C# :: RSA Decryption With Only Modulus And Exponent
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.
I am new to C programming and I am trying to compile and run an exponent program my instructor posted for us but it is giving me an error saying:
Warning c4550: expression evaluates to a function which is missing an argument list.
Why this is happening (she doesn't seem to find anything wrong with the code). From what I could gather there is some issue with the math but idk. It is supposed to prompt for the number and the exponent to raise it to, then calculate and output the result.
Code: #include <stdio.h> int main() { int base, exp; long long int value=1;
I am studying about recursion by myself and i want to make a recursive function that prompts the user to input the base and exponent and generate the final answer .
#include<iostream> using namespace std; int recursive(int x, int y); int main() { /*int total=1; int y, x;
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...
I just want to test AES from openSSL with this 3 modes: with 128,192 and 256 key length but my decrypted text is different from my input and I dont know why. Also, when I pass a huge inputs length (lets say 1024 bytes) my program shows `core dumped`... My input is always the same but it doesnt matter, at least for now. Heres the code:
We need an AES Encryption/Decryption program in C for college lab (Educational) purpose . So we cannot use any "aes.h" file for this . We need a C program which simulate the purpose of AES
Input : Text (e.g: Anes P.A) key (e.g:123op)
Output : Cipher Text using AES
I look this functionality done in a website : [URL] ....
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)?
I am having trouble with an assignment. The assignment consists of a basic encryption and decryption program already written for me, I just have to write the encryption function. What we have to get the program to do is enter an integer and a text, and get the program to increment each letter in the text by the integer given. I did this by using a for loop and incrementing each value in the string by the integer.
However, I still can't get it to decrypt and I need the program to work with only a-z letters (if I increment each letter by 3 and I have the letter Z, it should go to Z+3 = C).
I attached the description of the attachment and below are the codes: The first file does not need to be edited.
Code: /*******************Programming Assignment 1***************/ /****************Caesar's substitution cipher**************/ /*****************YOU MUST NOT EDIT THIS FILE**************/ /****Substitute alphabets in a string using rotation key***/ /****Leave all other characters unchanged******************/ /****Confirm correct encryption by decrypting**************/
How can decrypt the file that the program below encrypt?
// This program encrypts a file #include<iostream> #include<fstream> using namespace std; int main() { const int ENCRYPT=10; // amount to add to a chor const int SIZE= 255; // array size
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?
Write a program to do simple encryption and decryption. Encryption basically means to convert the message into unreadable form. In this assignment, it should be done by replacing each letter of a message with a different letter of the alphabet which is three positions further in the alphabet. Then, all the letters will be reversed. Decryption is the process of converting encrypted message back into its original message. Your program should use the following shifting method.
Note: You must use array.
#include <iostream> #include <string> using namespace std;
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++) {
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).
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?
