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Posts Tagged ‘tls’

What is TLS? Secure Email 101

Tuesday, November 27th, 2018

Transport Layer Security (TLS) is a widely used protocol in email security, the other being Secure Sockets Layer (SSL). Both are used to encrypt a communication channel between two computers over the internet.

An email client uses the Transport Control Protocol (TCP) – which enables two hosts to establish a connection and exchange data – via the transport layer to initiate a handshake with the email server before actual communication begins. The client tells the server the version of SSL or TLS it is running as well as the cipher suite (a set of algorithms that help in securing a network connection that uses SSL or TLS) it wants to use.

After this initial process, the email server verifies its identity to the client by sending a certificate the email client trusts. Once this trust is established, the client and server exchange a key, allowing messages exchanged between the two to be encrypted.

what is TLS

What parts of a message does TLS encrypt?

 The protocol encrypts the entire email message, including the header, body, attachments, email header, sender and receiver. TLS does not encrypt your IP address, server IP address, the domain you are connecting to, and the server port. The visible metadata informs where you are coming from, where you are connecting to and the service you’re connecting with, such as sending email or accessing a website. This article explains what is really protected by TLS and SSL.

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Stronger Email Security with SMTP MTA STS: Strict Transport Security

Wednesday, July 25th, 2018

Email transmission between servers has historically been extremely insecure.   A new draft internet standard called “SMTP Strict Transport Security” or “SMTP MTA STS” is aiming to help all email providers upgrade to a much more secure system for server-to-server mail transmission.    This article lays out where we are currently in terms of email transmission security and how SMTP MTA STS will help.

Email servers (a.k.a. Mail Transmission Agents or “MTAs”) talk to each other using the Simple Mail Transmission Protocol (SMTP). This protocol, developed in 1982, originally lacked any hint of security. As a result, a lot of the email shooting around the internet is still transmitted in plain text.  Its easily eavesdropped on, easily modified, untrusted and not private.

SMTP MTA STS

Back in 2002, an extension to SMTP called “STARTTLS” was standardized.  This extension permitted servers to “upgrade” SMTP communications from plain text to an encrypted TLS-secured channel, when both servers supported compatible levels of TLS.  This process is known as SMTP TLS. In principle, this security addition was really great.  The “TLS” used is the same encryption method used by your web browsers to talk to secure web sites (e.g., banks, Amazon, your email provider, etc.).  Your web browsers do relatively good job making sure that connections to these secure sites are safe.  I.e., they seek to ensure that there is encryption, that the encryption is sufficiently strong, and that there is no one actively eavesdropping on your connections.

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TLS 1.0 to 1.2 and NIST TLS Cipher Updates: Email Program and Web Browser Compatibility Issues

Thursday, June 7th, 2018

It happens at least every few years: system administrators need to update the security configuration of their servers to keep up with the latest best practices and to close newly found security issues(i.e., via changes to recommended TLS ciphers and protocols).  These updates can be rocky. Change often introduces incompatibilities that prevent certain systems or programs from being able to connect to the updated systems.

TLS Encryption Compatibility

In this article we are going to look at what email program an web browser incompatibilities arise when you migrate from using the “old standard:” TLS v1.0+ and the ciphers recommend by NIST 800-52r1 to using either TLS v1.0+ and the new NIST 800-52r2 ciphers or TLS v1.2+ and the new NIST 800-52r2 ciphers.

Why?

  1. PCI requires that servers that need to be PCI complaint use only TLS v1.1+ (which really means v1.2+) by the end of June, 2018.
  2. NIST 800-52r2 is in draft, but its updated cipher list removes many ciphers from revision 1 that are now considered “weak” and introduces a number of new, better ciphers.  Administrators should be moving towards NIST 800-52r2 cipher support as a best practice.
  3. Organizations that require HIPAA compliance should also follow the NIST guidelines and prepare NIST 800-52r2 support and, where possible, eventually eliminate pre-TLS 1.2 support. See: What level of TLS is required for HIPAA compliance?

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What Level of SSL or TLS is Required for HIPAA Compliance?

Saturday, June 2nd, 2018

SSL and TLS are not actually monolithic encryption entities that you either use or do not use to connect securely to email servers, web sites, and other systems.  SSL and TLS are evolving protocols which have many nuances to how they may be configured.  The “version” of the protocol you are using and the ciphers used directly impact the level of security achievable through your connections.

Some people use the terms SSL and TLS interchangeably, but TLS (version 1.0 and beyond) is actually the successor of SSL (version 3.0). … see SSL versus TLS – what is the difference?  In 2014 we saw that SSL v3 was very weak and should not be used going forward by anyone (see the POODLE attacks, for example); TLS v1.0 or higher must be used.

Among the many configuration nuances of TLS, protocol versions supported (e.g., 1.0, 1.1, or 1.2) anf which “ciphers” are permitted have the greatest impact on security.  A “cipher” specifies encryption algorithm to be used,  the secure hashing (message fingerprinting / authentication) algorithm to be used, and other related things such as how encryption keys are negotiated.   Some ciphers that have long been used, such as RC4, have become weak over time and should never be used in secure environments.  Other ciphers provide protection against people who record a secure conversation from being able to decrypt it in the future if somehow the server’s private keys are compromised (perfect forward secrecy).

What level of TLS is required by HIPAA?

Given the many choices of ciphers and TLS protocol versions, people are often at a loss as to what is specifically needed for HIPAA compliance for an appropriate and compliant level TLS security.  Simply “turning on TLS” without also configuring it appropriately is likely to leave your transmission encryption non-complaint.  

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SSL versus TLS – What’s the difference?

Saturday, May 12th, 2018

SSL versus TLS

TLS (Transport Layer Security) and SSL (Secure Sockets Layer) are protocols that provide data encryption and authentication between applications and servers in scenarios where that data is being sent across an insecure network, such as checking your email (How does the Secure Socket Layer work?). The terms SSL and TLS are often used interchangeably or in conjunction with each other (TLS/SSL), but one is in fact the predecessor of the other — SSL 3.0 served as the basis for TLS 1.0 which, as a result, is sometimes referred to as SSL 3.1. With this said though, is there actually a practical difference between the two?

SSL versus TLS: What is the differenc?

See also our Infographic which summarizes these differences.

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