Custom file type
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Hi I have a friend who's a photographer and he's looking for a way to burn DVDs for his customers with the photos on. He wants to include both low resolution and high resolution photos on the disc, but he doesn't want his customers to be able to access the high res photos. They must bring the disc to him if they want any photos printed. What I suggested to him was to create an application that will allow him to save the photos in a different file format, and only he must be able to open these photos with this application. I quickly fiddled with some code and saved an image in a different file format, but then of course one can still open these files by simply using the "Open With" dialog. I know there must be more to it than simply just saving it in a different file format. Maybe using some form of Serializer? Any help in the right direction would be appreciated.
A simple trick might be to write some binary value - an indicator byte/int/long plus some indicator of the type of image that the rest of the file contains (e.g. 0xD1CEDBEE + ".JPG" for a total of 8 bytes, or 12 if you save the string as multibyte characters) - at the beginning of a new file, then stream the binary of the high-res image immediately following that byte. Save the file with a custom extension 'xxx.hires' or somesuch. The presence of the custom header will prevent any standard software from being able to process the file as a recognized image file. The custom app can validate the header, then create a .Net Image object from the remainder of the content in the file. Specifying the embedded image type in the header allows for future implementations that use other file formats (which may not necessarily be images at all). If you don't like having ".JPG" in readable characters, XOR each byte of the string with some binary value, say 0x53. Just XOR them again when reading them back, to get back to the original characters. You should probably also include a length field describing the embedded string, for flexibility, instead of assuming that it is always going to be 4 characters; I would also include a version # "just in case".
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Hi I have a friend who's a photographer and he's looking for a way to burn DVDs for his customers with the photos on. He wants to include both low resolution and high resolution photos on the disc, but he doesn't want his customers to be able to access the high res photos. They must bring the disc to him if they want any photos printed. What I suggested to him was to create an application that will allow him to save the photos in a different file format, and only he must be able to open these photos with this application. I quickly fiddled with some code and saved an image in a different file format, but then of course one can still open these files by simply using the "Open With" dialog. I know there must be more to it than simply just saving it in a different file format. Maybe using some form of Serializer? Any help in the right direction would be appreciated.
I'm sorry - that was a little blunt. My fault! I was going to say: Encrypt the files - use the small file filename and some random-but-fixed data mixed together as the key and use the .NET Encryption services. Save the file with the extension ".encrypt" appended to the ".jpg" or whatever bit, and you are good to go.
Real men don't use instructions. They are only the manufacturers opinion on how to put the thing together.
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Hi I have a friend who's a photographer and he's looking for a way to burn DVDs for his customers with the photos on. He wants to include both low resolution and high resolution photos on the disc, but he doesn't want his customers to be able to access the high res photos. They must bring the disc to him if they want any photos printed. What I suggested to him was to create an application that will allow him to save the photos in a different file format, and only he must be able to open these photos with this application. I quickly fiddled with some code and saved an image in a different file format, but then of course one can still open these files by simply using the "Open With" dialog. I know there must be more to it than simply just saving it in a different file format. Maybe using some form of Serializer? Any help in the right direction would be appreciated.
What you are looking for is called encryption. The photos can be in the original format (.jpg or whatever), but the files should be encrypted using a good algorithm and a strong password to keep the data protected. You can either use some ready-to-use encryption software, or create your own program from scratch... If you decide to write your own program, see the
System.Security.Cryptographynamespace (there are high-quality encryption algortihms ready for you in the .NET library). There are also several articles about encryption here at CodeProject. -
Hi I have a friend who's a photographer and he's looking for a way to burn DVDs for his customers with the photos on. He wants to include both low resolution and high resolution photos on the disc, but he doesn't want his customers to be able to access the high res photos. They must bring the disc to him if they want any photos printed. What I suggested to him was to create an application that will allow him to save the photos in a different file format, and only he must be able to open these photos with this application. I quickly fiddled with some code and saved an image in a different file format, but then of course one can still open these files by simply using the "Open With" dialog. I know there must be more to it than simply just saving it in a different file format. Maybe using some form of Serializer? Any help in the right direction would be appreciated.
put the hi-res files inside a password-protected ZIP; or encrypt them. :)
Luc Pattyn [Forum Guidelines] [Why QA sucks] [My Articles] Nil Volentibus Arduum
Please use <PRE> tags for code snippets, they preserve indentation, and improve readability.
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Encryption
Real men don't use instructions. They are only the manufacturers opinion on how to put the thing together.
Never thought of encryption :) I did a quick search and came up with something that will work fine: File Encryption and Decryption in C#[^] Thanks guys
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I'm sorry - that was a little blunt. My fault! I was going to say: Encrypt the files - use the small file filename and some random-but-fixed data mixed together as the key and use the .NET Encryption services. Save the file with the extension ".encrypt" appended to the ".jpg" or whatever bit, and you are good to go.
Real men don't use instructions. They are only the manufacturers opinion on how to put the thing together.
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Hi I have a friend who's a photographer and he's looking for a way to burn DVDs for his customers with the photos on. He wants to include both low resolution and high resolution photos on the disc, but he doesn't want his customers to be able to access the high res photos. They must bring the disc to him if they want any photos printed. What I suggested to him was to create an application that will allow him to save the photos in a different file format, and only he must be able to open these photos with this application. I quickly fiddled with some code and saved an image in a different file format, but then of course one can still open these files by simply using the "Open With" dialog. I know there must be more to it than simply just saving it in a different file format. Maybe using some form of Serializer? Any help in the right direction would be appreciated.
An alternate idea... Save the high resolution images to a database on your computer. Associate a unique key to each photo, or just create a single key for an entire batch of images. Include that key(s) on the DVD with the low resolution images. When the customer gives you the DVD, use that key to lookup the high resolution pictures on your computer. The "database", "key", and "computer" can be anything you like. For example, one configuration might be:
Database: SQL Server
Key: GUID
Computer: PCAlternate cofiguration:
Database: Excel File
Key: Customer name and date the photos were put on the DVD
Computer: DVD's with the key written on themNo need to put the data in the user's hands.
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Hi I have a friend who's a photographer and he's looking for a way to burn DVDs for his customers with the photos on. He wants to include both low resolution and high resolution photos on the disc, but he doesn't want his customers to be able to access the high res photos. They must bring the disc to him if they want any photos printed. What I suggested to him was to create an application that will allow him to save the photos in a different file format, and only he must be able to open these photos with this application. I quickly fiddled with some code and saved an image in a different file format, but then of course one can still open these files by simply using the "Open With" dialog. I know there must be more to it than simply just saving it in a different file format. Maybe using some form of Serializer? Any help in the right direction would be appreciated.
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Which encryption algorithm would you recommend though? There are numerous included in .NET. The one I came across that works fine is "RijndaelManaged".
For your situation I wouldn't go for anything too complex - All you want is something that bollixes up the simple user from getting his high-res pics for free, I assume? Follow this[^] and you won't go too far wrong - it's pretty easy to follow, but without your key it's pretty much unbreakable. It won't stop the FBI or the mafia, but then I hope your pictures wouldn't interest either! :laugh:
Real men don't use instructions. They are only the manufacturers opinion on how to put the thing together.
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Hi I have a friend who's a photographer and he's looking for a way to burn DVDs for his customers with the photos on. He wants to include both low resolution and high resolution photos on the disc, but he doesn't want his customers to be able to access the high res photos. They must bring the disc to him if they want any photos printed. What I suggested to him was to create an application that will allow him to save the photos in a different file format, and only he must be able to open these photos with this application. I quickly fiddled with some code and saved an image in a different file format, but then of course one can still open these files by simply using the "Open With" dialog. I know there must be more to it than simply just saving it in a different file format. Maybe using some form of Serializer? Any help in the right direction would be appreciated.
The best way to keep secrets is to not have any. If they must come to him to have images printed anyway, why even store them on the disc? Keeping them does put the onus on the photographer for storage but I'd be surprised if doesn't already have a backup plan. It also gives the option for a client to call/email an order and have them sent.
I know the language. I've read a book. - _Madmatt
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For your situation I wouldn't go for anything too complex - All you want is something that bollixes up the simple user from getting his high-res pics for free, I assume? Follow this[^] and you won't go too far wrong - it's pretty easy to follow, but without your key it's pretty much unbreakable. It won't stop the FBI or the mafia, but then I hope your pictures wouldn't interest either! :laugh:
Real men don't use instructions. They are only the manufacturers opinion on how to put the thing together.
Yes you're completely right. While we're on the subject, would it be possible to compile all of these photos into one single encrypted package which can then only be opened by the application? That would be ideal, but if I have to store all the files separately then that's not a train smash either.
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The best way to keep secrets is to not have any. If they must come to him to have images printed anyway, why even store them on the disc? Keeping them does put the onus on the photographer for storage but I'd be surprised if doesn't already have a backup plan. It also gives the option for a client to call/email an order and have them sent.
I know the language. I've read a book. - _Madmatt
I asked the same question :-D The only reason I can think of is that he does not want to keep backups of all his photos.
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put the hi-res files inside a password-protected ZIP; or encrypt them. :)
Luc Pattyn [Forum Guidelines] [Why QA sucks] [My Articles] Nil Volentibus Arduum
Please use <PRE> tags for code snippets, they preserve indentation, and improve readability.
Luc Pattyn wrote:
a password-protected ZIP
very easy to copy and crack :thumbsdown:
Luc Pattyn wrote:
encrypt them
better alternative. :thumbsup:
Yusuf May I help you?
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Hi I have a friend who's a photographer and he's looking for a way to burn DVDs for his customers with the photos on. He wants to include both low resolution and high resolution photos on the disc, but he doesn't want his customers to be able to access the high res photos. They must bring the disc to him if they want any photos printed. What I suggested to him was to create an application that will allow him to save the photos in a different file format, and only he must be able to open these photos with this application. I quickly fiddled with some code and saved an image in a different file format, but then of course one can still open these files by simply using the "Open With" dialog. I know there must be more to it than simply just saving it in a different file format. Maybe using some form of Serializer? Any help in the right direction would be appreciated.
Another Idea. Leave the hi-res images as hi-res so the customer can open them and see the difference. But put distinct watermark, so when printed it does not look good.
Yusuf May I help you?
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Luc Pattyn wrote:
a password-protected ZIP
very easy to copy and crack :thumbsdown:
Luc Pattyn wrote:
encrypt them
better alternative. :thumbsup:
Yusuf May I help you?
You do realize that password-protecting a ZIP file is a form of encryption, right?
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You do realize that password-protecting a ZIP file is a form of encryption, right?
One of the weakest types of encryption, huh! :^)
Yusuf May I help you?
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One of the weakest types of encryption, huh! :^)
Yusuf May I help you?
I don't know, is 256-bit AES encryption weak?
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Yes you're completely right. While we're on the subject, would it be possible to compile all of these photos into one single encrypted package which can then only be opened by the application? That would be ideal, but if I have to store all the files separately then that's not a train smash either.
Yes - the encryption doesn't care what the content is. I would suggest either a simple directory structure, or just a length prefix/filename combination to each file so you can extract them from the decrypted stream.
Real men don't use instructions. They are only the manufacturers opinion on how to put the thing together.
