Base64 encoding is a standard method for converting 8-bit binary information into a limited subset of ASCII characters for safe transport through e-mail systems, and other systems that are not 8-bit safe. With OpenSSL, it is very easy to encode and decode Base64 data:
openssl enc -base64 -in myfile -out myfile.b64
openssl enc -d -base64 -in myfile.b64 -out myfile.decrypt