* specific length.
   *
   * <p>For example, if you need 1024-bit hash codes, you could join two {@link Hashing#sha512} hash
   * functions together: {@code Hashing.concatenating(Hashing.sha512(), Hashing.sha512())}.
   *
   * @since 19.0
   */
  public static HashFunction concatenating(
      HashFunction first, HashFunction second, HashFunction... rest) {

 *       array. This hashing API accepts an arbitrary sequence of byte and multibyte values (via
 *       {@link Hasher}), but this is merely a convenience; these are always translated into raw
 *       byte sequences under the covers.
 *   <li><b>hash code:</b> each hash function always yields hash codes of the same fixed bit length
 *       (given by {@link #bits}). For example, {@link Hashing#sha1} produces a 160-bit number,

        Hashing.md5().bits() + Hashing.md5().bits(),
        Hashing.concatenating(Hashing.md5(), Hashing.md5()).bits());
    assertEquals(
        Hashing.md5().bits() + Hashing.murmur3_32().bits(),
        Hashing.concatenating(Hashing.md5(), Hashing.murmur3_32()).bits());
    assertEquals(
        Hashing.md5().bits() + Hashing.murmur3_32().bits() + Hashing.murmur3_128().bits(),

        Hashing.md5().bits() + Hashing.md5().bits(),
        Hashing.concatenating(Hashing.md5(), Hashing.md5()).bits());
    assertEquals(
        Hashing.md5().bits() + Hashing.murmur3_32().bits(),
        Hashing.concatenating(Hashing.md5(), Hashing.murmur3_32()).bits());
    assertEquals(
        Hashing.md5().bits() + Hashing.murmur3_32().bits() + Hashing.murmur3_128().bits(),

    assertEquals(
        "Hashing.hmacMd5(Key[algorithm=HmacMD5, format=RAW])", Hashing.hmacMd5(MD5_KEY).toString());
    assertEquals(
        "Hashing.hmacMd5(Key[algorithm=HmacMD5, format=RAW])", Hashing.hmacMd5(keyData).toString());

    assertEquals(
        "Hashing.hmacSha1(Key[algorithm=HmacSHA1, format=RAW])",
        Hashing.hmacSha1(SHA1_KEY).toString());
    assertEquals(

    assertEquals(
        "Hashing.hmacMd5(Key[algorithm=HmacMD5, format=RAW])", Hashing.hmacMd5(MD5_KEY).toString());
    assertEquals(
        "Hashing.hmacMd5(Key[algorithm=HmacMD5, format=RAW])", Hashing.hmacMd5(keyData).toString());

    assertEquals(
        "Hashing.hmacSha1(Key[algorithm=HmacSHA1, format=RAW])",
        Hashing.hmacSha1(SHA1_KEY).toString());
    assertEquals(

        }
        if (!bits.get(combinedHash % bitSize)) {
          return false;
        }
      }
      return true;
    }
  },
  /**
   * This strategy uses all 128 bits of {@link Hashing#murmur3_128} when hashing. It looks different
   * from the implementation in MURMUR128_MITZ_32 because we're avoiding the multiplication in the
   * loop and doing a (much simpler) += hash2. We're also changing the index to a positive number by

    }

    if (hashTableKToV.length < minCapacity) {
      int newTableSize = Hashing.closedTableSize(minCapacity, 1.0);
      hashTableKToV = createFilledWithAbsent(newTableSize);
      hashTableVToK = createFilledWithAbsent(newTableSize);

      for (int entryToRehash = 0; entryToRehash < size; entryToRehash++) {
        int keyHash = Hashing.smearedHash(keys[entryToRehash]);
        int keyBucket = bucket(keyHash);

## Password hashing

"Hashing" means converting some content (a password in this case) into a sequence of bytes (just a string) that looks like gibberish.

Whenever you pass exactly the same content (exactly the same password) you get exactly the same gibberish.

But you cannot convert from the gibberish back to the password.

### Why use password hashing

  }

  public void testHashCode_equalsAndSerializable() throws Exception {
    sanityTester().testEqualsAndSerializable();
  }

  public void testRoundTripHashCodeUsingBaseEncoding() {
    HashCode hash1 = Hashing.sha1().hashString("foo", Charsets.US_ASCII);
    HashCode hash2 = HashCode.fromBytes(BaseEncoding.base16().lowerCase().decode(hash1.toString()));
    assertEquals(hash1, hash2);
  }

  public void testObjectHashCode() {