[][src]Function zkp_stark::verify

pub fn verify(constraints: &Constraints, proof: &Proof) -> Result<(), Error>

Stark verify


A VerifierChannel containing the proof. A ConstraintSystem which captures the claim that is made. A ProofParams object which configures the proof.

Verification process

Step 1: Read all commitments and draw random values

  • Read the trace polynomial commitment commitment.
  • Draw the constraint combination coefficients $\alpha_i$ and $\beta_i$.
  • Read the combined constraint polynomial commitment.
  • Draw the deep point $z$.
  • Read the deep values of the trace polynomials $T_i(z)$ ,$T_i(\omega \cdot z)$.
  • Read the deep values of the combined constraint polynomial $A_i(z^\mathrm{d})$ Draw the coefficients for the final combination $\alpha_i$, $\beta_i$ and $\gamma_i$.
  • Read the final polynomial commitment.
  • Draw the FRI folding coefficient.
  • Repeatedly read the FRI layer commitments and folding coefficients.
  • Read the final FRI polynomial.

Step 2: Verify proof of work

  • Draw proof of work challenge.
  • Read proof of work solution.
  • Verify proof of work solution.

Step 3: Read query decommitments

  • Draw query indices
  • Read evaluations of trace polynomial $T_0(x_0), T_1(x_0), \dots, T_0(x_1), T_1(x_1), \dots$
  • Read and verify merkle decommitments for trace polynomial
  • Read evaluations of the combined constraint polynomial $A_0(x_0), A_1(x_0), \dots, A_0(x_1), A_1(x_1), \dots$
  • Read and verify merkle decommitments for combined constraint polynomial

Step 4: FRI decommitments and final layer verification

Step 5: Verify deep point evaluation

Using the disclosed values of $T_i(z)$ and $T_i(\omega \cdot z)$, compute the combined constraint polynomial at the deep point $C(z)$.

$$ C(z) = \sum_i (\alpha_i + \beta_i \cdot z^{d_i}) \cdot C_i(z, T_0(z), T_0(\omega \cdot z), T_1(z), \dots) $$

Using the disclosed values of $A_i(z^{\mathrm{d}})$ compute $C(z)$.

$$ C'(z) = \sum_i z^i \cdot A_i(z^{\mathrm{d}}) $$

Verify that $C(z) = C'(z)$.

Step 6: Compute first FRI layer values

Divide out the deep point from the trace and constraint decommitments

$$ T_i'(x_j) = \frac{T_i(x_j) - T_i(z)}{x_j - z} $$

$$ T_i''(x_j) = \frac{T_i(x_j) - T_i(\omega \cdot z)}{x_j - \omega \cdot z} $$

$$ A_i'(x_j) = \frac{A_i(x_j) - A_i(z^{\mathrm{d}})}{x_j - z^{\mathrm{d}}} $$

and combine to create evaluations of the final polynomial $P(x_i)$.

$$ P(x_j) = \sum_i \left(\alpha_i \cdot T_i'(x_j) + \beta_i \cdot T_i''(x_j) \right) + \sum_i \gamma_i \cdot A_i'(x_j) $$

Step 7: Verify FRI proof

  • Draw coeffient
  • Reduce layer $n$ times
  • Read and verify decommitments
  • Repeat
  • Evaluate the final layer