---
name: "Crypt::AuthEnc::GCMSIV"
section: "3pm"
platform: "linux"
package: "perl-cryptx"
version: "0.091-2"
release: "Arch Linux 2026-11-01"
platforms: ["linux"]
url: "https://new.carta.tech/Crypt::AuthEnc::GCMSIV"
---

# Crypt::AuthEnc::GCMSIV(3pm)

Authenticated encryption in AES-GCM-SIV mode (RFC 8452)

## NAME

Crypt::AuthEnc::GCMSIV - Authenticated encryption in AES-GCM-SIV mode (RFC 8452)

## SYNOPSIS

```
  use Crypt::AuthEnc::GCMSIV qw( gcm_siv_encrypt_authenticate gcm_siv_decrypt_verify );
  my $ciphertext = gcm_siv_encrypt_authenticate('AES', $key, $nonce, $adata, $plaintext);
  my $plaintext  = gcm_siv_decrypt_verify('AES', $key, $nonce, $adata, $ciphertext); # undef on failure
```

## DESCRIPTION

*Since: CryptX-0.090*

AES-GCM-SIV is a nonce-misuse-resistant authenticated encryption scheme defined in RFC 8452 \<https://www.rfc-editor.org/rfc/rfc8452\>. Reusing a nonce with the same key no longer reveals the plaintext or the authentication key; it only reveals whether the same (plaintext, AAD) pair was encrypted twice.

The output of `"gcm_siv_encrypt_authenticate"` is the ciphertext with a 16-byte authentication tag appended (total output length is `"length($plaintext) + 16"`).

GCM-SIV is defined only for 128-bit block ciphers (i.e. AES); the nonce must be exactly 12 bytes long and the key must be 16 or 32 bytes (AES-128 / AES-256).

## EXPORT

Nothing is exported by default.

You can export selected functions:

```
  use Crypt::AuthEnc::GCMSIV qw( gcm_siv_encrypt_authenticate gcm_siv_decrypt_verify );
```

## FUNCTIONS

### gcm\_siv\_encrypt\_authenticate

```
  my $ciphertext = gcm_siv_encrypt_authenticate($cipher, $key, $nonce, $adata, $plaintext);
  # $cipher    ... [string] cipher name (must be 'AES')
  # $key       ... [binary string] 16- or 32-byte key
  # $nonce     ... [binary string] 12-byte nonce
  # $adata     ... [binary string | undef] optional associated data
  # $plaintext ... [binary string] plaintext to encrypt
```

Returns a string of `"length($plaintext) + 16"` bytes: ciphertext followed by the 16-byte authentication tag.

The required string/buffer arguments must be plain scalars; `$adata` may be `"undef"` to indicate no associated data. String-overloaded objects are accepted.

### gcm\_siv\_decrypt\_verify

```
  my $plaintext = gcm_siv_decrypt_verify($cipher, $key, $nonce, $adata, $ciphertext);
  # $cipher     ... [string] cipher name (must be 'AES')
  # $key        ... [binary string] 16- or 32-byte key
  # $nonce      ... [binary string] 12-byte nonce
  # $adata      ... [binary string | undef] optional associated data (must match the value used during encryption)
  # $ciphertext ... [binary string] ciphertext with 16-byte tag appended
```

Returns the plaintext on success, or `"undef"` if authentication fails. Malformed input shorter than 16 bytes croaks because it cannot contain the required appended tag.

## SEE ALSO

- •

  CryptX, Crypt::AuthEnc::GCM, Crypt::AuthEnc::SIV

- •

  RFC 8452 \<https://www.rfc-editor.org/rfc/rfc8452\>