1Convert::PEM::CBC(3) User Contributed Perl Documentation Convert::PEM::CBC(3)
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6 Convert::PEM::CBC - Cipher Block Chaining Mode implementation
7
9 use Convert::PEM::CBC;
10 my $cbc = Convert::PEM::CBC->new(
11 Cipher => 'Crypt::DES_EDE3',
12 Passphrase => 'foo'
13 );
14 my $plaintext = 'foo bar baz';
16 $cbc->encrypt($plaintext);
17
19 Convert::PEM::CBC implements the CBC (Cipher Block Chaining) mode for
20 encryption/decryption ciphers; the CBC is designed for compatability
21 with OpenSSL and may not be compatible with other implementations (such
22 as SSH).
23
25 $cbc = Convert::PEM::CBC->new(%args)
26 Creates a new Convert::PEM::CBC object and initializes it. Returns the
27 new object.
28 %args can contain:
30 · Cipher
32 Either the name of an encryption cipher class (eg. Crypt::DES), or
34 an object already blessed into such a class. The class must support
35 the keysize, blocksize, encrypt, and decrypt methods. If the value
36 is a blessed object, it is assumed that the object has already been
37 initialized with a key.
38 This argument is mandatory.
40 · Passphrase
42 A passphrase to encrypt/decrypt the content. This is different in
44 implementation from a key (Key), because it is assumed that a
45 passphrase comes directly from a user, and must be munged into the
46 correct form for a key. This "munging" is done by repeatedly
47 computing an MD5 hash of the passphrase, the IV, and the existing
48 hash, until the generated key is longer than the keysize for the
49 cipher (Cipher).
50 Because of this "munging", this argument can be any length (even an
52 empty string).
53 If you give the Cipher argument an object, this argument is
55 ignored. If the Cipher argument is a cipher class, either this
56 argument or Key must be provided.
57 · Key
59 A raw key, to be passed directly to the new cipher object. Because
61 this is passed directly to the cipher itself, the length of the key
62 must be equal to or greater than the keysize for the Cipher.
63 As with the Passphrase argument, if you give the Cipher argument an
65 already-constructed cipher object, this argument is ignored. If the
66 Cipher argument is a cipher class, either this argument or
67 Passphrase must be provided.
68 · IV
70 The initialization vector for CBC mode.
72 This argument is optional; if not provided, a random IV will be
74 generated. Obviously, if you're decrypting data, you should provide
75 this argument, because your IV should match the IV used to encrypt
76 the data.
77 $cbc->encrypt($plaintext)
79 Encrypts the plaintext $plaintext using the underlying cipher
80 implementation in CBC mode, and returns the ciphertext.
81 If any errors occur, returns undef, and you should check the errstr
83 method to find out what went wrong.
84 $cbc->decrypt($ciphertext)
86 Decrypts the ciphertext $ciphertext using the underlying cipher
87 implementation in CBC mode, and returns the plaintext.
88 If any errors occur, returns undef, and you should check the errstr
90 method to find out what went wrong.
91 $cbc->iv
93 Returns the current initialization vector. One use for this might be to
94 grab the initial value of the IV if it's created randomly (ie. you
95 haven't provided an IV argument to new):
96 my $cbc = Convert::PEM::CBC->new( Cipher => $cipher );
98 my $iv = $cbc->iv; ## Generated randomly in 'new'.
99 Convert::PEM uses this to write the IV to the PEM file when encrypting,
101 so that it can be known when trying to decrypt the file.
102 $cbc->errstr
104 Returns the value of the last error that occurred. This should only be
105 considered meaningful when you've received undef from one of the
106 functions above; in all other cases its relevance is undefined.
107
109 Please see the Convert::PEM manpage for author, copyright, and license
110 information.
111perl v5.28.0 2010-12-07 Convert::PEM::CBC(3)