/**
 * Cryptographic utilities for security-sensitive operations
 *
 * These utilities are designed to prevent timing attacks and other
 * side-channel vulnerabilities in authentication and validation code.
 */
/**
 * Performs a constant-time comparison of two strings.
 *
 * This function is designed to prevent timing attacks where an attacker
 * could measure response times to determine how many characters of a
 * secret value they have guessed correctly.
 *
 * The comparison always takes the same amount of time regardless of:
 * - How many characters match
 * - Where the first difference occurs
 * - The length difference between strings
 *
 * @param a - First string to compare
 * @param b - Second string to compare
 * @returns true if the strings are equal, false otherwise
 *
 * @example
 * ```typescript
 * // Use for token validation
 * const isValid = constantTimeCompare(userToken, storedToken)
 *
 * // Use for API key validation
 * const isValidKey = constantTimeCompare(providedKey, expectedKey)
 * ```
 */
export declare function constantTimeCompare(a: string, b: string): boolean;
/**
 * Performs a constant-time comparison of two Uint8Arrays.
 *
 * Similar to constantTimeCompare but for binary data.
 *
 * @param a - First buffer to compare
 * @param b - Second buffer to compare
 * @returns true if the buffers are equal, false otherwise
 */
export declare function constantTimeCompareBuffers(a: Uint8Array, b: Uint8Array): boolean;
/**
 * Generates a cryptographically secure random token.
 *
 * Uses the Web Crypto API for secure random number generation,
 * which is available in both browser and Cloudflare Workers environments.
 *
 * @param length - The number of random bytes (output will be 2x this in hex)
 * @returns A hex-encoded random string
 *
 * @example
 * ```typescript
 * const sessionToken = generateSecureToken(32) // 64 hex characters
 * const apiKey = generateSecureToken(16) // 32 hex characters
 * ```
 */
export declare function generateSecureToken(length?: number): string;
/**
 * Generates a URL-safe base64-encoded secure random token.
 *
 * @param length - The number of random bytes
 * @returns A URL-safe base64-encoded random string
 *
 * @example
 * ```typescript
 * const token = generateSecureTokenBase64(32)
 * ```
 */
export declare function generateSecureTokenBase64(length?: number): string;
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