<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; "><div><br></div><div>I've looked at it, and it seemed to me that it was pretty straight forward to build a cracker for it. There are commercial "Password recovery" programs. </div><div><br></div><div>This isn't a bad summary...</div><div><br></div><div><a href="http://www.cs.cmu.edu/~dst/Adobe/Gallery/anon21jul01-pdf-encryption.txt">http://www.cs.cmu.edu/~dst/Adobe/Gallery/anon21jul01-pdf-encryption.txt</a></div><div><br></div><div>and I think the answer to your question is....</div><div><blockquote style="margin: 0 0 0 40px; border: none; padding: 0px;"><div><pre style="word-wrap: break-word; white-space: pre-wrap; ">Adobe's PDF protection scheme is a classic example of security
throughd obscurity. They encrypt the content of a PDF file and hope
that no one figures out how to decrypt it.</pre></div></blockquote></div><div>personally I would use gpg for email.</div><br><div apple-content-edited="true">
<span class="Apple-style-span" style="border-collapse: separate; border-spacing: 0px; "><span class="Apple-style-span" style="border-collapse: separate; color: rgb(0, 0, 0); font-family: Helvetica; font-style: normal; font-variant: normal; font-weight: normal; letter-spacing: normal; line-height: normal; orphans: 2; text-align: -webkit-auto; text-indent: 0px; text-transform: none; white-space: normal; widows: 2; word-spacing: 0px; -webkit-border-horizontal-spacing: 0px; -webkit-border-vertical-spacing: 0px; -webkit-text-decorations-in-effect: none; -webkit-text-size-adjust: auto; -webkit-text-stroke-width: 0px; font-size: medium; "><div style="word-wrap: break-word; -webkit-nbsp-mode: space; -webkit-line-break: after-white-space; "><div>John Orthoefer</div><div>jco{at}<a href="http://direwolf.com">direwolf.com</a></div><div><br></div></div></span><br class="Apple-interchange-newline"></span><br class="Apple-interchange-newline">
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<br><div><div>On Feb 17, 2013, at 8:53 AM, Scott Ehrlich <<a href="mailto:srehrlich@gmail.com">srehrlich@gmail.com</a>> wrote:</div><br class="Apple-interchange-newline"><blockquote type="cite">How safe is a password-protected PDF file sent via email?<br><br>I've never run a sniffer to see what could be learned from doing this.<br><br>Thanks.<br><br>Scott<br><br>_______________________________________________<br>bblisa mailing list<br><a href="mailto:bblisa@bblisa.org">bblisa@bblisa.org</a><br>http://www.bblisa.org/mailman/listinfo/bblisa<br></blockquote></div><br></body></html>