Encrypt/Decrypt

This is a discussion on Encrypt/Decrypt within the C Programming forums, part of the General Programming Boards category; OK, I've decided that my 2 1/2 year old will be easier to figure out than the beginings of C ...

  1. #1
    Registered User
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    Oct 2001
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    3

    Unhappy Encrypt/Decrypt

    OK, I've decided that my 2 1/2 year old will be easier to figure out than the beginings of C programming. Well, I've tried all three and attempted modification (out of guessing) and still don't reach my needed result. Once again, out of any order of numbers such as 1234(I've just pick this size in digits, could be larger if I wanted), I need to encrypt that number by adding 7 to each charater: (1 becomes 8, 2 becomes 9, 3 becomes 0 and 4 becomes 1) The last digit of the roleover is not used. Can anyone see where I'm messing up?

    #include <stdio.h>
    #include <stdlib.h>

    int main(void)
    {
    system("cls");

    int temp, int exp = 0, int encrypted = 0, int normal;
    int pow

    while(normal > 0){
    temp = normal % 10;
    temp += 7;
    temp = temp % 10;
    encrypted += temp * pow(10,exp);
    exp ++;
    normal /= 10;

    printf("Enter your name: ");
    scanf("%s", name);

    printf("Enter a number to encrypt: ");
    scanf("%f", temp);

    printf("new number is: %f%f%f%f, ");


    return EXIT_SUCCESS;
    return 0;
    }

    Now the rest of this small snippit is to decrypt the number back to the orignal number set but should be nothing but reversing the encrypting part. any ideas.....,

  2. #2
    and the hat of wrongness Salem's Avatar
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    Code:
    #include <stdio.h>
    
    void encrypt ( char *buff ) {
        int i;
        for ( i = 0 ; i < strlen(buff) ; i++ ) {
            char c = buff[i] - '0';
            c = ( c + 7 ) % 10;
            buff[i] = c + '0';
        }
    }
    
    int main ( ) {
        char test[] = "1234";
        encrypt( test );
        printf( "%s\n", test );
        return 0;
    }
    If you dance barefoot on the broken glass of undefined behaviour, you've got to expect the occasional cut.
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  3. #3
    Registered User
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    Oct 2001
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    Hi there!

    I suggest you learn about the base 64bit encryption... it's easy and cool :-) /and unsafe...but safer thatn Ceaser's crypting.../.
    Here is a tutorial about it:
    http://www.cpp-home.com/tutorial.php?102_1

    Also, you may want to see about the XOR encryption at:
    http://www.cpp-home.com/tutorial.php?120_1

    and about the RSA encryption at:
    http://www.cpp-home.com/tutorial.php?139_1
    Ilia Yordanov,
    http://www.cpp-home.com ; C++ Resources

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