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seen May 10 at 9:38

A Spanish student of Computer Engineering and Mathematics.


Sep
24
awarded  Autobiographer
May
20
comment Selective format-compliant JPEG encryption?
Hello, e-sushi! Thank you for your reply, I was not really expecting any, anymore :) Still, I can't say I agree with what you're saying, sorry! If you mean compressing from e.g. BMP to JPEG, yeah, I'm with you - it has to be lossy. But if the compression is JPEG->JPEG, it doesn't have to. Think (as in the article linked above) of a procedure consisting in a traditional encryption (e.g. Caesar's encryption, just to keep it simple) on the JPEG coefficients. That would neither lose quality, nor increase the size of the message, would it? Maybe I'm not getting exactly what you mean?
Feb
18
revised Selective format-compliant JPEG encryption?
Added a correction on the problem pointed by fgrieu in comments
Feb
14
awarded  Nice Question
Feb
14
revised Selective format-compliant JPEG encryption?
Extra information provided; small typo corrected
Feb
14
awarded  Editor
Feb
14
revised Selective format-compliant JPEG encryption?
added 339 characters in body
Feb
14
comment Selective format-compliant JPEG encryption?
@fgrieu I was assuming it didn't, and I was wrong. Thanks for pointing that out. Although as you say, this just got a lot more complicated.
Feb
14
awarded  Analytical
Feb
14
revised Selective format-compliant JPEG encryption?
edited tags
Feb
14
awarded  Informed
Feb
14
comment Selective format-compliant JPEG encryption?
Oops, forgot to mention @fgrieu. I have checked, and indeed Facebook removes all EXIF data from the file :( Anyway, thank you for your interest!
Feb
14
comment Selective format-compliant JPEG encryption?
I thought about that approach too, with the EXIF fields (I think those are what you mean, please let me know if I'm wrong!), but they are somewhat limited: they can't grow over 64KB in total -which is a rather small threshold for an arbitrarily large list of regions-, and I'm not really sure if maybe some social networks remove some or all of them on uploading... I'm going to look into that now.
Feb
14
comment Selective format-compliant JPEG encryption?
I would like it to be able to work both with lossy and non-lossy files. Worst case scenario, just JPEG would be enough, since e.g. a BMP could be compressed to JPEG and then encrypted. Size, ideally, should not grow dramatically, but small variations would be OK. In the non-blurred area, pixel-for-pixel accuracy is not required, as long as it still "looks good" to the eye.
Feb
13
awarded  Student
Feb
13
asked Selective format-compliant JPEG encryption?