@Override
  public byte[] decrypt(final byte[] ciphertext, final byte[] associatedData)
      throws GeneralSecurityException {
    try {
      Map<String, Object> content = new HashMap<>();
      content.put("ciphertext", new String(ciphertext));
      content.put("context", Base64.getEncoder().encodeToString(associatedData));
      LogicalResponse resp = vaultApi.write(decPath, content);
      handleResponse(resp);
      return Base64.getDecoder().decode(resp.getData().get("plaintext").getBytes());
    } catch (VaultException e) {
      throw new GeneralSecurityException("decryption failed", e);
    }
  }
A {@link Aead} that forwards encryption/decryption requests to a key in <a
href="https://www.vaultproject.io/">Hashicorp Vault</a>.
java_src/src/main/java/com/google/crypto/tink/integration/hcvault/HcVaultAead.java