Crypt::...Enc::OCB(3)

📦
version 0.89.0 · 16 versions
, in opensuse-leap 16.0

🌸 NAME 🌸

Okay bestie, this is the Crypt::...Enc::OCB(3) page from User Contributed Perl Documentation, and the module is Crypt::AuthEnc::OCB. It's giving authenticated encryption in OCBv3 mode. 💅

✨ SYNOPSIS ✨

Two whole interfaces, both iconic. Copy these exactly, no cap:

        ### OO interface
        use Crypt::AuthEnc::OCB;

        my $key = '...';
        my $nonce = '...';
        my $tag_len = 16;
        my $expected_tag = '...';

        # encrypt and authenticate
        my $ae_enc = Crypt::AuthEnc::OCB->new("AES", $key, $nonce, $tag_len);
        $ae_enc->adata_add('additional_authenticated_data1');
        $ae_enc->adata_add('additional_authenticated_data2');
        my $ct = $ae_enc->encrypt_add('data1');
        $ct .= $ae_enc->encrypt_add('data2');
        $ct .= $ae_enc->encrypt_add('data3');
        $ct .= $ae_enc->encrypt_last('rest of data');
        my $tag = $ae_enc->encrypt_done();

        # decrypt and verify
        my $ae_dec = Crypt::AuthEnc::OCB->new("AES", $key, $nonce, $tag_len);
        $ae_dec->adata_add('additional_authenticated_data1');
        $ae_dec->adata_add('additional_authenticated_data2');
        my $pt = $ae_dec->decrypt_add('ciphertext1');
        $pt .= $ae_dec->decrypt_add('ciphertext2');
        $pt .= $ae_dec->decrypt_add('ciphertext3');
        $pt .= $ae_dec->decrypt_last('rest of data');
        my $computed_tag = $ae_dec->decrypt_done();
        die "decrypt failed" unless $computed_tag eq $expected_tag;

        #or
        my $result = $ae_dec->decrypt_done($expected_tag); # 0 or 1

        ### functional interface
        use Crypt::AuthEnc::OCB qw(ocb_encrypt_authenticate ocb_decrypt_verify);

        my $key = '...';
        my $nonce = '...';
        my $adata = '...';
        my $plaintext = '...';
        my $tag_len = 16;

        my ($ciphertext, $tag) = ocb_encrypt_authenticate('AES', $key, $nonce, $adata, $tag_len, $plaintext);
        my $decrypted = ocb_decrypt_verify('AES', $key, $nonce, $adata, $ciphertext, $tag);

🦋 DESCRIPTION 🦋

This module implements OCB v3 according to <https://www.rfc-editor.org/rfc/rfc7253>. 🔥

It's a stateful API, bestie — build one message by calling, in order: new, optional adata_add, zero or more encrypt_add or decrypt_add calls for full blocks, one optional encrypt_last or decrypt_last for the final partial block, then encrypt_done or decrypt_done. 🫶

Use a fresh object per message. When verifying, decrypt_done($expected_tag) is the safer one-step form; decrypt_done() without arguments only returns the calculated tag. The first encrypt_done / decrypt_done call finalizes the object. After that, further adata_add, encrypt_add, encrypt_last, decrypt_add, decrypt_last, encrypt_done, and decrypt_done calls croak. 😭

🎀 EXPORT 🎀

Nothing is exported by default.

You can export selected functions:

  use Crypt::AuthEnc::OCB qw(ocb_encrypt_authenticate ocb_decrypt_verify);

🔥 FUNCTIONS 🔥

⭐ ocb_encrypt_authenticate

        my ($ciphertext, $tag) = ocb_encrypt_authenticate($cipher, $key, $nonce, $adata, $tag_len, $plaintext);

        # $cipher .. [string] 'AES' or name of any other cipher with 16-byte block len
        # $key ..... [binary string] AES key of proper length (128/192/256 bits)
        # $nonce ... [binary string] unique nonce/salt (no need to keep it secret)
        # $adata ... [binary string] additional authenticated data
        # $tag_len . [integer] required length of output tag

Use tag lengths from 4 to 16 bytes. Out-of-range values passed to this functional helper are normalized to 16. ✨

🧚 ocb_decrypt_verify

         my $plaintext = ocb_decrypt_verify($cipher, $key, $nonce, $adata, $ciphertext, $tag);
         # on error returns undef

💜 METHODS 💜

Unless noted otherwise, assume $ae is an existing AEAD object created via new, for example:

        my $ae = Crypt::AuthEnc::OCB->new($cipher, $key, $nonce);

👑 new

        my $ae = Crypt::AuthEnc::OCB->new($cipher, $key, $nonce, $tag_len);

        # $cipher .. [string] 'AES' or name of any other cipher with 16-byte block len
        # $key ..... [binary string] AES key of proper length (128/192/256 bits)
        # $nonce ... [binary string] unique nonce/salt (no need to keep it secret)
        # $tag_len . [integer] required length of output tag

🍓 adata_add

Can be called only before the first encrypt_add, encrypt_last, decrypt_add, or decrypt_last. Returns the object itself (for chaining). 🫶

        $ae->adata_add($adata);                        #can be called multiple times

💅 encrypt_add

Returns a binary string of ciphertext (raw bytes).

        my $ciphertext = $ae->encrypt_add($data);      # can be called multiple times

        # note: \ must be a multiple of the block length (16 for AES)

🌈 encrypt_last

        my $ciphertext = $ae->encrypt_last($data);

⭐ encrypt_done

Returns the authentication tag as a binary string (raw bytes). This call finalizes the current message.

        my $tag = $ae->encrypt_done();                 # returns $tag value

🦋 decrypt_add

Returns a binary string of plaintext (raw bytes).

        my $plaintext = $ae->decrypt_add($ciphertext); # can be called multiple times

        # note: \ must be a multiple of the block length (16 for AES)

🧚 decrypt_last

        my $plaintext = $ae->decrypt_last($data);

💖 decrypt_done

Without argument returns the computed tag as a binary string. With $tag argument returns 1 (success) or 0 (failure). This call finalizes the current message.

        my $tag = $ae->decrypt_done;           # returns $tag value
        #or
        my $result = $ae->decrypt_done($tag);  # returns 1 (success) or 0 (failure)

🎀 blocksize

        my $bs = $ae->blocksize;   # always returns 16

Returns the block size of the underlying cipher (always 16, since OCB requires a 128-bit block cipher such as AES). Good.

🌸 clone

Returns a copy of the AEAD object in its current state.

        my $ae_new = $ae->clone;

🌈 SEE ALSO 🌈

That's the whole page, bestie — brought to you by perl v5.42.0, dated 2026-05-11, and filed under Crypt::...Enc::OCB(3). Periodt. 💅

📦 where this page comes from