The result of encrypting anything is a stream of bytes, many of which are not displayable on a screen or printer. For example if I encrypt the string:
"The rain in Spain falls mainly in the plain"
the result is
↔0!å°þ▒ë■&·lBZ■`(Ä(ı4OïödAÇ┤#è╠Ö¦~j┐↨7&$´♦ð↕l¤ðþPH↓}}§♫N|³½↔¡♫═Ï?╩▀◄|enx/┴U→|Ì=WîJ‼i<☻└☼J▄wn↔5
which on some systems may not be displayable. To ensure it is displayable you need to convert each byte into its hexadecimal equivalent and display that; something like:
1D302186F8E7B189FE26FA6C425AFE60288E28D5344F8B94644180B4238ACC99DD7E6ABF17372624EF4D0126CCFD0E75048197D7DF5E4E7CFCAB1DADECDD83FCADF117C656E782FC1551A7CDE3D578C4A13693C2C04B8F4ADC776E1D35