CHAPTER 38

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1. To store one second of voice conversation using PCM, the storage requirement is 8 Kbytes. To store 100 hours of conversation, Storage requirement = 360,000 × 8 KB = 360 × 8MB = 2880MB = 2.8GB

2. Listing C.15 encrypts the given message using RSA algorithm in C.

Listing C.15: Encryption using RSA algorithm.

 #include "stdio.h" #include "stdlib.h" #include "math.h" int main(void) {    int p=7,q=11;    int n, e, d, res1, k;    int flag=0;    int i=0,ch;    double fraction, integer;    double ex, d1;    char Message[] = {9,8,4,8,1,4,4,3,3,7,'\0'};    char EncryptedMessage[20];    char DecryptedMessage[20];    n = p * q;    k = (p -1) * (q - 1);    e = p;    while(flag != 1){       i++;       res1 = (k*i) + 1;       if((res1%e) == 0){             d = res1 / e;             flag = 1;       }    }    printf("\n\n\t\t\t\tRSA Algorithm\n\n");    printf("\n Public key: <%d,%d> ",e, n);    printf("\n Private key: <%d,%d> \n", d, n);    printf("\n Original Message: ");    for(i=0;i<strlen(Message);i++){       printf("%d ",Message[i]);       ch =(int)(Message[i]);       ex = pow((double)ch,(double)e);       d1 = (ex / n);       fraction = modf(d1, &integer);       EncryptedMessage[i] = (char)(fraction * n);    }    EncryptedMessage[i] = '\0';    printf("\n Encrypted Message: ");    for(i=0;i<strlen(EncryptedMessage);i++){       printf("%d ",EncryptedMessage[i]);    }    printf("\n");    return 0; } 

When you execute the program, the public key, private key, original message and encrypted message will be displayed as shown in Figure C.19.

Figure C.19: RSA algorithm output screen.

3. You can obtain the details form http://www.iseeyes.com, http://www.audiosoft.com.

4. You can obtain Steganography software from http://www.outguess.com or http://www.stegoarchive.com.

5. The hackers use trial-and-error methods to break the algorithms, and hence statistically, they will succeed! Every credit card holder is given a PIN, which is a 4-digit number. If the hacker tries these numbers systematically, he has to try all the possible 9999 combinations to succeed. However, the credit card company generates the PIN using an algorithm, and if the algorithm is stolen, the job is very simple!

6. To tap a telephone, you need to have a PC into which the interactive voice response hardware (a PC add-on card) is plugged in. The IVR hardware has to be connected in parallel to the telephone. The software running on the PC should be automatically invoked when the telephone is lifted, and the entire conversation needs to be recorded on the PC.

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