I wish to digitally sign my image collection which consists of JPG , TIFF , BMP , SWf , Fla files.
My question is how to digitally sign these images? If I sign JPG or Tiff , whether signature will get attached to these files (as it happens in document files like PDF or MS word etc)? If so where it get store in file metadata fields , or remain outside? Can i extract signature data?
Please note I wish to sign these images Individually and do not want to get converted into any other format like PDF. Also I donot wish to sign it using email client.
In general those formats were not designed with signing in mind, so your best option is to create a detached signature and keep it near the file. An alternative is to use wrapping signature but then other software won't be able to display the image until you remove the wrapper.
Storing the signature in metadata can be possible for some formats but what applications would be able to handle this?
I know it has been a long time, but you might want to look into steganography. Metadata can be extracted and removed from files. Steganography will allow you to embed digital signatures(encrypted phrases) in a way that is almost only detectable using statistical analysis.
You can also create a mime container which will contain the original image and a detached signature.
Attached signatures are only useful for specific apps, as they are not standard.
Try answering the posters question folks, and not giving another unneeded and unwanted opinion, it's way to common these days in my humble opinion.
Obviously what the poster asked for is to use a signature to copyright his works, so you need to sign the image, period, And a method to do so.
So let's see... grab Gimp or Photoshop. Get your image and create a new layer with transparent background. write in a signature with your mouse or digital pen in an area near the bottom right edge. Choose merge layers and flatten image. Seems like that would do it.
Related
Project Environment
The environment we are currently developing is using Windows 10. nodejs 10.16.0, express web framework. The actual environment being deployed is the Linux Ubuntu server and the rest is the same.
What technology do you want to implement?
The technology that I want to implement is the information that I entered when I joined the membership. For example, I want to automatically put it in the input text box using my name, age, address, phone number, etc. so that the user only needs to fill in the remaining information in the PDF. (PDF is on some of the webpages.)
If all the information is entered, the PDF is saved and the document is sent to another vendor, which is the end.
Current Problems
We looked at about four days for PDFs, and we tried to create PDFs when we implemented the outline, structure, and code, just like it was on this site at https://web.archive.org/web/20141010035745/http://gnupdf.org/Introduction_to_PDF
However, most PDFs seem to be compressed into flatDecode rather than this simple. So I also looked at Data extraction from /Filter /FlateDecode PDF stream in PHP and tried to decompress it using QPDF.
Unzip it for now.Well, I thought it would be easy to find out the difference compared to the PDF without Kim after putting it in the first name.
However, there is too much difference even though only three characters are added... And the PDF structure itself is more difficult and complex to proceed with.
Note : https://www.adobe.com/content/dam/acom/en/devnet/pdf/pdfs/PDF32000_2008.pdf (PDF official document in English)
Is there a way to solve the problem now?
It sounds like you want to create a PDF from scratch and possibly extract data from it and you are finding this a more difficult prospect than you first imagined.
Check out my answer here on why PDF creation and reading is non-trivial and why you should reach for a tool you help you do this:
https://stackoverflow.com/a/53357682/1669243
I'm looking at adding an image to an existing PDF in Node.js. None of the PDF libraries I found appear to have the ability to modify an existing PDF though, so I'm planning on implementing it myself. I'm trying to figure out if it's too much work, as I can always do it server side using iTextPDF instead, but I'd prefer to do it in my app (Electron which uses Node.js).
If I just want to modify an existing PDF and add an image, will I have to write a complete rendering library or is PDF structured in such a way that I can write a very small parser that just gets the page I want and inserts an image using the correct format?
Specifically, I'm asking because I've previously looked into writing a text extraction library, put in order to get the position of text you have to render pretty much the entire PDF because of how positioning is handled. That's too much work to get around server side processing in this case.
To be clear, just asking if it's possible to do, not how to do it (don't want to be too broad, I'm sure I can figure that part out).
To perform a small manipulation of a PDF, you'll need to implement generalized reading, decompression, encryption and traversal of PDF data structures. Some of the thing you would need to handle include:
basic parsing of PDF syntax
indexing via the cross reference index, and/or cross reference index and object streams
objects (num, byte-string, hex string, dictionary, arrays, booleans...)
filters and variants (LZW, Flate, RunLength, Predictors)
encryption (RC4, AES, Custom security handlers)
page tree traversal
basic handling of page content streams
image handling
serialization, either rewriting of the entire PDF, or incremental updates to an existing PDF
Anything's possible, but realistically, you will need a PDF library or toolkit, client or server-side, to accomplish this.
I have a client that wants to be able to find their proprietary images other places on the internet if someone steals them.
Is there a way to add meta information that we can track for this purpose inside a jpg file?
My answer was getting too long for comment so posting it as answer.
you can add an entry in EXIF IFD(metadata in binary) of jpeg image. It is not visible in image as it is. There are many EXIF editor/reader tools which will allow you to edit/read it. for example you can add a particular string in makernote of jpeg.
As I said, there are tools available in market, this also means that people can edit also reset the complete EXIF metadata which will erase your data too....
To get around this you can add your copyrighted IFD entry which only you can understand. For this you have to edit some EXIF tool and tweak according to your need.
But while adding your entry in JPEG metadata please take care that you adhere to EXIF/TIFF specifications so that image is not corrupted and readable in all platforms.
Here are some links to help you understand EXIF/TIFF -
http://gvsoft.homedns.org/exif/exif-explanation.html
and
http://www.exif.org/Exif2-2.PDF
I need to use PDF in a way similar to ZIP/RAR. To hold many images (ancient tibetan buddist literature), ideally 60000. But splitting in 10-100 volumes is OK.
Anything can be used for packing, but for unpacking we need Node.js. Because same PDF file must be served on web. But some users will need to use whole PDF.
So the question is, what node module I can use to read any single arbitrary image from huge PDF? Example would really help.
Every image is a single page. (Or in otherwords every page is single image)
We have been using https://github.com/mirkokiefer/Node-Magick for this....
But the pngs we get out sometimes are fairly low quality..
Imagine an environment in which users can upload images to a website by either uploading it from their pc or referring to a remote url.
As part of some security checks I'd like to make sure that the referenced object is indeed an image.
In the case of a remote-url, I of course check the content-type, but this isn't bullet-proof.
I figured I could use ImageMagick to do the task. Perhaps executing the ImageMagick.identify() method and if no error is returned and returned type is either JPG|GIF|,etc. the content is an image. (In a quick check I noticed that TXT files are identified correctly as well, so I have to blacklist these)
Is there any better way in doing this?
You could probably simply load the image via ImageMagick's appropriate function for your language of choice. If the image isn't formatted properly (in terms of internal formatting, not its aesthetic properties, that is), I would expect ImageMagick to refuse to load it and report an error. In PHP, for example, readImage returns false if the image fails to load.
Alternatively, you could read the first few hundred bytes of the file and determine if the expected image file format headers are present; e.g., "GIF89" etc.
These checks may backfire, if your image is in a compressable format (PNG, GIF) and it is constructed in a way similar to a zip bomb https://en.wikipedia.org/wiki/Zip_bomb
Some examples at ftp://ftp.aerasec.de/pub/advisories/decompressionbombs/pictures/ (nothing special about that site, I just googled decompression bombs)
Another related issue is that formats like SVG are in fact XML and some image processing tools are prone to a variant of "billion laughs" attack https://en.wikipedia.org/wiki/Billion_laughs
You should not store the original file. The generally recommended approach is to always re-process the image and convert it to an entirely new file. There have been vulnerabilites exploited inside valid image files (see GIFAR), so checking for this would have been useless.
Never expose your visitors to an image file that you have not written out yourself and for which you did not choose the file name yourself.