======e-Correspondence Package Structure======

ECP consists of components related to the document and package structure that are logically connected. The table below lists the ECP components.

^**M/O**^**  Package Components **^
|M|Cover Letter|
|M|Metadata|
|M|Final Metadata|
|O|Paraph Hash|
|O|Paraph Electronic Signature|
|M|Package Hash|
|M|Electronic Signature|
|M|Core|
|O|Attachment|
|M|Final Hash|
|M|Electronic Seal|

**M:** Mandatory - It is mandatory to include the specified component in the package

**O:** Optional - It is optional to include the specified component in the package

While the use of Electronic Signature and Electronic Seal is mandatory in ECP, the use of Paraph Electronic Signature is optional. For Paraph Electronic Signature and Electronic Signature, [[CAdES X-Long| CAdES-X Long]] signature format; for Electronic Seal, [[CAdES-A]] signature format is used.
 
[[sertifika_kontrolue|Certificate Control]] and [[zaman_damgası|Timestamp]] verification procedures must be performed before creating the Paraph Electronic Signature, Electronic Signature, and Electronic Seal used in ECP. The "Date" field in the Final Metadata component is expected to be the same as the timestamp information of the most recently created Electronic Signature. Information about all signers should be included in the “Document Signatures” field of the Final Metadata component.

**Paraph Electronic Signature:** It is created by signing the "ParafOzeti.xml" file that exists in the Paraph Hash component in the ECP by using Qualified Electronic Certificate. It must be used only in paraph made with an electronic signature. Cover Letter, Metadata, and Attachments components' hash values exist in the “PaketOzeti.xml”  file. The presence of Attachments is optional. The following table specifies the components that must be included and not included in the Paraph Electronic Signature.


^** Paraph Electronic Signature  **^** Component **^**M/O**^        
| Package Components Included in Paraph Electronic Signature  | Cover Letter             |M|
| :::                                 | Metadata             |M|
| :::                                 | Attachment (Internal Electronic File Attachment)        |O|        
|Paraph Electronic Signature         | [[cades_p3_x-long| P3 CAdES-X LONG]] / [[cades_p4_x-long| P4 CAdES-X LONG]]      |M|
|Package Components Not Included in Paraph Electronic Signature | Unsigned Attachments  |O|

**Electronic Signature:** It is created by signing the “PaketOzeti.xml” file that exists in the Package Hash component of the ECP by using the Qualified Electronic Certificate by the authorized personnel of the institution. Cover Letter, Metadata, Attachments, Paraph Hash, Paraph Electronic Signature components' hash values exist in the “PaketOzeti.xml” file. The presence of Attachments, Paraph Hash, and Paraph Electronic Signature is optional. The Electronic Signature component can include serial or parallel signers. The following table specifies the components that must be included and not included in the Electronic Signature.

^** Electronic Signature  **^** Component **^**M/O**^        
| Package Components Included in Electronic Signature    | Cover Letter             |M|
| :::                                    | Metadata              |M|
| :::                                    | Attachment (Internal Electronic File Attachment)         |O|        
| :::                                   | Paraph Hash         |O|
| :::                                   | Paraph Electronic Signature        |O|
|Electronic Signature       | [[cades_p3_x-long| P3 CAdES-X LONG]] / [[cades_p4_x-long| P4 CAdES-X LONG]]   |M|
|Package Components Not Included in Electronic Signature| Unsigned Attachments   |O|

**Electronic Seal:** The purpose of the Electronic Seal is to verify the identity of the institution that created the ECP. Electronic Seal is created by signing the "NihaiOzet.xml" file that exists in the Final Hash component by using the Electronic Seal certificate issued by Kamu SM on behalf of the public institutions and organizations within the scope of Prime Ministry Circular no 2017/21. Cover Letter, Metadata, Final Metadata, Core, Package Hash, Electronic Signature, Attachments, Paraph Hash and Paraph Electronic Signature components' hash values exist in the “NihaiOzet.xml” file. The presence of Attachment, Paraph Hash, and Paraph Electronic Signature components are optional. The Electronic Seal component can not include serial or parallel signers. The following table specifies the components that must be included and not included in the Electronic Seal. 

^** Electronic Seal **^** Component **^**M/O**^           
| Package Components Included in Electronic Seal   | Cover Letter      |M|
| :::                                   | Metadata        |M|
| :::                                   | Final Metadata        |M|
| :::                                   | Attachment (Internal Electronic File Attachment)  |O|        
| :::                                   | Paraph Hash    |O|
| :::                                   | Core        |M|
| :::                                   | Paraph Electronic Signature     |O|
| :::                                   | Package Hash    |M|
| :::                                   | Electronic Signature|M|
| Electronic Seal                                | [[p3_cades-a| P3 CAdES-A]] / [[p4_cades-a| P4 CAdES-A]]    |M|
| Package Components Not Included in Electronic Seal | Unsigned Attachments  |O|