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Non-repudiation is the assurance that someone cannot deny something.

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Need help with NFC Tags and cryptography

I have some NFC-Tags, which will be added to my devices. These NFC Tags are basically EEPROMs with an unique UUID (7-Byte, readonly, public) and some constant parameters (approx. 7-15 Bytes, read and ...
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1answer
63 views

Can non-repudiation be ensured without public-key cryptography?

Message authentication is ensured by using HMAC, which can be thought of as a symmetric-key construction. Source authentication in multicast communications can be guaranteed using TESLA, which is ...
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1answer
73 views

Why non-repudiation is not in Cryptography definition

According to the "Handbook of Applied Cryptography" Cryptography is the study of mathematical techniques related to aspects of information security such as confidentiality, data integrity, ...
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3answers
62 views

Does the Message Integrity Check in WPA(2) standard solve the problem of non-repudiation?

Whether the receiver can be sure that the message is sent by the source only and not spoofed by someone else?
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3answers
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Security services provided by digital signature

Which of the security services can be provided by digital signature? data integrity nonrepudiation sender authentication receiver authentication I think it can provide nonrepudiation. Because ...
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2answers
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Why/how is libsodium/nacl's cryptobox repudiable?

https://nacl.cr.yp.to/box.html see "security model". As far as I can see, Alice encrypts a message using her private key, Bob's public key and a nonce. Bob decrypts the message using Alice's public ...
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6answers
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Why MACs are so important despite digital signatures doing everything a MAC can do and more

When an entity A wants to send a message to entity B, he can attach a MAC to the message. Entity B on receiving the message can use the pre-shared key to compute the same MAC and confirm if the ...
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0answers
147 views

Non-repudiation in classical cryptosystem

How can we modify classical cryptography system to provide non-repudiation? I want to ensure non-repudiation in symmetric key cryptography so that we can find out who is sender of a particular ...
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2answers
309 views

When is data origin authentication necessary but non-repudiation not?

I have been considering this question now for a week and I just cannot find an answer. I understand that non-repudiation cannot be provided without data origin authentication but I cannot think of an ...
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1answer
231 views

Non-deniability of data sent over TLS

Andy is going to connect to a server Selma over TLS. Later, Andy would like to be able to publish everything (the ciphertexts, the plaintexts, all his keys) and prove to a mediator what data he sent ...
3
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1answer
119 views

Are HTTPS web sessions non-repudiable?

(This is probably a basic question, and may be a duplicate; if so, just let me know.) Suppose there are two clients A and B, ...
3
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2answers
246 views

How does DSA provide non-repudiation in proving a document was properly displayed (not altered or displayed incorrectly)?

I am building an iOS app that allows the user to sign a document served to them by a web server. So that page of the app simply has a document in the top pane, and at the bottom pane, a place to sign ...
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1answer
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Security properties and Cryptography objectives applied in algorithms

We all know there are five properties of Security. They are: Confidentiality Availability Authorization Integrity and Provenance As Security and Cryptography are co-related these properties also ...
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3answers
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How can we sign a contract digitally between two parties?

I'm trying to sign a contract with another party, without using handwritten signatures. I've just read through Applied Cryptography, but there doesn't seem to be a protocol that can solve this ...
0
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1answer
167 views

Generate random in secure message transfer

I’m doing a school assignment about secure communications between a Server and a Client. Basically, messages are exchanged between the clients and the server and these communications must implement ...
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3answers
566 views

Can one have an authentic, but repudiable, message without a previously shared secret?

Bob wants to send a message to Alice, such that Alice can be sure that the message came from Bob, but can't prove it to anyone else. If I understand right, this means that the same message could have ...
134
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1answer
64k views

What are the differences between a digital signature, a MAC and a hash?

A message may be accompanied with a digital signature, a MAC or a message hash, as a proof of some kind. Which assurances does each primitive provide to the recipient? What kind of keys are needed?
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3answers
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Can I use PGP to sign a message without providing cryptographic non-repudation?

The difference between a digital signature and a MAC is non-repudiation. A message with a digital signature proves that only the sender could have signed the message, whereas a message with a MAC ...
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2answers
1k views

Does a trace of SSL packets provide a proof of data authenticity?

I'm wondering if it would make sense to record a whole HTTPS session, publish its encryption keys and present it to third parties as a proof that this particular data was sent by a given server ...
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2answers
569 views

How should one implement a delegated shared trust protocol?

Consider the following (probably naive) scenario. Alice, who is very limited in her knowledge of security in general (clueless about securing a private key for example), wishes to delegate certain ...