encrypt and compress data

nanga

If you had to both encrypt and compress data during transmission, which would you do first, and why?

dynamik

My guess would be to compress it since compression algorithms would probably be more efficient with standard types of data. Once you scramble everything with encryption, you'll probably lose a lot of the common patterns that allow the highest amount of compression.

Like I said, that's just a guess. I wouldn't treat that as a definitive answer.

undomiel

I would have to concur with dynamik.

nanga

googled this

“Compress then encrypt. If you encrypt first you’ll have nothing but random data to work with, which will destroy any potential benefit from compression.”....

shednik

nanga wrote:

googled this

“Compress then encrypt. If you encrypt first you’ll have nothing but random data to work with, which will destroy any potential benefit from compression.”....

Sounds about right to me...

tiersten

If you get highly compressible data after you've encrypted it then your encryption algorithm sucks and you should find another one or operate it in different mode.

JDMurray

tiersten wrote:

If you get highly compressible data after you've encrypted it then your encryption algorithm sucks and you should find another one or operate it in different mode.

"Poorly-diffused cipher-text" is the term.