I want to know what is wrong with my code?

I had to write a steganography code which when propmted the user enters a picture and then a messege to hide into the picture. once the user uses the decoder, it reveals the messege that was typed. When i run my code, the encoder takes the messege but outputs the messege, from the decode, with different caracters. I have debugged my code numerous time and im guessing i am missing one detail. can someone help me please? i will post the code as soon as someone responds.

Answer 1

[Image Analyst]

Someone might be able to when you post your code and if you've followed the guidelines in this link.

The Mathworks does not allow discussion of steganography or encryption and may take down your post if you keep words like that.

I was able to post a similar program in my File Exchange http://www.mathworks.com/matlabcentral/fileexchange/54155-encoding-text-into-image-gray-levels only after I persuaded the Mathworks it was encoding, not encryption or crytography, and removed all mention of steganography, encryption, and similar words from the code and the post.

[Michael Mcclung]

thank you

[Jan]

@Image Analyst: This sentence does not contain my personal opinion about the policies The Mathworks is forced to follow. The term hilarious has no connection to the discussed topic. The meaning of this comment is not encrypted, but encoded.

You can download the code for a strong encryption from the NIST. The PDF contains the source code, but as text, not in a format, which can be executed directly. Therefore this publication is covered by the freedom of speech. A discussion in the forum cannot be executed directly also. Perhaps we are allowed to post answers as screenshots or as attached PDF file?

See: illegal prime numbers

[Walter Roberson]

The relevant legislation in the USA goes something like this:

1. Someone can make source code available (possibly with some restrictions, I have forgotten for the moment). But right after they make the source code available, they most notify the appropriate US department that it has been posted, lest you Suffer The Wrath.
2. Discussions of encryption is legal and does not need to be notified, provided that the discussion does not allow the reader to modify the key size to more than a certain number of bits
3. Discussions of encryption in which there is the possibility that the reader might be able to modify the key size to more than the limit number of bits, require that pre-approval be gained from the appropriate US department, which is authorized to forbid it, lest you Suffer The Wrath

As there are very few encryption techniques which cannot be extended to larger keys, the effect is to ban most discussion of encryption. For example, the easily broken Caeser Cipher, with its one small-valued parameter, has the obvious extension of using multiple parameters, and there is no inherent limit to the length of the key, so we cannot discuss how the Caeser Cipher works -- at least not without pre-approval.