Cuckoo

There are many variations of the Cuckoo Cycle algorithm - here only the ones that are needed are implemented. Cuckatoo32 probably should be implemented as well for Grin. The differences for each variation are as follows (along with header generation):

• Aeternity uses Cuckoo29 with a legacy version of the sipnode hasher -
  the only functional difference is the ROTL on the hasher.XorLanes() response (current versions of cuckoo do not do this)

func generateHeader(hash []byte, nonce uint64) []byte {
	nonceBytes := make([]byte, 8)
	binary.LittleEndian.PutUint64(nonceBytes, nonce)
	hashEncoded := []byte(base64.StdEncoding.EncodeToString(hash))
	nonceEncoded := []byte(base64.StdEncoding.EncodeToString(nonceBytes))
	header := append(hashEncoded, append(nonceEncoded, make([]byte, 24)...)...)

	return header
}

• Cortex uses Cuckaroo30 with a single difference - the sipblock hasher uses siphash48 instead of siphash24.

func generateHeader(hash []byte, nonce uint64) []byte {
	nonceBytes := make([]byte, 8)
	binary.LittleEndian.PutUint64(nonceBytes, nonce)
	header := append(hash, nonceBytes...)

	return header
}