Enum Tag 

#[non_exhaustive]
#[repr(u8)]
pub enum Tag {
    Message = 0,
    Push = 1,
    Rekey = 2,
    Final = 3,
}

Secret stream message tag.

Each message pushed to a DryocStream carries one tag, which is encrypted and authenticated with the message. The variants are exactly libsodium’s four crypto_secretstream_xchacha20poly1305_TAG_* values, and Tag::bits returns the byte stored in the stream. Convert a tag byte with Tag::try_from, which rejects every other byte.

Tag is #[non_exhaustive] so that a tag value libsodium may add to the secretstream format later can become a new variant without a breaking change; a match on Tag outside this crate therefore needs a wildcard arm.

Variants (Non-exhaustive)

Non-exhaustive enums could have additional variants added in future. Therefore, when matching against variants of non-exhaustive enums, an extra wildcard arm must be added to account for any future variants.

Message = 0

A normal message in a stream (TAG_MESSAGE, 0).

Push = 1

Marks the end of a series of messages in a stream, but not the end of the stream (TAG_PUSH, 1).

Rekey = 2

Derives a new key for the stream after this message (TAG_REKEY, 2).

Final = 3

Marks the end of the stream, and rekeys after this message (TAG_FINAL, 3).

Implementations

impl Tag

pub const fn bits(self) -> u8

Returns the tag byte, as stored in the stream and used by the Classic crypto_secretstream_xchacha20poly1305 functions.

Trait Implementations

impl Clone for Tag

fn clone(&self) -> Self

Returns a duplicate of the value.

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

Performs copy-assignment from source.

impl Copy for Tag

impl Debug for Tag

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

Formats the value using the given formatter.

impl Default for Tag

fn default() -> Self

Returns the “default value” for a type.

impl Eq for Tag

impl Hash for Tag

fn hash<__H: Hasher>(&self, state: &mut __H)

Feeds this value into the given Hasher.

fn hash_slice<H>(data: &[Self], state: &mut H)

where H: Hasher, Self: Sized,

Feeds a slice of this type into the given Hasher.

impl PartialEq for Tag

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

Equality operator ==.

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

Inequality operator !=.

impl StructuralPartialEq for Tag

impl TryFrom<u8> for Tag

fn try_from(bits: u8) -> Result<Self, Self::Error>

Converts a tag byte into a Tag.

Errors

Returns Error::InvalidValue with ErrorContext::Tag for any byte other than the four libsodium tag values.

type Error = Error

The type returned in the event of a conversion error.