Trait Aead 

pub trait Aead: Sized + Aead {
    const HPKE_AEAD_ID: u16;
    const MAX_PLAINTEXT_SIZE: u64;
    const MAX_CIPHERTEXT_SIZE: u64;

    // Required method
    fn new(key: &[u8]) -> Result<Self, HpkeError>;

    // Provided methods
    fn seal(
        &self,
        in_out: &mut [u8],
        nonce: &[u8],
        associated_data: &[u8],
    ) -> Result<Hash, HpkeError> { ... }
    fn open(
        &self,
        in_out: &mut [u8],
        nonce: &[u8],
        associated_data: &[u8],
        tag: &[u8],
    ) -> Result<(), HpkeError> { ... }
}

HPKE ciphersuite binding for an AEAD algorithm.

An AEAD is the symmetric cipher used to seal and open messages. This trait only adds what HPKE itself needs on top of [crypto::Aead] (from which the nonce size, tag size, and the underlying cipher operations are inherited):

• Aead::HPKE_AEAD_ID, the IANA “HPKE AEAD Identifiers” value used to build the ciphersuite suite_id,
• Aead::MAX_PLAINTEXT_SIZE and Aead::MAX_CIPHERTEXT_SIZE, the message length limits P_MAX and C_MAX defined by [RFC 5116],
• Aead::new, the construction of a ready-to-use cipher from the raw key schedule output.

Example

use hpke::aead::{Aead, Aes256Gcm, ExportOnly};

let cipher = <Aes256Gcm as Aead>::new(&[0x42u8; 32]).unwrap();
assert_eq!(Aes256Gcm::HPKE_AEAD_ID, 0x0002);
assert_eq!(ExportOnly::HPKE_AEAD_ID, 0xffff);

Custom AEADs

Implement [crypto::Aead] for the cipher’s operations, then implement this trait to give it an HPKE identifier, key size, and message length limits. Any nonce and tag size is supported as long as KEY_SIZE is at most 64 bytes and NONCE_SIZE is between 8 and 64 bytes; larger values fail to compile when the cipher is used with new_sender or new_recipient.

Required Associated Constants

const HPKE_AEAD_ID: u16

The HPKE AEAD identifier (draft-ietf-hpke-hpke-05 Section 7.3, IANA “HPKE AEAD Identifiers”), used to build the ciphersuite suite_id.

const MAX_PLAINTEXT_SIZE: u64

Maximum length, in bytes, of a plaintext passed to Aead::seal, i.e. P_MAX ([RFC 5116]).

HPKE refuses to encrypt longer plaintexts with HpkeError::MessageLimitReached: exceeding P_MAX would void the confidentiality and integrity guarantees of the AEAD (draft-ietf-hpke-hpke-05 Section 5.2). There is no default; every AEAD must state its limit.

const MAX_CIPHERTEXT_SIZE: u64

Maximum length, in bytes, of a ciphertext passed to Aead::open, i.e. C_MAX ([RFC 5116]).

HPKE refuses to open longer ciphertexts with HpkeError::MessageLimitReached (draft-ietf-hpke-hpke-05 Section 5.2). There is no default; every AEAD must state its limit.

Required Methods

fn new(key: &[u8]) -> Result<Self, HpkeError>

Instantiates the cipher from KEY_SIZE raw key bytes, as produced by the HPKE key schedule.

Errors

Returns HpkeError::InvalidKey when key does not have exactly [crypto::Aead::KEY_SIZE] bytes.

Provided Methods

fn seal( &self, in_out: &mut [u8], nonce: &[u8], associated_data: &[u8], ) -> Result<Hash, HpkeError>

Encrypts in_out in place and returns the detached authentication tag, forwarding to [crypto::Aead::encrypt_in_place].

Errors

Returns HpkeError::NotSupported when the cipher is the ExportOnly pseudo-AEAD.

fn open( &self, in_out: &mut [u8], nonce: &[u8], associated_data: &[u8], tag: &[u8], ) -> Result<(), HpkeError>

Decrypts in_out in place using the detached authentication tag, forwarding to [crypto::Aead::decrypt_in_place].

Errors

Returns HpkeError::OpenError when authentication fails, or HpkeError::NotSupported when the cipher is the ExportOnly pseudo-AEAD.

Dyn Compatibility

This trait is not dyn compatible.

In older versions of Rust, dyn compatibility was called "object safety".

Implementors

impl Aead for Aes256Gcm

AES-256-GCM (AEAD id 0x0002).

const HPKE_AEAD_ID: u16 = 0x0002

const MAX_PLAINTEXT_SIZE: u64 = AES_GCM_MAX_PLAINTEXT_SIZE

const MAX_CIPHERTEXT_SIZE: u64 = AES_GCM_MAX_CIPHERTEXT_SIZE

impl Aead for ChaCha20Poly1305

ChaCha20-Poly1305 (AEAD id 0x0003).

const HPKE_AEAD_ID: u16 = 0x0003

const MAX_PLAINTEXT_SIZE: u64 = CHACHA20_POLY1305_MAX_PLAINTEXT_SIZE

const MAX_CIPHERTEXT_SIZE: u64 = CHACHA20_POLY1305_MAX_CIPHERTEXT_SIZE

impl Aead for ExportOnly

const HPKE_AEAD_ID: u16 = 0xffff

const MAX_PLAINTEXT_SIZE: u64 = 0

const MAX_CIPHERTEXT_SIZE: u64 = 0