feat(AuthWit): chain_id and version in hash (#5331)

Fixes #5074 by including the `chain_id` and `version` as part of the message hash that we are signing over in the authwits.

noir-projects/aztec-nr/authwit/src/account.nr

@@ -76,7 +76,7 @@ impl AccountActions {
         // The `inner_hash` is "siloed" with the `msg_sender` to ensure that only it can 
         // consume the message.
         // This ensures that contracts cannot consume messages that are not intended for them.
-        let message_hash = compute_outer_authwit_hash(context.msg_sender(), inner_hash);
+        let message_hash = compute_outer_authwit_hash(context.msg_sender(), context.chain_id(), context.version(), inner_hash);
         let valid_fn = self.is_valid_impl;
         assert(valid_fn(context, message_hash) == true, "Message not authorized by account");
         context.push_new_nullifier(message_hash, 0);
@@ -90,7 +90,7 @@ impl AccountActions {
         // The `inner_hash` is "siloed" with the `msg_sender` to ensure that only it can 
         // consume the message.
         // This ensures that contracts cannot consume messages that are not intended for them.
-        let message_hash = compute_outer_authwit_hash(context.msg_sender(), inner_hash);
+        let message_hash = compute_outer_authwit_hash(context.msg_sender(), context.chain_id(), context.version(), inner_hash);
         let is_valid = self.approved_action.at(message_hash).read();
         assert(is_valid == true, "Message not authorized by account");
         context.push_new_nullifier(message_hash, 0);

noir-projects/aztec-nr/authwit/src/auth.nr

@@ -29,20 +29,37 @@ pub fn assert_current_call_valid_authwit_public(context: &mut PublicContext, on_
 
 // docs:start:compute_call_authwit_hash
 // Compute the message hash to be used by an authentication witness 
-pub fn compute_call_authwit_hash<N>(caller: AztecAddress, consumer: AztecAddress, selector: FunctionSelector, args: [Field; N]) -> Field {
+pub fn compute_call_authwit_hash<N>(
+    caller: AztecAddress,
+    consumer: AztecAddress,
+    chain_id: Field,
+    version: Field,
+    selector: FunctionSelector,
+    args: [Field; N]
+) -> Field {
     let args_hash = hash_args(args);
     let inner_hash = compute_inner_authwit_hash([caller.to_field(), selector.to_field(), args_hash]);
-    compute_outer_authwit_hash(consumer, inner_hash)
+    compute_outer_authwit_hash(consumer, chain_id, version, inner_hash)
 }
 // docs:end:compute_call_authwit_hash
 
 pub fn compute_inner_authwit_hash<N>(args: [Field; N]) -> Field {
     pedersen_hash(args, GENERATOR_INDEX__AUTHWIT_INNER)
 }
 
-pub fn compute_outer_authwit_hash(consumer: AztecAddress, inner_hash: Field) -> Field {
+pub fn compute_outer_authwit_hash(
+    consumer: AztecAddress,
+    chain_id: Field,
+    version: Field,
+    inner_hash: Field
+) -> Field {
     pedersen_hash(
-        [consumer.to_field(), inner_hash],
+        [
+        consumer.to_field(),
+        chain_id,
+        version,
+        inner_hash
+    ],
         GENERATOR_INDEX__AUTHWIT_OUTER
     )
 }

noir-projects/noir-contracts/contracts/uniswap_contract/src/main.nr

@@ -166,7 +166,7 @@ contract Uniswap {
     // if valid, it returns the IS_VALID selector which is expected by token contract
     #[aztec(public)]
     fn spend_public_authwit(inner_hash: Field) -> Field {
-        let message_hash = compute_outer_authwit_hash(context.msg_sender(), inner_hash);
+        let message_hash = compute_outer_authwit_hash(context.msg_sender(), context.chain_id(), context.version(), inner_hash);
         let value = storage.approved_action.at(message_hash).read();
         if (value) {
             context.push_new_nullifier(message_hash, 0);
@@ -192,6 +192,8 @@ contract Uniswap {
         let message_hash = compute_call_authwit_hash(
             token_bridge,
             token,
+            context.chain_id(),
+            context.version(),
             selector,
             [context.this_address().to_field(), amount, nonce_for_burn_approval]
         );

yarn-project/accounts/src/defaults/account_interface.ts

@@ -10,6 +10,8 @@ import { NodeInfo } from '@aztec/types/interfaces';
  */
 export class DefaultAccountInterface implements AccountInterface {
   private entrypoint: EntrypointInterface;
+  private chainId: Fr;
+  private version: Fr;
 
   constructor(
     private authWitnessProvider: AuthWitnessProvider,
@@ -22,14 +24,16 @@ export class DefaultAccountInterface implements AccountInterface {
       nodeInfo.chainId,
       nodeInfo.protocolVersion,
     );
+    this.chainId = new Fr(nodeInfo.chainId);
+    this.version = new Fr(nodeInfo.protocolVersion);
   }
 
   createTxExecutionRequest(executions: FunctionCall[], fee?: FeeOptions): Promise<TxExecutionRequest> {
     return this.entrypoint.createTxExecutionRequest(executions, fee);
   }
 
-  createAuthWit(message: Fr): Promise<AuthWitness> {
-    return this.authWitnessProvider.createAuthWit(message);
+  createAuthWit(messageHash: Fr): Promise<AuthWitness> {
+    return this.authWitnessProvider.createAuthWit(messageHash);
   }
 
   getCompleteAddress(): CompleteAddress {
@@ -39,4 +43,12 @@ export class DefaultAccountInterface implements AccountInterface {
   getAddress(): AztecAddress {
     return this.address.address;
   }
+
+  getChainId(): Fr {
+    return this.chainId;
+  }
+
+  getVersion(): Fr {
+    return this.version;
+  }
 }

yarn-project/accounts/src/ecdsa/account_contract.ts

@@ -30,9 +30,9 @@ export class EcdsaAccountContract extends DefaultAccountContract {
 class EcdsaAuthWitnessProvider implements AuthWitnessProvider {
   constructor(private signingPrivateKey: Buffer) {}
 
-  createAuthWit(message: Fr): Promise<AuthWitness> {
+  createAuthWit(messageHash: Fr): Promise<AuthWitness> {
     const ecdsa = new Ecdsa();
-    const signature = ecdsa.constructSignature(message.toBuffer(), this.signingPrivateKey);
-    return Promise.resolve(new AuthWitness(message, [...signature.r, ...signature.s]));
+    const signature = ecdsa.constructSignature(messageHash.toBuffer(), this.signingPrivateKey);
+    return Promise.resolve(new AuthWitness(messageHash, [...signature.r, ...signature.s]));
   }
 }

yarn-project/accounts/src/schnorr/account_contract.ts

@@ -30,9 +30,9 @@ export class SchnorrAccountContract extends DefaultAccountContract {
 class SchnorrAuthWitnessProvider implements AuthWitnessProvider {
   constructor(private signingPrivateKey: GrumpkinPrivateKey) {}
 
-  createAuthWit(message: Fr): Promise<AuthWitness> {
+  createAuthWit(messageHash: Fr): Promise<AuthWitness> {
     const schnorr = new Schnorr();
-    const signature = schnorr.constructSignature(message.toBuffer(), this.signingPrivateKey).toBuffer();
-    return Promise.resolve(new AuthWitness(message, [...signature]));
+    const signature = schnorr.constructSignature(messageHash.toBuffer(), this.signingPrivateKey).toBuffer();
+    return Promise.resolve(new AuthWitness(messageHash, [...signature]));
   }
 }

yarn-project/accounts/src/single_key/account_contract.ts

@@ -35,11 +35,11 @@ export class SingleKeyAccountContract extends DefaultAccountContract {
 class SingleKeyAuthWitnessProvider implements AuthWitnessProvider {
   constructor(private privateKey: GrumpkinPrivateKey, private partialAddress: PartialAddress) {}
 
-  createAuthWit(message: Fr): Promise<AuthWitness> {
+  createAuthWit(messageHash: Fr): Promise<AuthWitness> {
     const schnorr = new Schnorr();
-    const signature = schnorr.constructSignature(message.toBuffer(), this.privateKey);
+    const signature = schnorr.constructSignature(messageHash.toBuffer(), this.privateKey);
     const publicKey = generatePublicKey(this.privateKey);
     const witness = [...publicKey.toFields(), ...signature.toBuffer(), this.partialAddress];
-    return Promise.resolve(new AuthWitness(message, witness));
+    return Promise.resolve(new AuthWitness(messageHash, witness));
   }
 }

yarn-project/aztec.js/src/account/interface.ts

@@ -23,6 +23,8 @@ export interface AuthWitnessProvider {
    * If a message hash is provided, it will create a witness for that directly.
    * Otherwise, it will compute the message hash using the caller and the action of the intent.
    * @param messageHashOrIntent - The message hash or the intent (caller and action) to approve
+   * @param chainId - The chain id for the message, will default to the current chain id
+   * @param version - The version for the message, will default to the current protocol version
    * @returns The authentication witness
    */
   createAuthWit(
@@ -34,6 +36,10 @@ export interface AuthWitnessProvider {
           caller: AztecAddress;
           /** The action to approve */
           action: ContractFunctionInteraction | FunctionCall;
+          /** The chain id to approve */
+          chainId?: Fr;
+          /** The version to approve  */
+          version?: Fr;
         },
   ): Promise<AuthWitness>;
 }
@@ -59,5 +65,11 @@ export interface AccountInterface extends AuthWitnessProvider, EntrypointInterfa
 
   /** Returns the address for this account. */
   getAddress(): AztecAddress;
+
+  /** Returns the chain id for this account */
+  getChainId(): Fr;
+
+  /** Returns the rollup version for this account */
+  getVersion(): Fr;
 }
 // docs:end:account-interface

yarn-project/aztec.js/src/fee/private_fee_payment_method.ts

@@ -58,11 +58,16 @@ export class PrivateFeePaymentMethod implements FeePaymentMethod {
    */
   async getFunctionCalls(maxFee: Fr): Promise<FunctionCall[]> {
     const nonce = Fr.random();
-    const messageHash = computeAuthWitMessageHash(this.paymentContract, {
-      args: [this.wallet.getCompleteAddress().address, this.paymentContract, maxFee, nonce],
-      functionData: new FunctionData(FunctionSelector.fromSignature('unshield((Field),(Field),Field,Field)'), true),
-      to: this.asset,
-    });
+    const messageHash = computeAuthWitMessageHash(
+      this.paymentContract,
+      this.wallet.getChainId(),
+      this.wallet.getVersion(),
+      {
+        args: [this.wallet.getCompleteAddress().address, this.paymentContract, maxFee, nonce],
+        functionData: new FunctionData(FunctionSelector.fromSignature('unshield((Field),(Field),Field,Field)'), true),
+        to: this.asset,
+      },
+    );
     await this.wallet.createAuthWit(messageHash);
 
     const secretHashForRebate = computeMessageSecretHash(this.rebateSecret);

yarn-project/aztec.js/src/fee/public_fee_payment_method.ts

@@ -51,14 +51,20 @@ export class PublicFeePaymentMethod implements FeePaymentMethod {
    */
   getFunctionCalls(maxFee: Fr): Promise<FunctionCall[]> {
     const nonce = Fr.random();
-    const messageHash = computeAuthWitMessageHash(this.paymentContract, {
-      args: [this.wallet.getAddress(), this.paymentContract, maxFee, nonce],
-      functionData: new FunctionData(
-        FunctionSelector.fromSignature('transfer_public((Field),(Field),Field,Field)'),
-        false,
-      ),
-      to: this.asset,
-    });
+
+    const messageHash = computeAuthWitMessageHash(
+      this.paymentContract,
+      this.wallet.getChainId(),
+      this.wallet.getVersion(),
+      {
+        args: [this.wallet.getAddress(), this.paymentContract, maxFee, nonce],
+        functionData: new FunctionData(
+          FunctionSelector.fromSignature('transfer_public((Field),(Field),Field,Field)'),
+          false,
+        ),
+        to: this.asset,
+      },
+    );
 
     return Promise.resolve([
       this.wallet.setPublicAuthWit(messageHash, true).request(),

yarn-project/aztec.js/src/utils/authwit.ts

@@ -5,19 +5,23 @@ import { pedersenHash } from '@aztec/foundation/crypto';
 // docs:start:authwit_computeAuthWitMessageHash
 /**
  * Compute an authentication witness message hash from a caller and a request
- * H(target: AztecAddress, H(caller: AztecAddress, selector: Field, args_hash: Field))
+ * H(target: AztecAddress, chainId: Field, version: Field, H(caller: AztecAddress, selector: Field, args_hash: Field))
  * Example usage would be `bob` authenticating `alice` to perform a transfer of `10`
  * tokens from his account to herself:
- * H(token, H(alice, transfer_selector, H(bob, alice, 10, nonce)))
+ * H(token, 1, 1, H(alice, transfer_selector, H(bob, alice, 10, nonce)))
  * `bob` then signs the message hash and gives it to `alice` who can then perform the
  * action.
  * @param caller - The caller approved to make the call
+ * @param chainId - The chain id for the message
+ * @param version - The version for the message
  * @param action - The request to be made (function call)
  * @returns The message hash for the witness
  */
-export const computeAuthWitMessageHash = (caller: AztecAddress, action: FunctionCall) => {
+export const computeAuthWitMessageHash = (caller: AztecAddress, chainId: Fr, version: Fr, action: FunctionCall) => {
   return computeOuterAuthWitHash(
     action.to.toField(),
+    chainId,
+    version,
     computeInnerAuthWitHash([
       caller.toField(),
       action.functionData.selector.toField(),
@@ -51,12 +55,14 @@ export const computeInnerAuthWitHash = (args: Fr[]) => {
  * It is used as part of the `computeAuthWitMessageHash` but can also be used
  * in case the message is not a "call" to a function, but arbitrary data.
  * @param consumer - The address that can "consume" the authwit
+ * @param chainId - The chain id that can "consume" the authwit
+ * @param version - The version that can "consume" the authwit
  * @param innerHash - The inner hash for the witness
  * @returns The outer hash for the witness
  */
-export const computeOuterAuthWitHash = (consumer: AztecAddress, innerHash: Fr) => {
+export const computeOuterAuthWitHash = (consumer: AztecAddress, chainId: Fr, version: Fr, innerHash: Fr) => {
   return pedersenHash(
-    [consumer.toField(), innerHash].map(fr => fr.toBuffer()),
+    [consumer.toField(), chainId, version, innerHash].map(fr => fr.toBuffer()),
     GeneratorIndex.AUTHWIT_OUTER,
   );
 };

yarn-project/aztec.js/src/wallet/account_wallet.ts

@@ -19,6 +19,14 @@ export class AccountWallet extends BaseWallet {
     return this.account.createTxExecutionRequest(execs, fee);
   }
 
+  getChainId(): Fr {
+    return this.account.getChainId();
+  }
+
+  getVersion(): Fr {
+    return this.account.getVersion();
+  }
+
   /**
    * Computes an authentication witness from either a message or a caller and an action.
    * If a message is provided, it will create a witness for the message directly.
@@ -35,6 +43,10 @@ export class AccountWallet extends BaseWallet {
           caller: AztecAddress;
           /** The action to approve */
           action: ContractFunctionInteraction | FunctionCall;
+          /** The chain id to approve */
+          chainId?: Fr;
+          /** The version to approve  */
+          version?: Fr;
         },
   ): Promise<AuthWitness> {
     const messageHash = this.getMessageHash(messageHashOrIntent);
@@ -59,6 +71,10 @@ export class AccountWallet extends BaseWallet {
           caller: AztecAddress;
           /** The action to approve */
           action: ContractFunctionInteraction | FunctionCall;
+          /** The chain id to approve */
+          chainId?: Fr;
+          /** The version to approve  */
+          version?: Fr;
         },
     authorized: boolean,
   ): ContractFunctionInteraction {
@@ -84,16 +100,26 @@ export class AccountWallet extends BaseWallet {
           caller: AztecAddress;
           /** The action to approve */
           action: ContractFunctionInteraction | FunctionCall;
+          /** The chain id to approve */
+          chainId?: Fr;
+          /** The version to approve  */
+          version?: Fr;
         },
   ): Fr {
     if (Buffer.isBuffer(messageHashOrIntent)) {
       return Fr.fromBuffer(messageHashOrIntent);
     } else if (messageHashOrIntent instanceof Fr) {
       return messageHashOrIntent;
-    } else if (messageHashOrIntent.action instanceof ContractFunctionInteraction) {
-      return computeAuthWitMessageHash(messageHashOrIntent.caller, messageHashOrIntent.action.request());
+    } else {
+      return computeAuthWitMessageHash(
+        messageHashOrIntent.caller,
+        messageHashOrIntent.chainId || this.getChainId(),
+        messageHashOrIntent.version || this.getVersion(),
+        messageHashOrIntent.action instanceof ContractFunctionInteraction
+          ? messageHashOrIntent.action.request()
+          : messageHashOrIntent.action,
+      );
     }
-    return computeAuthWitMessageHash(messageHashOrIntent.caller, messageHashOrIntent.action);
   }
 
   /**
@@ -113,6 +139,10 @@ export class AccountWallet extends BaseWallet {
           caller: AztecAddress;
           /** The action to approve */
           action: ContractFunctionInteraction | FunctionCall;
+          /** The chain id to approve */
+          chainId?: Fr;
+          /** The version to approve  */
+          version?: Fr;
         },
   ): Promise<{
     /** boolean flag indicating if the authwit is valid in private context */
@@ -148,6 +178,10 @@ export class AccountWallet extends BaseWallet {
           caller: AztecAddress;
           /** The action to approve */
           action: ContractFunctionInteraction | FunctionCall;
+          /** The chain id to approve */
+          chainId?: Fr;
+          /** The version to approve  */
+          version?: Fr;
         },
   ): ContractFunctionInteraction {
     const message = this.getMessageHash(messageHashOrIntent);

yarn-project/aztec.js/src/wallet/base_wallet.ts

@@ -31,6 +31,10 @@ export abstract class BaseWallet implements Wallet {
 
   abstract getCompleteAddress(): CompleteAddress;
 
+  abstract getChainId(): Fr;
+
+  abstract getVersion(): Fr;
+
   abstract createTxExecutionRequest(execs: FunctionCall[], fee?: FeeOptions): Promise<TxExecutionRequest>;
 
   abstract createAuthWit(
@@ -42,6 +46,10 @@ export abstract class BaseWallet implements Wallet {
           caller: AztecAddress;
           /** The action to approve */
           action: ContractFunctionInteraction | FunctionCall;
+          /** The chain id to approve */
+          chainId?: Fr;
+          /** The version to approve  */
+          version?: Fr;
         },
   ): Promise<AuthWitness>;