- Hash function: A function that maps a message of any length into a fixed- length hash value, which serves as the authenticator
- Message encryption: The ciphertext of the entire message serves as its authen- ticator
- Message authentication code (MAC): A function of the message and a secret key that produces a fixed-length value that serves as the authenticator
What is message authentication and how does it work?
Message authentication is typically achieved by using message authentication codes (MACs), authenticated encryption (AE) or digital signatures. The message authentication code, also known as digital authenticator, is used as an integrity check based on a secret key shared by two parties to authenticate information transmitted between them.
What is an authenticator?
Authentication Functions Any message authentication or digital signature mechanism has two levels of functionality. At the lower level, there must be some sort of function that produces an authenticator: a value to be used to authenticate a message.
What are the two functionality levels of message authentication?
All message authentication and digital signature mechanisms are based on two functionality levels: Lower level: At this level, there is a need for a function that produces an authenticator, which is the value that will further help in the authentication of a message.
What is the difference between a message authentication code and hash?
As with the message authentication code, a hash function accepts a variable-size message M as input and produces a fixed-size output, referred to as a hash code H ( M ). Unlike a MAC, a hash code does not use a key but is a function only of the input message. The hash code is also referred to as a message digest or hash value.
What is the authentication function?
Authentication is used by a server when the server needs to know exactly who is accessing their information or site. Authentication is used by a client when the client needs to know that the server is system it claims to be. In authentication, the user or computer has to prove its identity to the server or client.
What is message authentication and types?
Message authentication is another form of security. Similar to data encryption to ensure data confidentiality, the message authentication data security feature: Provides services to ensure the integrity of data for selected LU-LU sessions.
What are MAC functions?
Message Authentication Code (MAC), also referred to as a tag, is used to authenticate the origin and nature of a message. MACs use authentication cryptography to verify the legitimacy of data sent through a network or transferred from one person to another.
What are the function used to produce an authenticator?
Hash function: A public function that maps a message of any length into a fixed length hash value, which serves as the authenticator. A variation on the message authentication code is the one way hash function.
What is message authentication and hash function?
A message authentication code (MAC) is similar to a cryptographic hash, except that it is based on a secret key. When secret key information is included with the data that is processed by a cryptographic hash function, the resulting hash is known as an HMAC.
What are message authentication requirements?
A MAC requires two inputs: a message and a secret key known only to the originator of the message and its intended recipient(s). This allows the recipient of the message to verify the integrity of the message and authenticate that the messege's sender has the shared secret key.
Which type of function is a MAC?
A Message Authentication Code (MAC) is a hash function that uses a key. A common MAC implementation is Cipher Block Chaining Message Authentication Code (CBC-MAC), which uses the CBC mode of a symmetric block cipher such as DES to create a MAC.
What does MAC stand for?
medium access control1. Short for medium access control, or MAC address. Known as a physical address and hardware address whose number is uniquely formatted in hexadecimal format and given to each computer or network device on a computer network.
What is the difference between MAC and hash function?
Essentially, MAC is an algorithm that takes, as input, a message combined with a shared secret key. Let's continue with a conceptual comparison where we define security goals for both processes. Hash functions are used to ensure data integrity. Any change in the original message results in generating a different Hash.
What are the three types of message authentication methods?
Message authentication is typically achieved by using message authentication codes (MACs), authenticated encryption (AE) or digital signatures.
What are the types of attacks addressed by message authentication?
What types of attacks are addressed by message authentication? Content modification: Changes to the contents of the message. Sequence modification: Any modification to a sequence of messages between parties, including insertion, deletion and recording. Timing modification: Delay or replay of messages.
What is the difference between message integrity and message authentication?
AnswerThe main difference between MAC and HMAC is that MAC is a tag or a piece of informationthat helps to authenticate a message, while HMAC is a special type of MAC with acryptographic hash function and a secret cryptographic key.
What are the types of attacks addressed by message authentication?
What types of attacks are addressed by message authentication? Content modification: Changes to the contents of the message. Sequence modification: Any modification to a sequence of messages between parties, including insertion, deletion and recording. Timing modification: Delay or replay of messages.
What are the types of attacks on encrypted message?
There are two types of attacks – 'passive attacks' and 'active attacks'. Snooping on data, eavesdropping is simple examples of 'passive attacks'.
What is HMAC and CMAC?
Well, CMACs (Cipher-based message authentication codes) create message authentication codes (MACs) using a block cipher and a secret key. They differ from HMACs in that they use a block symmetric key method for the MACs rather than a hashing method. The code to implement this is [here]: import os.
What is the difference between a MAC and an HMAC?
The main difference between MAC and HMAC is that MAC is a tag or a piece of information that helps to authenticate a message, while HMAC is a special type of MAC with a cryptographic hash function and a secret cryptographic key. Cryptography is the process of sending data securely from the source to the destination.
How to use MAC authentication code?
Message Authentication Code (MAC) 1 The sender uses some publicly known MAC algorithm, inputs the message and the secret key K and produces a MAC value. 2 Similar to hash, MAC function also compresses an arbitrary long input into a fixed length output. The major difference between hash and MAC is that MAC uses secret key during the compression. 3 The sender forwards the message along with the MAC. Here, we assume that the message is sent in the clear, as we are concerned of providing message origin authentication, not confidentiality. If confidentiality is required then the message needs encryption. 4 On receipt of the message and the MAC, the receiver feeds the received message and the shared secret key K into the MAC algorithm and re-computes the MAC value. 5 The receiver now checks equality of freshly computed MAC with the MAC received from the sender. If they match, then the receiver accepts the message and assures himself that the message has been sent by the intended sender. 6 If the computed MAC does not match the MAC sent by the sender, the receiver cannot determine whether it is the message that has been altered or it is the origin that has been falsified. As a bottom-line, a receiver safely assumes that the message is not the genuine.
What does the receiver do on receipt of a message?
On receipt of the message and the MAC, the receiver feeds the received message and the shared secret key K into the MAC algorithm and re-computes the MAC value.
What is MAC algorithm?
MAC algorithm is a symmetric key cryptographic technique to provide message authentication. For establishing MAC process, the sender and receiver share a symmetric key K.
Does MAC provide a non-repudiation service?
MAC technique does not provide a non-repudiation service. If the sender and receiver get involved in a dispute over message origination, MACs cannot provide a proof that a message was indeed sent by the sender.
Does the sender forward the message along with the MAC address?
The sender forwards the message along with the MAC. Here, we assume that the message is sent in the clear, as we are concerned of providing message origin authentication, not confidentiality. If confidentiality is required then the message needs encryption .
SSPI Functions
Security Support Provider Interface (SSPI) functions fall into the following major categories.
Network Provider Functions
The following topics provide reference information for the network provider functions.
LSA Logon Functions
The following Local Security Authority (LSA) authentication functions authenticate and log on users, and they provide logon session information.
Functions Implemented by Authentication Packages
Custom authentication packages must implement these functions, which are called by the Local Security Authority (LSA). These functions are implemented by the MSV1_0 and Kerberos authentication packages provided by Microsoft.
LSA Functions Called by Authentication Packages
The following Local Security Authority (LSA) functions can be called from a custom authentication package. When the LSA calls LsaApInitializePackage to initialize the package, it passes a table of support functions.
Subauthentication Functions
The following subauthentication functions can be called by Microsoft-provided authentication packages to provide additional, user-created logon authentication.
Credentials Management Functions
The following topics provide reference information for the credentials management functions.
Authentication Requirements
Revelation: It means releasing the content of the message to someone who does not have an appropriate cryptographic key.
Message Authentication Functions
All message authentication and digital signature mechanisms are based on two functionality levels:
What is message authentication code?from geeksforgeeks.org
Message Authentication Codes are the codes which plays their role in two important functions : Authentication Detection and Falsification Detection. Where do we need these codes ?
What is the algorithm that efficiently returns a tag given the key and the message?from en.wikipedia.org
A signing algorithm efficiently returns a tag given the key and the message.
How does MAC tag work?from en.wikipedia.org
In this example, the sender of a message runs it through a MAC algorithm to produce a MAC data tag. The message and the MAC tag are then sent to the receiver. The receiver in turn runs the message portion of the transmission through the same MAC algorithm using the same key, producing a second MAC data tag. The receiver then compares the first MAC tag received in the transmission to the second generated MAC tag. If they are identical, the receiver can safely assume that the message was not altered or tampered with during transmission ( data integrity ).
What is MAC algorithm?from en.wikipedia.org
MAC algorithms can be construct ed from other cryptographic primitives, like cryptographic hash functions (as in the case of HMAC) or from block cipher algorithms ( OMAC, CCM, GCM, and PMAC ). However many of the fastest MAC algorithms like UMAC - VMAC and Poly1305-AES are constructed based on universal hashing.
What is universal hashing?from en.wikipedia.org
Universal hashing and in particular pairwise independent hash functions provide a secure message authentication code as long as the key is used at most once. This can be seen as the one-time pad for authentication.
How does MAC differ from digital signature?from en.wikipedia.org
MACs differ from digital signatures as MAC values are both generated and verified using the same secret key. This implies that the sender and receiver of a message must agree on the same key before initiating communications, as is the case with symmetric encryption.
What is digital signature?from en.wikipedia.org
In contrast, a digital signature is generated using the private key of a key pair, which is public-key cryptography. Since this private key is only accessible to its holder, a digital signature proves that a document was signed by none other than that holder. Thus, digital signatures do offer non-repudiation.
What is message authentication?
In information security, message authentication or data origin authentication is a property that a message has not been modified while in transit ( data integrity) and that the receiving party can verify the source of the message. Message authentication does not necessarily include the property of non-repudiation.
What is message authentication without secrecy?
Some cryptographers distinguish between "message authentication without secrecy" systems – which allow the intended receiver to verify the source of the message, but they don't bother hiding the plaintext contents of the message – from authenticated encryption systems.
What is message authentication code?
Message Authentication Codes are the codes which plays their role in two important functions : Authentication Detection and Falsification Detection. Where do we need these codes ?
Can B decrypt a message?
Then in that case, B has no way to realize that it has been falsified.When B decrypts the message, it will get the wrong message. Unknown to the fact B will think wrong information to be the right. Although you can decrypt or encrypt the data later on but these operations, you are applying on the wrong data.
What is the function of authentication?
At the lower level, there must be some sort of function that produces an authenticator: a value to be used to authenticate a message.
Why is it important to authenticate SNMP messages?
For some applications, it may not be of concern to keep messages secret , but it is important to authenticate messages. An example is the Simple Network Management Protocol Version 3 (SNMPv3), which separates the functions of confidentiality and authentication. For this application, it is usually important for a managed system to authenticate incoming SNMP messages, particularly if the message contains a command to change parameters at the managed system. On the other hand, it may not be necessary to conceal the SNMP traffic.
What is a hash function?
Hash function: A function that maps a message of any length into a fixed-length hash value, which serves as the authenticator
Why does B know that the message was generated by A?
Why? The message must have come from A because A is the only other party that possesses K and therefore the only other party with the information necessary to construct ciphertext that can be decrypted with K. Furthermore, if M is recovered, B knows that none of the bits of M have been altered, because an opponent that does not know K would not know how to alter bits in the ciphertext to produce desired changes in the plaintext.
How to add confidentiality to an approach of E?
Confidentiality can be added to the approach of (e) by encrypting the entire message plus the hash code.
Why is authentication less vulnerable to being broken than encryption?
It turns out that because of the mathematical properties of the authentication function, it is less vulnerable to being broken than encryption.
When confidentiality is not required, methods (b) and (c) have an advantage over those that encrypt the?
When confidentiality is not required, methods (b) and (c) have an advantage over those that encrypt the entire message in that less computation is required. Nevertheless, there has been growing interest in techniques that avoid encryption (Figure 11.5e). Several reasons for this interest are pointed out in [TSUD92]:
