encrypt and decrypt data

https://www.cyberciti.biz/tips/linux-how-to-encrypt-and-decrypt-files-with-a-password.html

Encrypting a file in Linux or Unix

To encrypt a single file, use command gpg as follows:
$ gpg -c filename
To encrypt myfinancial.info.txt file, type the command:
$ gpg -c myfinancial.info.txt
Sample output:

Enter passphrase:<YOUR-PASSWORD>
Repeat passphrase:<YOUR-PASSWORD>

This will create a myfinancial.info.txt.gpg file:
$ ls -l myfinancial.info.txt*
Sample outputs:

-rw-rw-r-- 1 vivek vivek  23 Jan 13 15:01 myfinancial.info.txt
-rw-rw-r-- 1 vivek vivek 113 Jan 13 15:01 myfinancial.info.txt.gpg

Where,

• -c : Encrypt with a symmetric cipher using a passphrase. The default symmetric cipher used is AES128, but may be chosen with the --cipher-algo option.

You can delete myfinancial.info.txt file:
$ rm myfinancial.info.txt
Please note that if you ever forgot your password (passphrase), you cannot recover the data as it use very strong encryption.

Decrypt a file in Linux or Unix-like system

To decrypt file use the gpg command as follow:
$ gpg myfinancial.info.txt.gpg
OR
$ gpg -d myfinancial.info.txt.gpg
OR
$ gpg --decrypt myfinancial.info.txt.gpg
Sample outputs:

gpg myfinancial.info.txt.gpg
gpg: CAST5 encrypted data
Enter passphrase:<YOUR-PASSWORD>

To view your file, type:
$ ls -l myfinancial.info.txt
$ cat myfinancial.info.txt
$ vi myfinancial.info.txt
Decrypt file and write output to file vivek.info.txt you can run command:
$ gpg myfinancial.info.gpg -o vivek.info.txt
OR
$ gpg -d myfinancial.info.gpg --output vivek.info.txt
Also note that if file extension is .asc, it is a ASCII encrypted file and if file extension is .gpg, it is a binary encrypted file.

The windows tool is provided 

https://gnupg.org/download/