package main

import (
    "crypto/aes"
    "crypto/cipher"
)

var bigBlockSize = 512

type BigBlock struct {
    cipher.Block
}

func (*BigBlock) BlockSize() int { return bigBlockSize }

func main() {
    buf := make([]byte, 512)
    aesBlock, _ := aes.NewCipher(buf[:16])
    bigBlock := &BigBlock{aesBlock}
    ctr := cipher.NewCTR(bigBlock, buf)
    ctr.XORKeyStream(buf, buf) // Infinite Loop if bigBlockSize >= 512
}