Hot answers tagged

5

I'll assume the question really is: when I perform low-order-bit steganography on an uncompressed image (inserting 6 bits encoding a character into the low-order bit of 6 bytes coding the R, G and B channels of 2 pixels), I find that compressing the resulting image gives a bigger file than compressing the original image for a given setting of the program ...


4

What you are looking for is a definition of PEM, privacy enhanced mail. Obviously PEM is not just used for mail anymore. The definition of the header lines seems to be best described by section 4.6: "Summary of Encapsulated Header Fields" of RFC 1421: "Privacy Enhancement for Internet Electronic Mail: Part I: Message Encryption and Authentication ...


4

The obvious answer to your question is "yes". The kernel mode implementation pointed to by otus clearly shows that it can be done. That it can be done doesn't mean it gets done however. Many Google searches for sourcecode don't show any OpenSSL code that implements this functionality. In general, OpenSSL doesn't rely on the crypto code of the kernel. So, ...


2

The answer is simple. AES is in itself a pseudorandom function, so an output from a single block encryption will produce 128-bits of pseudorandom numbers. Now to use AES to generate longer sequences, you will have to use a block-cipher mode that lets you do the same. Here is a small list of a few very popular modes ment for PRNGs: Counter(CTR): Counter ...


2

(Q1) Assuming that you talk about the size of the secret key elements which equals the input size of the OWF when you talk about the "input", this should be at least as much as the output size. Consider a function $f: \{0,1\}^m \rightarrow \{0,1\}^n$.The thing to worry about when you choose $m < n$ is a brute force search for a preimage, which in this ...


1

Diffie-Hellman relies on a mathematical problem on positive integers. To use it with bytes you just have to convert the bytes to - or use the bytes as - an integer. Usually this would be a unsigned big-endian (or network order) integer. For Diffie-Hellman the parameters consist of the modulus and the base. The public value could be 1024 bits (128 bytes). ...


1

You'll have to write the function you are trying to calculate as a polynomial in the two inputs $x$ and $y$. If you are working over the field with $q$ elements as plaintexts, you have to calculate for equality the polynomial $(x-y)^{q-1}$. Greater-than-or-equal (however you define that for finite fields) will be even more complicated.



Only top voted, non community-wiki answers of a minimum length are eligible