private static com.google.crypto.tink.proto.AesEaxParams getProtoParams(
      AesEaxParameters parameters) throws GeneralSecurityException {
    /** Current implementation restricts to 16-byte tag value */
    if (parameters.getTagSizeBytes() != 16) {
      throw new GeneralSecurityException(
          String.format(
              "Invalid tag size in bytes %d. Currently Tink only supports aes eax keys with tag"
                  + " size equal to 16 bytes.",
              parameters.getTagSizeBytes()));
    }
    return com.google.crypto.tink.proto.AesEaxParams.newBuilder()
        .setIvSize(parameters.getIvSizeBytes())
        .build();
  }
Parse LEGACY prefix to CRUNCHY, since they act the same for this type of key
java_src/src/main/java/com/google/crypto/tink/aead/internal/AesEaxProtoSerialization.java