Random tests now added

• The instructions say to include "any and all spaces" but you're right about leading dots and consecutive dot separators; I'll modify the descrption
• see first point
• good point, I'll stop discriminating against empty text

Thanks!

Needs random tests

• Leading spaces/dots are not specified anywhere
• Consecutive dot separaters are not specified anywhere either
• Why empty ciphertext should return null? Empty ciphertext has a one-to-one correspondence to empty text. I don't think you should discriminate empty text ;-)