Transferring ciphers as e-mail attachments:

A frequent source of confusion for recipients of academic signature ciphers via e-mail is an insane treatment by some mailers or the apple OS of mail-attached files. Mailers or the apple OS at the receiving side may rearrange or remove bytes(e.g. arbitrarily removing the byte Ox0d) in mail attachments without prompting the user for awareness let alone for consent.
Of course this defacement renders attached ciphers undecipherable.
The mailer or the apple OS have no idea what they are dealing with, yet they may decide to rearrange or delete bytes. What do IT-people think when coding this junk behavior  !???

If necessary, the sender can prevent that with the quick fix of sending ciphers in a zip archive as container. Zip archives are usually respected as binary files at the receiving side and are spared from defacement by the mail program or the apple OS, repectively.

A more convenient but dirtier fix may be to give the cipher the name extension ".png" or ".mp3" or possibly other media type's extensions. Any common compressed format will be sensitive to arbitrary editing and will probably be protected from mailer/OS infringement. Selecting these extensions will usually trick the mailer(or the apple OS) into keeping it's sticky fingers off the attachment and not e.g. steal the carriage returns.

On your first cryptographically protected contact with an apple or windows user, it is recommended you explicitly sign your cipher. Furthermore you should inform the recipient about the potential problem with attachment alterations. Few people are aware of such mailer/OS assaults.
The recipient can then detect if the cipher has been defaced and request a retransmission in a form that is protected from mailer/OS infringement at the receiving side.

Changing such aberrant mailer/OS behavior is beyond my potential, so I regret that inconvenient workarounds might be necessary.

Nota bene:
Signatures and time stamps are human readable text. They are insensitive to the annoying mailer/OS infringements.
On a Linux, mailers always seem to behave reasonably and leave attachments alone by default.