Struct ring::error::Unspecified

pub struct Unspecified;

An error with absolutely no details.

ring uses this unit type as the error type in most of its results because (a) usually the specific reasons for a failure are obvious or are not useful to know, and/or (b) providing more details about a failure might provide a dangerous side channel, and/or (c) it greatly simplifies the error handling logic.

Result<T, ring::error::Unspecified> is mostly equivalent to Result<T, ()>. However, ring::error::Unspecified implements std::error::Error and users of ring can implement From<ring::error::Unspecified> to map this to their own error types, as described in “Error Handling” in the Rust Book:

use ring::rand::{self, SecureRandom};

enum Error {
    CryptoError,

    IOError(std::io::Error),
    // [...]
}

impl From<ring::error::Unspecified> for Error {
    fn from(_: ring::error::Unspecified) -> Self { Error::CryptoError }
}

fn eight_random_bytes() -> Result<[u8; 8], Error> {
    let rng = rand::SystemRandom::new();
    let mut bytes = [0; 8];

    // The `From<ring::error::Unspecified>` implementation above makes this
    // equivalent to
    // `rng.fill(&mut bytes).map_err(|_| Error::CryptoError)?`.
    rng.fill(&mut bytes)?;

    Ok(bytes)
}

assert!(eight_random_bytes().is_ok());

Experience with using and implementing other crypto libraries like has shown that sophisticated error reporting facilities often cause significant bugs themselves, both within the crypto library and within users of the crypto library. This approach attempts to minimize complexity in the hopes of avoiding such problems. In some cases, this approach may be too extreme, and it may be important for an operation to provide some details about the cause of a failure. Users of ring are encouraged to report such cases so that they can be addressed individually.

Trait Implementations

impl Display for Unspecified

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

Formats the value using the given formatter.

impl Debug for Unspecified

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

Formats the value using the given formatter.

impl PartialEq<Unspecified> for Unspecified

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

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

#[must_use] fn ne(&self, other: &Rhs) -> bool

This method tests for !=.

impl Copy for Unspecified

impl From<EndOfInput> for Unspecified

fn from(_: EndOfInput) -> Self

Performs the conversion.

impl From<TryFromSliceError> for Unspecified

fn from(_: TryFromSliceError) -> Self

Performs the conversion.

impl From<KeyRejected> for Unspecified

fn from(_: KeyRejected) -> Self

Performs the conversion.

impl Clone for Unspecified

fn clone(&self) -> Unspecified

Returns a copy of the value.

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

Performs copy-assignment from source.