Are Stream Ciphers Less Secure?

Question

This is by no means a scientific observation, but it seems to me that stream ciphers receive a lot less attention than block ciphers. Is there any reason for this? (Is it because block ciphers are accepted as superior?)

Additionally, since there is no "AES" of stream ciphers, is there any reference of currently secure stream ciphers other than the few green entries on this Wikipedia page? I know about NESSIE/eSTREAM but much of the trust in an algorithm comes not just from its claimed security, but also from the amount of scrutiny it has received, and it seems that none of those ciphers has been the subject of much debate.

Answer 1

Block ciphers receive more attention because they are relatively easier to handle. You may apply a study on one block cipher to another. Attack on a block cipher may be generalized to other ciphers of similar properties. Modern stream ciphers require unique approach in most cases, whatever you do on one stream cipher may not be useful on another. In this sense, a block cipher is more attractive and rewarding subject. Being more attractive, block ciphers receive more attention and thus better studied (formal proofs, etc.) Better studied means more preferable.

Plus, block ciphers are universal because of modes and easier to use safely for practitioners.

Answer 2

The fact that block ciphers can be run in stream like modes diminishes the need for stream ciphers. Add to this the fact that a number of processors today are being built with instructions to speed up AES, and even the performance advantages of stream ciphers is less.

RC4 is still used today, but has shown significant weaknesses and is therefore not recommended in newer designs. The eStream project was put forth to develop new stream ciphers and the ciphers picked for the final portfolio have been well analyzed. They are still probably too new for general acceptability, but I have started to see some of the being used in the wild, especially Salsa20.

Personally, if I were designing a new system and needed a stream cipher, I'd use AES in GCM or CCM. That way you get the streaming capabilities of CTR mode, with authentication.