Hash Class

Overview

The Hash class provides basic hashing functionality.

Methods

Hash.crc32

Calculates a crc32 value

Hash.md5

Calculates an md5 hash value

Hash.md5sum

Calculates an md5sum of a file

Example

// Hash computes MD5 digests and CRC32 checksums.  Every method is
// static; there is nothing to construct.  md5() and crc32() each take a
// String or a MemoryBuffer -- a String is hashed as its UTF-8 bytes.

const text = "The quick brown fox jumps over the lazy dog";

let output = `md5:    ${Hash.md5(text)}\n`;
output += `crc32:  ${Hash.crc32(text)}\n\n`;

// -- a file --

// (Environment.getTempPath() has no trailing separator)
const path = `${Environment.getTempPath()}/hash_example.txt`;

// write() rather than writeLine(), so the file holds exactly these bytes
const writer = File.createText(path);
writer.write(text);
writer.close();

// md5sum() hashes the bytes on disk, so for plain ASCII text it agrees
// with md5() of the string that was written
output += `md5sum:        ${Hash.md5sum(path)}\n`;
output += `matches md5(): ${Hash.md5sum(path) === Hash.md5(text)}\n`;

// a missing file gives null -- there is no exception to catch
const missing = Hash.md5sum(`${path}.nope`);
output += `missing file:  ${missing}\n\n`;

// -- binary data --

// a MemoryBuffer is hashed as raw bytes, with no text conversion; this
// is the form for images, downloads and anything else that is not text
const buf = new MemoryBuffer(256);
for (let i = 0; i < 256; ++i) {
    buf[i] = i;
}

output += `buffer md5:    ${Hash.md5(buf)}\n`;
output += `buffer crc32:  ${Hash.crc32(buf)}`;

alert(output);