Is CBC-Mac collision resistant?

This example also shows that a CBC-MAC cannot be used as a collision-resistant one-way function: given a key it is trivial to create a different message which “hashes” to the same tag.

What is MAC information security?

A message authentication code (MAC), or tag, is a security code that is typed in by the user of a computer to access accounts or portals. This code is attached to the message or request sent by the user.

Why is CBC-MAC insecure?

1 Answer. In its plain form, CBC-MAC is vulnerable to “length extension attack”, where you just add some blocks at the end. So in order to stop people from doing that, you need to somehow mark the final block as indeed the final block. And not treat it like any other block.

Why is CBC-MAC with IV insecure?

Your implementation uses a random Initialization Vector. Using a random (or variable IV) is bad for the simple reason that verifying a CBC-MAC requires you to know the IV, and to know the IV you probably need to read it from somewhere. Typically this means the same untrusted place where you were storing your message.

What is MAC why it is required explain HMAC algorithm?

HMAC algorithm stands for Hashed or Hash-based Message Authentication Code. It is a result of work done on developing a MAC derived from cryptographic hash functions. HMAC is a great resistance towards cryptanalysis attacks as it uses the Hashing concept twice. The FIPS 198 NIST standard has also issued HMAC.

What is MAC explain the properties of MAC?

A message authentication code (MAC) is a cryptographic checksum on data that uses a session key to detect both accidental and intentional modifications of the data. A MAC requires two inputs: a message and a secret key known only to the originator of the message and its intended recipient(s).

Is OFB MAC secure?

We show that OFB and CTR are secure assuming that the underlying block cipher is a standard secure PRF (a pseudorandom function secure under classical queries).

Is ECB MAC secure?

Thus, AES ECB used on 128-bit messages is a secure MAC as long as you use a key for (significantly) fewer than 264 messages.

What is a MAC algorithm?

A MAC algorithm is a family of cryptographic functions – parameterized by a symmetric key – that can be used to provide data origin authentication, as well as data integrity, by producing a MAC tag on arbitrary data (the message).

What is MAC explain in detail?

It stands for Media Access Control, and also known as Physical address, hardware address, or BIA (Burned In Address). It is globally unique; it means two devices cannot have the same MAC address.

What is MAC explain?

What does CBC MAC stand for?

Jump to navigation Jump to search. In cryptography, a cipher block chaining message authentication code (CBC-MAC) is a technique for constructing a message authentication code from a block cipher.

How do you calculate the CBC-MAC of a message?

To calculate the CBC-MAC of message m, one encrypts m in CBC mode with zero initialization vector and keeps the last block. The following figure sketches the computation of the CBC-MAC of a message comprising blocks

Is CBC MAC secure for variable length messages?

Security with fixed and variable-length messages. If the block cipher used is secure (meaning that it is a pseudorandom permutation), then CBC-MAC is secure for fixed-length messages. However, by itself, it is not secure for variable-length messages.

How can an intruder attack CBC MAC security without encryption?

Without the last algorithm step (that is, without encryption using the second key), an intruder could attack CBC MAC security using a chosen-plaintext attack: The intruder chooses a message m of size of one block. The intruder obtains a value of authentication code of the message from the attacked system: t = F (k, m).

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