/**
 * Cryptographic utilities for signature verification
 */
import type { HashAlgorithm, Algorithm } from './types.js';
/**
 * Decode base64url to Uint8Array
 */
export declare function base64UrlDecode(str: string): Uint8Array;
/**
 * Encode Uint8Array to base64url
 */
export declare function base64UrlEncode(bytes: Uint8Array): string;
/**
 * Compute hash of payload using specified algorithm
 */
export declare function computeHash(payload: unknown, algorithm: HashAlgorithm): Promise<string>;
/**
 * Extract public key bytes from did:key
 * Format: did:key:z<multibase-encoded-public-key>
 */
export declare function extractPublicKeyFromDidKey(did: string): Uint8Array | null;
export declare function base58Decode(str: string): Uint8Array;
/**
 * Verify Ed25519 signature using Web Crypto API
 */
export declare function verifySignature(algorithm: Algorithm, publicKeyBytes: Uint8Array, signature: Uint8Array, message: Uint8Array): Promise<boolean>;
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