NodeJS Crypto custom padding example

nodeJSCustomPadding.js

// Following an answer I posted to my question here: 
// http://stackoverflow.com/questions/21856892/node-crypto-aes256-cbc-0x0-padding-example/21858749#21858749


//I'm expecting a utf8 encoded string
function customPadding(str, blockSize, padder, format) {
  str = new Buffer(str,"utf8").toString(format);
  //1 char = 8bytes
  var bitLength = str.length*8;

  if(bitLength < blockSize) {
    for(i=bitLength;i<blockSize;i+=8) {
      str += padder;
    }
  } else if(bitLength > blockSize) {
    while((str.length*8)%blockSize != 0) {
      str+= padder;
    }
  }
  return new Buffer(str, format).toString("utf8");
}


function encrypt(str) {
  var cipher = crypto.createCipheriv('aes-256-cbc', key, iv).setAutoPadding(false);
  str = customPadding(str, 256, 0x0, "hex"); // magic happens here
  var crypt = cipher.update(str, 'utf8', 'base64');
  crypt += cipher.final("base64");
  return crypt;
}

var t = encrypt("dude");

Hey, thank you for posting this. Im facing an issue where my padding needs to be 0x0001 (KCS7Padding) on the decryption side, would this example work for this?

It should, go ahead and try it.