@aptos-labs/ts-sdk/src/core/crypto/privateKey.ts

Aptos TypeScript SDK

import { HexInput, PrivateKeyVariants } from "../../types/index.js";
import { Hex } from "../hex.js";
import { PublicKey } from "./publicKey.js";
import { Signature } from "./signature.js";
import { warnIfDevelopment } from "../../utils/helpers.js";

/**
 * Represents a private key used for signing messages and deriving the associated public key.
 * @group Implementation
 * @category Serialization
 */
export interface PrivateKey {
  /**
   * Sign the given message with the private key to create a signature.
   * @param message - The message to be signed, provided in HexInput format.
   * @returns A Signature object representing the signed message.
   * @group Implementation
   * @category Serialization
   */
  sign(message: HexInput): Signature;

  /**
   * Derive the public key associated with the private key.
   * @group Implementation
   * @category Serialization
   */
  publicKey(): PublicKey;

  /**
   * Get the private key in bytes (Uint8Array).
   * @group Implementation
   * @category Serialization
   */
  toUint8Array(): Uint8Array;
}

export class PrivateKey {
  /**
   * The AIP-80 compliant prefixes for each private key type. Append this to a private key's hex representation
   * to get an AIP-80 compliant string.
   *
   * [Read about AIP-80](https://github.com/aptos-foundation/AIPs/blob/main/aips/aip-80.md)
   */
  public static readonly AIP80_PREFIXES = {
    [PrivateKeyVariants.Ed25519]: "ed25519-priv-",
    [PrivateKeyVariants.Secp256k1]: "secp256k1-priv-",
    [PrivateKeyVariants.Secp256r1]: "secp256r1-priv-",
  };

  /**
   * Format a HexInput to an AIP-80 compliant string.
   *
   * [Read about AIP-80](https://github.com/aptos-foundation/AIPs/blob/main/aips/aip-80.md)
   *
   * @param privateKey - The HexString or Uint8Array format of the private key.
   * @param privateKeyType - The private key type
   */
  public static formatPrivateKey(privateKey: HexInput, type: PrivateKeyVariants): string {
    const aip80Prefix = PrivateKey.AIP80_PREFIXES[type];

    // Remove the prefix if it exists
    let formattedPrivateKey = privateKey;
    if (typeof formattedPrivateKey === "string" && formattedPrivateKey.startsWith(aip80Prefix)) {
      formattedPrivateKey = formattedPrivateKey.split("-")[2];
    }

    return `${aip80Prefix}${Hex.fromHexInput(formattedPrivateKey).toString()}`;
  }

  /**
   * Parse a HexInput that may be a HexString, Uint8Array, or a AIP-80 compliant string to a Hex instance.
   *
   * [Read about AIP-80](https://github.com/aptos-foundation/AIPs/blob/main/aips/aip-80.md)
   *
   * @param value - A HexString, Uint8Array, or a AIP-80 compliant string.
   * @param privateKeyType - The private key type
   * @param strict - If true, the value MUST be compliant with AIP-80.
   */
  public static parseHexInput(value: HexInput, type: PrivateKeyVariants, strict?: boolean): Hex {
    let data: Hex;

    const aip80Prefix = PrivateKey.AIP80_PREFIXES[type];
    if (typeof value === "string") {
      if (!strict && !value.startsWith(aip80Prefix)) {
        // HexString input
        data = Hex.fromHexInput(value);
        // If the strictness is false, the user has opted into non-AIP-80 compliant private keys.
        if (strict !== false) {
          warnIfDevelopment(
            "[Aptos SDK] It is recommended that private keys are AIP-80 compliant (https://github.com/aptos-foundation/AIPs/blob/main/aips/aip-80.md). You can fix the private key by formatting it with `PrivateKey.formatPrivateKey(privateKey: string, type: 'ed25519' | 'secp256k1'): string`.",
          );
        }
      } else if (value.startsWith(aip80Prefix)) {
        // AIP-80 Compliant String input
        data = Hex.fromHexString(value.split("-")[2]);
      } else {
        if (strict) {
          // The value does not start with the AIP-80 prefix, and strict is true.
          throw new Error("Invalid HexString input while parsing private key. Must AIP-80 compliant string.");
        }

        // This condition should never be reached.
        throw new Error("Invalid HexString input while parsing private key.");
      }
    } else {
      // The value is an Uint8Array
      data = Hex.fromHexInput(value);
    }

    return data;
  }
}