The Infona portal uses cookies, i.e. strings of text saved by a browser on the user's device. The portal can access those files and use them to remember the user's data, such as their chosen settings (screen view, interface language, etc.), or their login data. By using the Infona portal the user accepts automatic saving and using this information for portal operation purposes. More information on the subject can be found in the Privacy Policy and Terms of Service. By closing this window the user confirms that they have read the information on cookie usage, and they accept the privacy policy and the way cookies are used by the portal. You can change the cookie settings in your browser.
We investigate and compare several constructions of pseudorandom number generators based on block ciphers in counter mode. An idealized models of those constructions are considered, where the block ciphers are assumed to be random permutations. For these models we compute lower and upper bounds for conditional probabilities for the next element to appear given a prefix. We also consider a few criteria...