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Convert byte array to integer with lower and upper bound [closed]

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I have a method that pseudo-randomly encrypts a byte array. I would like to convert the encrypted byte-array to a C# int (4 bytes), while observing a user-specified lower and upper bound (e.g. give me a number between 1 and 10)
What is the most secure and performant way of achieving this?

You could use System.ByteConverter.ToInt32(arr, start_index).
From your description of the array, the start index would likely be zero.
I am not sure what you mean by upper and lower bound, but if you mean you want a random number, you could use a variety of functions to get a value in between the two numbers. If you have semi-uniform distribution, the modulus function would work nicely. In that case, your random number would simply be lowerBound + (System.ByteConverter.ToInt32(arr, start_index) % (upperBound - lowerBound)).

How to store a bit in C# [closed]

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I have the following code:
void MyBitMaker(int inputNumber)
{
Console.WriteLine(inputNumber << 1);
//TODO
//Bit bitHolder = inputNumber << 1;
//InitMico(ref bitHolder);
}
There is not a type for storing bits in C#. Is there any way to store bits in a variable.
I am programming a micro controller using C#, It uses the bits that are coming from a web service, fetches them and sends them to the controller to open, close, sleep and such things using an interface to change the input data to appropriate bits. My problem is that the micro has just 16 bytes memory in ram and I can not store more than two bytes, the micro should store the history of previous actions (this is extra, maybe, jargon). I have low space and need this small unit. I searched a lot and did not find anything. currently I am using bit operators using a class that I myself have implemented but it's not efficient at all because of using bit operations. I was wondering if someone has faced something that can help me.

The smallest addressable unit is a byte, so use that, or a bool which is still 8 bits, but only has two possible values to be set.
You can't reference a bit, so that would be useless anyway. If you need to address a specific position in a byte, you can pass along the position. Still, you can only change the bit's value by setting the entire byte.

I just want to store bits
Trivial solution: bool array.
If it really needed to store the bits in a compacted form, you can use the BitArray type, which uses an int array internally. You can index it similarly to a normal array:
var myBits = new BitArray(20); // initialize for 20 bits (1 int will be stored internally)
myBits[5] = true; // similar to this: myInt |= 1 << 5;

C# sbyte is written to the file as an unsigned byte [closed]

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Using the BinaryWriter I write an sbyte variable to a file but it gets written to the file as unsigned and not signed as it should be.
sbyte a = (sbyte)image.pixelData[i + 0];
bw.Write(a);
For example, the above code writes values ranging from 0x00 to 0xFF. (These are the values I see in a hex editor.)

You are demonstrating a fundamental misunderstanding of how data is stored in memory, files, etc.
All computer data is in binary form.
The different data types determine how the data is treated, how calculations are performed, how values are formatted, etc.
If you write a signed value to a file, it is always written using binary form (the only format a computer understands). If you read that data with a hex editor, then the hex editor will translate the data using whatever translation it considers to be appropriate.
If you write data to a file as a signed byte, and then you read that same data back as a signed byte, then the data will be the same as the data written. You should expect no more, and no less.
(Note: If you use the hex editor I wrote (Cygnus Hex Editor), you can inspect the data using any data type. In that case, you can have it appear in the format you expect. Otherwise, the hex editor is converting it to hex, or whatever, which tells you nothing about how the data is stored in the file.)

Splitting a 200 bit hexadecimal bitmask [closed]

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I have a bitmask of 200 bit stored as a hexadecimal value.
In order to apply the & bit operator, I have to first convert the hex to an integer but 200 bit is too big for a uint64 so my question is : how do I split my bitmask in 4 different hexadecimal value without loosing data?
So that I can also split my 200 bit data and then compare every chunk of data with the corresponding chunk of bitmask without altering the result.

You can use the BigInteger from System.Numerics (it's a separate assembly):
BigInteger bi = BigInteger.Parse("01ABC000000000000000000000000000000000", System.Globalization.NumberStyles.HexNumber);
VERY IMPORTANT: prepend a "0" before the hex number! (because BigInteger.Parse("F", NumberStyles.HexNumber) == -1, while BigInteger.Parse("0F", NumberStyles.HexNumber) == 15
BigInteger implement the "classical" logical operators (&, |, ^)
Requires .NET 4.0

The most efficient way of achieving this is writing a class that can store and do binary operations on 200bits of data, have strings as input, etc.

C# 64 characters key [closed]

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I don't know C# but I have to do a update to a function that send a key to be encrypted.
I need to send a key with 64 characters, but the function that I have here only accepts 32 characters.
The function that initialize this process is:
Byte[] kkey = System.Text.Encoding.UTF8.GetBytes(sEncKey);
What I have to do for this accept a 64 characteres key?

The code you have included creates an array of type Byte which includes a number of elements matching whatever number of characters you provide in sEncKey.
It is my understanding that you are passing kkey to some function that will perform the encryption, and that this function only accepts a byte array of size 32. If this is correct, then you can't automatically increase the key size to 64 just by sending a longer key - it is the function you will have to change first, not it`s input.
Sound's like you're trying to increase security by using a larger key without replacing the lock first. Get a bigger lock first, then you can use a bigger key.
Also, if you need more help or guidance with this, you will need to provide info about the function, as well as some relevant code.