function.bits(),
            function);
      }
    }

    @Override
    HashCode makeHash(Hasher[] hashers) {
      byte[] bytes = new byte[bits() / 8];
      int i = 0;
      for (Hasher hasher : hashers) {
        HashCode newHash = hasher.hash();
        i += newHash.writeBytesTo(bytes, i, newHash.bits() / 8);
      }
      return HashCode.fromBytesNoCopy(bytes);
    }

}

// Borrow a single hasher.
func (h *HashBorrower) Borrow() hash.Hash {
	hasher := h.pool.Get()
	h.borrowed = append(h.borrowed, hasher)
	hasher.Reset()
	return hasher
}

// ReturnAll will return all borrowed hashes.
func (h *HashBorrower) ReturnAll() {
	for _, hasher := range h.borrowed {
		h.pool.Put(hasher)
	}
	h.borrowed = nil
}

// StandardClaims are basically standard claims with "accessKey"

    Random random2 = new Random(2L);
    Hasher hasher1 = hashFunction.newHasher();
    Hasher hasher2 = hashFunction.newHasher();
    for (int i = 0; i < numActions; i++) {
      RandomHasherAction.pickAtRandom(random1).performAction(random1, ImmutableSet.of(hasher1));
      RandomHasherAction.pickAtRandom(random2).performAction(random2, ImmutableSet.of(hasher2));
    }

    Assert.assertEquals(expected1, hasher1.hash());

    hasher.putShort((short) 0x0201);
    hasher.assertBytes(new byte[] {1, 2});
  }

  public void testInt() {
    TestHasher hasher = new TestHasher();
    hasher.putInt(0x04030201);
    hasher.assertBytes(new byte[] {1, 2, 3, 4});
  }

  public void testLong() {
    TestHasher hasher = new TestHasher();
    hasher.putLong(0x0807060504030201L);
    hasher.assertBytes(new byte[] {1, 2, 3, 4, 5, 6, 7, 8});

If your database is stolen, the thief won't have your users' plaintext passwords, only the hashes.

So, the thief won't be able to try to use that password in another system (as many users use the same password everywhere, this would be dangerous).

## Install `pwdlib` { #install-pwdlib }

pwdlib is a great Python package to handle password hashes.

It supports many secure hashing algorithms and utilities to work with them.

  protected void update(byte[] b) {
    update(b, 0, b.length);
  }

  /** Updates this hasher with {@code len} bytes starting at {@code off} in the given buffer. */
  protected void update(byte[] b, int off, int len) {
    for (int i = off; i < off + len; i++) {
      update(b[i]);
    }
  }

  /** Updates this hasher with bytes from the given buffer. */
  protected void update(ByteBuffer b) {

    assertThrows(IllegalStateException.class, () -> hasher.putInt(42));
  }

  public void testHashTwice() {
    Hasher hasher = sha512().newHasher();

    assertThat(
            hasher
                .putString("The quick brown fox jumps over the lazy dog", UTF_8)
                .hash()
                .toString())

    assertThrows(IllegalStateException.class, () -> hasher.putInt(42));
  }

  public void testHashTwice() {
    Hasher hasher = sha512().newHasher();

    assertThat(
            hasher
                .putString("The quick brown fox jumps over the lazy dog", UTF_8)
                .hash()
                .toString())

 */
@NullUnmarked
public class HashingOutputStreamTest extends TestCase {
  private Hasher hasher;
  private HashFunction hashFunction;
  private final ByteArrayOutputStream buffer = new ByteArrayOutputStream();

  @SuppressWarnings("DoNotMock")
  @Override
  protected void setUp() throws Exception {
    super.setUp();
    hasher = mock(Hasher.class);
    hashFunction = mock(HashFunction.class);

    }

    @Override
    public Hasher putByte(byte b) {
      ensureCapacity(Byte.BYTES);
      buffer.put(b);
      return this;
    }

    @Override
    public Hasher putBytes(byte[] bytes, int off, int len) {
      ensureCapacity(len);
      buffer.put(bytes, off, len);
      return this;
    }

    @Override
    public Hasher putBytes(ByteBuffer bytes) {