Criticisms of a cipher system such as \'the ciphertext from one message must be

Question

Criticisms of a cipher system such as 'the ciphertext from one message must be indistinguishable from the ciphertext of a second message" surely only apply when there are very large amounts of ciphertext available. If a stream cipher involves a limited number of messages (say 10) of limited length (say 1000 characters each) enciphered with differently keyed streams, then surely there is not sufficient information available for breaking the cipher?

The focus of modern cryptology on computer systems that pump out billions of characters is in fact just on a partial domain of all cryptology.

Explanation / Answer

A viable answer to the question, as posed in the title, is: No

If a stream cipher involves a limited number of messages (say 10) of limited length (say 1000 characters each) enciphered with differently keyed streams, then surely there is not sufficient information available for breaking the cipher?

As you would expect, this depends completely on the scheme. If the cipher is very weak then no, even this might not be sufficient (eg the age-old Caesar/rotation cipher might be broken within 10 character messages). On the other hand, if a scheme is still secure even when 256 characters have been sent, then it will certainly be secure if we limit to just 104?213 characters!

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