> For the complete documentation index, see [llms.txt](https://docs.uaepass.ae/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://docs.uaepass.ae/feature-guides/signature-integration-guide/hash-signing/introduction.md).

# Introduction

UAEPASS provides a **"Hash Signing"** feature for digital document signing, ensuring a more secure method to sign PDF documents without the need to send them outside the organization's premises.

**Here's how it works:** 

When a user logs into a document signature portal or application through UAEPASS authentication, the entity requests the signing of a document from UAEPASS. The entity sends the document's hash to UAEPASS and UAEPASS signs the hash of the document to send it back to the entity in PKCS#1 format. Entity should embed the signed hash back into the document in PKCS#7 format. At the end user can view and download the signed document.

Below is the high-level architectural diagram of UAEPASS Hash Signing:

![Fig 1: High Level Architecture of UAEPASS Hash Signing](https://4217816688-files.gitbook.io/~/files/v0/b/gitbook-legacy-files/o/assets%2F-MekZ3RZxqIxNNSkEFZ1%2F-MkkRM3POa_-GuKRii45%2F-MkkRuwuVnYyGIsnSZpe%2FHash%20Signing.png?alt=media\&token=0c2032db-c4e2-455d-b976-b27a521bf71c)

![Fig 2 : Hash Signing Work Flow](https://4217816688-files.gitbook.io/~/files/v0/b/gitbook-x-prod.appspot.com/o/spaces%2F-MekZ3RZxqIxNNSkEFZ1%2Fuploads%2F9lAkc8qbK2BwarjvkVNO%2Fhash-signing-slide1.png?alt=media\&token=cbfbf1d3-d5bf-4279-928f-e81684b923da)

![Fig 3: Hash Signing Flow](https://4217816688-files.gitbook.io/~/files/v0/b/gitbook-x-prod.appspot.com/o/spaces%2F-MekZ3RZxqIxNNSkEFZ1%2Fuploads%2FxjeM2kpvkQaAkZMDZ4V4%2Fhash-signing-slide2.png?alt=media\&token=17895a4c-cb3d-4282-994f-0da19026c094)