I think that requiring line breaks is silly. Most Base64 parsers handle arbitrary whitespace. OpenSSL's parser is just plain nasty (yes, I once made the mistake of reading the code), but even with OpenSSL's parser there's a straightforward (if ridiculous) workaround: http://subvert-rpki.hactrn.net/trunk/rp/rcynic/bio_f_linebreak.c http://subvert-rpki.hactrn.net/trunk/rp/rcynic/bio_f_linebreak.h I really don't think we need to enshrine OpenSSL's warts in the specification. I prefer Richard's option 2 (allow but do not require linebreaks), which is what RFC 6490 RP implementations had to support anyway.