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Posts Tagged ‘opportunistic TLS’

Opportunistic TLS for SMTP

Tuesday, December 15th, 2020

If you want to make sure your emails are secure and private, opportunistic TLS for SMTP won’t quite cut it. To explain why, first we have to step back a bit.

Most people don’t put a lot of thought into how their emails are sent and received, so it’s not unusual for them to think it works akin to teleportation or magic–that messages somehow just appear right in their inboxes.

While the rapid delivery speeds may seem to justify such presumptions, there are actually a bunch of steps under the hood. When you send an email, it uses a protocol called the Simple Mail Transfer Protocol (SMTP) to make its way through to your recipient’s server. From there, your recipient uses another protocol such as ActiveSync, POP3, MAPI, or IMAP, or a Web-based interface, to pick it up and read it.

Opportunistic TLS

Unfortunately, these aren’t always secure by default. Under its original design, emails are sent as plaintext. This means that anyone along the email’s journey can see (and even change) their contents. This can include those in charge of the servers, the government, and even hackers that intercept the data.

Thankfully, engineers weren’t completely oblivious to this glaring security hole, and they have introduced a number of mechanisms that can be leveraged to protect email.

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SMTP TLS: All About Secure Email Delivery over TLS

Monday, October 2nd, 2017

TLS stands for “Transport Layer Security” and is the successor of “SSL” (Secure Socket Layer). TLS is one of the standard ways that computers on the internet transmit information over an encrypted channel. In general, when one computer connects to another computer and uses TLS, the following happens:

  1. Computer A connects to Computer B (no security)
  2. Computer B says “Hello” (no security)
  3. Computer A says, “Let’s talk securely over TLS” (no security)
  4. Computer A and B agree on how to do this (secure)
  5. The rest of the conversation is encrypted (secure)

In particular:

  • The meat of the conversation is encrypted
  • Computer A can verify the identity of Computer B (by examining its SSL certificate, which is required for this dialog)
  • The conversation cannot be eavesdropped upon (without Computer A knowing)
  • A third party cannot modify the conversation
  • Third parties cannot inject other information into the conversation.

TLS and SSL are used for many different reasons on the internet and help make the internet a more secure place. One of the popular uses of TLS is SMTP for securely transmitting email messages between servers. See also:

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The Case For Email Security

Tuesday, March 31st, 2015

We all know that regular email is insecure; however, it may surprise you to learn just how insecure it really is. For example, did you know that messages you deleted years ago may be on servers halfway around the world? Or that your messages can sometimes be read and modified in transit, even before they reach their destination? Did you know that forging email is very, very easy? Can you trust what you read in an email? Email was not designed with security in mind, and as a result, many different solutions have evolved to plug the multitude of resulting issues.

This article will explain how email works, what the real email security issues are, what mitigations to these are generally in use, and what else you can do to protect your email.

Case for Email Security

Information security and integrity are essential as we use email to send confidential and sensitive information over this medium every day. While reading this article, imagine how these security problems could affect your business, your personal life, and your identity if they have not already.

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