import { ValidationRule, ValidationContext, ValidationSeverity } from '../interfaces';
/**
 * Options for UnicodeSecurityRule
 */
export interface UnicodeSecurityOptions {
    /** Block zero-width characters (default: true) */
    blockZeroWidth?: boolean;
    /** Block bidirectional control characters (default: true) */
    blockBidi?: boolean;
    /** Block homoglyph characters in identifiers (default: true) */
    blockHomoglyphs?: boolean;
    /** Block invisible/formatting characters (default: true) */
    blockInvisible?: boolean;
    /** Allow specific Unicode characters (whitelist) */
    allowedCharacters?: string[];
    /** Check string literals for Unicode attacks (default: false) */
    checkStringLiterals?: boolean;
    /** Check template literals for Unicode attacks (default: false) */
    checkTemplateLiterals?: boolean;
    /** Check comments for Unicode attacks (default: true for bidi) */
    checkComments?: boolean;
}
/**
 * Rule that detects and blocks Unicode-based attacks
 *
 * This rule protects against:
 * 1. **Trojan Source attacks** - Bidirectional text control characters
 *    that can visually reorder code to hide malicious logic
 * 2. **Homoglyph attacks** - Characters that look like ASCII but are
 *    different (e.g., Cyrillic 'а' vs Latin 'a')
 * 3. **Zero-width injection** - Invisible characters that can hide
 *    in identifiers or strings
 * 4. **Invisible character attacks** - Formatting characters that
 *    don't render but affect string comparisons
 *
 * @example
 * ```typescript
 * // Trojan Source attack - bidi override makes code look different
 * // Code with U+202E (RLO) visually reverses text direction
 *
 * // Homoglyph attack - Cyrillic U+0430 looks like Latin 'a'
 * // const \u0430dmin = true;  // looks like "admin" but is different
 *
 * // Zero-width injection
 * // const x = "hello\u200Bworld";  // Invisible ZWSP in string
 * ```
 */
export declare class UnicodeSecurityRule implements ValidationRule {
    readonly name = "unicode-security";
    readonly description = "Detects Unicode-based security attacks (homoglyphs, bidi, zero-width)";
    readonly defaultSeverity = ValidationSeverity.ERROR;
    readonly enabledByDefault = true;
    private options;
    private allHomoglyphs;
    constructor(options?: UnicodeSecurityOptions);
    validate(context: ValidationContext): void;
    /**
     * Check source code for bidirectional control characters
     * These can appear in comments and are not visible in the AST
     */
    private checkSourceForBidi;
    /**
     * Check a string for Unicode security issues
     */
    private checkString;
    /**
     * Detect all Unicode violations in a string
     */
    private detectViolations;
    /**
     * Convert a character position to line and column numbers
     */
    private getLineAndColumn;
}
/**
 * Helper function to normalize a string by replacing homoglyphs with ASCII equivalents
 * Useful for comparison or logging purposes
 */
export declare function normalizeHomoglyphs(str: string): string;
/**
 * Helper function to detect if a string contains any Unicode security issues
 * Returns true if the string is safe, false if it contains suspicious characters
 */
export declare function isUnicodeSafe(str: string): boolean;