Struct RdSeed

pub struct RdSeed(/* private fields */);

A cryptographically secure non-deterministic random bit generator.

This generator produces high-entropy output and is suited to seed other pseudo-random generators.

This instruction is only supported by recent architectures such as Intel Broadwell and AMD Zen.

This generator is not intended for general random number generation purposes and should be used to seed other generators implementing rand_core::SeedableRng.

Implementations

impl RdSeed

pub fn new() -> Result<Self, ErrorCode>

Create a new instance of the random number generator.

This constructor checks whether the CPU the program is running on supports the instruction necessary for this generator to operate. If the instruction is not supported, an error is returned.

pub unsafe fn new_unchecked() -> Self

Create a new instance of the random number generator.

Safety

This constructor is unsafe because it doesn’t check that the CPU supports the instruction, but devolves this responsibility to the caller.

pub fn try_next_u16(&self) -> Result<u16, ErrorCode>

Generate a single random u16 value.

The underlying instruction may fail for variety reasons (such as actual hardware failure or exhausted entropy), however the exact reason for the failure is not usually exposed.

This method will retry calling the instruction a few times, however if all the attempts fail, it will return None.

In case Err is returned, the caller should assume that a non-recoverable failure has occured and use another random number genrator instead.

pub fn try_next_u32(&self) -> Result<u32, ErrorCode>

Generate a single random u32 value.

The underlying instruction may fail for variety reasons (such as actual hardware failure or exhausted entropy), however the exact reason for the failure is not usually exposed.

This method will retry calling the instruction a few times, however if all the attempts fail, it will return None.

In case Err is returned, the caller should assume that a non-recoverable failure has occured and use another random number genrator instead.

pub fn try_next_u64(&self) -> Result<u64, ErrorCode>

Generate a single random u64 value.

The underlying instruction may fail for variety reasons (such as actual hardware failure or exhausted entropy), however the exact reason for the failure is not usually exposed.

This method will retry calling the instruction a few times, however if all the attempts fail, it will return None.

In case Err is returned, the caller should assume that a non-recoverable failure has occured and use another random number genrator instead.

Note, that on 32-bit targets, there’s no underlying instruction to generate a 64-bit number, so it is emulated with the 32-bit version of the instruction.

pub fn try_fill_bytes(&mut self, dest: &mut [u8]) -> Result<(), ErrorCode>

Fill a buffer dest with random data.

This method will use the most appropriate variant of the instruction available on the machine to achieve the greatest single-core throughput, however it has a slightly higher setup cost than the plain next_u32 or next_u64 methods.

The underlying instruction may fail for variety reasons (such as actual hardware failure or exhausted entropy), however the exact reason for the failure is not usually exposed.

This method will retry calling the instruction a few times, however if all the attempts fail, it will return an error.

If an error is returned, the caller should assume that an non-recoverable hardware failure has occured and use another random number genrator instead.

Trait Implementations

impl Clone for RdSeed

fn clone(&self) -> RdSeed

Returns a copy of the value.

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

Performs copy-assignment from source.

impl RngCore for RdSeed

fn next_u32(&mut self) -> u32

Generate a single random u32 value.

The underlying instruction may fail for variety reasons (such as actual hardware failure or exhausted entropy), however the exact reason for the failure is not usually exposed.

Panic

This method will retry calling the instruction a few times, however if all the attempts fail, it will panic.

In case panic occurs, the caller should assume that an non-recoverable hardware failure has occured and use another random number genrator instead.

fn next_u64(&mut self) -> u64

Generate a single random u64 value.

The underlying instruction may fail for variety reasons (such as actual hardware failure or exhausted entropy), however the exact reason for the failure is not usually exposed.

Note, that on 32-bit targets, there’s no underlying instruction to generate a 64-bit number, so it is emulated with the 32-bit version of the instruction.

Panic

This method will retry calling the instruction a few times, however if all the attempts fail, it will panic.

In case panic occurs, the caller should assume that an non-recoverable hardware failure has occured and use another random number genrator instead.

fn fill_bytes(&mut self, dest: &mut [u8])

Fill a buffer dest with random data.

See try_fill_bytes for a more extensive documentation.

Panic

This method will panic any time try_fill_bytes would return an error.

fn try_fill_bytes(&mut self, dest: &mut [u8]) -> Result<(), Error>

Fill a buffer dest with random data.

This method will use the most appropriate variant of the instruction available on the machine to achieve the greatest single-core throughput, however it has a slightly higher setup cost than the plain next_u32 or next_u64 methods.

The underlying instruction may fail for variety reasons (such as actual hardware failure or exhausted entropy), however the exact reason for the failure is not usually exposed.

This method will retry calling the instruction a few times, however if all the attempts fail, it will return an error.

If an error is returned, the caller should assume that an non-recoverable hardware failure has occured and use another random number genrator instead.

impl Copy for RdSeed

impl CryptoRng for RdSeed