From 95fa04264482bcc748a39840492cd83128cbe9af Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Pablo=20Andr=C3=A9s=20Dorado=20Su=C3=A1rez?=
 <hola@pablodorado.com>
Date: Mon, 14 Oct 2024 12:26:17 -0500
Subject: [PATCH] wip(pass-webauthn): apply changes and leave for finishing
 `Attestation`.

---
 pass-webauthn/src/impls.rs | 79 ++++++++++++--------------------------
 pass-webauthn/src/lib.rs   | 25 ++++++------
 2 files changed, 39 insertions(+), 65 deletions(-)

diff --git a/pass-webauthn/src/impls.rs b/pass-webauthn/src/impls.rs
index 96decc3..45260bb 100644
--- a/pass-webauthn/src/impls.rs
+++ b/pass-webauthn/src/impls.rs
@@ -1,11 +1,10 @@
-use core::marker::PhantomData;
-
 use codec::Decode;
 use frame_support::{sp_runtime::traits::TrailingZeroInput, Parameter};
 use serde_json::Value;
+use sp_io::hashing::blake2_256;
 use traits_authn::{
-    AuthorityId, Challenge, Challenger, DeviceChallengeResponse, DeviceId, HashedUserId,
-    UserChallengeResponse,
+    util::VerifyCredential, AuthorityId, Challenge, Challenger, DeviceChallengeResponse, DeviceId,
+    HashedUserId, UserChallengeResponse,
 };
 use verifier::webauthn_verify;
 
@@ -15,25 +14,6 @@ impl<Cx> Attestation<Cx>
 where
     Cx: Parameter,
 {
-    pub fn new(
-        authenticator_data: Vec<u8>,
-        client_data: Vec<u8>,
-        signature: Vec<u8>,
-        public_key: Vec<u8>,
-    ) -> Self {
-        Self {
-            __phantom: PhantomData,
-            authenticator_data,
-            client_data,
-            signature,
-            public_key,
-        }
-    }
-
-    fn context(&self) -> Cx {
-        todo!("Extract `context` into `Cx` format (you can conveniently use `.decode()`)");
-    }
-
     fn challenge(&self) -> Challenge {
         || -> Result<AuthorityId, ()> {
             let client_data_json =
@@ -64,7 +44,7 @@ where
     }
 
     fn used_challenge(&self) -> (Cx, Challenge) {
-        (self.context(), self.challenge())
+        (self.context, self.challenge())
     }
 
     fn authority(&self) -> AuthorityId {
@@ -83,7 +63,7 @@ where
     }
 
     fn device_id(&self) -> &DeviceId {
-        todo!("Extract `device_id`, format into `DeviceId` format (that is, [u8; 32])");
+        &self.credential_id
     }
 }
 
@@ -94,14 +74,29 @@ where
     CxOf<Ch>: Parameter + Copy + 'static,
 {
     fn from(value: Attestation<CxOf<Ch>>) -> Self {
-        Device::new(DeviceInfo(value.device_id().clone()))
+        Device::new(DeviceInfo {
+            device_id: value.device_id().clone(),
+            public_key: value.public_key,
+        })
+    }
+}
+
+impl<Cx> VerifyCredential<Credential<Cx>> for DeviceInfo {
+    fn verify(&self, credential: &Credential<Cx>) -> Option<()> {
+        webauthn_verify(
+            &credential.authenticator_data,
+            &credential.client_data,
+            &credential.signature,
+            &self.public_key,
+        )
+        .ok()
     }
 }
 
 #[cfg(any(feature = "runtime", test))]
 impl AsRef<DeviceId> for DeviceInfo {
     fn as_ref(&self) -> &DeviceId {
-        &self.0
+        &self.device_id
     }
 }
 
@@ -109,25 +104,6 @@ impl<Cx> Credential<Cx>
 where
     Cx: Parameter,
 {
-    pub fn new(
-        authenticator_data: Vec<u8>,
-        client_data: Vec<u8>,
-        signature: Vec<u8>,
-        public_key: Vec<u8>,
-    ) -> Self {
-        Self {
-            __phantom: PhantomData,
-            authenticator_data,
-            client_data,
-            signature,
-            public_key,
-        }
-    }
-
-    fn context(&self) -> Cx {
-        todo!("Extract `context` into `Cx` format (you can conveniently use `.decode()`)");
-    }
-
     fn challenge(&self) -> Challenge {
         todo!("Extract `challenge`, format into `Challenge` format (that is, [u8; 32])");
     }
@@ -138,18 +114,13 @@ impl<Cx> UserChallengeResponse<Cx> for Credential<Cx>
 where
     Cx: Parameter + Copy + 'static,
 {
+    // TODO: @jgutierrezre please check if there are necessary validations involved here.
     fn is_valid(&self) -> bool {
-        webauthn_verify(
-            self.authenticator_data.as_ref(),
-            &self.client_data,
-            &self.signature,
-            &self.public_key,
-        )
-        .is_ok()
+        true
     }
 
     fn used_challenge(&self) -> (Cx, Challenge) {
-        (self.context(), self.challenge())
+        (self.context, self.challenge())
     }
 
     fn authority(&self) -> AuthorityId {
diff --git a/pass-webauthn/src/lib.rs b/pass-webauthn/src/lib.rs
index 506a6ec..f361008 100644
--- a/pass-webauthn/src/lib.rs
+++ b/pass-webauthn/src/lib.rs
@@ -1,20 +1,19 @@
 #![cfg_attr(not(feature = "std"), no_std)]
 
-use core::marker::PhantomData;
-
 use codec::{Decode, Encode, MaxEncodedLen};
 use scale_info::TypeInfo;
 use traits_authn::{
     util::{Auth, Dev},
-    Challenger, DeviceId,
+    Challenger, DeviceId, HashedUserId,
 };
 
 type CxOf<Ch> = <Ch as Challenger>::Context;
 
+mod impls;
 #[cfg(test)]
 mod tests;
 
-mod impls;
+pub type DEREncodedPublicKey = [u8; 91];
 
 #[cfg(any(feature = "runtime", test))]
 pub type Authenticator<Ch, A> = Auth<Device<Ch, A>, Attestation<CxOf<Ch>>>;
@@ -23,22 +22,26 @@ pub type Device<Ch, A> = Dev<DeviceInfo, A, Ch, Credential<CxOf<Ch>>>;
 
 #[cfg(any(feature = "runtime", test))]
 #[derive(MaxEncodedLen, TypeInfo, Decode, Encode)]
-pub struct DeviceInfo(DeviceId);
+pub struct DeviceInfo {
+    device_id: DeviceId,
+    //. A DER-encoded public key
+    public_key: DEREncodedPublicKey,
+}
 
 #[derive(Encode, Decode, TypeInfo, Debug, PartialEq, Eq, Clone)]
 pub struct Attestation<Cx> {
-    __phantom: PhantomData<Cx>,
+    pub(crate) credential_id: DeviceId,
+    pub(crate) context: Cx,
     pub(crate) authenticator_data: Vec<u8>,
-    pub(crate) client_data: Vec<u8>,
-    pub(crate) public_key: Vec<u8>,
-    pub(crate) signature: Vec<u8>,
+    pub(crate) attestation_data: Vec<u8>,
+    pub(crate) public_key: DEREncodedPublicKey,
 }
 
 #[derive(Encode, Decode, TypeInfo, Debug, PartialEq, Eq, Clone)]
 pub struct Credential<Cx> {
-    __phantom: PhantomData<Cx>,
+    pub(crate) user_id: HashedUserId,
+    pub(crate) context: Cx,
     pub(crate) authenticator_data: Vec<u8>,
     pub(crate) client_data: Vec<u8>,
-    pub(crate) public_key: Vec<u8>,
     pub(crate) signature: Vec<u8>,
 }