Struct AesGcm 

pub struct AesGcm<Aes, NonceSize, TagSize = U16>
where
    TagSize: TagSize,
{
    pub(crate) cipher: Aes,
    pub(crate) ghash: GHash,
    pub(crate) nonce_size: PhantomData<NonceSize>,
    pub(crate) tag_size: PhantomData<TagSize>,
}

AES-GCM: generic over an underlying AES implementation and nonce size.

This type is generic to support substituting alternative AES implementations (e.g. embedded hardware implementations)

It is NOT intended to be instantiated with any block cipher besides AES! Doing so runs the risk of unintended cryptographic properties!

The NonceSize generic parameter can be used to instantiate AES-GCM with other nonce sizes, however it’s recommended to use it with typenum::U12, the default of 96-bits.

The TagSize generic parameter can be used to instantiate AES-GCM with other authorization tag sizes, however it’s recommended to use it with typenum::U16, the default of 128-bits.

If in doubt, use the built-in Aes128Gcm and Aes256Gcm type aliases.

⚠️ WARNING: Hazmat!

When using short authentication tags, namely 32-bit tags with typenum::U4 or 64-bit tags with typenum::U8 (which require the crate feature hazmat), it is RECOMMENDED that a key not be used for more than the maximum invocations of authenticated decryption specified in Table 1 or Table 2 of NIST SP 800-38D, respectively.

Fields

cipher: Aes

Encryption cipher.

ghash: GHash

GHASH authenticator.

nonce_size: PhantomData<NonceSize>

Length of the nonce.

tag_size: PhantomData<TagSize>

Length of the tag.

Implementations

impl<Aes, NonceSize, TagSize> AesGcm<Aes, NonceSize, TagSize>

where Aes: BlockSizeUser<BlockSize = U16> + BlockCipherEncrypt, NonceSize: ArraySize, TagSize: TagSize,

pub(crate) fn init_ctr( &self, nonce: &Nonce<NonceSize>, ) -> (CtrCore<&Aes, Ctr32BE>, Array<u8, U16>)

Initialize counter mode.

See algorithm described in Section 7.2 of NIST SP800-38D: https://nvlpubs.nist.gov/nistpubs/Legacy/SP/nistspecialpublication800-38d.pdf

Define a block, J0, as follows: If len(IV)=96, then J0 = IV || 0{31} || 1. If len(IV) ≠ 96, then let s = 128 ⎡len(IV)/128⎤-len(IV), and J0=GHASH(IV||0s+64||[len(IV)]64).

pub(crate) fn compute_tag( &self, mask: Array<u8, U16>, associated_data: &[u8], buffer: &[u8], ) -> Tag

Authenticate the given plaintext and associated data using GHASH.

Trait Implementations

impl<Aes, NonceSize, TagSize> AeadCore for AesGcm<Aes, NonceSize, TagSize>

where NonceSize: ArraySize, TagSize: TagSize,

const TAG_POSITION: TagPosition = TagPosition::Postfix

The AEAD tag position.

type NonceSize = NonceSize

The length of a nonce.

type TagSize = TagSize

The maximum length of the tag.

impl<Aes, NonceSize, TagSize> AeadInOut for AesGcm<Aes, NonceSize, TagSize>

where Aes: BlockSizeUser<BlockSize = U16> + BlockCipherEncrypt, NonceSize: ArraySize, TagSize: TagSize,

fn encrypt_inout_detached( &self, nonce: &Nonce<NonceSize>, associated_data: &[u8], buffer: InOutBuf<'_, '_, u8>, ) -> Result<Tag<TagSize>, Error>

Encrypt the data in the provided InOutBuf, returning the authentication tag.

fn decrypt_inout_detached( &self, nonce: &Nonce<NonceSize>, associated_data: &[u8], buffer: InOutBuf<'_, '_, u8>, tag: &Tag<TagSize>, ) -> Result<(), Error>

Decrypt the data in the provided InOutBuf, returning an error in the event the provided authentication tag is invalid for the given ciphertext (i.e. ciphertext is modified/unauthentic).

fn encrypt_in_place( &self, nonce: &Array<u8, Self::NonceSize>, associated_data: &[u8], buffer: &mut dyn Buffer, ) -> Result<(), Error>

Encrypt the given buffer containing a plaintext message in-place.

fn decrypt_in_place( &self, nonce: &Array<u8, Self::NonceSize>, associated_data: &[u8], buffer: &mut dyn Buffer, ) -> Result<(), Error>

Decrypt the message in-place, returning an error in the event the provided authentication tag does not match the given ciphertext.

impl<Aes: Clone, NonceSize: Clone, TagSize> Clone for AesGcm<Aes, NonceSize, TagSize>

where TagSize: TagSize + Clone,

fn clone(&self) -> AesGcm<Aes, NonceSize, TagSize>

Returns a duplicate of the value.

fn clone_from(&mut self, source: &Self)

Performs copy-assignment from source.

impl<Aes, NonceSize, TagSize> Debug for AesGcm<Aes, NonceSize, TagSize>

where TagSize: TagSize,

fn fmt(&self, f: &mut Formatter<'_>) -> Result

Formats the value using the given formatter.

impl<Aes, NonceSize, TagSize> From<Aes> for AesGcm<Aes, NonceSize, TagSize>

where Aes: BlockSizeUser<BlockSize = U16> + BlockCipherEncrypt, TagSize: TagSize,

fn from(cipher: Aes) -> Self

Converts to this type from the input type.

impl<Aes, NonceSize, TagSize> KeyInit for AesGcm<Aes, NonceSize, TagSize>

where Aes: BlockSizeUser<BlockSize = U16> + BlockCipherEncrypt + KeyInit, TagSize: TagSize,

fn new(key: &Key<Self>) -> Self

Create new value from fixed size key.

fn new_from_slice(key: &[u8]) -> Result<Self, InvalidLength>

Create new value from variable size key.

fn generate_key<R>(rng: &mut R) -> Array<u8, Self::KeySize>

where R: CryptoRng,

👎Deprecated since 0.2.0: use the Generate trait impl on Key instead

DEPRECATED: generate random key using the provided CryptoRng.

impl<Aes, NonceSize, TagSize> KeySizeUser for AesGcm<Aes, NonceSize, TagSize>

where Aes: KeySizeUser, TagSize: TagSize,

type KeySize = <Aes as KeySizeUser>::KeySize

Key size in bytes.

fn key_size() -> usize

Return key size in bytes.