WIP: Initial skeleton of snark proof of age verification

CONTRIBUTING.md

@@ -4,6 +4,12 @@ When contributing to this repository, please first discuss the change you wish t
 
 Join the telegram channel: https://t.me/StarknetByExample
 
+The release branch is `main`. The development branch is `dev` and is considered stable (but not released yet).
+When you want to contribute, please create a new branch from `dev` and open a pull request to merge your changes back into `dev`.
+You should never open a pull request to merge your changes directly into `main`.
+
+The `dev` branch is deployed at https://starknet-by-example-dev.voyager.online/
+
 Please note we have a code of conduct, please follow it in all your interactions with the project.
 
 ## Table of Contents

listings/advanced-concepts/proof_of_age/.tool-versions

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+scarb 2.8.4

listings/advanced-concepts/proof_of_age/.tools-versions

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+scarb 2.8.4

listings/advanced-concepts/proof_of_age/Scarb.lock

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+# Code generated by scarb DO NOT EDIT.
+version = 1
+
+[[package]]
+name = "garaga"
+version = "0.14.0"
+source = "git+https://github.com/keep-starknet-strange/garaga.git?tag=v0.14.0#eb9be301d0cd61df8ffa546742e092b5e67e1505"
+
+[[package]]
+name = "proof_of_age"
+version = "0.1.0"
+dependencies = [
+ "garaga",
+]

listings/advanced-concepts/proof_of_age/Scarb.toml

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+[package]
+name = "proof_of_age"
+version = "0.1.0"
+edition = "2024_07"
+
+[dependencies]
+garaga = { git = "https://github.com/keep-starknet-strange/garaga.git", tag = "v0.14.0" }
+starknet = "2.8.4"
+
+[cairo]
+sierra-replace-ids = false
+
+[[target.starknet-contract]]
+casm = true
+casm-add-pythonic-hints = true

listings/advanced-concepts/proof_of_age/cairo/.tools-versions

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+scarb 2.8.4

listings/advanced-concepts/proof_of_age/cairo/Scarb.toml

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+[package]
+name = "cairo"
+version = "0.1.0"
+edition = "2024_07"
+
+[dependencies]
+garaga = { git = "https://github.com/keep-starknet-strange/garaga.git", tag = "v0.14.0" }
+starknet = "2.8.4"
+
+[cairo]
+sierra-replace-ids = false
+
+[[target.starknet-contract]]
+casm = true
+casm-add-pythonic-hints = true

listings/advanced-concepts/proof_of_age/cairo/src/groth16_verifier.cairo

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+use super::groth16_verifier_constants::{N_PUBLIC_INPUTS, vk, ic, precomputed_lines};
+
+#[starknet::interface]
+trait IGroth16VerifierBN254<TContractState> {
+    fn verify_groth16_proof_bn254(
+        self: @TContractState, full_proof_with_hints: Span<felt252>,
+    ) -> Option<Span<u256>>;
+}
+
+#[starknet::contract]
+mod Groth16VerifierBN254 {
+    use starknet::SyscallResultTrait;
+    use garaga::definitions::{G1Point, G1G2Pair};
+    use garaga::groth16::{multi_pairing_check_bn254_3P_2F_with_extra_miller_loop_result};
+    use garaga::ec_ops::{G1PointTrait, ec_safe_add};
+    use garaga::ec_ops_g2::{G2PointTrait};
+    use garaga::utils::calldata::{deserialize_full_proof_with_hints_bn254};
+    use super::{N_PUBLIC_INPUTS, vk, ic, precomputed_lines};
+
+    const ECIP_OPS_CLASS_HASH: felt252 =
+        0x70c1d1c709c75e3cf51d79d19cf7c84a0d4521f3a2b8bf7bff5cb45ee0dd289;
+    use starknet::ContractAddress;
+
+    #[storage]
+    struct Storage {}
+
+    #[abi(embed_v0)]
+    impl IGroth16VerifierBN254 of super::IGroth16VerifierBN254<ContractState> {
+        fn verify_groth16_proof_bn254(
+            self: @ContractState, full_proof_with_hints: Span<felt252>,
+        ) -> Option<Span<u256>> {
+            // DO NOT EDIT THIS FUNCTION UNLESS YOU KNOW WHAT YOU ARE DOING.
+            // This function returns an Option for the public inputs if the proof is valid.
+            // If the proof is invalid, the execution will either fail or return None.
+            // Read the documentation to learn how to generate the full_proof_with_hints array given
+            // a proof and a verifying key.
+            let fph = deserialize_full_proof_with_hints_bn254(full_proof_with_hints);
+            let groth16_proof = fph.groth16_proof;
+            let mpcheck_hint = fph.mpcheck_hint;
+            let small_Q = fph.small_Q;
+            let msm_hint = fph.msm_hint;
+
+            groth16_proof.a.assert_on_curve(0);
+            groth16_proof.b.assert_on_curve(0);
+            groth16_proof.c.assert_on_curve(0);
+
+            let ic = ic.span();
+
+            let vk_x: G1Point = match ic.len() {
+                0 => panic!("Malformed VK"),
+                1 => *ic.at(0),
+                _ => {
+                    // Start serialization with the hint array directly to avoid copying it.
+                    let mut msm_calldata: Array<felt252> = msm_hint;
+                    // Add the points from VK and public inputs to the proof.
+                    Serde::serialize(@ic.slice(1, N_PUBLIC_INPUTS), ref msm_calldata);
+                    Serde::serialize(@groth16_proof.public_inputs, ref msm_calldata);
+                    // Complete with the curve indentifier (0 for BN254):
+                    msm_calldata.append(0);
+
+                    // Call the multi scalar multiplication endpoint on the Garaga ECIP ops contract
+                    // to obtain vk_x.
+                    let mut _vx_x_serialized = core::starknet::syscalls::library_call_syscall(
+                        ECIP_OPS_CLASS_HASH.try_into().unwrap(),
+                        selector!("msm_g1"),
+                        msm_calldata.span()
+                    )
+                        .unwrap_syscall();
+
+                    ec_safe_add(
+                        Serde::<G1Point>::deserialize(ref _vx_x_serialized).unwrap(), *ic.at(0), 0
+                    )
+                }
+            };
+            // Perform the pairing check.
+            let check = multi_pairing_check_bn254_3P_2F_with_extra_miller_loop_result(
+                G1G2Pair { p: vk_x, q: vk.gamma_g2 },
+                G1G2Pair { p: groth16_proof.c, q: vk.delta_g2 },
+                G1G2Pair { p: groth16_proof.a.negate(0), q: groth16_proof.b },
+                vk.alpha_beta_miller_loop_result,
+                precomputed_lines.span(),
+                mpcheck_hint,
+                small_Q
+            );
+            if check == true {
+                return Option::Some(groth16_proof.public_inputs);
+            } else {
+                return Option::None;
+            }
+        }
+    }
+}
+