Which asymmetric cryptographic system provides confidentiality and non repudiation
|
I have read on wikipedia "However, symmetric ciphers also can be used for non-repudiation purposes by ISO 13888-2 standard." Show Then again and I read on another wiki page, "Non-repudiation, or more specifically non-repudiation of origin, is an important aspect of digital signatures. By this property an entity that has signed some information cannot at a later time deny having signed it. Similarly, access to the public key only does not enable a fraudulent party to fake a valid signature. This is in contrast to symmetric systems, where both sender and receiver share the same secret key, and thus in a dispute a third party cannot determine which entity was the true source of the information." This means one page says symmetric algorithms have non-repudiation and another page says they don't have it and therefore they are not used for digital signatures. So do symmetric keys have non-repudiation or not? It makes sense that they can not be used for signatures and non-repudiation since symmetric keys are the same and thus the system can't distinguish which one belongs to which person and which one is first etc. In that case I think symmetric keys are only a tool for confidentiality and not used for non-repudiation or digital signatures. asked Oct 24, 2010 at 16:06 As for non-repudiation, the tricky part is that it's not technical but rather legal term and it causes a lot of misunderstanding if placed in technical context. The thing is that you can always repudiate anything you have done. And that's why there are courts. In the court two parties are confronted and try to prove each other wrong using evidence. Here's where technology comes, as it allows to collect sufficient electronic evidence to prove wrong the party that tries to deny a transaction, message etc. And this is exactly what ISO 13888 series does in part 1: it provides guidelines on what evidence to collect and how to protect it to maximise your chances of countering a repudiation of electronic transaction. This standard talks about a number of tokens that serve this purpose. These tokens are for example: identifiers of both parties, timestamps, message hashes etc. Then it goes into details on how you should protect these tokens so that they retain their value as evidence. The two other parts (2 and 3) describe specific cryptographic techniques that can be applied to obtain tokens. Symmetric ones are just keyed hashes if I remember correctly (such as HMAC), while assymetric is digital signature. answered Nov 15, 2013 at 23:37
kravietzkravietz 10.2k2 gold badges32 silver badges27 bronze badges I think the answer depends on whether the shared key is public or not. If the parties agree to public source (third party) for their shared key there is non-repudiation of origin. answered Oct 24, 2010 at 16:21
FergusFergus 2,7532 gold badges26 silver badges39 bronze badges 2 ISO 13888-2 introduces structures and protocols which can be used to introduce non-repudiation services, in the context of symmetric techniques. However all these "tricks" rely on the existence of a Trusted Third Party. The point of the second Wikipedia citation in the question is that asymmetric key systems intrinsically [and without the need of thrid parties] offer non-repudiation features (specifically NRO i.e. non-repudation of the the Origin). answered Oct 24, 2010 at 16:30
mjvmjv 71.5k14 gold badges111 silver badges156 bronze badges 1 You've used BitLocker to implement full volume encryption on a notebook system. The notebook motherboard does not have a TPM chip, so you've used an external USB flash drive to store the BitLocker startup key. You use EFS to encrypt the C:\Secrets folder and its contents. -If the C:\Secrets\confidential.docx file is copied to an external USB flash drive, the file will remain in an encrypted state. -The EFS encryption process will fail. -Only the user who encrypted the C:\Secrets\confidential.docx file is able to boot the computer from the encrypted hard disk. -Any user who is able to boot the computer from the encrypted hard disk will be able to open the C:\Secrets\confidential.docx file. -By default, only the user who encrypted the C:\Secrets\confidential.docx file will be able to open it. -If the C:\Secrets\confidential.docx file is copied to an external USB flash drive, the file will be saved in an unencrypted state. Does asymmetric encryption provide nonAsymmetric encryption also offers: Authentication —Asymmetric encryption helps you to verify identities in a way that no one can fake or contest (this is known as non-repudiation), which makes this process is ideal for encrypting data between third parties who don't know each other.
Does asymmetric encryption provide confidentiality?This system provides no confidentiality, because anyone can decrypt the message using the owner's public key. However, it does verify the sender's identity, because if the associated public key will decrypt the message, it could only have been encrypted with that person's private key.
How can asymmetric key cryptosystems being used to ensure nonIn 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.
Which protocol symmetric or asymmetric does have better nonFrom the security perspective, asymmetric encryption is undoubtedly better as it ensures authentication and non-repudiation. However, the performance is also an aspect that we can't afford to ignore, and that's why symmetric encryption will always be needed. A single key is used to encrypt and decrypt data.
|
