This post let you login to SharePoint onpremise application using google account as trusted identity provider/ Authenticate SharePoint using Google account/ Google to Authenticate SharePoint application.
Select App Services, Active Directoryand finally Access Control
Enter a name for your access control namespace, select the region you are in and click Create
Click on Active Directoryfrom the navigation menu on the left
Click on Access Control Namespaces
Select the namespace that you have just created and click on Manage
Step 3: Configure Access Control Service
Click on Identity providers
Select Google and click on Next
Enter the Client ID and Client secret that you copied from your Google app in step 1 and click Save
Click Relying party applications
Click on Add
Enter a name for the replying party application in the name field
In Realm enter the URL of your SharePoint web application
In return URL enter the URL of your SharePoint web application followed by /_trust
In the token format select SAML 1.1
Change the token lifetime (secs) to 3000and clickSave
Click on Rule Groups
Click on Add
Enter a name for the rule group and click Save
Click on Generate
Select Googleand click on Generate
Step 4: Certificates and Keys
Click on Certificates and Keys
Click on Save
Select your relying party application from the drop down list (You created it in step 3)
On the page copy the MakeCert command
On your client machine you will need to generate a certificate to be used for the trust. Launch a command prompt as administrator, navigate to the directory where makecert is installed and run the copied command.
If you don't have makecert you can get it from here: makecert
The certificate will be deployed to your certificate store, you will need to export a .CER and .PFX. (spauthenticate.cer / spauthenticate.pfx)
Return to your access control service browser window.
Click on Browse
Browse to the .pfx file you created in the previous step and click open
Enter the password and click Save
Step 5: SharePoint Configuration
Logon to your SharePoint server
Copy the .cer file you created in a previous step to the server
Open the SharePoint Management Shell as administrator
Run the following PowerShell commands
Where the url is the url of your SharePoint web application
Once you have run the PowerShell commands you will need to add the identity provider to your web application.
Open SharePoint Central Administration
Click on Application Management
Click on Manage Web Applications
Select the Web Application that will be using Google for authentication
Click on authenticationproviders in the toolbar
Select the relevant zone, this will be default if you only have one zone.
Scroll down the window, select Trusted Identity provider and select Google Authentication
Step 6: Testing
Open a web browser and navigate to your root site collection on the web application. You should get a drop down list showing the logon options. You can customize this page and set as the custom login page for Trusted Identity provider.
Select Google Authentication and you should get the Google authentication page.
Enter your google credentials and click sign in.
You should be returned to your SharePoint page. You will probably be given an access denied message because the account has not been given any rights to your site. Just grant rights as you would normally.
When granting rights to Google users you will need to use the full email address. People picker will not resolve the name unless the user is already added but you will still be able to add new users.