Message Authentication

Message authentication is the process to confirm that a message has not been modified while in transit and that the receiving party can confirm the source of the message. In simple terms, it verifies that the received message is authentic and that the contents have not been altered.

Message authentication is important in security applications where data integrity should be sustained. This is, for instance, the case where any financial account needs to be accessed.

How Does Message Authentication Work?
Message authentication usually relies on a message authentication code (MAC), authenticated encryption (AE), or digital signatures to check the integrity of a message. The MAC is based on a secret key shared between two parties to authenticate the information shared between them.

This code is based on a cryptographic hash or symmetric encryption algorithm and is shared by exactly two parties and the authentication will fail when a third party possesses the key since the algorithm will no longer detect forgeries.

In practice, when the sender sends a message, an algorithm generates a cryptographic hash or MAC and appends it to the message. On the receiver’s end, another MAC is generated and compared to the code received from the sender. This then confirms the authenticity of the message.

Keep in mind, though, that MACs differ from digital signatures, another method of verifying the authenticity of messages, in that MAC values are both generated and verified using the same key. This means that both the sender and the receiver must agree on the same key before sending any communication. It also means that MACs do not provide non-repudiation offered by signatures, and any user who can verify a MAC can generate MACs for other messages.

Email authentication works similarly, with the primary methods of email authentications also verifying either a domain name identifier or IP address. In this case, the information is sent with the message from the sender and is checked on the receiver’s side to establish whether the message is authentic.

Why Should I Set up Message Authentication?
Message authentication is necessary for any application where security is important. When it comes to email authentication, it serves an additional purpose because it can affect the email deliverability of a message. So, for any business or marketing-related purpose, email authentication is vital to ensure that important messages are delivered to the people they are intended for.