cryptopals 1.5

gistfile1.txt

package main

import (
  "fmt"
  "encoding/hex"
  "strings"
)

func main () {

  cleartext := []byte(fmt.Sprintf("Burning 'em, if you ain't quick and nimble\nI go crazy when I hear a cymbal"))
  dst := make([]byte, len(cleartext))

  initkey := rotatekey(dst[0])

  for i, c := range cleartext {

    dst[i] = c ^ initkey
    initkey = rotatekey(initkey)

  }
  
  output := make([]byte, hex.EncodedLen(len(dst)))
  hex.Encode(output, dst)

  fmt.Printf("%s\n", output)

}

func rotatekey (inchar byte) byte {
  bytearray := []byte("ICE")
  switch string(inchar) {
    case "I":
      return bytearray[1]
    case "C":
      return bytearray[2]
    case "E":
      return bytearray[0]
    default:
      return bytearray[0]
  }

}