4 ms·
>An encrypted signal can't be "too random" It should if encryption is good. After all, security proofs for encryption define "secure" as "indistinguishable fro
by romaniv 11y ago
>An encrypted signal can't be "too random"
It should if encryption is good. After all, security proofs for encryption define "secure" as "indistinguishable from random".
- mojuba 11y agoA signal that contains anything other than noise can not be absolutely indistinguishable from noise. Otherwise you won't be able to decrypt it.
- DanBC 11y ago> Otherwise you won't be able to decrypt it. Why not?
- mojuba 11y agoBecause the only way to make your signal appear more random is to add more redundancy. In order to make it look like an absolute random signal you'd have to add infinite redundancy.
- DanBC 11y agoRedundant data is compressible data. Random data is not compressible. Adding redundant data to random data will make it more compressible - less random.
- stouset 11y agoIt's computationally distinguishable from noise iff you have the decryption key. The key word here is "computationally". A signal encrypted with a non-OTP symmetric key can be distinguished from noise without the key — unfortunately, for modern key sizes (128, 196, or 256 bits), the cost of doing so is prohibitively expensive for even arbitrarily advanced civilizations, unless (as Brice Schneier put it) they are building computers out of something other than matter that occupy something other than space.