4
votes
2answers
194 views

Authenticated encryption without padding

I want to encrypt data and protect its integrity and confidentiality. However, I cannot increase the length of the data. Are there any cipher modes of operation which provide confidentiality and ...
8
votes
2answers
473 views

Why should I use Authenticated Encryption instead of just encryption?

There are various different modes of operation for block cipher use, some of which provide "encryption" and some of which provide authenticated encryption. Why should I use an authenticated ...
7
votes
2answers
1k views

Practical disadvantages of GCM mode encryption

It seems that GCM mode encryption has a clear advantage over CBC + HMAC in the sense that it only requires a single key. But it seems that there are some experts here that do not trust it enough to ...
4
votes
1answer
300 views

Authenticated encryption mode for stream cipher?

E. g. block ciphers have GCM or OCB, that take single cryptographic primitive (block cipher) and provide both authentication and encryption. Are there similar constructs for stream ciphers, which ...
5
votes
1answer
449 views

Practical uses of Manipulation Detection Code (MDC) and IGE

I've just skimmed over most of the paper "On Message Integrity in Symmetric Encryption". I've included (the last) part of the abstract below: We show that generic compositions of ...
3
votes
2answers
87 views

Is it possible to insert a key derivation function when using EAX?

I am currently investigating use of EAX mode for a dedicated application and following useful clarifications received from my previous post , to consider according to my applicable input security ...
4
votes
1answer
136 views

Does EAX use the same keys for encryption and authentication?

I am actually checking use of EAX AEAD mode, and following EAX spec review (scheme definition for my part), my question is: what about the derivation of the authentication and encryption keys? In the ...
1
vote
1answer
107 views

How to build a secure AE scheme with generic composition?

I am actually looking for using a secure Encrypt-Then-MAC AE scheme , and consider using either an existing "ready-to-use" dedicated AEAD mode (GCM, OCB, CCM, EAX, etc ..) or an alternate composed ...
3
votes
1answer
127 views

What “Tag Length” should be used for the EAX MAC?

Since EAX is very flexible with regard to the length of the calculated MAC (what they call "tag" is the MAC value right?), and the EAX paper as well as other documentations carefully avoid suggesting ...
9
votes
2answers
2k views

Why do we need special key-wrap algorithms?

Wikipedia says: Key Wrap constructions are a class of symmetric encryption algorithms designed to encapsulate (encrypt) cryptographic key material. We are using these algorithms to encrypt ...
13
votes
1answer
861 views

Why choose an authenticated encryption mode instead of a separate MAC?

What are cryptographic reasons to choose an authenticated-encryption mode of operation (such as GCM) over a traditional encryption mode plus an independent MAC, or vice versa? Assume there is no ...