How to encrypt email attachments and transfer your files safely

Would you like to send sensitive info without worrying about privacy? Learn how to encrypt email attachments and protect your files from unauthorized access.
Email attachment with file size list.
From private photos to sensitive docs, there are many files you don’t want anyone but the email recipient to see. Encrypting your attachments is an excellent way to ensure confidentiality and keep your correspondence safe from third parties or online attacks.Understanding how email encryption works is crucial to gaining control over your files, as not every encryption type is as secure as advertised. This guide will show you the most effective privacy practices by explaining:
  • How much security you get with typical email encryption
  • What protocols are used to encrypt emails and attachments
  • Which encryption type ensures complete privacy
  • How to encrypt email attachments in Skiff
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Does encrypted email protect attachments? The truth behind most providers’ security practices

Email and attachment encryption primarily relies on your service provider. Every ESP uses some form of encryption, but only a handful offer sufficient protection.The most common standard is TLS (Transport Layer Security), a safer alternative to the SMTP (Simple Mail Transfer Protocol).TLS is a basic encryption protocol used to protect data in transit. It scrambles your email’s contents—including attachments—so they can safely travel between servers before reaching the recipient. The protocol prevents interceptions by third parties by ensuring they can’t read the email even if they get ahold of it.Free encrypted email services like Gmail and Outlook use TLS, promising privacy to their users. While the emails sent through them are technically encrypted, these services don’t guarantee enough security to ensure peace of mind.Most popular ESPs create and store decryption keys on their servers. They have full access to your emails and often use this data to improve personalized features and target you with ads. This invasion of privacy means your conversations and attachments aren’t as confidential as tech giants promise. Combining encryption at rest (files remain encrypted while resting on servers) and in transit gives you more security. Still, it’s not enough to ensure confidentiality since your ESP holds the decryption key.Unfortunately, any attack on the ESP’s servers puts you at risk of data leaks because the keys can be hacked. Such breaches have happened several times in the past few years, and some of them exposed massive amounts of private data.Luckily, there’s an alternative that lets you send private emails and attachments without security concerns.

End-to-end encryption—the best way to encrypt email attachments

As the name implies, end-to-end encryption (E2EE) offers comprehensive security between endpoints. The sender encrypts the email with all attachments on their device, making contents invisible to everyone but the recipient, who owns the decryption key. Hackers, ESPs, or other third parties can’t decipher the email, so your files are safe from snoopy individuals and businesses.By ensuring only one person can decrypt your email and its attachments, E2EE offers numerous benefits:
  1. Minimizing the attack options
  2. Preventing identity theft
  3. Reducing business risks
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E2EE removes most network vulnerabilities

Hackers can exploit vulnerabilities at any point in an unencrypted connection. Besides attacking the ESP’s server, they can intercept an email to execute the so-called message replay attack. An attacker might delay and modify the message, exposing the recipient to various risks.Emails with attachments are especially problematic in this case, as a hacker might replace your file with a corrupt one or use it for phishing.E2EE eliminates all risks of such attacks because the email leaves your device encrypted. Even if someone intercepts it (which is highly unlikely), all they’ll see are random characters.

You can send personal information without fear

Your attachments can contain sensitive data like bank account details or Social Security numbers. Without E2EE, there’s a significant risk of identity theft if such private information falls into the wrong hands.As long as the decryption key is safely stored on the user’s device, your data is safe even in case of a leak. E2EE will mask all your information, making it unusable by unauthorized third parties.

E2EE allows you to keep your business affairs private

E2EE is paramount in business correspondence, as the risk goes beyond threats to personal information. Companies are responsible for keeping their customers’ and employees’ data safe, which requires proper security measures.If you’re a business owner, implementing E2EE can save you many headaches in the long run. Doing so is even explicitly required by various compliance standards, such as:
  • CJIS
  • CFPB
You likely send numerous attachments to customers, and protecting them with E2EE is the best way to ensure they reach the recipient intact.

E2EE implementation can make or break your safety

While E2EE is the gold standard for safe online communication, not every encryption service offers the same level of protection. It all comes down to the protocols used and how well they’re implemented.PGP (Pretty Good Privacy) and S/MIME (Secure/Multipurpose Internet Mail Extensions) are among the most common E2EE encryption standards. The following table breaks down their main features and differences:
Used byIndividuals and businessesMainly businesses
PurposeGeneral-purpose standard applied to email securityDeveloped specifically for email protection
Number of public keys40961024
Cryptography typeSymmetric and asymmetricAsymmetric
Both standards had been considered highly effective until the EFAIL exploit was discovered in 2018. Security experts revealed that certain implementations of PGP and S/MIME allowed hackers to access email contents in two ways:
  1. Inserting malicious code that exfiltrates plaintext when a message is decrypted
  2. Manipulating users into revealing their private keys
Despite the exploit, many E2EE email services still use PGP and S/MIME. Google offers S/MIME encryption to paid G Suite users, while many third-party email encryption platforms rely on PGP. Providers like Skiff use more advanced solutions for exceptional security and privacy.

Skiff Mail—send encrypted email attachments without privacy concerns

Skiff Mail is an E2EE email service giving users complete control over their data. You can send attachments without the risk of anyone but the recipient accessing them. Your private key is created and stored on your device, so not even Skiff’s team can see your correspondence.
Source: @haroovkaUnlike many E2EE solutions, Skiff doesn’t require installing any certificates or proprietary software. Even beginners can use it without hassle thanks to the carefully-designed, intuitive user interface.If you’re a member of the crypto community, you know the importance of secure and anonymous file sharing. Skiff leverages the power of web3 and offers integration with various wallets:
Source: @MetaMaskThe platform is open source, so the cryptography libraries are open for reviews and contributions by independent developers. The same goes for the UI library—designers can use Skiff’s secure system to build new components. You can check out the whitepaper for more information.

Rise above manual file sharing with Skiff’s rich suite of collaboration tools

Skiff provides secure collaboration beyond sending encrypted email attachments. By signing up for a Skiff Mail account, you’ll get access to three additional privacy-first tools:
  • Skiff Pages—Create and work on an unlimited number of documents without the risk of security breaches
  • Skiff Drive—Store files of any type on Skiff or use InterPlanetary File System (IPFS) integration if you prefer decentralized storage
  • Skiff Calendar—Schedule private events and tailor the calendar to your needs
Source: @SlaveFreeSystemAll Skiff products are end-to-end encrypted to ensure unparalleled protection from third parties. Whether you want to store and manage private files or gather your team to work on new projects, you can rest assured your data is safe.

Sign up for a free Skiff account

Skiff is free to use without time limitations. Here’s how to get started:
  1. Head to the signup page
  2. Choose your account name and password (you don’t need to leave any personal information)
  3. Explore Skiff Mail and other privacy-first products
If you’re using another ESP, you can migrate your emails and files to Skiff in a few quick steps. Your data will be encrypted from the moment you migrate, and Skiff won’t save any unencrypted copies.
Source: @0xUnifiedThe free plan comes with 10 GB of storage and 4 aliases letting you manage multiple accounts. The maximum upload size per file is 50 MB, which should be enough for most attachments. If you want to bump the upload limit to 1 GB and enjoy extra features like custom domains, you can upgrade to Skiff’s Essential, Pro, or Business plans:
Essential planPro planBusiness plan
10 Skiff Aliases10 Skiff Aliases15 Skiff Aliases
1 Short Alias1 Short Alias1 Short Alias
1 custom domain2 custom domains5 custom domains
15 GB storage100 GB storage1 TB storage

Secure email attachments beyond correspondence to avoid loopholes

Skiff or other E2EE solutions can’t protect your data and files if your device is compromised by malware. Exercising proper security measures can prevent this from happening, and it doesn’t involve any tedious work. You can protect your device and accounts by following a few simple tips:
  • Fortify your passwordsStrong passwords and two-factor authentication can prevent various attacks. Make sure your device, wi-fi, and accounts are shielded by complex passwords
  • Always download software from trusted sources—Shady software is the most common source of malware, so stay away from unreputable websites and developers
  • Invest in a comprehensive antivirus solution—A solid antivirus software can help you avoid downloading corrupt files by scanning them before they’re stored on your device. It can also scan emails and websites to warn you about malware
  • Keep your software updated—Operating systems, browsers, and other tools often receive updates containing security patches. Keep everything up to date to stay ahead of sophisticated attacks
  • Secure your network—A firewall is an excellent way to ward off online threats and keep your connection safe. The same goes for intrusion detection and prevention systems, so explore different options to strengthen your network security

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