# Crypt::AuthEnc::ChaCha20Poly1305 - phpMan

## NAME
    [Crypt::AuthEnc::ChaCha20Poly1305] - Authenticated encryption in
    ChaCha20-Poly1305 mode

## SYNOPSIS
     ### OO interface
     use [Crypt::AuthEnc::ChaCha20Poly1305];

     # encrypt and authenticate
     my $ae = [Crypt::AuthEnc::ChaCha20Poly1305]->new($key, $iv);
     $ae->adata_add('additional_authenticated_data1');
     $ae->adata_add('additional_authenticated_data2');
     my $ct = $ae->encrypt_add('data1');
     $ct .= $ae->encrypt_add('data2');
     $ct .= $ae->encrypt_add('data3');
     my $tag = $ae->encrypt_done();

     # decrypt and verify
     my $ae = [Crypt::AuthEnc::ChaCha20Poly1305]->new($key, $iv);
     $ae->adata_add('additional_authenticated_data1');
     $ae->adata_add('additional_authenticated_data2');
     my $pt = $ae->decrypt_add('ciphertext1');
     $pt .= $ae->decrypt_add('ciphertext2');
     $pt .= $ae->decrypt_add('ciphertext3');
     my $tag = $ae->decrypt_done();
     die "decrypt failed" unless $tag eq $expected_tag;

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

     ### functional interface
     use [Crypt::AuthEnc::ChaCha20Poly1305] qw(chacha20poly1305_encrypt_authenticate chacha20poly1305_decrypt_verify);

     my ($ciphertext, $tag) = chacha20poly1305_encrypt_authenticate($key, $iv, $adata, $plaintext);
     my $plaintext = chacha20poly1305_decrypt_verify($key, $iv, $adata, $ciphertext, $tag);

## DESCRIPTION
    Provides encryption and authentication based on ChaCha20 + Poly1305 as
    defined in RFC 7539 - <<https://tools.ietf.org/html/rfc7539>>

## EXPORT
    Nothing is exported by default.

    You can export selected functions:

      use [Crypt::AuthEnc::ChaCha20Poly1305] qw(chacha20poly1305_encrypt_authenticate chacha20poly1305_decrypt_verify);

## FUNCTIONS
  chacha20poly1305_encrypt_authenticate
     my ($ciphertext, $tag) = chacha20poly1305_encrypt_authenticate($key, $iv, $adata, $plaintext);

     # $key ..... key of proper length (128 or 256 bits / 16 or 32 bytes)
     # $iv ...... initialization vector (64 or 96 bits / 8 or 12 bytes)
     # $adata ... additional authenticated data (optional)

  chacha20poly1305_decrypt_verify
     my $plaintext = chacha20poly1305_decrypt_verify($key, $iv, $adata, $ciphertext, $tag);
     # on error returns undef

## METHODS
  new
     my $ae = [Crypt::AuthEnc::ChaCha20Poly1305]->new($key, $iv);

     # $key ..... encryption key of proper length (128 or 256 bits / 16 or 32 bytes)
     # $iv ...... initialization vector (64 or 96 bits / 8 or 12 bytes)

  adata_add
    Add additional authenticated data. Can be called before the first
    "encrypt_add" or "decrypt_add";

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

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

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

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

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

  set_iv
     my $ae = [Crypt::AuthEnc::ChaCha20Poly1305]->new($key)->set_iv($iv);
     # $iv ...... initialization vector (64 or 96 bits / 8 or 12 bytes)

  set_iv_rfc7905
    See <<https://tools.ietf.org/html/rfc7905>>

     my $ae = [Crypt::AuthEnc::ChaCha20Poly1305]->new($key)->set_iv_rfc7905($iv, $seqnum);
     # $iv ...... initialization vector (96 bits / 12 bytes)
     # $seqnum .. 64bit integer (sequence number)

  clone
     my $ae_new = $ae->clone;

## SEE ALSO
    *   CryptX, [Crypt::AuthEnc::GCM], [Crypt::AuthEnc::CCM],
        [Crypt::AuthEnc::EAX], [Crypt::AuthEnc::OCB]

    *   <<https://tools.ietf.org/html/rfc7539>>