Re: encrypting files
I have been thinking about encrypting some private files on my laptop, in case it gets stolen. I have a general comment, and a specific software suggestion: General comment: Whatever encryption solution you use, think seriously about backups! That is, if your data is important enough to encrypt, it's surely important enough to need backups. If you backup the plaintext, do you trust the security of whereever those backups get stored? Maybe you want to backup the ciphertext instead... Now for the specific software suggestion: I have been using cvs (available in ports) for 10+ years now, and am happy with it. It's an encrypting file system. Advantages: * transparent encryption, with keys on a per-directory-tree granularity * can run on many different Unix flavors without needing custom kernels Disadvantages: * performance is a lot lower than an in-kernel crypto filesystem (but for modern hardware and moderate-sized files, the cryto overheads are still only tiny fractions of a second) * security is probably good enough to stop casual snooping, but likely wouldn't stop serious spooks like the NSA et al (see http://www.usenix.org/publications/login/2004-08/pdfs/howard.pdf for some recent cryptanalysis work) * it's pretty close to unmaintained now -- the cfs-users mailing list seems to have been dead for several years :( ciao, -- -- Jonathan Thornburg [EMAIL PROTECTED] Max-Planck-Institut fuer Gravitationsphysik (Albert-Einstein-Institut), Golm, Germany, Old Europe http://www.aei.mpg.de/~jthorn/home.html Washing one's hands of the conflict between the powerful and the powerless means to side with the powerful, not to be neutral. -- quote by Freire / poster by Oxfam
Re: Encrypting files
On Sun, Jul 02, 2006 at 02:14:59AM +0200, Rico Secada wrote: Hi I have been thinking about encrypting some private files on my laptop, in case it gets stolen. I have no prior experience in this field. I have been thinking about using mcrypt with blowfish, but is this a good way to go about? Are there a better alternative? And is blowfish the best way to encrypt it? Please bear with me if these questions are ignorent. There are many solutions; not mentioned yet is gnupg, which has quite a few bells and whistles you don't need but is otherwise a rather solid program (or so I used to think; there have been a few vulnerabilities in the past month or two). However, svnd is probably the most convenient if you are running -current. Do remember to remove the original files; rm -P, as suggested, works. Joachim
Re: Encrypting files
Joachim Schipper wrote: On Sun, Jul 02, 2006 at 02:14:59AM +0200, Rico Secada wrote: Hi I have been thinking about encrypting some private files on my laptop, in case it gets stolen. I have no prior experience in this field. I have been thinking about using mcrypt with blowfish, but is this a good way to go about? Are there a better alternative? And is blowfish the best way to encrypt it? Please bear with me if these questions are ignorent. There are many solutions; not mentioned yet is gnupg, which has quite a few bells and whistles you don't need but is otherwise a rather solid program (or so I used to think; there have been a few vulnerabilities in the past month or two). However, svnd is probably the most convenient if you are running -current. Do remember to remove the original files; rm -P, as suggested, works. A users tmp files should be encrypted as well. Setting TMPDIR to point into an encrypted filesystem may be enough, assuming that the application(s) respect TMPDIR. /Sigfred
Re: Encrypting files
On Sun, Jul 02, 2006 at 12:00:34PM +0200, Sigfred H?versen wrote: Joachim Schipper wrote: On Sun, Jul 02, 2006 at 02:14:59AM +0200, Rico Secada wrote: Hi I have been thinking about encrypting some private files on my laptop, in case it gets stolen. I have no prior experience in this field. I have been thinking about using mcrypt with blowfish, but is this a good way to go about? Are there a better alternative? And is blowfish the best way to encrypt it? Please bear with me if these questions are ignorent. There are many solutions; not mentioned yet is gnupg, which has quite a few bells and whistles you don't need but is otherwise a rather solid program (or so I used to think; there have been a few vulnerabilities in the past month or two). However, svnd is probably the most convenient if you are running -current. Do remember to remove the original files; rm -P, as suggested, works. A users tmp files should be encrypted as well. Setting TMPDIR to point into an encrypted filesystem may be enough, assuming that the application(s) respect TMPDIR. Yes, indeed, I should have pointed that out. Thoroughly wiping the filesystem /tmp resides on (at boot?) works, too. However, many important files may be kept elsewhere; for instance, vim uses .filename.swp for swap files, and while this certainly has advantages, it does not make for optimal security... All in all, svnd is probably the most convenient option; any other option requires a lot of work. Note that, on other systems, a huge problem is that files may be written to swap at any time unless the memory was specifically allocated not to allow this (certain high-security programs, like gnupg, do this for at least part of the memory; but editors typically don't). This means that the swap partition(s) also need periodic overwriting. However, OpenBSD uses encrypted swap by default, at least on more-or-less recent versions. Joachim
Re: Encrypting files
Bear in mind that if you're serious about keeping plaintext away from people who you don't want to see it, this could get quite tricky. What happens if an application generates temporary files? What happens if an application swaps? What happens if an application crashes and dumps core? What happens if the kernel crashes and dumps core? What happens if you accidentally copy and past some content into your shell, thereby logging it into your .history? Certain editors (vim for sure, probably emacs too) can encrypt your files on the fly. I don't use that feature, but if you do, make sure they handle temp files properly, etc. Be very careful - just because your long-term, bulk storage is encrypted there is no guarantee that you haven't left plaintext anywhere. And that's not even taking into account that the thief might just put trojan horses all over your laptop before letting you have it back. Think of how often you hear of windows machines being turned into spambots with keyloggers. Just because it seems to be mostly windows machines doesn't mean it can't happen. *NIX makes it easy for even a moderately competent programmer to write a trivial keylogger. CK -- GDB has a 'break' feature; why doesn't it have 'fix' too?
Re: Encrypting files
On Sun, Jul 02, 2006 at 10:57:42AM -0600, Chris Kuethe wrote: Bear in mind that if you're serious about keeping plaintext away from people who you don't want to see it, this could get quite tricky. What happens if an application generates temporary files? What happens if an application swaps? What happens if an application crashes and dumps core? What happens if the kernel crashes and dumps core? Well, in that case, you are usually sufficiently alerted to clean out the relevant parts of the disk. (Note that the case where you do not have administrator access is not relevant, as root can read your files any time you can, anyway.) What happens if you accidentally copy and past some content into your shell, thereby logging it into your .history? Certain editors (vim for sure, probably emacs too) can encrypt your files on the fly. I don't use that feature, but if you do, make sure they handle temp files properly, etc. Be very careful - just because your long-term, bulk storage is encrypted there is no guarantee that you haven't left plaintext anywhere. But this is still good advice; a crashing kernel is not very believable, but such mundane mistakes are likely to provide at least snippets of information. More importantly, a file like ~/.viminfo contains quite a bit of information. I *suppose* vim handles encrypted files in a sane fashion, but I am not sure. And that's not even taking into account that the thief might just put trojan horses all over your laptop before letting you have it back. Think of how often you hear of windows machines being turned into spambots with keyloggers. Just because it seems to be mostly windows machines doesn't mean it can't happen. *NIX makes it easy for even a moderately competent programmer to write a trivial keylogger. If you do *that*, however, you are just being stupid. Wipe and reinstall; if the data is important, preserve that - but no binaries or somesuch. Joachim
Re: Encrypting files
On 7/2/06, Chris Kuethe [EMAIL PROTECTED] wrote: Bear in mind that if you're serious about keeping plaintext away from people who you don't want to see it, this could get quite tricky. And that's not even taking into account that the thief might just put trojan horses all over your laptop before letting you have it back. Think of how often you hear of windows machines being turned into spambots with keyloggers. Just because it seems to be mostly windows machines doesn't mean it can't happen. *NIX makes it easy for even a moderately competent programmer to write a trivial keylogger. This is a good thread! I have some questions though: How can you make a keylogger on UNIX? I thought that UNIX segmented it's memory spaces, unlike Windows which has the problem of a global key trampoline (I'm sorry, I read this somewhere once and do not remember exactly what it was called). I suppose if you replaced the kernel than you could do this but I don't think that's what was meant. How do you choose between svnd and vnd devices? I'm guessing the type of the device is determined by whether you do `vnconfig svnd...` or `vnconfig vnd` but the manpage doesn't explicitly say this. -Nick
Re: Encrypting files
On Sun, Jul 02, 2006 at 02:56:03PM -0400, Nick Guenther wrote: I have some questions though: How can you make a keylogger on UNIX? I thought that UNIX segmented it's memory spaces, unlike Windows which has the problem of a global key trampoline (I'm sorry, I read this somewhere once and do not remember exactly what it was called). I suppose if you replaced the kernel than you could do this but I don't think that's what was meant. I think this was meant. man wskbd tells a little about the keyboard and the routines for this are in /sys/dev/wscons I think. Because you have the source, can recompile and the code is written with KISS in mind you'll be able to patch something up. However if you do you should check your morals, they come back to haunt you if you abuse them. Running a default kernel compiled by deraadt directly from the CD-ROM should ensure that no keylogger of any sort is installed in the kernel. There really isn't much reason to compile your own kernel unless you add your own stuff or want to change something. -peter -- Here my ticker tape .signature My name is Peter Philipp lynx -dump http://en.wikipedia.org/w/index.php?title=Pufferfisholdid=20768394; | sed -n 131,136p So long and thanks for all the fish!!!
Re: Encrypting files
On 7/2/06, Peter Philipp [EMAIL PROTECTED] wrote: On Sun, Jul 02, 2006 at 02:56:03PM -0400, Nick Guenther wrote: I have some questions though: How can you make a keylogger on UNIX? I thought that UNIX segmented it's memory spaces, unlike Windows which has the problem of a global key trampoline (I'm sorry, I read this somewhere once and do not remember exactly what it was called). I suppose if you replaced the kernel than you could do this but I don't think that's what was meant. I think this was meant. man wskbd tells a little about the keyboard and the routines for this are in /sys/dev/wscons I think. Because you have the source, can recompile and the code is written with KISS in mind you'll be able to patch something up. However if you do you should check your morals, they come back to haunt you if you abuse them. Running a default kernel compiled by deraadt directly from the CD-ROM should ensure that no keylogger of any sort is installed in the kernel. There really isn't much reason to compile your own kernel unless you add your own stuff or want to change something. Ah, okay, thank you! I see a lot go across on this list only half-explained, which is good for those who know what is going on but not for newbies like me. It's nice that this list is the sort of place where you are expected to use your own morals instead of blindly following the no hacking is bad! mantra. For the record, I was just curious, I'm not actually planning on bugging my systems. -Nick
Re: Encrypting files
On Sun, Jul 02, 2006 at 02:56:03PM -0400, Nick Guenther wrote: On 7/2/06, Chris Kuethe [EMAIL PROTECTED] wrote: Bear in mind that if you're serious about keeping plaintext away from people who you don't want to see it, this could get quite tricky. And that's not even taking into account that the thief might just put trojan horses all over your laptop before letting you have it back. Think of how often you hear of windows machines being turned into spambots with keyloggers. Just because it seems to be mostly windows machines doesn't mean it can't happen. *NIX makes it easy for even a moderately competent programmer to write a trivial keylogger. This is a good thread! I have some questions though: How can you make a keylogger on UNIX? I thought that UNIX segmented it's memory spaces, unlike Windows which has the problem of a global key trampoline (I'm sorry, I read this somewhere once and do not remember exactly what it was called). I suppose if you replaced the kernel than you could do this but I don't think that's what was meant. UNIX offers some very nice things, including ptys, ttys, and pipes. ptys were made for the explicit purpose of allowing programs to send and receive stuff to a tty-like interface, but with a program on the other end (instead of a terminal). You are right that reading keystrokes out of kernel memory is not trivial, and impossible without superuser priviliges, but if you already are the user whose keystrokes you want to snoop, it's not very difficult. How do you choose between svnd and vnd devices? I'm guessing the type of the device is determined by whether you do `vnconfig svnd...` or `vnconfig vnd` but the manpage doesn't explicitly say this. That's correct, you will want to name a complete device, though - so vnconfig svnd0 (...). Joachim
Re: Encrypting files
On Sun, Jul 02, 2006 at 09:34:50PM +0200, Peter Philipp wrote: On Sun, Jul 02, 2006 at 02:56:03PM -0400, Nick Guenther wrote: I have some questions though: How can you make a keylogger on UNIX? I thought that UNIX segmented it's memory spaces, unlike Windows which has the problem of a global key trampoline (I'm sorry, I read this somewhere once and do not remember exactly what it was called). I suppose if you replaced the kernel than you could do this but I don't think that's what was meant. I think this was meant. man wskbd tells a little about the keyboard and the routines for this are in /sys/dev/wscons I think. Because you have the source, can recompile and the code is written with KISS in mind you'll be able to patch something up. However if you do you should check your morals, they come back to haunt you if you abuse them. Running a default kernel compiled by deraadt directly from the CD-ROM should ensure that no keylogger of any sort is installed in the kernel. Well, provided the BIOS (or equivalent) cannot be flashed from the kernel, yes. Of course, worrying about this requires raging paranoia. But from a quick look, flashing the BIOS and combining it with an attack like the recent Blue Pill http://theinvisiblethings.blogspot.com/2006/06/introducing-blue-pill.html (and elsewhere, but this one looks pretty complete) method would make for a *very* nasty rootkit. Just rewriting the kernel that is loaded by the bootloader would also be nasty, and potentially undetectable from software, too - but that's old news, and I have a vague notion that the above could likely be done in fewer instructions, which means that it's easier to put in what limited space is available. Of course, if you have people who can do this and are willing to invest the time to actually do it after you, be glad you're running OpenBSD, be careful with ports and new code, and remember - it's not paranoia if they really are out to get you. There really isn't much reason to compile your own kernel unless you add your own stuff or want to change something. Of course, that's still true. Joachim
Re: Encrypting files
On Sun, Jul 02, 2006 at 03:59:41PM -0400, Nick Guenther wrote: On 7/2/06, Peter Philipp [EMAIL PROTECTED] wrote: On Sun, Jul 02, 2006 at 02:56:03PM -0400, Nick Guenther wrote: How can you make a keylogger on UNIX? I think this was meant. (...) Ah, okay, thank you! I see a lot go across on this list only half-explained, which is good for those who know what is going on but not for newbies like me. It's nice that this list is the sort of place where you are expected to use your own morals instead of blindly following the no hacking is bad! mantra. For the record, I was just curious, I'm not actually planning on bugging my systems. Note that, under certain circumstances, it can make sense to bug your own systems, and in most (all?) jurisdictions it is legal if the users are warned beforehand. This can make sense if you run a shell provider, and d00m10rd_t3h_1337 is running another ssh scan, for instance... Plus, you need at least a high-level theoretical knowledge of an attack to be able to adequately defend yourself from it. Joachim
Re: Encrypting files
On Sun, Jul 02, 2006 at 10:25:35PM +0200, Joachim Schipper wrote: Well, provided the BIOS (or equivalent) cannot be flashed from the kernel, yes. Of course, worrying about this requires raging paranoia. But from a Paranoia isn't necessarily a bad thing. It motivates people to seek true or possible points of compromise in a system. Motivation is the key in productivity and security. -peter
Re: Encrypting files
On Sun, 2 Jul 2006 10:57:42 -0600 Chris Kuethe [EMAIL PROTECTED] wrote: Bear in mind that if you're serious about keeping plaintext away from people who you don't want to see it, this could get quite tricky. After a bout of homocidal paranoia and time spent wondering just what to do with several hundred pounds of tin foil... Crypted data is good. It will stop snooping office workers and common laptop thieves. But if some organization wants your data, they could trick it out of you (keyloggers, et al.) Or more crude physical methods. I once advocated some insane crypto here, which was indeed silly of me. I have seen the light. svnd is a fantastic _practical and real_ solution. I'm happy that there is such a fantastic OS for me to run... though I wonder what I will do 60 years down the line. Anyhow, thanks for the great OS guys. When can I buy the next release? =) Travers
Encrypting files
Hi I have been thinking about encrypting some private files on my laptop, in case it gets stolen. I have no prior experience in this field. I have been thinking about using mcrypt with blowfish, but is this a good way to go about? Are there a better alternative? And is blowfish the best way to encrypt it? Please bear with me if these questions are ignorent. Best regards, Rico
Re: Encrypting files
On Sun, Jul 02, 2006 at 02:14:59AM +0200, Rico Secada wrote: Hi I have been thinking about encrypting some private files on my laptop, in case it gets stolen. I have no prior experience in this field. I have been thinking about using mcrypt with blowfish, but is this a good way to go about? Are there a better alternative? And is blowfish the best way to encrypt it? Please bear with me if these questions are ignorent. Best regards, Rico I use openssl if I have to encrypt a file, it's fairly portable across systems. $ echo supersecretcontent file $ openssl enc -bf-cbc -in file -out file.X enter bf-cbc encryption password: Verifying - enter bf-cbc encryption password: $ hexdump -C file.X 53 61 6c 74 65 64 5f 5f 48 bf cb c8 f0 42 b0 35 |Salted__H?KHpB05| 0010 ba 2a 39 32 e6 63 92 a4 52 78 b1 f8 ce 09 ac 6e |:*92fc.$Rx1xN.,n| 0020 d0 e7 6a e6 26 0d 48 b0 |Pgjf.H0| 0028 $ # this is important afterwards $ rm -P file $ -peter -- Here my ticker tape .signature My name is Peter Philipp lynx -dump http://en.wikipedia.org/w/index.php?title=Pufferfisholdid=20768394; | sed -n 131,136p So long and thanks for all the fish!!!
Re: Encrypting files
On Sun, 2 Jul 2006 02:14:59 +0200 Rico Secada [EMAIL PROTECTED] wrote: Hi I have been thinking about encrypting some private files on my laptop, in case it gets stolen. tedu just improved svnd's crypto... add -K option which uses a salt file and pkcs5 pbkdf2 to create a more secure key... Thanks tedu djm and markus! Travers
Re: Encrypting files
On Sun, Jul 02, 2006 at 02:14:59AM +0200, Rico Secada wrote: | Hi | | I have been thinking about encrypting some private files on my | laptop, in case it gets stolen. If someone can steal your laptop, can they also take it for a short while, fiddle with it (eg install a malicious kernel) and return it to you without noticing, only to come by later to steal it again ? Consider this, because in such a case your private files may get exposed while you think you are secure. | I have no prior experience in this field. | | I have been thinking about using mcrypt with blowfish, but is this | a good way to go about? Are there a better alternative? And is | blowfish the best way to encrypt it? Apaart from the other suggestions already mentioned, you could try using security/gnupg : gpg -e INPUTFILE OUTPUTFILE rm -P INPUTFILE gpg OUTPUTFILE Good luck. Paul 'WEiRD' de Weerd -- [++-]+++.+++[---].+++[+ +++-].++[-]+.--.[-] http://www.weirdnet.nl/ [demime 1.01d removed an attachment of type application/pgp-signature]
