C language-based file encryption technology

I recently learned about file operations and felt that file encryption is still interesting. So I learned it carefully and made a simple summary. The following describes one of the methods-command encryption.

The command encryption method instructs the user to type a complete file name, including the file path and file name. For example, enter the encryption password to encrypt the specified file.

Principle of encryption: Read the characters in the file and write them to the new file. The decryption process is the same as the encryption principle.

ProgramWrite as follows:

# Include <stdio. h>

# Pragma hdrstop

# Include <tchar. h>

# Pragma argsused

Int _ tmain (INT argc, _ tchar * argv [])

{

File * file1, * file2;

Int I;

Int paslen;

Char ch;

Char source [30], DESTIN [30], password [10];

Printf ("Please input the source file (less than 30 charcters): \ n ");

Gets (source );

Printf ("Please input the destination file (less than 30 charcters): \ n ");

Gets (DESTIN );

Printf ("Please input the password (less than 10 ditigals): \ n ");

Gets (password );

Paslen = strlen (password); // get the password length

If (file1 = fopen (source, "rb "))! = NULL)

{

Printf ("the source file % s opened successfully. \ n", source );

If (file2 = fopen (DESTIN, "WB + "))! = NULL)

{

Printf ("the destination file % s created successfully \ n", DESTIN );

Ch = fgetc (file1 );

I = 0;

While (Ch! = EOF)

{

Ch = CH ^ (password [I ++]); // use the password for encryption

If (I> = paslen)

I = 0;

Fputc (CH, file2 );

Ch = fgetc (file1 );

}

Fclose (file1 );

Fclose (file2 );

}

Else

{

Printf ("the destination file % s created error \ n", DESTIN );

}

}

Else

{

Printf ("the source file % s opened error. \ n", source );

}

Getchar ();

Return 0;

}

the running result cannot be displayed. Sorry. I will send my summary to csdn.net. If necessary, I will download the summary. After all, it takes a long time to learn the summary, so I still need some points. Sorry, if you have any questions, please contact me. Thank you! The file contains three common encryption methods, including principles, algorithms , programs, and running results. More support! My csdn.net username is andamajing and the file name is "C language-based file encryption technology ".