C++ :: How To Use Modulus
Mar 16, 2013
if i have 4 intergers for example :
1378 2496 3587 5389
how can i use the modulus operator to disect them so i can get the first number of each integer .what i mean is how can i take 1 form 1378 and 2 from 2496 etc...
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Aug 18, 2013
I have to develop minimalistic implementation of RSA algorithm in C for an embedded device.
I'm doing that for two days but I have run into a problem. The N modulus is the limitation for the maximum message value to be encrypted with RSA.
For example theoretically RSA-1024 can encrypt/decrypt messages 1024 bits long but I still cannot understand how to choose p and q values to produce N == pow(2, 1024).
Is it possible to encrypt/decrypt 1024 bits long messages in practice if the N < pow(2, 1024)?
So far I'm getting the following results
Code:
Encrypting with RSA
d=15689981, e=21, n=16484947
In=16484942, Encrypted= 6074492, Out=16484942 (OK)
In=16484943, Encrypted= 5468920, Out=16484943 (OK)
[Code] ....
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Oct 23, 2013
Code:
while ((y % 12) != 0) {
y++;
}
I liked that the above code does not put the result into a variable and then test the variable which would use more memory, and more lines of code. Is this thinking bad?
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Nov 26, 2014
How to perform RSA decryption with just the modulus and public exponent. I know that in RSA the private key does the decrypt, but thats not what I need to do. It is actually more of a verify used to recover information for the purposes of integrity (stupid I know) but its the problem I have to solve. Basically I need to do an RSA operation with the modulus and public key. When I try it I receive the error:
System.Security.Cryptography.CryptographicException: Key does not exist.
at System.Security.Cryptography.CryptographicException.ThrowCryptographicException(Int32 hr)
at System.Security.Cryptography.RSACryptoServiceProvider.DecryptKey(SafeKeyHandle pKeyContext, Byte[] pbEncryptedKey, Int32 cbEncryptedKey, Boolean fOAEP, ObjectHandleOnStack ohRetDecryptedKey)
at System.Security.Cryptography.RSACryptoServiceProvider.Decrypt(Byte[] rgb, Boolean fOAEP)
at IssuerPublicKeyRecoveryApp.Form1.PerformVerification() in C:devMarvinDevIssuerPublicKeyRecoveryAppIssuerPublicKeyRecoveryAppForm1.cs:line 543.
My Code is as follows:
try{
//Create a new instance of RSACryptoServiceProvider.
using (RSACryptoServiceProvider RSA = new RSACryptoServiceProvider()) {
//Build the RSA key parameters to perform decrypt
RSAParameters RSAKeyInfo = new RSAParameters();
[Code] ....
I have verified that my values are good on : [URL] ....
This example is strait off the MSDN website, and I realize it says that you need the private key information on the RSA import. For what I am doing, I do not have that, since I am doing a decrypt(not really). Since I know that the Math of an RSA operation is actually identical weather you are doing encrypt or decrypt, and it is just a convention of length for the exponent, I tried to do an Encrypt operation to decrypt the data, and the error checking caught that it was the wrong length in stead of performing the operation.
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Apr 13, 2014
I am making a random number generator. I have fixed all issues except for one. I am supposed to ask the user for how many digits the user wants the numbers to have. How many numbers does the user want. Then randomly generate numbers according to what the user entered. So if the user said 2 digits and wanted 4 numbers then it would output 4 random numbers in the range of 10 to 99.
My notes from class show this working correctly. And it does work correctly. But I don't understand the math here or how the modulus effects it. I was able to get 1 and 2 digits to work but once I get to 5 it doesn't generate numbers correctly. it will only generate number s
Code: int min =1;
int max = 9;int number1 = rand();
cout << number1 % max + min << " "; h
Here is the 3 digit code I have. I also need to figure out how to make it unique so no number generates more then once. I think the issue may be that the numbers are not unique and it is generating the same number and that is somehow effecting the numbers it is outputting. It is either that or my math is wrong.
Code:
if (intLength == 5) {
for (int i = 0; i<intQuantity; i++) {
[Code]....
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Jan 31, 2013
I am trying to get a remainder of a number with a = 0.9144, rm = ry % a; however, I keep getting a divide by zero error (I believe due to the program rounding 0.9144 down to the integer 0).
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Mar 21, 2013
For part of my program in class I have to take a pointer address and determine if it is equal to 0 modulus 16. But I can't figure it out.
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Oct 18, 2014
where are operators defined in C/C++? in headers or compiled code?
looking for the definition of how % modulus is calulated
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Mar 13, 2013
how can we use modulus operator with double type variables
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May 27, 2013
Say I wanted to overload the modulus operator to return the remainder of a division between two floating point numbers. Why isn't a custom double operator%(double, double) allowed even though that function isn't available in the standard anyway?
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