generate keys with:

openssl genrsa -des3 -out private_key.pem 2056
openssl rsa -pubout -in private_key.pem -out public_key.pem

example key files provided, the passfrase of the private key is password

you can check signing running the sign_test scripts.

you can check encrypting and decrypting running the script with some input, for example:

echo "test message" | ./crypt.php | ./decrypt.rb
./java/encrypt.sh test | ./decrypt.rb

and you should get the plain message back.