@AccessesPartialKey
  static AesSivKey newKey(AesSivParameters parameters, @Nullable Integer idRequirement)
      throws GeneralSecurityException {
    validateParameters(parameters);
    return AesSivKey.builder()
        .setParameters(parameters)
        .setIdRequirement(idRequirement)
        .setKeyBytes(SecretBytes.randomBytes(parameters.getKeySizeBytes()))
        .build();
  }
This key manager generates new {@code AesSivKey} keys and produces new instances of {@code
AesSiv}.
java_src/src/main/java/com/google/crypto/tink/daead/AesSivKeyManager.java