cksum
JavaScript implementation of cksum
usage
var cksum = require('cksum')
cksum(new Buffer('testwhatever')) // returns buffer (big endian) with 32bit checksum
cksum('test') // converts 'test' to buffer and then calcuates the checksum
readStream.pipe(cksum.stream(function (sum, length) {
console.log(sum.readUInt32BE(0), len)
}))