/**
 * Ed25519 Signature Operations
 *
 * Provides key generation, signing, and verification using Ed25519.
 * Uses tweetnacl for cryptographic operations.
 *
 * @see docs/rfc/proof-bundle-v1.md#5-signature-procedure
 */
/**
 * Ed25519 key pair
 */
export interface KeyPair {
    publicKey: Uint8Array;
    secretKey: Uint8Array;
}
/**
 * Key storage paths
 */
export interface KeyPaths {
    privateKey: string;
    publicKey: string;
}
/**
 * Get default key storage directory
 */
export declare function getKeyDirectory(): string;
/**
 * Get key file paths
 */
export declare function getKeyPaths(): KeyPaths;
/**
 * Generate new Ed25519 key pair
 *
 * @returns Key pair (public + secret)
 */
export declare function generateKeys(): KeyPair;
/**
 * Save key pair to disk
 *
 * @param keyPair - Key pair to save
 * @param paths - Optional custom paths (defaults to ~/.qa360/keys/)
 */
export declare function saveKeys(keyPair: KeyPair, paths?: KeyPaths): Promise<void>;
/**
 * Load key pair from disk
 *
 * @param paths - Optional custom paths (defaults to ~/.qa360/keys/)
 * @returns Key pair
 * @throws Error if keys don't exist
 */
export declare function loadKeys(paths?: KeyPaths): Promise<KeyPair>;
/**
 * Check if keys exist
 *
 * @param paths - Optional custom paths
 * @returns true if both keys exist
 */
export declare function keysExist(paths?: KeyPaths): Promise<boolean>;
/**
 * Initialize keys (generate if they don't exist)
 *
 * @param paths - Optional custom paths
 * @returns Key pair (existing or newly generated)
 */
export declare function initializeKeys(paths?: KeyPaths): Promise<KeyPair>;
/**
 * Ensure proof keys exist (generate if missing)
 *
 * @param homeDir - QA360 home directory
 * @returns Result with creation status, paths, and optional keys
 */
export declare function ensureProofKeys(homeDir: string): Promise<{
    created: boolean;
    paths: {
        pub: string;
        priv: string;
    };
    keys?: KeyPair;
}>;
/**
 * Compute SHA-256 hash of data
 *
 * @param data - Data to hash (UTF-8 string)
 * @returns SHA-256 hash as Buffer
 */
export declare function sha256(data: string): Buffer;
/**
 * Sign data with Ed25519
 *
 * @param data - Data to sign (canonical JSON string)
 * @param secretKey - Ed25519 secret key (64 bytes)
 * @returns Base64-encoded signature (88 chars)
 */
export declare function sign(data: string, secretKey: Uint8Array): string;
/**
 * Verify Ed25519 signature
 *
 * @param data - Original data (canonical JSON string)
 * @param signatureB64 - Base64-encoded signature
 * @param publicKey - Ed25519 public key (32 bytes)
 * @returns true if signature is valid
 */
export declare function verify(data: string, signatureB64: string, publicKey: Uint8Array): boolean;
/**
 * Sign and verify roundtrip test
 *
 * @param data - Test data
 * @param keyPair - Key pair to test
 * @returns true if roundtrip succeeds
 */
export declare function testRoundtrip(data: string, keyPair: KeyPair): boolean;