How to Read Encrypted Attachments using Gmail API?

Published On: 11 March 2022.By .
  • Product & platform Engineering

What is Encrypted Attachment?

The attachments which are unreadable without a digital key. In generalize form, those files which contents can’t be read without having a digital key (password) are known as encrypted attachments.

Why do we need encrypted attachment?

  • To protect the user’s personal information in the case if the data/device is being hacked.
  • To keep sensitive personal information safe from bad actors.
  • To be used in Government or Banking sectors, so that some account statements of users can be sent in encrypted pdfs.


What is Gmail API?

  • The Gmail Api provides us with a RESTful access to the features you usually have with Gmail.
  • Send and receive emails with attachments.
  • Send and receive HTML emails.
  • CRUD operations with messages, drafts, threads, and labels.
  • Access control of your Gmail Inbox.
  • Perform specific queries.
  • To get specific attachment data of specific messages.


How to start reading Emails using Gmail API?

  1. Create a Project at Google Api Console.

    If you want to have access to your Gmail from your mobile or web app, you should start with Google Developer Console.

  2. Enable Gmail API

    After making project and necessary configuration Enter “Gmail API” in the search bar and click on it once found. Now, you need to enable the API for your project. For more information you can visit google support.

  3. Credentials and authentication with OAuth 2.0

    Once the Gmail API is enabled we need credentials . We can generate our credentials by going to the following site  Google Developer Console. Then credentials -> create credentials -> oAuth client id->select appropriate configuration as per your project requirement -> download a JSON file with your credentials.

  4. API Client Library.

    Now create a Maven Spring boot project and add the following dependencies  in pom.xml file.

    Other dependencies are Spring boot starter web and spring boot starter test. These are necessary dependencies required for running  a spring project.

  5. Ready to Access Gmail Account.

    In this we need to authorize access to your gmail account. For this we need to follow.Official Documentation.

    • Now first you have to make an authorization flow . That contains Access token and Refresh Token.
    • This is how we can authorize and set the flow of authorization.
    • We also have to set the scope. Scopes are related to like what are the things we can do with gmail api. Some of the scopes are SEND, READ ONLY, INSERT, MODIFY. To know more about scopes Click Here.
    • After authorization we get access token in response object that is used to create a gmail service builder.Now We build a gmail Builder that can give us the mails that we have to fetch.
    • Now we can fetch mails by setting a query and the date between when we want the mail.

  6. Fetch Messages From Inbox of User Email.

    Endpoint: /mails?date1=?&date2=?&username=?
    Controller: getMailsBetweenDate

    1. Request end point controller, from here,next is to generate a gmail builder.
    2. Generate a gmail Builder.
    3. Now, get mails by defining a query to take only those emails which show transaction information.
    4. Now, create files/attachments at location /files/file_name.pdf
    5. If attachments are encrypted, than decrypt attachments as follows.

Pros of using Gmail API

  1. Time Saving

  2. We need less back and forth communication between servers . So it can save lots of time and is a faster method.

  3. Analytics

  4. An gmail api usually includes statistical insights into recipient-email interactions like email deliverability, open rate, unsubscribes, and more.

  5. Security

  6. When using email API to send emails, you need to use an API key. This protects your website or application from phishers or spammers.

Cons of using Gmail API

  1. Requirement of Technical Knowledge

  2. Setting up and running email APIs is difficult since it requires extensive knowledge of a programming language and client libraries. Even if you have extensive documentation, understanding and putting it into practise for email sending can be difficult.

  3. Needs Repeated Updates

  4. API versions, unlike SMTP, change with each passing year. As a result, you’ll need to keep an eye out for upgrades and make adjustments to accommodate the new protocols.

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