::OpenPGP* object), the error
can be obtained as a class method:

    Crypt::OpenPGP->errstr

For example, if you try to decrypt some encrypted text, and you do not
give a passphrase to unlock your secret key:

    my $pt = $pgp->decrypt( Filename => "encrypted_data" )
        or die "Decryption failed: ", $pgp->errstr;

SAMPLES/TUTORIALS Take a look at bin/pgplet for an example of usage of Crypt::OpenPGP. It gives you an example of using the four main major methods (encrypt, sign, decrypt, and verify), as well as the various parameters to those methods. It also demonstrates usage of the callback parameters (eg. PassphraseCallback).

bin/pgplet currently does not have any documentation, but its interface
mirrors that of *gpg*.

LICENSE Crypt::OpenPGP is free software; you may redistribute it and/or modify it under the same terms as Perl itself.

AUTHOR & COPYRIGHT Except where otherwise noted, Crypt::OpenPGP is Copyright 2001 Benjamin Trott, cpan@stupidfool.org. All rights reserved.

REFERENCES 1 RFC4880 - OpenPGP Message Format (2007). http://www.faqs.org/rfcs/rfc4880.html