get-smooth · qd-qd · Aug 7, 2023 · Aug 4, 2023
diff --git a/script/DeployWebAuthn.s.sol b/script/DeployWebAuthn.s.sol
@@ -6,10 +6,10 @@ import { WebAuthn } from "../src/WebAuthn.sol";
 
 contract LibraryWrapper {
     function verify(
-        bytes calldata authData,
-        bytes1 authDataFlagMask,
+        bytes1 authenticatorDataFlagMask,
+        bytes calldata authenticatorData,
         bytes calldata clientData,
-        bytes32 clientChallenge,
+        bytes calldata clientChallengeBase64,
         uint256 clientChallengeOffset,
         uint256 r,
         uint256 s,
@@ -20,7 +20,15 @@ contract LibraryWrapper {
         returns (bool)
     {
         return WebAuthn.verify(
-            authData, authDataFlagMask, clientData, clientChallenge, clientChallengeOffset, r, s, qx, qy
+            authenticatorDataFlagMask,
+            authenticatorData,
+            clientData,
+            clientChallengeBase64,
+            clientChallengeOffset,
+            r,
+            s,
+            qx,
+            qy
         );
     }
 }
@@ -56,13 +64,13 @@ contract MyScript is BaseScript {
 
     example:
         cast call 0x387ca8d38f379710a3d24d710ba2940787f7b4a1 \
-        "verify(bytes,bytes1,bytes,bytes32,uint256,uint256,uint256,uint256,uint256)(bool)" \
-        0xf8e4b678e1c62f7355266eaa4dc1148573440937063a46d848da1e25babbd20b010000004d \
+        "verify(bytes1,bytes,bytes,bytes,uint256,uint256,uint256,uint256,uint256)(bool)" \
         0x01 \
+        0xf8e4b678e1c62f7355266eaa4dc1148573440937063a46d848da1e25babbd20b010000004d \
         0x7b2274797065223a22776562617574686e2e676574222c226368616c6c656e6765223a224e546f2d316\
 1424547526e78786a6d6b61544865687972444e5833697a6c7169316f776d4f643955474a30222c226f7269\
 67696e223a2268747470733a2f2f66726573682e6c65646765722e636f6d222c2263726f73734f726967696e223a66616c73657d\
-        0x353a3ed5a0441919f1c639a46931de872ac3357de2ce5aa2d68c2639df54189d \
+        4e546f2d3161424547526e78786a6d6b61544865687972444e5833697a6c7169316f776d4f643955474a30 \
         0x24 \
         45847212378479006099766816358861726414873720355505495069909394794949093093607 \
         55835259151215769394881684156457977412783812617123006733908193526332337539398 \

diff --git a/src/WebAuthn.sol b/src/WebAuthn.sol
@@ -1,75 +1,53 @@
 // SPDX-License-Identifier: MIT
 pragma solidity >=0.8.19 <0.9.0;
 
-import { Base64 } from "../lib/solady/src/utils/Base64.sol";
+// import { Base64 } from "../lib/solady/src/utils/Base64.sol";
 import { ECDSA256r1 } from "../lib/secp256r1-verify/src/ECDSA256r1.sol";
 
 error InvalidAuthenticatorData();
 error InvalidClientData();
 
+/// dev: this implementation assumes the caller check if User Presence (0x01) or User Verification (0x04) are set
 library WebAuthn {
-    function format(
-        bytes calldata authenticatorData,
+    function generateMessage(
         bytes1 authenticatorDataFlagMask,
+        bytes calldata authenticatorData,
         bytes calldata clientData,
-        bytes32 clientChallenge,
+        bytes calldata clientChallenge,
         uint256 clientChallengeOffset
     )
         internal
         pure
-        returns (bytes32 result)
+        returns (bytes32)
     {
-        // Let the caller check if User Presence (0x01) or User Verification (0x04) are set
-        {
+        unchecked {
+            // Let the caller check if User Presence (0x01) or User Verification (0x04) are set
             if ((authenticatorData[32] & authenticatorDataFlagMask) != authenticatorDataFlagMask) {
                 revert InvalidAuthenticatorData();
             }
-            // Verify that clientData commits to the expected client challenge
-            string memory challengeEncoded = Base64.encode(abi.encodePacked(clientChallenge), true, true);
-            bytes memory challengeExtracted = new bytes(
-                bytes(challengeEncoded).length
-            );
 
-            assembly {
-                calldatacopy( // copy from calldata to memory
-                    add(challengeExtracted, 32), // destOffset
-                    add(clientData.offset, clientChallengeOffset), // offset
-                    mload(challengeExtracted) // size
-                )
-            }
+            // TODO: Pass non-encode challenge? Convert the challenge to `bytes memory` and encode it to Base64
+            // bytes memory challengeEncoded = bytes(Base64.encode(abi.encodePacked(clientChallenge), true, true));
 
-            bytes32 moreData; //=keccak256(abi.encodePacked(challengeExtracted));
-            assembly {
-                moreData := keccak256(add(challengeExtracted, 32), mload(challengeExtracted))
-            }
-            if (keccak256(abi.encodePacked(bytes(challengeEncoded))) != moreData) {
+            // Extract the challenge from the client data and hash it
+            bytes32 challengeHashed =
+                keccak256(clientData[clientChallengeOffset:(clientChallengeOffset + clientChallenge.length)]);
+
+            // hash the encoded challenge and check both challenges are equal
+            if (keccak256(clientChallenge) != challengeHashed) {
                 revert InvalidClientData();
             }
-        }
 
-        // Verify the signature over sha256(authenticatorData || sha256(clientData))
-        bytes memory verifyData = new bytes(authenticatorData.length + 32);
-        assembly {
-            calldatacopy( // copy from calldata to memory
-                add(verifyData, 32), // destOffset
-                authenticatorData.offset, // offset
-                authenticatorData.length // size
-            )
+            // Verify the signature over sha256(authenticatorData || sha256(clientData))
+            return sha256(abi.encodePacked(authenticatorData, sha256(clientData)));
         }
-        bytes32 more = sha256(clientData);
-        assembly {
-            mstore(add(verifyData, add(authenticatorData.length, 32)), more)
-        }
-
-        return sha256(verifyData);
     }
 
-    /// note: this implementation assumes the caller check if User Presence (0x01) or User Verification (0x04) are set
     function verify(
-        bytes calldata authenticatorData,
         bytes1 authenticatorDataFlagMask,
+        bytes calldata authenticatorData,
         bytes calldata clientData,
-        bytes32 clientChallenge,
+        bytes calldata clientChallenge,
         uint256 clientChallengeOffset,
         uint256 r,
         uint256 s,
@@ -79,9 +57,13 @@ library WebAuthn {
         internal
         returns (bool)
     {
-        bytes32 message =
-            format(authenticatorData, authenticatorDataFlagMask, clientData, clientChallenge, clientChallengeOffset);
+        unchecked {
+            // Verify the signature over sha256(authenticatorData || sha256(clientData))
+            bytes32 message = generateMessage(
+                authenticatorDataFlagMask, authenticatorData, clientData, clientChallenge, clientChallengeOffset
+            );
 
-        return ECDSA256r1.verify(message, r, s, qx, qy);
+            return ECDSA256r1.verify(message, r, s, qx, qy);
+        }
     }
 }
diff --git a/test/WebAuthn.t.sol b/test/WebAuthn.t.sol
@@ -1,15 +1,31 @@
 // SPDX-License-Identifier: MIT
 pragma solidity >=0.8.19 <0.9.0;
 
-import { Test } from "forge-std/Test.sol";
+import { Test } from "../lib/forge-std/src/Test.sol";
 import { WebAuthn } from "../src/WebAuthn.sol";
 
 contract WebAuthnImplementation {
-    function verify(
+    function generateMessage(
+        bytes1 authenticatorDataFlagMask,
         bytes calldata authenticatorData,
+        bytes calldata clientData,
+        bytes calldata clientChallengeBase64,
+        uint256 clientChallengeOffset
+    )
+        external
+        pure
+        returns (bytes32)
+    {
+        return WebAuthn.generateMessage(
+            authenticatorDataFlagMask, authenticatorData, clientData, clientChallengeBase64, clientChallengeOffset
+        );
+    }
+
+    function verify(
         bytes1 authenticatorDataFlagMask,
+        bytes calldata authenticatorData,
         bytes calldata clientData,
-        bytes32 clientChallenge,
+        bytes calldata clientChallengeBase64,
         uint256 clientChallengeOffset,
         uint256 r,
         uint256 s,
@@ -20,10 +36,10 @@ contract WebAuthnImplementation {
         returns (bool)
     {
         return WebAuthn.verify(
-            authenticatorData,
             authenticatorDataFlagMask,
+            authenticatorData,
             clientData,
-            clientChallenge,
+            clientChallengeBase64,
             clientChallengeOffset,
             r,
             s,
@@ -40,37 +56,51 @@ contract ContractTest is Test {
         implem = new WebAuthnImplementation();
     }
 
-    function test_Webauthn() public {
-        bytes memory authenticatorData =
-            hex"f8e4b678e1c62f7355266eaa4dc1148573440937063a46d848da1e25babbd20b" hex"010000004d";
-        bytes1 authenticatorDataFlagMask = 0x01;
-        bytes memory clientData = hex"7b2274797065223a22776562617574686e2e676574222c226368616c6c656e67"
-            hex"65223a224e546f2d3161424547526e78786a6d6b61544865687972444e583369"
-            hex"7a6c7169316f776d4f643955474a30222c226f726967696e223a226874747073"
-            hex"3a2f2f66726573682e6c65646765722e636f6d222c2263726f73734f726967696e223a66616c73657d";
-        bytes32 clientChallenge = hex"353a3ed5a0441919f1c639a46931de872ac3357de2ce5aa2d68c2639df54189d";
-        uint256 clientChallengeDataOffset = 0x24; // 36
-        uint256 r =
-            45_847_212_378_479_006_099_766_816_358_861_726_414_873_720_355_505_495_069_909_394_794_949_093_093_607;
-        uint256 s =
-            55_835_259_151_215_769_394_881_684_156_457_977_412_783_812_617_123_006_733_908_193_526_332_337_539_398;
-        uint256 qx =
-            114_874_632_398_302_156_264_159_990_279_427_641_021_947_882_640_101_801_130_664_833_947_273_521_181_002;
-        uint256 qy =
-            32_136_952_818_958_550_240_756_825_111_900_051_564_117_520_891_182_470_183_735_244_184_006_536_587_423;
-
+    function test_Verify() public {
         assertTrue(
             implem.verify(
-                authenticatorData,
-                authenticatorDataFlagMask,
-                clientData,
-                clientChallenge,
-                clientChallengeDataOffset,
-                r,
-                s,
-                qx,
-                qy
+                // authenticatorDataFlagMask
+                0x01,
+                // authenticatorData
+                hex"f8e4b678e1c62f7355266eaa4dc1148573440937063a46d848da1e25babbd20b010000004d",
+                // clientData
+                hex"7b2274797065223a22776562617574686e2e676574222c226368616c6c656e67"
+                hex"65223a224e546f2d3161424547526e78786a6d6b61544865687972444e583369"
+                hex"7a6c7169316f776d4f643955474a30222c226f726967696e223a226874747073"
+                hex"3a2f2f66726573682e6c65646765722e636f6d222c2263726f73734f726967696e223a66616c73657d",
+                // clientChallengeBase64
+                hex"4e546f2d3161424547526e78786a6d6b61544865687972444e5833697a6c7169316f776d4f643955474a30",
+                // clientChallengeOffset
+                0x24,
+                // r
+                45_847_212_378_479_006_099_766_816_358_861_726_414_873_720_355_505_495_069_909_394_794_949_093_093_607,
+                // s
+                55_835_259_151_215_769_394_881_684_156_457_977_412_783_812_617_123_006_733_908_193_526_332_337_539_398,
+                // qx
+                114_874_632_398_302_156_264_159_990_279_427_641_021_947_882_640_101_801_130_664_833_947_273_521_181_002,
+                // qy
+                32_136_952_818_958_550_240_756_825_111_900_051_564_117_520_891_182_470_183_735_244_184_006_536_587_423
             )
         );
     }
+
+    function test_GenerateMessage() public {
+        bytes32 message = implem.generateMessage(
+            // authenticatorDataFlagMask
+            0x01,
+            // authenticatorData
+            hex"f8e4b678e1c62f7355266eaa4dc1148573440937063a46d848da1e25babbd20b010000004d",
+            // clientData
+            hex"7b2274797065223a22776562617574686e2e676574222c226368616c6c656e67"
+            hex"65223a224e546f2d3161424547526e78786a6d6b61544865687972444e583369"
+            hex"7a6c7169316f776d4f643955474a30222c226f726967696e223a226874747073"
+            hex"3a2f2f66726573682e6c65646765722e636f6d222c2263726f73734f726967696e223a66616c73657d",
+            // clientChallengeBase64
+            hex"4e546f2d3161424547526e78786a6d6b61544865687972444e5833697a6c7169316f776d4f643955474a30",
+            // clientChallengeOffset
+            0x24
+        );
+
+        assertEq(message, 0x4bfd0c06e1609b41d94e18b705de3163f6bf61fa44dcb8127c94bab7ba55fb9c);
+    }
 }