passkey signer rough in

packages/signers/src/signers/passkey-signer.ts

@@ -0,0 +1,97 @@
+import { DirectSignResponse, makeSignBytes } from "@cosmjs/proto-signing";
+import { SignDoc } from "cosmjs-types/cosmos/tx/v1beta1/tx";
+import { AAccountData, AASigner } from "../interfaces/AASigner";
+import { encodeHex, getAuthenticatorIdByAuthenticatorIndex } from "./utils";
+import { AAAlgo } from "../interfaces";
+
+/**
+ * This class is an implementation of the AASigner interface using WebAuthn.
+ * This class is designed to be used with WebAuthn authenticators for signing transactions.
+ * It ensures that the signer address is replaced with a valid wallet address
+ * (as to the abstract account address) before signing the transaction.
+ *
+ * Note: instance variable abstractAccount must be set before any signing.
+ * @abstractAccount the abstract account address of the signer
+ * @accountAuthenticatorIndex the index of the abstract account authenticator
+ * @implements AASigner
+ */
+export class AAPasskeySigner extends AASigner {
+  accountAuthenticatorIndex: number;
+  indexerUrl: string;
+
+  constructor(
+    abstractAccount: string,
+    accountAuthenticatorIndex: number,
+    indexerUrl?: string,
+  ) {
+    super(abstractAccount);
+    this.accountAuthenticatorIndex = accountAuthenticatorIndex;
+    this.indexerUrl =
+      indexerUrl || "https://api.subquery.network/sq/burnt-labs/xion-indexer";
+  }
+
+  async signDirect(
+    signerAddress: string,
+    signDoc: SignDoc,
+  ): Promise<DirectSignResponse> {
+    if (!this.abstractAccount) {
+      throw new Error("No abstract account");
+    }
+
+    const signBytes = makeSignBytes(signDoc);
+    const signBytesBuffer = Buffer.from(new Uint8Array(signBytes));
+
+    const credential = (await navigator.credentials.get({
+      publicKey: {
+        challenge: signBytesBuffer,
+        allowCredentials: [
+          {
+            id: Buffer.from(this.abstractAccount),
+            type: "public-key",
+          },
+        ],
+        userVerification: "preferred",
+      },
+    })) as PublicKeyCredential;
+
+    if (!credential) {
+      throw new Error("Failed to get WebAuthn credential");
+    }
+
+    const response = credential.response as AuthenticatorAssertionResponse;
+    const byteArray = new Uint8Array(response.signature);
+    const base64String = btoa(String.fromCharCode(...byteArray));
+
+    return {
+      signed: signDoc,
+      signature: {
+        pub_key: {
+          type: "tendermint/PubKeySecp256k1",
+          value: "", // This doesn't matter. All we need is the signature below
+        },
+        signature: base64String,
+      },
+    };
+  }
+
+  async getAccounts(): Promise<readonly AAccountData[]> {
+    if (this.abstractAccount === undefined) {
+      return [];
+    }
+
+    return [
+      {
+        address: this.abstractAccount,
+        algo: "secp256k1", // we don't really care about this
+        pubkey: new Uint8Array(),
+        authenticatorId: await getAuthenticatorIdByAuthenticatorIndex(
+          this.abstractAccount,
+          this.accountAuthenticatorIndex,
+          this.indexerUrl,
+        ),
+        accountAddress: this.abstractAccount,
+        aaalgo: AAAlgo.passkey,
+      },
+    ];
+  }
+}