File Integrity Verifier

Build a file integrity verification system that computes cryptographic checksums for files and verifies them later.

Requirements

Create a module that provides two main functions:

1. computeChecksum(filePath): Reads a file in chunks and computes its SHA-256 hash

   • Read the file in 8KB chunks to efficiently handle large files
   • Return the hex-encoded hash string
   • Handle file reading errors appropriately

2. verifyChecksum(filePath, expectedHash): Verifies if a file matches an expected hash

   • Compute the current file hash
   • Compare with the provided expected hash
   • Return true if they match, false otherwise

The implementation should handle files of any size efficiently by processing them in chunks rather than loading them entirely into memory.

Dependencies { .dependencies }

@stablelib/sha256 { .dependency }

Provides SHA-256 cryptographic hashing functionality.

@stablelib/hex { .dependency }

Provides hexadecimal encoding/decoding utilities.

Test Cases

• Computing checksum of a small file (< 1KB) returns correct SHA-256 hash in hex format @test
• Computing checksum of a large file (> 100KB) processed in chunks returns correct hash @test
• Verifying a file against correct checksum returns true @test
• Verifying a file against incorrect checksum returns false @test

Implementation

@generates

API

/**
 * Computes the SHA-256 checksum of a file by reading it in chunks.
 *
 * @param filePath - Path to the file to hash
 * @returns Promise that resolves to hex-encoded SHA-256 hash
 * @throws Error if file cannot be read
 */
export function computeChecksum(filePath: string): Promise<string>;

/**
 * Verifies if a file matches an expected SHA-256 checksum.
 *
 * @param filePath - Path to the file to verify
 * @param expectedHash - Expected hex-encoded SHA-256 hash
 * @returns Promise that resolves to true if hash matches, false otherwise
 * @throws Error if file cannot be read
 */
export function verifyChecksum(filePath: string, expectedHash: string): Promise<boolean>;