bcomnes / xor-stream

Take two readable streams and return a readable stream with the xor of the two input chunks

xor-stream

Take two readable streams and return a readable stream that contains chunkA XOR chunkB

npm install xor-stream

This can be used to calculate pairty blobs of the contents of two streams.

Example

var xorStream = require('xor-stream')
var streamEqual = require('stream-equal')
var rs = require('fs').createReadStream

var pairity = xorStream(rs('pathA'), rs('pathB'))
var contentOfA = xorStream(pairity, rs('pathB'))

streamEqual(rs('pathA'), contentOfA, function (err, equal) {
  console.log(equal) // true if file A is larger than File B
})

Right now, if one file is longer than the other, xor-stream pads the shorter stream with 0 bytes, so recovering shorter files from the longer file XOR pairty will have extra byte padding at the end.

Background

• https://nodejs.org/api/buffer.html#buffer_new_buffer_str_encoding
• https://github.com/feross/safe-buffer
• https://www.npmjs.com/package/through2
• http://www.snapraid.it/compare
• https://en.wikipedia.org/wiki/Parchive
• ((chunkA) || 0byte) xor (chunkB || 0byte )
• https://github.com/mafintosh/stream-iterate
• https://github.com/mafintosh/sorted-union-stream