Struct MerlinTranscript 

pub struct MerlinTranscript { /* private fields */ }

A transcript of a public-coin argument.

The prover’s messages are added to the transcript using append_message, and the verifier’s challenges can be computed using challenge_bytes.

Creating and using a Merlin transcript

To create a Merlin transcript, use Transcript::new(). This function takes a domain separation label which should be unique to the application.

To use the transcript with a Merlin-based proof implementation, the prover’s side creates a Merlin transcript with an application-specific domain separation label, and passes a &mut reference to the transcript to the proving function(s).

To verify the resulting proof, the verifier creates their own Merlin transcript using the same domain separation label, then passes a &mut reference to the verifier’s transcript to the verification function.

Implementing proofs using Merlin

For information on the design of Merlin and how to use it to implement a proof system, see the documentation at merlin.cool, particularly the Using Merlin section.

Implementations

impl Transcript

pub fn new(label: &'static [u8]) -> Transcript

Initialize a new transcript with the supplied label, which is used as a domain separator.

Note

This function should be called by a proof library’s API consumer (i.e., the application using the proof library), and not by the proof implementation. See the Passing Transcripts section of the Merlin website for more details on why.

pub fn append_message(&mut self, label: &'static [u8], message: &[u8])

Append a prover’s message to the transcript.

The label parameter is metadata about the message, and is also appended to the transcript. See the Transcript Protocols section of the Merlin website for details on labels.

pub fn commit_bytes(&mut self, label: &'static [u8], message: &[u8])

👎Deprecated since 1.1.0: renamed to append_message for clarity.

Deprecated. This function was renamed to append_message.

This is intended to avoid any possible confusion between the transcript-level messages and protocol-level commitments.

pub fn append_u64(&mut self, label: &'static [u8], x: u64)

Convenience method for appending a u64 to the transcript.

The label parameter is metadata about the message, and is also appended to the transcript. See the Transcript Protocols section of the Merlin website for details on labels.

Implementation

Calls append_message with the 8-byte little-endian encoding of x.

pub fn commit_u64(&mut self, label: &'static [u8], x: u64)

👎Deprecated since 1.1.0: renamed to append_u64 for clarity.

Deprecated. This function was renamed to append_u64.

This is intended to avoid any possible confusion between the transcript-level messages and protocol-level commitments.

pub fn challenge_bytes(&mut self, label: &'static [u8], dest: &mut [u8])

Fill the supplied buffer with the verifier’s challenge bytes.

The label parameter is metadata about the challenge, and is also appended to the transcript. See the Transcript Protocols section of the Merlin website for details on labels.

pub fn build_rng(&self) -> TranscriptRngBuilder

Fork the current Transcript to construct an RNG whose output is bound to the current transcript state as well as prover’s secrets.

See the TranscriptRngBuilder documentation for more details.

Trait Implementations

impl Clone for Transcript

fn clone(&self) -> Transcript

Returns a duplicate of the value.

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

Performs copy-assignment from source.

impl Transcript for MerlinTranscript

type Rng = TranscriptRng

The type of the RNG derived from the transcript.

fn new(protocol_info: &'static ProtocolInfo, session_id: &SessionId) -> Self

Create a new transcript for a specific protocol with a session ID for domain separation.

fn append_with<T: AsRef<[u8]>>(&mut self, label: &'static [u8], message: &T)

Append a message with a label to the transcript.

fn append_many_with<T: AsRef<[u8]>>( &mut self, label: &'static [u8], values: &[T], )

Append multiple messages with a common label to the transcript.

fn extract(&mut self, label: &'static [u8]) -> Seed

Extract pseudorandom bytes based on the transcript state. Note: two consecutive extractions must yield different outputs.

fn derive_rng(&mut self, label: &'static [u8]) -> Self::Rng

Derive a CSPRNG from the transcript state with a specific label. Allows arbitrary-length output generation

impl Zeroize for Transcript

fn zeroize(&mut self)

Zero out this object from memory using Rust intrinsics which ensure the zeroization operation is not “optimized away” by the compiler.