======ECP Encryption======

With the regulation numbered 2017/21, it is also possible to send official letters transmitted electronically in encrypted form. 

In order to increase the security of the e-Correspondence Package during transmission, the content of the package can be encrypted. The encryption mechanism is designed to prevent third parties from accessing the content of the package. In the encryption process, the original e-Correspondence Package is placed in a new outer OPC package in encrypted form. Information about the encryption method, the “Final Hash” component of the encrypted package and the elements that need to be known to ensure transmission are added to this outer package. The following table lists the components of the encrypted e-Correspondence Package.

^**M/O**^**  Package Components **^
|M|Encrypted Content|
|M|Encrypted Content Information|
|M|Core|
|M|Final Hash|
|O|Document Target|

The Encrypted Content component contains the encrypted e-Correspondence Package. The components of the e-Correspondence Package are included in the [[e-yazisma_paketi_yapisi|e-Correspondence Package Structure]] section. 

Encrypted Content Information contains the information required for the encryption and decryption of the e-Correspondence Package.

If the cryptographic keys required for decryption of the encrypted package are lost, access to the package is not possible. For this reason, the original package contained in the encrypted package must be recorded separately by the institution that created the package.

===== Procedure =====

You can access **ECP Encryption Test Package** from [[https://yazilim.kamusm.gov.tr/?q=tr/system/files/private/eyp_sifreleme_test_paketi.zip|here]].


You can access **Test Root Certificates** from [[https://yazilim.kamusm.gov.tr/?q=tr/system/files/private/rootcerts.rar|here]].

The following table provides the names and properties of the encrypted ECP files to be used in the procedures. Packages in the procedure have been prepared according with the current version of the “e-Correspondence Technical Guide”.

^**  M/O  **^**  Package Name  **^**  Package Property  **^**Package Validation Result**^**Explanation**^
|  M  |ENC_1.eyps |Valid encrypted e-Correspondence Package |  VALID  |The decryption process is expected to be successful. The user must be clearly informed that the package has been successfully decrypted.|
|  M  |ENC_2.eyps|Encrypted e-Correspondence Package with forged Final Hash value|  INVALID  |Process details must be shown.|
|  M  |ENC_3.eyps |Encrypted e-Correspondence Package with forged Encrypted Content component|  INVALID  |Process details must be shown.|
|  M  |ENC_EYPG_1.eyps|Valid encrypted update package|  VALID  |The decryption process is expected to be successful. The user must be clearly informed that the package has been successfully decrypted.|

**M:** Mandatory - The specified items must be provided. In case the item is not provided, ECP evaluation will result in negative.