@deftypefun {int} {gnutls_aead_cipher_decrypt} (gnutls_aead_cipher_hd_t @var{handle}, const void * @var{nonce}, size_t @var{nonce_len}, const void * @var{auth}, size_t @var{auth_len}, size_t @var{tag_size}, const void * @var{ctext}, size_t @var{ctext_len}, void * @var{ptext}, size_t * @var{ptext_len})
@var{handle}: is a @code{gnutls_aead_cipher_hd_t}  type.

@var{nonce}: the nonce to set

@var{nonce_len}: The length of the nonce

@var{auth}: additional data to be authenticated

@var{auth_len}: The length of the data

@var{tag_size}: The size of the tag to use (use zero for the default)

@var{ctext}: the data to decrypt (including the authentication tag)

@var{ctext_len}: the length of data to decrypt (includes tag size)

@var{ptext}: the decrypted data

@var{ptext_len}: the length of decrypted data (initially must hold the maximum available size)

This function will decrypt the given data using the algorithm
specified by the context. This function must be provided the complete
data to be decrypted, including the authentication tag. On several
AEAD ciphers, the authentication tag is appended to the ciphertext,
though this is not a general rule. This function will fail if
the tag verification fails.

@strong{Returns:} Zero or a negative error code on verification failure or other error.

@strong{Since:} 3.4.0
@end deftypefun