Now your document is secure and protected. (Or, if you have already saved this document, click Save, and you’re done.)

Also, please refer to “Background Info” at the end of this article.ħ. It’s better to make a PDF of the document if you’re looking to let someone read but not edit. Also, the Modify password IS limited to 15 characters and not very secure. * a hex String that results from encrypting the given password.Note that your password length may be limited to 15-18 characters depending on the encryption you choose. * password should be a plain text password. * Use to encrypt passwords using MD5 algorithm The user enters a password, you compute the hash of it, then compare the computed hash with the hash value read from the file: import A common way to encrypt a password is with an MD5 hash function. If you prefer, you could save another password file in the same directory and use that to authenticate the user before deciding if the user has the right to view the file. If your file is not human-readable, and only your program understands it, then I would make the first line or first n Bytes of the file a password. If you want to dive more into it, you can look at the Java Cryptography architectre and the javax.crypto java docs. You can use the comment by to help you get started in this direction. So IF the file is a text file, then I think you must use encryption. If the file is a plain text file, then not giving the user access to the file without a password in your program does not really password-protect the data, because the user can just open the file with some other program. password converted to an array of bytesīyte encryptedData = c.doFinal(dataToSend) Theres an unsafe approach that is 'native' to java (symmetric key) that may work out for you:Įncryption: byte key = //. GnuPG is an executable that manages assymmetric encryption, you may build a class to work with GnuPG and let GnuPG manage ur encryption/decryption process.

If you want a really safe approach, you should download GnuPG. This would be the more 'professional' approach. Public keys are used to encrypt files, private keys to decrypt. One is called the public key and the other is called a private key. You may encrypt a file using 2 approaches:ġ - Symmetric key - A secret word (usually a huge string of chars or a password set by the user) will encrypt your file and password, and the same password will be used to decrypt.Ģ - Asymmetric key - You generate a pair of keys.

Build another method to convert the array of bytes back to the string/file. You should start by building a class or method to convert ur string/file to an array of bytes. When you want to encrypt files, strings, etc there are 2 main approaches.

How to put password on excel file