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Table of contents
Message Authentication Code
How MAC in Cryptography Works?
MAC in Cryptography’s limitations
Frequently Asked Questions
What cryptographic security features are there in MAC?
Is it safe to utilize CBC-MAC?
What does SSL MAC mean?
What three forms of SSL are there?
What does SSL MAC mean?
Last Updated: Mar 27, 2024

Unconditionally Secure MACs in Cryptography

Author Yashi Agarwal
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The threat we're concerned with when developing cryptographic systems that ensure integrity and authentication is from adversaries sending messages purporting to be from a trustable participant (spoofing) or altering the content of a message sent by an honest participant. We will offer cryptographic techniques that allow the recipient to recognize spoofing and tampering to counteract these risks.

secure macs in cryptography

This section will define the Unconditionally Secure Macs in Cryptography and demonstrate how they provide integrity and authenticity.ure Macs in Cryptography and demonstrate how they provide integrity and authenticity.

Message Authentication Code

what is mac?

Message Authentication Code is referred to as MAC. The asymmetric critical cryptography method for message authentication is the MAC algorithm. The transmitter and receiver use the same symmetric key K to establish the MAC procedure.

In other words, MAC is an encrypted checksum created on the underlying message sent along with a message to provide message authentication. A MAC in cryptography is a message's keyed checksum sent with the message. It accepts a message of any length and a fixed-length secret key and outputs a fixed-length checksum. Any modification to the message will invalidate the checksum, according to a secure MAC in Cryptography. The sender creates a fixed-size output known as a cryptographic message or checksum authentication code and appends it to the original message in MAC, where the sender and receiver share the same key. To verify the message's originality, the recipient also produces the code and compares it to what they have received. These are its parts:

  • Key
  • Mac algorithm
  • MAC value
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How MAC in Cryptography Works?

working of mac

Let's fully comprehend the procedure.

  • The sender enters the message and the secret key K into a publicly available MAC algorithm and generates a MAC in Cryptographyvalue.
  • The MAC function compresses an arbitrarily long input into a fixed-length output, much like the hash function. Hash and MAC differ significantly because MAC in Cryptography utilizes a secret key to compress data.
  • The sender forwards the message and MAC. Since we are only concerned with providing message origin authentication in this case and not message secrecy, we presume the message is sent in the open. Encryption is necessary if confidentiality is required for the message.
  • After receiving the message and MAC, the receiver updates the MAC in Cryptography value by feeding the shared secret key K and the received message into the MAC in the Cryptography algorithm.
  • Now, the receiver verifies that the freshly computed MAC and the MAC it received from the sender are the same. If they do, the message is accepted, and the recipient is sure that the designated sender sent it.
  • The receiver cannot distinguish between an altered message and an altered origin if the computed MAC differs from the MAC transmitted by the sender. Ultimately, a recipient can assume that the message is not genuine.

MAC in Cryptography’s limitations

Due to its symmetric mode of operation, MAC in Cryptography has two primary constraints.

  1. Creation of a shared secret
  • A shared key can allow message authentication between predetermined valid users.
  • Before using MAC in Cryptography, this necessitates the creation of a shared secret.

2. Having No Non-Repudiation to Offer

  • The guarantee of non-repudiation states that the sender of a message cannot retract any earlier messages, commitments, or actions.
  • The MAC in Cryptography approach does not offer a non-repudiation service. A message cannot be proven to have been sent by the sender using MACs if the sender and receiver disagree about who sent the message.
  • Even though a third party cannot compute the MAC, the sender may still claim that the recipient forwarded the message because it is impossible to tell which of the two parties added the MAC.
  • The public key-based digital signatures discussed in the section below can get around both restrictions.

3.  Reverse engineering can reveal plain text or even the key, which are issues with MAC in Cryptography. Here, input and output have been mapped; therefore, to get around this, we go on to hash functions that are "One way."

Frequently Asked Questions

What cryptographic security features are there in MAC?

Completely secure Macs, using cryptography.

The MAC algorithm is a symmetric key cryptography technique for message authentication. The transmitter and receiver establish the MAC protocol using the same symmetric key K. To offer message authentication, a MAC is essentially an encrypted checksum made on the underlying message that is sent with a message.

Is it safe to utilize CBC-MAC?

Abstract. CBC-MAC, or cipher block chaining message authentication code, is a well-known method for producing message authentication codes. Unfortunately, it is not secure against arbitrary domain forging.

What does SSL MAC mean?

The message authentication code is a method for confirming the validity and integrity of a communication (MAC).

What three forms of SSL are there?

Additional Validation (EV), Validation of Organization (OV), and Validating a Domain are three categories of SSL certificate authentication types that are widely accepted.

What does SSL MAC mean?

The message authentication code is a method for confirming a message's validity and integrity (MAC).


This article discussed the Unconditionally secure Macs in Cryptography, their working, and limitations. 

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