What is yEnc ?

yEnc is a new encoding method which offers efficient and proper transmission for binaries on the Usenet (or by eMail and other applications).
Other encodings are BASE64, BinHex, UUencode, Quoted Printable, …..

yEnc is NOT an audio format (as MP3) or a video format (as AVI, MOV,…) or a picture format (as GIF or JPEG).

What is an encoding – and why is it used ?

News and Mail transfer require that a binary attachment is “encoded” before it is sent. And they are “decoded” after they have been received. Normally all this is done by your newsreader (or mail-program). You dont see it. Most dont even know it.

The encoding is necessary because the special methods for the transfer of news & mail (protocols) require it. A message with a binary which is not encoded is corrupted during transmission – or transmission is denied at all.

Transport of messages by News and Mail was restricted to US-ASCII characters when the protocols were written (20 years ago). These services have been created to transport only plain US-text. Special characters (control-characters, symbols, non-US-characters) were forbidden – and used for special purposes. But because people wanted to send also binary attachments by News and Mail some ‘tricks’ were implemented: The binary was changed to “allowed US-ASCII-characters” before transmission (encoding) – and back to a binary after transmission (decoding). The usual encoding methods are still respecting these old limitations – and are used everywhere.
Unfortunately there is a price for this ‘trick’: Encoding makes a message longer. And not just a little, but 33%-40% longer than the original attachments. This results in 33%-40% more bytes for a message – 33%-40% more time for the transmission – 33-40% more diskspace on the harddisk where there messages are stored (on news- and mail-servers).

Meanwhile Usenet is able to to transport more than “US-ASCII”, it could also transport other characters. Just a few special characters are still forbidden. Unfortunetaly the encodings were never changed. We are all still using BASE64, BinHex, UUencode. We are all wasting every day bandwidth, time, diskspace and money.

yEnc is now a proposed encoding method which is using the fact that news-servers can today transport binaries more efficient. On eMail the situation is far more complicated because there are a lot of older programs and computers involved. But also there would be potential for savings.