Which of the following security services assures that messages are received as sent?

Cryptography is the science of writing in secret code so that no other person except the intended receipient could read

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Goals of Cryptography
What is nonrepudiation?
Information assurance and nonrepudiation
Nonrepudiation, message authentication code and digital signatures
Drawbacks of nonrepudiation with digital signatures
Which of the following security services ensures that messages are received as sent with no duplication insertion modification reordering or replays?
Which of the following security services ensures that message?
What are the 5 security services?
Which of the following security services the protection of transmitted data?

Cryptography is the practice and study of techniques for secure communication in the presence of third parties. More generally, it is about constructing and analyzing protocols that overcome the influence of attackers or outside people and which are related to various aspects in information security such as data confidentiality, data integrity, authentication, and non-repudiation. Applications of cryptography include ATM cards, computer passwords.

Cryptography is the science of using mathematics to encrypt and decrypt data. Cryptography enables you to store sensitive information or transmit it across insecure networks (like the Internet) so that it cannot be read by anyone except the intended recipient.

Goals of Cryptography

The Main Goals of cryptography

Data Privacy(confidentiality)
Data Authenticity(it came from from where it claims)
Data integrity(it has not been modified on the way) in the digital world

Confidentiality

Confidentiality is most commonly addressed goal
The meaning of a message is concealed by encoding it
The sender encrypts the message using a cryptographic key
The recipient decrypts the message using a cryptographic key that may or may not be the same as the one used by the sender

Data Integrity

Integrity Ensures that the message received is the same as the message that was sent
Uses hashing to create a unique message digest from the message that is sent along with the message
Recipient uses the same technique to create a second digest from the message to compare to the original one
This technique only protects against unintentional alteration of the message
A variation is used to create digital signatures to protect against malicious alteration

Authentication

A user or system can prove their identity to another who does not have personal knowledge of their identity
Accomplished using digital certificates
Kerberos is a common cryptographic authentication system

What is nonrepudiation?

Nonrepudiation ensures that no party can deny that it sent or received a message via encryption and/or digital signatures or approved some information. It also cannot deny the authenticity of its signature on a document.

Although it originated as a legal concept, nonrepudiation is also widely used in computing, information security and communications.

Information assurance and nonrepudiation

Nonrepudiation is one of the five pillars of information assurance (IA), which is the practice of managing information-related risks and protecting information systems, like computers, servers and enterprise networks. The other four pillars are the following:

integrity
availability
authentication
confidentiality

Nonrepudiation provides proof of the origin, authenticity and integrity of data. It provides assurance to the sender that its message was delivered, as well as proof of the sender's identity to the recipient. This way, neither party can deny that a message was sent, received and processed.

Nonrepudiation is like authentication, particularly with respect to implementation. For instance, a public key signature can be a nonrepudiation device if only one party can produce signatures.

In general, nonrepudiation combines both authentication and integrity.

Nonrepudiation is one of the pillars of information assurance.

Nonrepudiation, message authentication code and digital signatures

Nonrepudiation is achieved through cryptography, like digital signatures, and includes other services for authentication, auditing and logging.

In online transactions, digital signatures ensure that a party cannot later deny sending information or deny the authenticity of its signature. A digital signature is created using the private key of an asymmetric key pair, which is public key cryptography, and verified with a corresponding public key.

Only the private key holder can access this key and create this signature, proving that a document was electronically signed by that holder. This ensures that a person cannot later deny that they furnished the signature, providing nonrepudiation.

In cryptography, a message authentication code (MAC), also known as a tag, is used to authenticate a message or confirm that the message came from the stated sender and was not changed along the way. Unlike digital signatures, MAC values are generated and verified using the same secret key, which the sender and recipient must agree on before initiating communications.

A MAC can protect against message forgery by anyone who doesn't know the shared secret key, providing both integrity and authentication. However, MAC algorithms, like cipher-based MAC and hash-based MAC, cannot provide nonrepudiation.

In addition to digital signatures, nonrepudiation is also used in digital contracts and email. Email nonrepudiation involves methods such as email tracking.

Drawbacks of nonrepudiation with digital signatures

Since no security technology is foolproof, some experts warn that a digital signature alone may not always guarantee nonrepudiation. Some suggest using multiple approaches to ensure nonrepudiation. One such practice is to capture biometric information and other data about the sender or signer that collectively would be difficult to repudiate.

It's also important to know that the current definitions of nonrepudiation in the digital space consider only the validity of the signature itself. They do not allow for the possibility that the signer was manipulated, forced or tricked into signing. It's also feasible that a virus, worm or other type of malware can compromise a sender's private key, possibly stealing or forging its digital signature and jeopardizing nonrepudiation.

Specific information about a sender or signer through biometrics strengthens the nonrepudiation process.

To avoid such issues and to ensure that a digital signature is valid -- and, therefore, the appropriate choice for nonrepudiation -- it must be established through a secure and fully trusted document handling and signature mechanism.

Another concern is the possibility that a digital signature remains the same, even if it's been faked by someone who has the private key. The U.S. Department of Defense addressed this problem with the common access card (CAC), a type of smart card for active duty defense personnel.

The CAC proves the holder's identity and enables physical access to controlled spaces and defense computer systems. It satisfies the requirements for digital signatures, as well as three IA pillars: nonrepudiation, integrity and authentication.

This was last updated in August 2021

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Which of the following security services ensures that messages are received as sent with no duplication insertion modification reordering or replays?

So the third element, data confidentiality ensures that the messages are received as sent with no duplication, insertion, modification, reordering, replay or loss.

Which of the following security services ensures that message?

The authentication service is concerned with assuring that a communication is authentic. In the case of a single message, such as a warning or alarm signal, the function of the authentication service is to assure the recipient that the message is from the source that it claims to be from.