ClassifyIt video · 3 minutes 34 seconds
CryptIt - Encrypt Email Attachments with Certificates
Follow a complete Outlook use case from scratch: create your certificate and private key, exchange and verify public certificates, encrypt an attachment and reopen your sent copy.
3 minutes 34 seconds · English captions · Published 2026-10-23
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Video transcript
This video demonstrates a certificate-based encryption use case from scratch in CryptIt. We create our own certificate and private key, exchange public certificates, and encrypt an email attachment.
First, create your own digital certificate with its matching private key. Open the CryptIt menu and choose Certificate Management. If you have no current certificate, select Generate New. CryptIt guides you through the setup. You will need your email address and a password to protect your private key.
Enter your complete email address. Then choose a strong certificate password with at least ten characters. The simple password shown here is only a demonstration. Keep this password safe: CryptIt warns that it cannot be recovered. This protects your private key; it is not a password that you send to recipients. CryptIt confirms that your certificate has been created. Share the public certificate. Keep the private key protected.
Prepare your email and attach the file. This example uses a Word document, but attachment encryption supports any file type. Open the CryptIt menu and select Certificate. Then press the upper CryptIt button to encrypt the attachment. Here, CryptIt warns that the recipient’s public certificate is missing. To protect the attachment for that recipient, you first need their public certificate.
Ask the recipient to send you their public certificate. You can share yours at the same time. In the CryptIt menu, choose Attach my Public Key. CryptIt attaches your public certificate in a package with a dot CRT, dot TDF filename ending. Your private key is not included. The recipient can use your public certificate to send encrypted attachments back to you.
The recipient replies with their public certificate attached. CryptIt recognises that it is not yet in your trusted certificate folder and offers to import it. Before accepting, verify through a trusted process that the certificate belongs to the intended recipient. Importing a certificate does not, by itself, establish someone’s identity. Confirm the import. CryptIt reports that the public certificate has been imported.
Return to your prepared email and press CryptIt again. The original attachment becomes a protected Trusted Data Format container, with a dot TDF file extension added to its filename. The recipient’s public certificate allows CryptIt to protect the attachment for them. Their matching private key allows them to decrypt it. Send the email as usual. The attachment is encrypted; the email body remains readable.
CryptIt also includes the sender, so you can reopen your own encrypted attachment from the sent message. Open the message and press CryptIt. When prompted, enter your certificate password to unlock your private key. The original attachment is restored and can be opened or saved. The recipient decrypts their copy using their own matching private key and certificate password.
Create your certificate. Exchange and verify public certificates. Select Certificate mode and encrypt. Share your public certificate, not your private key or its password. CryptIt’s integration into Outlook, together with certificates named after email addresses, makes strong encryption mechanisms easy to use to protect the confidentiality of attachments.