Strange garbage in RSA decryption

[Patrick Coleman]

Hi,
I'm trying to do some basic encryption/decryption tests with the openssl RSA routines. 
A message seems 
to encrypt ok, but when it decrypts theres some random garbage appended onto the end. 
Is this normal, 
or is it a bug in my code?

This is what I'm doing:

<encrypt.cpp>
#include <iostream>
#include <fstream>
#include <stdlib.h>


#include <openssl/rsa.h>
#include <openssl/engine.h>

using namespace std;


int main() {
        string message;
        char pubfile[128], privfile[128], seed[1024];
        unsigned int keylength;
        RSA *key;

        cout<<"Test encryption program for OpenSSL.\n";

        cout<<"Key Generation:\nEnter a keylength (bits):\n";
        cin>>keylength;
                
        key = RSA_generate_key(keylength, 65537, NULL, NULL);


        cout<<"Enter message:\n";
        ws(cin);
        getline(cin,message);
        
        cout<<"Your message is: "<<message<<endl<<"Size: 
"<<message.length()<<endl<<"Keysize: "<<RSA_size(key)<<endl;

        FILE *fd;
        fd = fopen("key.dat", "w");

        char ciphertext[RSA_size(key)];
        char decrypted[RSA_size(key)];
        strcpy(ciphertext, ""); //Initialise the strings
        strcpy(decrypted, "");

        if (RSA_private_encrypt(message.length(), (const unsigned char 
*)message.c_str(), (unsigned char *)ciphertext, key, RSA_PKCS1_PADDING) == -1) {
                cout<<"Error Encrypting Data!\n";
        }
        cout << "Ciphertext: " << ciphertext << endl;
        if (RSA_public_decrypt(sizeof(ciphertext), (const unsigned char *)ciphertext, 
(unsigned char *)decrypted, key, RSA_PKCS1_PADDING) == -1) {
                cout<<"Error Decrypting Data!\n";
        }
        cout << "Decrypted: " << decrypted << endl;

        return(0);
}
</encrypt.cpp>

This is the output I get from it:
<output>
bash-2.05b# ./encrypt
Test encryption program for OpenSSL.
Key Generation:
Enter a keylength (bits):
2048
Enter message:
Testing, Testing, 123
Your message is: Testing, Testing, 123
Size: 21
Keysize: 256

Ciphertext: ,éGéï¯+¦'áñSö¤XÍðw3ýjÙ\:£?ÞX¦§¬Í
Decrypted: Testing, Testing, [EMAIL PROTECTED]@0òÿ¿òÿ¿
bash-2.05b#
</output>

The garbage I'm talking about is the '[EMAIL PROTECTED]@0òÿ¿òÿ¿' appended to the 
original message 'Testing, Testing, 123'.
Thanks for any assistance,
Patrick

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