@biconomy/abstractjs/dist/_esm/account/utils/toP256Signer.js

SDK for Biconomy integration with support for account abstraction, smart accounts, ERC-4337.

import { p256 } from "@noble/curves/nist.js";
import { hashMessage, hashTypedData, hexToBytes, keccak256, toHex } from "viem";
import { toAccount } from "viem/accounts";
/**
 * Checks if a signer is a P256 signer.
 * @param signer - The signer to check
 * @returns True if the signer is a P256 signer
 */
export const isP256Signer = (signer) => signer?.source === "p256";
/**
 * Creates a P256 (secp256r1) signer that implements viem's LocalAccount interface.
 *
 * The signer produces raw P256 ECDSA signatures (r || s, 64 bytes) suitable for
 * on-chain verification by P256StatelessValidator.
 *
 * The publicKey field contains the uncompressed P256 public key (04 || x || y).
 * To extract coordinates for ownership data:
 *   x = publicKey.slice(4, 68)  // 32 bytes hex
 *   y = publicKey.slice(68, 132) // 32 bytes hex
 *
 * @param privateKey - The P256 private key as a hex string
 * @returns A LocalAccount<'p256'> with P256 signing capabilities
 */
export const toP256Signer = (privateKey) => {
    const privateKeyBytesArray = hexToBytes(privateKey);
    const publicKeyBytes = p256.getPublicKey(privateKeyBytesArray, false); // uncompressed: 04 || x || y
    const publicKey = toHex(publicKeyBytes);
    // Derive an Ethereum-style address from the P256 public key coordinates for type compatibility
    const xyHex = toHex(publicKeyBytes.slice(1)); // x || y (64 bytes)
    const address = keccak256(xyHex).slice(0, 42);
    const signP256 = (hash) => {
        const hashBytesArray = hexToBytes(hash);
        // sign returns compact format (r || s, 64 bytes) by default with prehash: false
        const sigBytes = p256.sign(hashBytesArray, privateKeyBytesArray, {
            prehash: false
        });
        // This has some type issues and it is bypassed but still everything works
        return toHex(sigBytes);
    };
    const account = toAccount({
        address,
        async sign({ hash }) {
            return signP256(hash);
        },
        async signMessage({ message }) {
            const hash = hashMessage(message);
            return signP256(hash);
        },
        async signTransaction(_) {
            throw new Error("signTransaction is not supported for P256 signer");
        },
        async signTypedData(typedData) {
            const hash = hashTypedData(typedData);
            return signP256(hash);
        }
    });
    return {
        ...account,
        signP256,
        publicKey,
        source: "p256"
    };
};
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