$pem = Convert::PEM->new( %arg )

Constructs a new Convert::PEM object designed to read/write an object of a specific type (given in %arg, see below). Returns the new object on success, "undef" on failure (see ERROR HANDLING for details).

%arg can contain:

• Name

  The name of the object; when decoding a PEM-encoded stream, the name in the encoding will be checked against the value of Name. Similarly, when encoding an object, the value of Name will be used as the name of the object in the PEM-encoded content. For example, given the string "FOO BAR", the output from encode will start with a header like:

      -----BEGIN FOO BAR-----
      

  Name is a required argument.

• ASN

  An ASN.1 description of the content to be either encoded or decoded.

  ASN is an optional argument.

• Macro

  If your ASN.1 description (in the ASN parameter) includes more than one ASN.1 macro definition, you will want to use the Macro parameter to specify which definition to use when encoding/decoding objects. For example, if your ASN.1 description looks like this:

      Foo ::= SEQUENCE {
          x INTEGER,
          bar Bar
      }
      Bar ::= INTEGER
      

  If you want to encode/decode a "Foo" object, you will need to tell Convert::PEM to use the "Foo" macro definition by using the Macro parameter and setting the value to "Foo".

  Macro is an optional argument when an ASN.1 description is provided.

• InForm

  Specify what type of file to expect when using the read method. Value may be either PEM or DER. Default is "PEM".

  If "DER" is specified, encryption options are ignored when using the read method and file is read as an unencrypted blob. This option does not affect the decode behavior.

  InForm is an optional argument.

• OutForm

  Specify what type of file the write method should output. Value may be either PEM or DER. Default is "PEM".

  If "DER" is specified, encryption options are ignored when using the write method and the file is written as an uncrypted blob. This option does not affect the encode behavior.

  OutForm is an optional argument.

$obj = $pem->decode(%args)

Decodes, and, optionally, decrypts a PEM file, returning the object as decoded by Convert::ASN1. The difference between this method and read is that read reads the contents of a PEM file on disk; this method expects you to pass the PEM contents as an argument.

If an error occurs while reading the file or decrypting/decoding the contents, the function returns undef, and you should check the error message using the errstr method (below).

%args can contain:

• Content

  The PEM contents.

• Password

  The password with which the file contents were encrypted.

  If the file is encrypted, this is a mandatory argument (well, it's not strictly mandatory, but decryption isn't going to work without it). Otherwise it's not necessary.

$blob = $pem->encode(%args)

Constructs the contents for the PEM file from an object: ASN.1-encodes the object, optionally encrypts those contents.

Returns undef on failure (encryption failure, file-writing failure, etc.); in this case you should check the error message using the errstr method (below). On success returns the constructed PEM string.

%args can contain:

• Content

  This method requires either Content or DER. An error will be generated if one of these arguments are not present.

  A hash reference that will be passed to Convert::ASN1::encode, and which should correspond to the ASN.1 description you gave to the new method. The hash reference should have the exact same format as that returned from the read method.

  This is required unless DER is specified.

• DER

  A string containing actual binary of the contents to be encoded. This bypasses ASN.1 encoding.

  May be used in lieu of Content. If specified, will override Content.

• Password

  A password used to encrypt the contents of the PEM file. This is an optional argument; if not provided the contents will be unencrypted.

• Cipher

  The Cipher to use if a password is provided. This is an optional argument; if not provided, the default of DES-EDE3-CBC will be used or the cipher configured is $Convert::PEM::DefaultCipher. See below for a list of supported ciphers.

$obj = $pem->read(%args)

Reads, decodes, and, optionally, decrypts a PEM file, returning the object as decoded by Convert::ASN1 (or binary blob if ASN.1 description was not provided). This is implemented as a wrapper around decode, with the bonus of reading the PEM file from disk for you.

If an error occurs while reading the file or decrypting/decoding the contents, the function returns undef, and you should check the error message using the errstr method (below).

In addition to the arguments that can be passed to the decode method (minus the Content argument), %args can contain:

• Filename

  The location of the PEM file that you wish to read.

• InForm

  Specify what file type to read. Description can be found under new method. If specified, will override InForm provided in new method.

$pem->write(%args)

Constructs the contents for the PEM file from an object: ASN.1-encodes the object, optionally encrypts those contents; then writes the file to disk. This is implemented as a wrapper around encode, with the bonus of writing the file to disk for you.

Returns undef on failure (encryption failure, file-writing failure, etc.); in this case you should check the error message using the errstr method (below). On success returns the constructed PEM string.

In addition to the arguments for encode, %args can contain:

• Filename

  The location on disk where you'd like the PEM file written.

• OutForm

  Specify format to write out. Description can be found under new method. If specified, will override OutForm provided in new method.

$pem->from_der(%args)

Method used internally, but may be accessed directly decode an ASN.1 string into a perl structure object. If the Convert::PEM object has no ASN.1 definition, this method has no effect.

• DER

  Binary string to convert to an object.

  This option is required.

• Macro

  If the object has an ASN definition, a Macro may be specified. If specified, it will override the object's Macro if one exists.

  Macro is an optional argument.

$pem->to_der(%args)

Method used internally, but may be accessed directly to encode Content into binary data. If the Convert::PEM object has no ASN.1 definition, this method has no effect.

• Content

  An object to be ASN.1 encoded to a binary string.

• Macro

  If the object has an ASN definition, a Macro may be specified. If specified, it will override the object's Macro if one exists.

  Macro is an optional argument.

$pem->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.

$pem->asn

Returns the Convert::ASN1 object used internally to decode and encode ASN.1 representations. This is useful when you wish to interact directly with that object; for example, if you need to call configure on that object to set the type of big-integer class to be used when decoding/encoding big integers:

    $pem->asn->configure( decode => { bigint => 'Math::Pari' },
                          encode => { bigint => 'Math::Pari' } );

$pem->inform

Retruns the InForm configured for the object.

$pem->outform

Retruns the OutForm configured for the object.

$pem->cipher

Returns the Cipher configured for the object.

$pem->name

Returns the PEM Name of the object.

$Convert::PEM::DefaultCipher or $OBJ->DefaultCipher([NEW_CIPHER])

Used to configure a default cipher when writing to the disk. When using the method form " $OBJ-"DefaultCipher([NEW_CIPHER]) >, if NEW_CIPHER is not specified, will return the current setting. If the specified cipher is not recognized/valid, an error will be raised.

To list supported ciphers, use "Convert::PEM::list_ciphers". Here is a list of supported Ciphers:

• DES-CBC
• DES-EDE3-CBC
• AES-128-CBC
• AES-192-CBC
• AES-256-CBC
• CAMELLIA-128-CBC
• CAMELLIA-192-CBC
• CAMELLIA-256-CBC
• IDEA-CBC
• SEED-CBC

Convert::PEM->has_cipher($cipher_name)

Will see if the cipher is supported and is configured with an encryption module.

Convert::PEM->has_cipher_module($cipher_name)

Will see if the cipher is supported and if the configured encryption module is usable. If it is not usable, will return "undef". If it is usable, will return the name of the cipher module.

Convert::PEM->set_cipher_module($cipher,$module[,$all])

This function/method is used to specify a module name for a supported cipher. It accepts 2 or 3 arguments.

    Convert::PEM->set_cipher_module(<cipher_name>, <module_name>[,0])
    or
    $OBJ->set_cipher_module(<cipher_name>, <module_name>[,0])

"cipher_name"

A supported cipher name. Use Convert::PEM::list_ciphers() to retrieve a list of supported ciphers.

"module_name"

A cipher module. The module must support the following methods:

    $cipher_object = Cipher->new($key)
    $cipher_object->encrypt($plaintext)
    $cipher_object->decrypt($ciphertext)
    $cipher_object->blocksize()
    

"all"

An optional boolean argument. If true will replace the modules for all supported ciphers matching the cipher being set. Default is true. If setting a cipher, only set this to false if it is desired to use a separate cipher for different key lengths of the same algorithm.

Convert::PEM->list_cipher_modules([$cipher_name])

If a cipher_name is provided, will return the module configured for the matching cipher name or "undef" if cipher is not supported. If cipher_name is not provided, will return a list of modules names configured as an array in array context or as a colon separated list in scalar context.

Here is a list of the cipher modules used by default.

• Crypt::DES
• Crypt::DES_EDE3
• Crypt::Rijndael - "AES-128-CBC, AES-192-CBC and AES-256-CBC"
• Crypt::Camellia - "CAMELLIA-128-CBC, CAMELLIA-192-CBC and CAMELLIA-256-CBC"
• Crypt::IDEA
• Crypt::SEED