YEnc ( homophone for "why encode? ", in German: " why encode? ") is a coding method to transfer binary files on Usenet or via e -mail. Due to the almost complete utilization of the eight bits of a byte, it requires only about one to two percent of additional data ( overhead, at UUencode and Base64 about 33 to 40 percent), but this is achieved only at the expense of transmission security. However, this is ensured in the range of current networks typically to approximately 100%.

There is no RFC for yEnc, but the yEnc website describes a rudimentary specification and grammar, but not the RFC 2822 or RFC 2045 corresponds.


As well as allows UUencode yEnc not the reliable detection of the encoded portions. Furthermore, the majority of these restrictions has already been solved years earlier by MIME. Furthermore, not all transport routes 8 -bit compatible. However, this is absolutely necessary for yEnc, otherwise data loss can occur.

Despite the drawbacks yEnc has strong distribution in binary groups on Usenet. Just as there are special programs for UUencode to encode files in several Usenet postings or decode them from such. Many newsreaders support yEnc now.