/**
 * Optimized cryptographic utilities for MCP-I with lazy loading
 * Implements Ed25519 signing and verification with caching
 */
/**
 * Precomputed key pair with cached base64 strings
 */
export interface PrecomputedKeyPair {
    publicKey: string;
    privateKey: string;
    publicKeyBytes?: Uint8Array;
    privateKeyBytes?: Uint8Array;
}
/**
 * Generate a new Ed25519 key pair with precomputed values
 */
export declare function generateKeyPair(): Promise<PrecomputedKeyPair>;
/**
 * Sign a message with Ed25519 (with caching)
 */
export declare function sign(message: string | Buffer, privateKeyBase64: string): Promise<string>;
/**
 * Verify an Ed25519 signature
 */
export declare function verify(message: string | Buffer, signatureBase64: string, publicKeyBase64: string): Promise<boolean>;
/**
 * Generate a cryptographically secure nonce
 */
export declare function generateNonce(length?: number): Promise<string>;
export declare function generateNonceSync(length?: number): string;
/**
 * Constant-time string comparison to prevent timing attacks
 */
export declare function constantTimeEqual(a: string, b: string): boolean;
/**
 * Convert Ed25519 public key to did:key format
 */
export declare function publicKeyToDid(publicKeyBase64: string): string;
/**
 * Encrypt data using AES-256-GCM (for key storage)
 */
export declare function encrypt(data: string, password: string): Promise<string>;
/**
 * Decrypt data using AES-256-GCM
 */
export declare function decrypt(encryptedData: string, password: string): Promise<string>;
/**
 * Clear signature cache (useful for testing or memory management)
 */
export declare function clearCache(): void;
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