Module aead 

Authenticated encryption with detached authentication tags.

This module wraps BoringSSL’s EVP_AEAD interface and is intended for protocols that keep ciphertext and authentication tag in separate buffers.

Overview

AeadCtx is the main type. Create one with an Algorithm and a key, then use it to encrypt and decrypt:

• AeadCtxRef::seal_in_place / AeadCtxRef::open_in_place — encrypt or decrypt a buffer in place with a detached tag. These cover the common case (TLS record framing, packet formats with explicit tag fields, etc.).

• AeadCtxRef::seal_scatter / AeadCtxRef::open_gather — lower-level scatter/gather operations for protocols that split ciphertext output across multiple buffers.

When to use crate::symm instead

If you want one-shot helpers that allocate output buffers or APIs centered on EVP_CIPHER, prefer crate::symm, including crate::symm::encrypt_aead and crate::symm::decrypt_aead.

Nonce guidance

Never reuse a nonce with the same key. Nonce reuse can completely undermine AEAD security.

Nonces are usually public (not secret). They must either be transmitted with the message or derived by both sides (for example from a shared sequence number).

Different algorithms can have different nonce-length requirements and safety considerations around nonce generation. The caller is responsible for following safe nonce practices for the selected algorithm. Algorithm::nonce_len returns the required nonce size in bytes.

Example

use boring::aead::{AeadCtx, Algorithm};

let algorithm = Algorithm::aes_128_gcm();
let ctx = AeadCtx::new_default_tag(&algorithm, &[0u8; 16]).unwrap();
let nonce = [0u8; 12];
let aad = b"record-header";
let mut payload = b"hello world".to_vec();
let mut tag = vec![0u8; algorithm.max_overhead()];

ctx.seal_in_place(&nonce, payload.as_mut_slice(), &mut tag, aad)
    .unwrap();

ctx.open_in_place(&nonce, payload.as_mut_slice(), &tag, aad)
    .unwrap();

assert_eq!(payload.as_slice(), b"hello world");

Structs

AeadCtx

An AEAD encryption/decryption context wrapping BoringSSL’s EVP_AEAD_CTX.

AeadCtxRef

A borrowed reference to a AeadCtx.

Algorithm

Represents a specific AEAD algorithm.