The given code implements the Chaum-Pedersen protocol in two different versions: one based on discrete logarithms and the other based on elliptic curves. The Chaum-Pedersen protocol is typically used for proving that the discrete logarithms of two known values are equal to a third, unknown value without revealing the value itself. This is commonly used in cryptographic protocols, particularly in zero-knowledge proofs.
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Imports and Dependencies:
curve25519_dalek
: A Rust library that provides implementations for the Ristretto group, a prime order group using elliptic curves.num_bigint
,num_traits
: Libraries for big integer arithmetic.rand
: A library for generating random numbers.
-
Params Structure:
Params
is a generic struct that holds the base parameters for the protocol:g
,h
,p
, andq
. These parameters have typeT
, which allows the struct to be used for both discrete logarithm and elliptic curve versions.
-
ChaumPedersen Trait:
- A trait defining the common interface for the Chaum-Pedersen protocol, including methods for creating new instances, calculating commitments, committing, generating challenges, calculating responses, and verification.
-
DiscreteLogChaumPedersen Struct:
- An implementation of the
ChaumPedersen
trait for the discrete logarithm version. It usesBigUint
for its computations.
- An implementation of the
-
EllipticCurveChaumPedersen Struct:
- An implementation of the
ChaumPedersen
trait for the elliptic curve version. It usesRistrettoPoint
andScalar
from thecurve25519_dalek
library.
- An implementation of the
-
execute_protocol Function:
- A generic function to execute the protocol. It takes a mutable reference to a protocol instance, the parameters, and the secret
x
. It goes through the steps of the protocol: calculate commitment, commit, challenge, calculate response, and verify.
- A generic function to execute the protocol. It takes a mutable reference to a protocol instance, the parameters, and the secret
- calculate_commitment: Calculates the commitments
y1
,y2
,r1
,r2
, and a random valuek
. - commit: Stores the commitment values in the protocol instance.
- challenge: Generates and returns a random challenge
c
. - calculate_response: Calculates the response
s
based onk
,c
, and the secretx
. - verify: Verifies if the calculated response
s
is valid.
- calculate_commitment: Similar to the discrete log version, but uses elliptic curve operations.
- commit: Stores the commitment values in the protocol instance.
- challenge: Generates and returns a random challenge
c
. - calculate_response: Calculates the response
s
using elliptic curve arithmetic. - verify: Verifies if the calculated response
s
is valid using elliptic curve operations.
- Demonstrates the usage of the discrete logarithm version of the protocol with randomly generated secret
x
and fixed parametersg
,h
,p
, andq
. - Demonstrates the usage of the elliptic curve version with a secret
x
, basepointg
, and randomly generatedh
.
The code provides a flexible implementation of the Chaum-Pedersen protocol for both discrete logarithm and elliptic curve settings. It demonstrates the essential steps of the protocol: commitment, challenge, response, and verification, allowing users to execute zero-knowledge proofs securely.