> For the complete documentation index, see [llms.txt](https://docs.signius.eu/api/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://docs.signius.eu/api/harmony-api-1/introduction.md).

# Introduction

With this API you are able to authorize users and sign hashes of documents.

To sign document you need to follow this steps:

1. Login user
2. Verify user session
3. Get user certificate
4. Initialize user authorization
5. Authorize user using the SMS code (OTP token)
6. Sign the document

To use this API, you need to import the .p12 certificate, which was provided by our team, or the certificate generated by you, which we imported into our truststore.

<figure><img src="https://460888612-files.gitbook.io/~/files/v0/b/gitbook-x-prod.appspot.com/o/spaces%2FSeXBiWY6b3bNA3Klj03S%2Fuploads%2F7fJYeBrbmU9RH3dvkA0b%2FHashSigningWithSigniusHarmonyAPI.png?alt=media&amp;token=8f06e57f-b25d-4682-bd8f-4f2f6bd98eb4" alt=""><figcaption></figcaption></figure>