Re: A cipher operates with more possible plaintexts than possible keys. What does this mean?
 From: kg <kristiag+news@xxxxxxxxxxxx>
 Date: Sat, 12 Mar 2011 09:13:56 +0000 (UTC)
rossum <rossum48@xxxxxxxxxxxx> wrote:
On Tue, 08 Mar 2011 17:07:23 GMT, unruh
<unruh@xxxxxxxxxxxxxxxxxxxxxxx> wrote:
Any cypher except theOTP has a smaller key than plaintexts. It meansNitpick: Any cypher except the OTP has a smaller key than _the largest
that it is theoretically breakable, if the plaintext has structure to
it.
possible_ plaintexts.
I may want to encipher "No" which is smaller than most keys. Even
with padding it will not be larger than most block cypher keys.
While we're picking nits: There are many ciphers with a key that's larger
than the largest possible plaintext.
Example: The alphabet is Zn, the key is a sequence of pairs (ai,bi),
such that ai is invertible in Zn, and we encrypt (x1,x2,...,xn) as
(a1*x1+b1, ..., an*xn+bn).
The key is much larger than the largest possible plaintext.

kg
.
 References:
 A cipher operates with more possible plaintexts than possible keys. What does this mean?
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 Re: A cipher operates with more possible plaintexts than possible keys. What does this mean?
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 Re: A cipher operates with more possible plaintexts than possible keys. What does this mean?
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