Comment:
(I am) Still confused about public key cryptography.
Follow-up:
Simply put, in a public key cryptosystem, each user owns a pair of keys, one made public and the other kept secret. To send a message securely, the public key of the intended recipient is used for the encryption so that only the recipient can decrypt it. On the other hand, for digital signature, the signer uses his/her own private key to encrypt the message (or actually the digest of the message) so that everyone can decrypt it using the signer’s public key to verify it.
For those of you who are interested in the mathematical details, please study the attached lecture notes on public key cryptography (file: module3-PublicKeyCrypto.pdf).
Comment:
How does KDC work?
Follow-up:
The KDC shares secret key (or symmetric key) with every register user. Thus, by using this key, the KDC can send a newly generated key (denoted as R1 in Presentation #5) to a user requesting for a new key to be shared with another register user of the KDC. Once getting this R1, the two users can then transform it further using some agreed-upon protocol to generate the actual shared key which is unknown to the KDC.
Comment:
I want to know if it is possible to combine the use of public and private keys as follows.
Follow-up:
Yes of course your suggestion would work. In fact, it provides not only “confidentiality” but “non-repudiation” as well.
I was confused about public key cryptography mechanism. This article has helped me a lot to understand the whole idea. You have nicely explained and provided an absolute detail about this concept. Thanks.
ReplyDeletepublic key infrastructure