gpg signature for photography (jpeg)

[ThierryIT]

Hello there,

I am using gpg to encrypt and sign documents and emails.
I am wondering if it is possible to include in a photography a gpg signature (not separate) ?
Something similar to a copyright.

Thx


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[Le Forgeron]

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Le 09/02/2016 08:15, ThierryIT a écrit :
> Hello there,
>
> I am using gpg to encrypt and sign documents and emails. I am
> wondering if it is possible to include in a photography a gpg
> signature (not separate) ? Something similar to a copyright.
>
> Thx

What would you sign ? obviously not the whole file (problem of
self-reference, hard to perform when the signature is not the very end
of the file)

How would that be like a copyright ? a copyright is a legal matter.
Or did you mean like a copyright tag ? kind of a watermark ?

You might want to look for watermark and steganography.


You could sign the picture block, adding the signature in some tag
inside the data part, but that would not disallow someone to remove
that tag. The purpose of a signature would be to check the
non-tampering of the signed part, by itself it does not provides any
protection about tampering the container and dropping the signature.

What format is the photography in ? most usual formats allow for
metadata, some have open-specification and tags, which means that
conformant readers would jump over unknown sections.

But the easy way to get ride of any meta-data is to convert to a
format which do not have any, then back to whatever is suitable. If
someone can view the picture, it can be transformed to another format
for the same visual aspect, and any attached string can be removed.

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