/**
 * Signature Tempering Utility
 *
 * Security testing tool to intentionally corrupt signatures so tests can prove
 * the on-chain validator rejects invalid signatures.
 *
 * WARNING: TESTING ONLY. `maybeTemperSignature` refuses to corrupt signatures
 * when `NODE_ENV === "production"`, regardless of the config flag. The previous
 * behavior (any caller could flip `temperSignaturesTest: true` to corrupt every
 * signature) was an audit finding — the function is now defense-in-depth.
 */
/**
 * Tempers a signature by modifying the 3rd character with a random valid hex character
 * that differs from the original.
 *
 * @param signature - Original signature (0x prefixed hex string)
 * @returns Tempered signature with 3rd character modified
 *
 * @example
 * const original = "0x1234567890abcdef...";
 * const tempered = temperSignature(original);
 * // tempered = "0x12X4567890abcdef..." where X != 3
 */
export declare function temperSignature(signature: string): string;
/**
 * Conditionally tempers a signature based on config flag.
 * Returns original signature if tempering is disabled.
 *
 * @param signature - Original signature
 * @param shouldTemper - Whether to apply tempering
 * @param operationName - Name of operation for logging (optional)
 * @returns Original or tempered signature
 */
export declare function maybeTemperSignature(signature: string, shouldTemper: boolean | undefined, operationName?: string): string;
