how i can encrypt each file with its own public key for example :-

there exist 3 company (X,Y and Z)each company sent to me its own public key so that i have now 3 public key

1- x.pub

2- y.pub

3- z.pub

now i want to send file to each company and encrypt it by its company public key

1- encrypt file1.txt by x.pub and send it to company X

2- encrypt file2.txt by y.pub and send it to company Y

3- encrypt file3.txt by z.pub and send it to company Z

please how i can do the above by writting batch file my operating system is Windows