Probably, that should have been obvious to me from the beginning, but sometimes it takes a while :( Eventually, I decided it would work best as an implementation of ICryptoTransform. However, I soon realized that, although I could read the data as text, I was really dealing with bytes.

Initially, I started coding the encoder as an implementation of. To me, that is a separate challenge, which I'll leave to someone else. My implementation of the algorithm deals purely with encoding and decoding the data, not parsing of messages, or even parsing of the yEnc headers and footers. The reason for the '=y' is that, due to the nature of the algorithm, it could never occur naturally as part of the data. The data ends with a line starting with =yend. The tag has additional attributes that specify the number of bytes to expect, as well as the name of the file and the length of the lines. YEnc data begins with a =ybegin tag at the start of a line. Lines are broken at 128 characters, or 256 characters, by convention. However, individual encoders are free to escape other characters as they wish. The current yEnc algorithm escapes out CR, LF and the NULL character by default. some characters have meaning, and as such need to be escaped out.messages must be broken into lines, max around 1000 characters.There are some peculiarities of newsgroup messages: It is implemented as a cryptographic transform - more on that later.It is the only open-source one written in C#.My implementation is interesting from 2 points of view: It has additional benefits as well, in the form of an optional CRC32 check. Smaller means quicker to upload and download, which is important when dealing with large binary files. This makes messages encoded with yEnc smaller by a factor of 33-40%, according to the website. YEnc's popularity is due to the fact that it uses a full byte to encode the data, whereas other methods use only 7-bits.

Since binary data is usually stored as 8-bit bytes, it does not have to accomplish too much :) It uses 8-bit characters to encode binary data. yEnc is not an official standard, but it is nonetheless a very popular encoding method on binary newsgroups. This is an implementation of the yEnc algorithm, as described at.

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