private static Map<String, Parameters> namedParameters() throws GeneralSecurityException {
    Map<String, Parameters> result = new HashMap<>();

    result.put(
        "AES128_GCM_SIV",
        AesGcmSivParameters.builder()
            .setKeySizeBytes(16)
            .setVariant(AesGcmSivParameters.Variant.TINK)
            .build());
    result.put(
        "AES128_GCM_SIV_RAW",
        AesGcmSivParameters.builder()
            .setKeySizeBytes(16)
            .setVariant(AesGcmSivParameters.Variant.NO_PREFIX)
            .build());
    result.put(
        "AES256_GCM_SIV",
        AesGcmSivParameters.builder()
            .setKeySizeBytes(32)
            .setVariant(AesGcmSivParameters.Variant.TINK)
            .build());
    result.put(
        "AES256_GCM_SIV_RAW",
        AesGcmSivParameters.builder()
            .setKeySizeBytes(32)
            .setVariant(AesGcmSivParameters.Variant.NO_PREFIX)
            .build());

    return Collections.unmodifiableMap(result);
  }
This key manager generates new {@code AesGcmSivKey} keys and produces new instances of {@code
AesGcmSiv}.
java_src/src/main/java/com/google/crypto/tink/aead/AesGcmSivKeyManager.java