0x20, 0x20, 0x20, 0x20, 0x20, 0x20, 0x20, 0x20,
	0x20, 0x20, 0x20, 0x20, 0x20, 0x20, 0x20, 0x20,
}

// signedMessage returns the pre-hashed (if necessary) message to be signed by
// certificate keys in TLS 1.3. See RFC 8446, Section 4.4.3.
func signedMessage(sigHash crypto.Hash, context string, transcript hash.Hash) []byte {
	if sigHash == directSigning {
		b := &bytes.Buffer{}
		b.Write(signaturePadding)
		io.WriteString(b, context)

	// https://github.com/dchest/siphash#usage
	k0, k1 := binary.LittleEndian.Uint64(id[0:8]), binary.LittleEndian.Uint64(id[8:16])
	sum64 := siphash.Hash(k0, k1, []byte(key))
	return int(sum64 % uint64(cardinality))
}

// hashOrder - hashes input key to return consistent
// hashed integer slice. Returned integer order is salted
// with an input key. This results in consistent order.

/**
 * This is an implementation of the HMACT64 keyed hashing algorithm.
 * HMACT64 is defined by Luke Leighton as a modified HMAC-MD5 (RFC 2104)
 * in which the key is truncated at 64 bytes (rather than being hashed
 * via MD5).
 */ 
public class HMACT64 extends MessageDigest implements Cloneable {

    private static final int BLOCK_LENGTH = 64;

    private static final byte IPAD = (byte) 0x36;

/**
 * This is an implementation of the HMACT64 keyed hashing algorithm.
 * HMACT64 is defined by Luke Leighton as a modified HMAC-MD5 (RFC 2104)
 * in which the key is truncated at 64 bytes (rather than being hashed
 * via MD5).
 */
class HMACT64 extends MessageDigest implements Cloneable {

    private static final int BLOCK_LENGTH = 64;

    private static final byte IPAD = (byte) 0x36;

      new RegularImmutableSet<>(EMPTY_ARRAY, 0, EMPTY_ARRAY, 0);

  private final transient Object[] elements;
  private final transient int hashCode;
  // the same values as `elements` in hashed positions (plus nulls)
  @VisibleForTesting final transient @Nullable Object[] table;
  // 'and' with an int to get a valid table index.
  private final transient int mask;

  // The first `size` elements are non-null.
  @VisibleForTesting final transient @Nullable Object[] elements;
  private final transient int hashCode;
  // the same values as `elements` in hashed positions (plus nulls)
  @VisibleForTesting final transient @Nullable Object[] table;
  // 'and' with an int to get a valid table index.
  private final transient int mask;
  private final transient int size;

)

// xxhash64 is the state of a xxHash-64 checksum.
type xxhash64 struct {
	len uint64    // total length hashed
	v   [4]uint64 // accumulators
	buf [32]byte  // buffer
	cnt int       // number of bytes in buffer
}

// reset discards the current state and prepares to compute a new hash.
// We assume a seed of 0 since that is what zstd uses.
func (xh *xxhash64) reset() {
	xh.len = 0

   *
   * Per-thread hash codes are initialized to random values.
   * Contention and/or table collisions are indicated by failed
   * CASes when performing an update operation (see method
   * retryUpdate). Upon a collision, if the table size is less than
   * the capacity, it is doubled in size unless some other thread
   * holds the lock. If a hashed slot is empty, and lock is

   *
   * Per-thread hash codes are initialized to random values.
   * Contention and/or table collisions are indicated by failed
   * CASes when performing an update operation (see method
   * retryUpdate). Upon a collision, if the table size is less than
   * the capacity, it is doubled in size unless some other thread
   * holds the lock. If a hashed slot is empty, and lock is

   *
   * Per-thread hash codes are initialized to random values.
   * Contention and/or table collisions are indicated by failed
   * CASes when performing an update operation (see method
   * retryUpdate). Upon a collision, if the table size is less than
   * the capacity, it is doubled in size unless some other thread
   * holds the lock. If a hashed slot is empty, and lock is