# Contains? & ltstdio.h & gt
# Contains? & ltstring.h & gt
# Contains? & ltstdlib.h & gt
# Contains? & lttime.h & gt
const？ Not signed? int？ Maximum key length? =? 1000;
int？ Code (char? const？ * data file? Charles? const？ * key fill)；
int？ Decoding (char? const？ * data file? Charles? const？ * keyfile)；
int？ loadKey(char？ const？ * key file,? int？ * key,? Not signed? int？ Size);
int？ saveKey(char？ const？ * key file,? int？ * key,? Not signed? int？ Size);
int？ generateKey(int？ * key,? Not signed? int？ Size);
int？ main(int？ argc，？ Charles? const？ *argv[])
{
Charles? Data file []? =? ”encrypted . txt”；
Charles? keyfile[]？ =? ”key . txt”；
int？ retcode，？ Choice,? Cycle? =? 1;
Charles? ch[5]？ =? {'\0'};
while( 1)
{
printf(" 1。 ? Encryption. \ n ")；
printf("2。 ? Decryption. \ n ")；
printf("3。 ? Quit \ n ")；
Printf ("Select? ( 1,2,3):");
fgets(ch，sizeof(ch)，？ stdin)；
sscanf(ch，？ "%d", & select);
Switch (selection)
{
Case? 1:?
retcode？ =? Coding (data file, keyfile);
What if? (retcode？ ! =? 0)? Printf ("Error, %d\0", retcode);
Break;
Case? 2:
retcode？ =? Decoding (key file);
What if? (retcode？ ! =? 0)? Printf ("Error, %d\0", retcode);
Break;
Case? 3:
Cycle? =? 0;
Break;
Default value:
Break;
}
What if? (0? ==? Cycle)? Break;
}
Return? 0;
}
int？ generateKey(int？ * key,? Not signed? int？ Size)?
{
Charles? str[]= " 0 123456789 abcdefghijklmnopqrstuvwxyzabcdefghijklmnopqrstuvwxyz，。 /; \ " ' & lt& gt？ ";
size_t？ str_len？ =? sizeof(str)/sizeof(str[0])；
int？ Me;
srand(time(NULL))；
For what? (me? =? 0; ? Me? & lt？ Size; ? ++i)
keys[i]？ =? str[rand()？ %? str _ len]；
Return? 0;
}
int？ loadKey(char？ const？ * key file,? int？ * key,? Not signed? int？ Size)
{
int？ Me? =? 0;
Documents? * pfile
int？ retcode？ =? 0;
pfile？ =? Fopen (key file, "R");
What if? (pfile？ ==? NULL)？ Return? - 1;
What time? (? ! feof(pfile)？ )? {
What if? (me? & lt？ Size)
fscanf(pfile，" %d？" ,? & ampkeys[i++])；
other
Break;
}
fclose(pfile)；
Return? Me;
}
int？ saveKey(char？ const？ * key file,? int？ * key,? Not signed? int？ Size)?
{
Documents? * pfile
int？ Me;
pfile？ =? Fopen (key file, "w");
What if? (pfile？ ==? NULL)？ Return? - 1;
For (me? =? 0; ? Me? & lt？ Size; ? ++i)？ {
fprintf(pfile，" %d？" ,? keys[I])；
}
fclose(pfile)；
Return? 0;
}
int？ Code (char? const？ * data file? Charles? const？ *keyfile)？
{
Charles? Original [MAX_KEY_LENGTH]? =? {'\0'};
Charles? Encrypted [MAX_KEY_LENGTH]? =? {'\0'};
int？ Me? Size;
int？ keys[MAX _ KEY _ LENGTH]；
Documents? *pdatafile，？ * pkeyfile
pkeyfile？ =? Fopen (key file, "w");
What if? (NULL？ ==? pkeyfile)？ Return? - 1;
fclose(pkey file)；
puts("？ Input? Message: ");
Get (original);
Size? =? Strlen (original);
What if? (0? ! =? GenerateKey (key, size)? Return? -2;
What if? (0? ! =? SaveKey(keyfile, key? Size)? )? Return? -3;
pdatafile？ =? Fopen (data file, "W");
What if? (NULL？ ==? pdatafile)？ Return? -4;
For what? (me? =? 0; ? Me? & lt？ Size; ? ++i)？ {
Encryption [i]? =? Original [me]? +? keys[I]；
Fputc (encryption [i],? pdata file)；
Fputc (encryption [i],? stdout)；
}
printf(" \ n ")；
fclose(pdatafile)；
Return? 0;
}
int？ Decoding (char? const？ * data file? Charles? const？ * key file)
{
Documents? *pdatafile，？ * pkeyfile
int？ keys[MAX_KEY_LENGTH]？ =? {0};
Charles? Original [MAX_KEY_LENGTH]? =? {'\0'};
Charles? Encrypted [MAX_KEY_LENGTH]? =? {'\0'};
int？ Me? Size;
pkeyfile？ =? Fopen (key file, "R");
What if? (NULL？ ==? pkeyfile)？ Return? - 1;
fclose(pkey file)；
pdatafile？ =? Fopen (data file, "R");
What if? (NULL？ ==? pdatafile)？ Return? -2;
Fscanf(pdatafile, "%s", encrypted);
fclose(pdatafile)；
Size? =? LoadKey(keyfile, key? Maximum key length);
What if? (size? & lt？ 1)? Return? -3;
For what? (me? =? 0; ? Me? & lt？ Strlen (encryption); ? ++i)？ {
Original [me]? =? Encryption [I]- key [I];
fputc(original[i]，？ stdout)；
}
printf(" \ n ")；
Return? 0;
} Running result:
1. encryption.
2. Decryption.
Step 3 quit.
Select (1, 2, 3): 1
Enter message:
This is a test!
╓┐? ╞L？ ╗ù|t▄╬╢╒è
1. encryption.
2. Decryption.
Step 3 quit.
Selection (1, 2,3): 2
This is a test!
1. encryption.
2. Decryption.
Step 3 quit.
Selection (1, 2,3): 3