What is S/MIME Encryption and How Does It Work?

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S/MIME encryption – Let’s understand how S/MIME encryption works and what it is.

Are you wondering what S/MIME encryption is all about? Don’t worry; it is not just you who is unaware of this term. Many internet users are unaware of S/MIME encryption. Many of us send and receive several emails a day, but we may not know that our emails could be accessed and modified by third parties like hackers. They can steal sensitive information that is sent through an email. This is why we will have to encrypt our emails and make sure no one else other than the intended recipient can access our emails. Read on to know how you can secure your emails using S/MIME and how this technology works.

What is S/MIME?

S/MIME stands for “Secure/Multipurpose Internet Mail Extensions.” It’s a technology that is used to encrypt emails. This email signing protocol uses encryption to enhance email security. S/MIME is implemented using S/MIME certificates. This technology will let you sign your emails thereby letting you verify that you are the legitimate sender of the email. This will help your recipients fight off phishing attacks and safeguard your emails from unauthorized access.

How Does S/MIME Encrypt My Email?

S/MIME uses mathematically related public and private keys to operate. This technology is based on asymmetric cryptography. It is close to impossible to find out the private key even if you have the public key. When you use this technology to encrypt your emails, the email you send will be encrypted using the public key of the recipient. Without the corresponding private key, it is impossible to decrypt the email. The intended recipient of the email is the one who will possess the private key. No one other than the intended recipient of the email can read the emails you send or access sensitive attachments you send across. Only if the private key is compromised, hackers or others can access the email you send.

S/MIME will let you sign your emails and establish that you are the legitimate sender of the email. When we say you can sign your email, this does not mean your emails will manually be signed using a pen. This technology will sign your emails digitally. The private key assigned to your email will apply your unique Digital Signature to the email you send. This will be done every time you send an email. The public key will verify your signature when the recipient opens the email you sent. This signature will give the recipient the assurance that you are the legitimate sender of the email and it will also authenticate your identity.

You may wonder why you have to sign your emails. But with the surge in phishing emails and online crimes, it is mandatory to secure sensitive data you send online through an email. It is getting tougher to differentiate between fake and legitimate emails, so it is important to make sure the emails you send do not get into the wrong hands. With a surge in phishing attacks, it is important to verify the identities of the senders of emails. Considering the security features a S/MIME certificate offers, it is wise to implement S/MIME.

Now that you know S/MIME certificates use asymmetric encryption to encrypt emails, let’s understand exactly how a S/MIME certificate works.

How Does a S/MIME Certificate Work?

S/MIME certificates encrypt emails using asymmetric encryption. When you send an email to your friend and do not want anyone else to read it, you will need to secure that email. In order to make your email tamper-proof, you can use a public key to encrypt your email. This public key can be accessed by anyone and not just your friend whom you intend to send that secure email to. However, no one except your friend can access the contents of the email without the private key. Only the intended recipient, your friend, can access the private key and decrypt and access the email. This is how a S/MIME certificate works.

To sign and encrypt your email, you will need an email signing certificate – which you can purchase from a certificate authority. You can use this certificate to digitally sign your email. Once you purchase this certificate, it will get attached to your email automatically.

While the private key is used to generate the digital signature, the public key is used for authentication. The public and private keys are the two keys with which the digital signature is associated. The digital signature shows that the email sent is unaltered and not accessible to anyone else other than the intended recipient.

Features and Benefits of S/MIME Certificates

  • S/MIME certificates make sure the emails you send are accessible only by the recipient and not by any other third party.
  • These certificates use asymmetric encryption.
  • Public and private keys will be used to encrypt and decrypt emails so that you can be assured that the emails you send cannot be accessed by anyone else other than the recipient.
  • S/MIME certificates secure emails and make sure hackers do not access the contents of the email or make changes to it.
  • Digital signatures, as well as encryption, are both offered.
  • While asymmetric encryption lets you keep your data confidential, digital signatures offer authentication and message integrity.
  • S/MIME certificates are installed on email clients.

Uses of S/MIME

S/MIME can be used to

  • Make sure the email you sent has not been altered by any third party.
  • Create digital signatures to sign your emails.
  • Encrypt all your emails.
  • Verify the email client you use.

Document signing and client authentication are two of the additional features S/MIME certificates come with.

Document Signing

S/MIME certificates can be used for document signing, as well. Similar to email signing, you can sign documents using a digital signature. You can use your private key to sign your documents digitally. Using the unique digital signature, the recipient will be able to verify that the document was signed by you with your digital signature and that it has not been tampered.

If someone happens to tamper with the document you sent, the recipient will receive a warning message.

Client Authentication

Client authentication is another feature that S/MIME certificates offer. This feature helps users to secure apps, servers, and the network using certificate-based two-factor authentication. This feature will let you grant access to servers and apps to only authorized users. Only the users who have a client certificate installed will be able to access important data and the servers. Securing servers with passwords may not be a great option as passwords can be cracked. 

Having a S/MIME certificate with the client authentication feature is a great way to secure your servers and all-important data.

Final Word

The most popular form of electronic communication, emails, are largely used by businesses and individuals. It is also used by hackers for phishing purposes and to breach an organization’s network security. S/MIME certificates will prevent your emails from being tampered with. This is an important reason why you will need a S/MIME certificate to digitally sign your email and secure its contents so that no one other than the intended recipient can access it. Now that you know what a S/MIME certificate is and how it works, you might better understand the importance of these certificates for the security of your organization. Though S/MIME is implemented to strengthen email encryption, this technology can also help you stay away from social engineering attacks.

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