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);
    }

    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())

pkg hash/maphash, type ComparableHasher[$0 comparable] struct #70471
pkg hash/maphash, type Hasher[$0 interface{}] interface { Equal, Hash } #70471
pkg hash/maphash, type Hasher[$0 interface{}] interface, Equal($0, $0) bool #70471

@command(b'goreposum', [], _('url'), norepo=True)
def goreposum(ui, url):
  """
  goreposum computes a checksum of all the named state in the remote repo.
  It hashes together all the branch names and hashes
  and then all the bookmark names and hashes.
  Tags are stored in .hgtags files in any of the branches,
  so the branch metadata includes the tags as well.
  """
  h = hashlib.sha256()
  peer = hg.peer(ui, {}, url)

      }
      // We need to ensure that at least 4 bytes have been put into the hasher or else
      // Hasher#hash will throw an ISE.
      int intToPut = random.nextInt();
      for (Hasher hasher : sinksAndControl) {
        hasher.putInt(intToPut);
      }
      for (Sink sink : sinks) {
        HashCode unused = sink.hash();
      }