Making a file password protected in java

Till now, i have been creating a file (txt/excel) using buffered Writer for creating a text file and JExcel API for creating a Excel file. These files i have been creating using Java only.

Now i want to make the file password protected in both the cases, that to something like, the file can be ac开发者_Python百科cessed by number of people, but only selected may access it using there own login ids/password.

Is it possible to do so?..

Thanks

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The answer completely depends on what way you want to open your protected files.

If it is opened by your (java) program or an application, then you can simply simply encrypt it with a password upon saving, and decrypt it with something the user provides, and use some checksum or header to see if the result is valid - or some garbage due to bad password, some crypto APIs will do it for you right out of the box.

Second option - if you meant encrypting files with a program (like a notepad file, or something), and you expect windows or notepad to ask you for the password, then it depends on the format of the file you use. Some can be password protected, some can not -like text files usually associated with notepad). In this case password protection works as described in the format's own documentation, and you have to research a bit, I guess it will be too much work

we can do password protection of zip files with the core Java API.

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Yes, it is possible to do that, you would have to write your own encryption and decryption tool or write a plugin for excel to do the decryption.

Usually the best approach is to use the security of the OS and specify which users can read or read/write the document. This is transparent to the user and doesn't require a encryption/decryption tool.

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yes it is possible. You can use either AES or DES encryption. password is nothing but the key using which the file can be be encrypted or decrypted. you can create your own listener which will prompt you for password. If you enter the password then it will take the password and try to decrypt the file