# June 2026 Pre-Release Notes
source: https://developer.mastercard.com/mdes-token-connect/documentation/pre-release-notes/prereleasenote_june2026/index.md

## Release Change Summary {#release-change-summary}

The MDES June 2026 release will support Advanced Encryption Standard (AES) Galois/Counter Mode (GCM) cipher mode for enhanced security. It will be supported in addition to the existing Cipher Block Chaining (CBC) mode as part of the wrapped encrypt/decrypt supported for MDES Token Connect APIs.

##### Impacted API: {#impacted-api}

* Push Multiple Accounts

## Release Dates {#release-dates}

* MTF - 20 May 2026
* Production - 17 June 2026

### Impacted Market {#impacted-market}

Functionality Available - Global

## Change 1 - Enhanced the EncryptedPayload object {#change-1---enhanced-the-encryptedpayload-object}

Three new fields are added to the encrypted payload object.

* algorithmCipherMode
* tag
* aad

In addition, the existing parameter iv has been updated to support the field size changes required to support GCM encryption.

|                                                                                                                            Field and Description                                                                                                                            | Data Type | Min Length | Max Length |                                       Required                                       |
|-----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|-----------|------------|------------|--------------------------------------------------------------------------------------|
| **algorithmCipherMode** The AES cipher mode used for the encrypted data. Must be one of the following values: * CBC - When CBC cipher mode to be used * GCM - When GCM cipher mode to be used                                                                               | String    | 3          | 3          | Conditional -- Required when algorithmCipherMode used is GCM.                        |
| **tag** Tag to verify during data decryption.                                                                                                                                                                                                                               | String    | 1          | 36         | Conditional -- Required when algorithmCipherMode used is GCM, not present otherwise. |
| **aad** Additional authentication data used in GCM mode. Hex-encoded data (case-insensitive).                                                                                                                                                                               | String    | 1          | 36         | Conditional -- optional when algorithmCipherMode used is GCM, not present otherwise. |
| **iv** Initialization vector used when encrypting data using the onetime use AES key. Must be exactly 12 bytes (24 character hex string) when using GCM and 16 bytes (32 character hex string) when using CBC to match the block size. Hex-encoded data (case-insensitive). | String    | 24         | 32         | No                                                                                   |


API Reference: `GET /connect/{maj}/pushMultipleAccounts`

## Impact {#impact}

Customers can choose to support either the GCM or CBC encryption mode to encrypt the payload. Please follow the requirements described in the API specification to implement this functionality.

### Personal data and Privacy Note {#personal-data-and-privacy-note}

Issuers are reminded that the information presented via the Token Connect includes personal data which is subject to data privacy laws. Issuer must satisfy themselves that the processing of such personal data is compliant with applicable privacy laws.