virto-signer/dist/esm/signer.js

A signer for constructing a signed extrinsic using Pass-provided authenticators

import { Bytes, Option, Struct, u64, u8 } from "scale-ts";
import blake2b from "blake2b";
import { getTypedMetadata } from "./utils.js";
import { mergeUint8 } from "@polkadot-api/utils";
const UncheckedExtrinsic = Struct({
    version: u8,
    prelude: Struct({
        extensionVersion: u8,
        extensions: Bytes(),
    }),
    call: Bytes(),
});
const PassAuthenticate = Option(Struct({
    deviceId: Bytes(),
    credentials: Bytes(),
}));
const EXTRINSIC_V5 = 0b0000_0101;
const EXTRINSIC_FORMAT_GENERAL = 0b0100_0000;
export class PassSigner {
    authenticator;
    publicKey;
    constructor(authenticator) {
        this.authenticator = authenticator;
        this.publicKey = blake2b(32)
            .update(mergeUint8(authenticator.hashedUserId, authenticator.hashedUserId))
            .digest();
    }
    async signTx(call, signedExtensions, encodedMetadata, atBlockNumber, hasher) {
        const metadata = getTypedMetadata(encodedMetadata);
        const context = u64.enc(BigInt(atBlockNumber));
        const hasherFn = hasher ?? ((data) => blake2b(32).update(data).digest());
        const extensions = await Promise.all(metadata.extrinsic.signedExtensions.map(async ({ identifier }) => {
            const signedExtension = signedExtensions[identifier];
            if (!signedExtension)
                throw new Error(`Missing ${identifier} signed extension`);
            if (identifier === "PassAuthenticate") {
                signedExtensions[identifier].value = PassAuthenticate.enc({
                    deviceId: this.authenticator.deviceId,
                    credentials: await this.authenticator.credentials(hasherFn(context)),
                });
            }
            return signedExtension.value;
        }));
        return UncheckedExtrinsic.enc({
            version: EXTRINSIC_V5 | EXTRINSIC_FORMAT_GENERAL,
            prelude: {
                extensionVersion: 0,
                extensions: mergeUint8(...extensions),
            },
            call,
        });
    }
    async signBytes(_) {
        throw new Error("signBytes not implemented");
    }
}