/**
 * Cryptographic hash utilities using Node.js crypto (Bun compatible)
 *
 * Security considerations:
 * - Uses native SHAKE256 XOF when available (Node.js 12+)
 * - Falls back to counter-mode SHA3-256 construction
 * - Intermediate buffers are zeroized
 * - Domain separation uses length-prefixed encoding to prevent collisions
 */
/**
 * SHAKE256 extendable output function (XOF)
 * Uses native SHAKE256 when available, falls back to counter-mode SHA3-256
 *
 * @param input - Input data to hash
 * @param outputLength - Desired length of output in bytes
 * @returns Hash output of specified length
 */
export declare function shake256(input: Uint8Array, outputLength: number): Uint8Array;
/**
 * Fallback SHAKE256 implementation using counter-mode SHA3-256
 * Only used when native SHAKE256 is unavailable
 *
 * SECURITY WARNING: This fallback construction:
 * - Is not a standard XOF and lacks formal security proofs
 * - May not provide the full security margin of native SHAKE256
 * - Should only be used for compatibility; prefer native SHAKE256
 *
 * For high-security applications, ensure native SHAKE256 is available.
 *
 * @param input - Input data to hash
 * @param outputLength - Desired length of output in bytes
 * @returns Hash output of specified length
 */
export declare function shake256Fallback(input: Uint8Array, outputLength: number): Uint8Array;
/**
 * SHA3-256 hash
 *
 * @param input - Input data to hash
 * @returns 32-byte hash output
 */
export declare function sha3_256(input: Uint8Array): Uint8Array;
/**
 * Hash multiple inputs with length-prefixed encoding
 * Uses length prefixes to prevent collision attacks from concatenation
 * e.g., H("AB", "C") != H("A", "BC")
 *
 * Format: [len1:4][data1][len2:4][data2]...
 *
 * @param inputs - Variable number of Uint8Array inputs
 * @returns Hash of concatenated inputs
 */
export declare function hashConcat(...inputs: Uint8Array[]): Uint8Array;
/**
 * Domain-separated hash with length-prefixed encoding
 * Format: [1-byte domain length][domain bytes][input bytes]
 *
 * @param domain - Domain string (max 255 bytes)
 * @param input - Input data
 * @returns Hash output
 */
export declare function hashWithDomain(domain: string, input: Uint8Array): Uint8Array;
/**
 * Query whether native SHAKE256 is available in this runtime.
 * Useful for application code that wants to enforce native-XOF availability
 * (recommended for production deployments). Returns true if native SHAKE256
 * is available, false otherwise.
 */
export declare function isNativeShake256Available(): boolean;
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