# Tag Info

0

First the block cipher can take on more than one general form provided certain criteria are met and in terms of: block cipher, Fk, secure CBC-MAC,and of course CBC mode. Pseudo random generators and permutations as an aside an in response to above are very related in terms of inversion. In symbols F:K*X---> PRP. If a given block cipher is secure this does ...

1

To quote from the paper you linked: The above particular values of $\mathrm{opad}$ and $\mathrm{ipad}$ were chosen to have a very simple representation (to simplify the function’s specification and minimize the potential of implementation errors), and to provide a high Hamming distance between the pads. The latter is intended to exploit the mixing ...

0

The really important thing is, not encrypt-and-mac. The other two, you can debate, but both are at least theoretically sound -- one might just practically be better than the other. Encrypt-and-MAC falls apart for a very simple reason, though: the MAC is not meant to keep the plaintext secret. The MAC is based on the plaintext. Authentication is not designed ...

0

Yes, I don't see why this scheme would not be secure. It uses a MAC over known data - protected against replay. If that data is received or calculated locally shouldn't matter. But as you already showed yourself, you bring down the security of the tag with the amount of bits required to calculate the options. So in the end you could as well just CTR-encrypt ...

3

My understanding of the term 'pepper' is that it more matches your definition 2, in that a pepper is an unknown salt, which makes it a cryptographic secret, but not a key. However, in use it is not as limited by either of your definitions: The pepper can be different (or random) for all users (like a salt). The pepper can be the same for all users (like a ...

2

From the Catena paper, version 2. A salt refers to an additional random input value for the password scrambler, stored together with the password hash. It enables a password scrambler to derive lots of different password hashes from a single password like an initialization vector enables an encryption scheme to derive lots of different ciphertexts from a ...

1

There are two parts to this proposal: the use of a code book and a scheme to send short confidential and authenticated messages utilising an existing shared symmetric key. A code book can be used alone to provide a degree of confidentiality, or can be used to ascribe specific pre-agreed meanings to short messages, in combination with any scheme for sending ...

Top 50 recent answers are included