Questions tagged [non-repudiation]
Non-repudiation is the assurance that someone cannot deny something.
30 questions
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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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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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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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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 ...
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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 ...
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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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How can you prove that a certain file was downloaded from a certain website?
Let's say you downloaded a file from a certain website, and later the website claims that it didn't made that file available, is there any way to prove that the website is lying?
Example 1: You ...
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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 ...
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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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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 ...
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Security services provided by digital signature
Which of the security services can be provided by digital signature?
data integrity
non-repudiation
sender authentication
receiver authentication
I think it can provide non-repudiation. Because ...
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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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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, ...
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Names and games for security properties preventing substitution of signed message by the signer
Some signature schemes, notably ECDSA, unwillingly allow users to prepare their public/private key pair as a function of two arbitrary messages of their choice, and compute a signature that checks for ...
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Non Repudiation - Message Authentications methods
According to a definition given by my professor:
Message authentication methods verify that the message is from the
right sender, however they don't guarantee non-repudiation.
To me this sounds ...
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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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Data Origin Authentication vs Non Repudiation?
I'm looking into how authenticated encryption primitives work and was wondering if non-repudiation is provided with these. Investigating further into them led to the answer being that data origin ...
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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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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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Non-repudiation isn't a part of cryptography?
According to the "Handbook of Applied Cryptography" by Alfred J. Menezes, Paul C. van Oorschot, and Scott A. Vanstone (CRC Press, 1997; p.4):
Cryptography is the study of mathematical ...
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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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Non-Repudiation vs Identity-Binding
There are 3 properties offered by a cryptographic digital signature scheme:
Integrity guarantee of the message signed.
Authenticity guarantee of the message signed.
Non-repudiation of the message ...
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Non-repudiation and digital signature of a dishonest participant
Let's assume a dishonest Alice who sends, encrypts & digitally signs a message to Bob.
Bob stores the decrypted message and the digital signature in a database.
However, Alice is a bad girl and ...
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How to use OpenSSL to prove non-repudiation
If I download https://example.com/foo.txt, how can I prove to a third party that I got it from https://example.com.
I understand that their private key is used to secure the channel, rather than to ...
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If I want Integrity and Authentication AND Non-Repudiation, can the Digital Signature be based on the MAC?
Let's say I'm making a digital signature like this:
hash = hash(message)
digital signature = encrypt_with_private_key(hash)
where the private key is Alice's ...
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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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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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Bandwidth-Efficient Non-Repudiation
I'm working on a project that involves broadcast (uni-directional) streaming and requires non-repudiation. Essentially, a device broadcasts a data stream over the air, and any receiving station needs ...
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Prove a response was received from the particular Tor hidden service
Consider a Tor hidden service. I want to retrieve the main page of such website in such a way that I can later prove to a skeptical third party that the website with this certificate (identified by ...
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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 ...
