Convert::PEM::CBC - phpMan

NAME
    Convert::PEM::CBC - Cipher Block Chaining Mode implementation

SYNOPSIS
        use Convert::PEM::CBC;
        my $cbc = Convert::PEM::CBC->new(
                             Cipher     => 'Crypt::DES_EDE3',
                             Passphrase => 'foo'
               );

        my $plaintext = 'foo bar baz';
        $cbc->encrypt($plaintext);

DESCRIPTION
    *Convert::PEM::CBC* implements the CBC (Cipher Block Chaining) mode for
    encryption/decryption ciphers; the CBC is designed for compatability
    with OpenSSL and may not be compatible with other implementations (such
    as SSH).

USAGE
  $cbc = Convert::PEM::CBC->new(%args)
    Creates a new *Convert::PEM::CBC* object and initializes it. Returns the
    new object.

    *%args* can contain:

    *   Cipher

        Either the name of an encryption cipher class (eg. *Crypt::DES*), or
        an object already blessed into such a class. The class must support
        the *keysize*, *blocksize*, *encrypt*, and *decrypt* methods. If the
        value is a blessed object, it is assumed that the object has already
        been initialized with a key.

        This argument is mandatory.

    *   Passphrase

        A passphrase to encrypt/decrypt the content. This is different in
        implementation from a key (*Key*), because it is assumed that a
        passphrase comes directly from a user, and must be munged into the
        correct form for a key. This "munging" is done by repeatedly
        computing an MD5 hash of the passphrase, the IV, and the existing
        hash, until the generated key is longer than the keysize for the
        cipher (*Cipher*).

        Because of this "munging", this argument can be any length (even an
        empty string).

        If you give the *Cipher* argument an object, this argument is
        ignored. If the *Cipher* argument is a cipher class, either this
        argument or *Key* must be provided.

    *   Key

        A raw key, to be passed directly to the new cipher object. Because
        this is passed directly to the cipher itself, the length of the key
        must be equal to or greater than the keysize for the *Cipher*.

        As with the *Passphrase* argument, if you give the *Cipher* argument
        an already-constructed cipher object, this argument is ignored. If
        the *Cipher* argument is a cipher class, either this argument or
        *Passphrase* must be provided.

    *   IV

        The initialization vector for CBC mode.

        This argument is optional; if not provided, a random IV will be
        generated. Obviously, if you're decrypting data, you should provide
        this argument, because your IV should match the IV used to encrypt
        the data.

  $cbc->encrypt($plaintext)
    Encrypts the plaintext *$plaintext* using the underlying cipher
    implementation in CBC mode, and returns the ciphertext.

    If any errors occur, returns *undef*, and you should check the *errstr*
    method to find out what went wrong.

  $cbc->decrypt($ciphertext)
    Decrypts the ciphertext *$ciphertext* using the underlying cipher
    implementation in CBC mode, and returns the plaintext.

    If any errors occur, returns *undef*, and you should check the *errstr*
    method to find out what went wrong.

  $cbc->iv
    Returns the current initialization vector. One use for this might be to
    grab the initial value of the IV if it's created randomly (ie. you
    haven't provided an *IV* argument to *new*):

        my $cbc = Convert::PEM::CBC->new( Cipher => $cipher );
        my $iv = $cbc->iv;   ## Generated randomly in 'new'.

    *Convert::PEM* uses this to write the IV to the PEM file when
    encrypting, so that it can be known when trying to decrypt the file.

  $cbc->errstr
    Returns the value of the last error that occurred. This should only be
    considered meaningful when you've received *undef* from one of the
    functions above; in all other cases its relevance is undefined.

AUTHOR & COPYRIGHTS
    Please see the Convert::PEM manpage for author, copyright, and license
    information.