<html><head><meta http-equiv="Content-Type" content="text/html charset=us-ascii"></head><body style="word-wrap: break-word; -webkit-nbsp-mode: space; -webkit-line-break: after-white-space;">On Jan 13, 2015, at 11:22 PM, Phillip Hallam-Baker <<a href="mailto:phill@hallambaker.com">phill@hallambaker.com</a>> wrote:<br><div><blockquote type="cite"><div dir="ltr"><div class="gmail_extra"><div class="gmail_quote"><div><font color="#000000">...</font>Yes, it is not possible to compress encrypted data if the encryption is any good and this is actually a good check to see if you have goofed by using ECB or whatever. But don't be too sure that random data can't compress. Sometimes it can - we get down to 3-4 bits per revoked cert.</div></div></div></div></blockquote>That's because you aren't actually compressing the certs - you're compressing deltas on pre-communicated sets of certs - and you can make assumptions about the nature of the deltas. Very different problem. The technique is *very* nice, but it amounts to recognizing and working with the exact kind of non-randomness inherent in the data you're compressing.</div><div><div> -- Jerry</div><div><br></div></div><br></body></html>