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Dec
10
comment Can I use PGP to sign a message without providing cryptographic non-repudation?
@AJ Henderson - That would provide non-repudiation, which is an undesired property. The recipient can pass Encrypt(symmetric_key, (message, mac)) and Encrypt(public_key, Sign(private_key, symmetric_key)) to a third party, and the third party can be confident the message originated from the sender, since the recipient could not have forged it.
Dec
10
awarded  Commentator
Dec
10
comment What are the differences between a digital signature, a MAC and a hash?
Why am I being downvoted? It's not homework, and any way, homework questions are allowed.
Dec
10
comment Can I use PGP to sign a message without providing cryptographic non-repudation?
Your solution would be to pass Encrypt(symmetric_key, (message, mac)) and Encrypt(public_key, symmetric_key) to the recipient. How does this provide authentication? Surely, any attacker could form this pair of cipher-texts.
Dec
10
comment Can I use PGP to sign a message without providing cryptographic non-repudation?
Someone deleted my comment.
Dec
10
comment Can I use PGP to sign a message without providing cryptographic non-repudation?
That's what I want to find out.
Dec
10
comment Can I use PGP to sign a message without providing cryptographic non-repudation?
Yes, there is a difference between authentication and non-repudiation.
Dec
10
answered What are the differences between a digital signature, a MAC and a hash?
Dec
10
asked What are the differences between a digital signature, a MAC and a hash?
Dec
10
comment Can I use PGP to sign a message without providing cryptographic non-repudation?
I downvoted this answer, because it does not distinguish correctly between a digital signature, a MAC and a hash.
Dec
10
comment Can I use PGP to sign a message without providing cryptographic non-repudation?
A digital signature proves that the message has been signed by the holder of the signature key, this proof can be passed to a third party, such as a judge. A MAC proves that the message has been signed by either the sender or the recipient, the recipient can not pass it to a third party to prove that the sender signed the message, since the recipient could also have generated the MAC. A hash proves that the message has not been modified assuming that the hash has not been modified, but it does not provide authentication, since anyone can create a hash.
Dec
9
comment Can I use PGP to sign a message without providing cryptographic non-repudation?
Is there any way using asymmetric encryption that you can achieve what a MAC achieves: authentication without non-repudiation?
Dec
9
comment Can I use PGP to sign a message without providing cryptographic non-repudation?
You don't have to publish your private key to remove non-repudiation, you can simply use a MAC. See this
Dec
9
asked Can I use PGP to sign a message without providing cryptographic non-repudation?
Dec
5
awarded  Scholar
Dec
5
accepted Is there any research on the problem of making a number more memorable to humans?
Dec
3
awarded  Student
Dec
3
asked Is there any research on the problem of making a number more memorable to humans?
Nov
7
awarded  Supporter