Struct tindercrypt::metadata::Metadata

pub struct Metadata {
    pub key_deriv_algo: KeyDerivationAlgorithm,
    pub enc_algo: EncryptionAlgorithm,
    pub ciphertext_size: usize,
}

The collection of all encryption-related metadata.

This struct holds all the metadata necessary for the encryption process. The end product of the encryption will contain a serialized version of this struct, so that it can be retrieved during decryption.

Examples

We can serialize the metadata to a buffer and then deserialize them again. The reported size of the serialized metadata and their contents should be the same in both cases:

use tindercrypt::metadata::Metadata;

let data = "The cake is a lie";
let meta = Metadata::generate_for_passphrase(data.len());
let (buf, meta_size) = meta.to_buf();
assert_eq!(Metadata::from_buf(&buf)?, (meta, meta_size));

We can also convert the metadata to and from the respective Protocol Buffers message (proto::metadata::Metadata):

use tindercrypt::metadata::Metadata;

let data = "The cake is a lie";
let meta = Metadata::generate_for_key(data.len());
let proto_meta = meta.to_proto();
assert_eq!(meta, Metadata::from_proto(&proto_meta)?);

Fields

key_deriv_algo: KeyDerivationAlgorithm

The key derivation algorithm to be used.

enc_algo: EncryptionAlgorithm

The encryption algorithm to be used.

ciphertext_size: usize

The size of the ciphertext.

Note that depending on the encryption algorithm used, the ciphertext may also contain its digest. So, this value also takes the digest into account.

Implementations

impl<'a> Metadata

pub fn new(
    key_deriv_algo: KeyDerivationAlgorithm,
    enc_algo: EncryptionAlgorithm,
    plaintext_size: usize
) -> Self

Create the metadata from user-provided values.

pub fn calculate_ciphertext_size(
    plaintext_size: usize,
    enc_algo: &EncryptionAlgorithm
) -> usize

Calculate the ciphertext size, from the plaintext size and the encryption algorithm.

pub fn generate_for_key(plaintext_size: usize) -> Self

Generate the necessary metadata for encrypting data with a symmetric key.

The default suggestion for encrypting data with a symmetric key is to forego any key derivation algorithm, and just use the AES-256-GCM encryption algorithm.

pub fn generate_for_passphrase(plaintext_size: usize) -> Self

Generate the necessary metadata for encrypting data with a passphrase.

The default suggestion for encrypting data with a passphrase is to use the PBKDF2 key derivation algorithm, and the AES-256-GCM encryption algorithm.

pub fn from_proto(proto_meta: &Metadata) -> Result<Self, Error>

Create the metadata from the respective protobuf-generated metadata.

This method may return an error, if the protobuf-generated metadata have any invalid fields.

pub fn to_proto(&self) -> Metadata

Convert the metadata to the respective protobuf-generated metadata.

pub fn from_buf(buf: &'a [u8]) -> Result<(Self, usize), Error>

Create a metadata struct from a serialized buffer.

Deserialize the buffer that was created by the .to_buf() method into a tuple that contains the Metadata struct and its serialized size. If the buffer does not contain a metadata header or the header contains invalid fields, this method returns an error.

pub fn to_buf(&self) -> (Vec<u8>, usize)

Serialize a metadata struct into a buffer.

Create a buffer that is large enough to hold the serialized metadata and the ciphertext. Then, serialize the metadata and store them at the start of the buffer. Finally, return the new buffer and the size of the serialized metadata.

Trait Implementations

impl Clone for Metadata

fn clone(&self) -> Metadata

Returns a copy of the value.

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

Performs copy-assignment from source.

impl Debug for Metadata

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

Formats the value using the given formatter.

impl PartialEq<Metadata> for Metadata

fn eq(&self, other: &Metadata) -> bool

This method tests for self and other values to be equal, and is used by ==.

fn ne(&self, other: &Metadata) -> bool

This method tests for !=.

impl Copy for Metadata

impl StructuralPartialEq for Metadata