Calculate & Verify File Hashes Instantly Calculate SHA-1, SHA-256, and SHA-512 hashes of uploaded files for integrity verification.

The tool works by utilizing the Web SubtleCrypto API's crypto.subtle.digest() function to compute hashes for files using algorithms such as SHA-1, SHA-256, and SHA-512. When a file is dropped or selected, it is processed locally without being uploaded anywhere, ensuring security and efficiency. The FileReader.readAsArrayBuffer() method is used in conjunction with crypto.subtle.digest() to read the file contents into an ArrayBuffer, which is then passed to the digest function for hash computation. The resulting hash values are converted from ArrayBuffers to hexadecimal strings using a custom arrayBufferToHex function, which maps each byte of the ArrayBuffer to its corresponding two-digit hexadecimal representation.

This process allows it to calculate and display hashes such as SHA-256, which produces a 64-character hexadecimal string that serves as a unique identifier for the file content. The use of modern browser hardware-accelerated cryptography enables fast computation of these hashes, making the tool suitable for files of varying sizes. Upon calculating the hashes, they are stored in an object alongside other file metadata like filename and size, which is then formatted into a human-readable format using the formatSize function to display sizes in bytes, kilobytes, megabytes, or gigabytes.

In terms of data structures, the tool employs objects and arrays to manage file information and hash values. For instance, an array of objects containing label-value pairs for each hash algorithm is used to map hash types like SHA-1, SHA-256, and SHA-512 to their respective calculated hash strings. This structured approach facilitates easy access and manipulation of the data within the tool's React-based user interface. When verifying a file against a known hash, it uses string comparison to check if the calculated hash matches the provided hash, ignoring case differences for more flexible matching.