Here’s a comprehensive guide on different ways to secure Excel files and send them securely over email.
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1. Password-Protect the Excel File
Protecting the Excel file itself is the first layer of security. Excel allows you to encrypt files with a password, so only people with the password can open the document.
Steps to Encrypt an Excel File with a Password:
Open the Excel File: Open the file you want to secure.
Go to File > Info: Click on "File," then "Info" in the top menu.
Protect Workbook: Select "Protect Workbook" > "Encrypt with Password."
Set a Password: Enter your desired password and click "OK." Re-enter it to confirm.
Important Tips:
Choose a strong password, ideally a mix of letters, numbers, and symbols.
Do not share the password in the same email as the attachment. Use a different method, such as a phone call or a secure messaging app, to share the password.
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2. Use ZIP Compression with Encryption
Compressing the Excel file and adding a password is another effective way to protect your file. This method works on most systems and is simple to set up.
Steps to Create a Password-Protected ZIP File:
Windows:
Right-click on the Excel file.
Choose "Send to" > "Compressed (zipped) folder."
Use a third-party tool (like WinRAR or 7-Zip) to add a password to the ZIP file.
Open the compressed file with the tool, select "Set Password," then choose and confirm your password.
Mac:
Right-click the file, select "Compress [File Name]."
Use software like Keka or The Unarchiver to add encryption.
Tip: For the highest security, avoid using default ZIP options since these typically don’t support strong encryption without additional software.
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3. Encrypt the Email Message
Another layer of security is to encrypt the email message itself. Encrypted emails ensure that only the intended recipient can open and read the email.
Options for Email Encryption:
Microsoft Outlook:
Go to Options > Encrypt > Encrypt with S/MIME or Encrypt-Only.
If your organization uses Office 365, you may also have the option to restrict permissions and prevent forwarding.
Gmail:
Gmail supports confidential mode, which restricts the recipient's ability to forward, copy, download, or print the content. However, this mode doesn’t fully encrypt the email.
For full encryption, consider using a service like ProtonMail or Mailfence.
Third-Party Encryption Tools:
ProtonMail and Tutanota are two highly secure email services with end-to-end encryption built-in.
Both sender and recipient need accounts to take full advantage of these services' encryption.
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4. Use a Secure File-Sharing Service
Secure file-sharing services add encryption automatically, making them great for transferring sensitive files.
Recommended Secure File-Sharing Services:
Dropbox with Password Protection:
Dropbox Professional and Business users can add password protection to shared links.
Google Drive with Permission Controls:
Google Drive allows you to set file permissions, such as restricting downloads, making files view-only, or requiring a Google account to access.
OneDrive with Link Protection:
Microsoft OneDrive offers password-protected and expiration-dated links.
Dedicated Secure Transfer Services:
WeTransfer Pro and Tresorit provide encrypted file-sharing with advanced security, such as expiration dates and download tracking.
Tip: Share a link to the encrypted Excel file instead of attaching the file directly. This method also keeps sensitive information out of your inbox.
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5. Use End-to-End Encrypted Messaging Apps for the Password
If sharing the password separately from the file, do so over a secure platform. Many messaging apps now offer end-to-end encryption.
Popular Secure Messaging Apps:
WhatsApp: Offers end-to-end encryption, commonly used for quick, secure messages.
Signal: Known for its high level of privacy and strong encryption. Great for secure communication.
Telegram (Secret Chats): Allows secret chats with end-to-end encryption.
iMessage: If both sender and recipient use iPhones, iMessage provides a secure way to share sensitive information.
Using one of these apps, you can securely send the password without risking exposure through email.
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6. Tips for Secure Excel File Transmission
Best Practices:
Don’t send the file and password together: If an attacker gains access to the email, they’ll have both the file and the password. Instead, send the password through a different channel.
Consider the sensitivity of the data: For highly sensitive data, avoid using email if possible. A more secure method (such as end-to-end encrypted email or a dedicated file-sharing service) might be warranted.
Enable Multi-Factor Authentication (MFA): For services like email and file-sharing platforms, enabling MFA adds another layer of security.
Check the recipient’s email service: Ensure the recipient is also using secure email (or file-sharing) settings, as this minimizes risks on their end.
Using these methods individually or in combination ensures that your sensitive Excel files are as secure as possible when sharing via email.