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</o:shapelayout></xml><![endif]--></head><body lang=EN-US link=blue vlink=purple><div class=WordSection1><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'><o:p> </o:p></span></p><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'><o:p> </o:p></span></p><div style='border:none;border-left:solid blue 1.5pt;padding:0in 0in 0in 4.0pt'><div><div style='border:none;border-top:solid #B5C4DF 1.0pt;padding:3.0pt 0in 0in 0in'><p class=MsoNormal><b><span style='font-size:10.0pt;font-family:"Tahoma","sans-serif"'>From: </span></b><span style='font-size:10.0pt;font-family:"Tahoma","sans-serif"'>Mariano Martinez Peck<br><br><o:p></o:p></span></p></div></div><div><div><div><p class=MsoNormal>On Mon, Feb 17, 2014 at 7:25 PM, Ron Teitelbaum <<a href="mailto:ron@usmedrec.com" target="_blank">ron@usmedrec.com</a>> wrote:<o:p></o:p></p><div><div><p class=MsoNormal style='mso-margin-top-alt:auto;mso-margin-bottom-alt:auto'><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'>Hi Mariano, </span><span style='color:#1F497D'><o:p></o:p></span></p><p class=MsoNormal style='mso-margin-top-alt:auto;mso-margin-bottom-alt:auto'><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'>Before I give you an answer, you should never ever ever not even for any reason, ever, did I mention ever, store a user’s password. You can hash a password, which means you store the hash value of the password. You can make it more secure by salting the hash or embedding your own key to the hash, or doing a number of other things. But you should always store an encrypted hash and never a recoverable password. The way this works is that your user knows the password and can generate a hash at any time that you can compare. You store the hash of the password to compare. The reason for this should be obvious. You don’t want anyone to have access to that password. Not even programmers. Your program doesn’t need it either since the user can generate that hash for you at any time. It really is all you ever need to store.</span><o:p></o:p></p><p class=MsoNormal style='mso-margin-top-alt:auto;mso-margin-bottom-alt:auto'><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'> </span><o:p></o:p></p></div></div><div><p class=MsoNormal><o:p> </o:p></p></div><div><p class=MsoNormal>Hi Ron,<o:p></o:p></p></div><div><p class=MsoNormal><o:p> </o:p></p></div><div><p class=MsoNormal>Thanks for the advice. I have been warned about this in the past so I am NOT using this for storing passwords. Instead, there are instVars from certain objects that are "password protected" because they represent some sensible data. So these fields need to be encrypted/decrypted. The user needs to supply a password for editing/viewing them. These fields were encrypted/decrypted with Blowfish. And the key for the blowfish is the " SecureHashAlgorithm new hashMessage: aString" of the password used to protect them...<o:p></o:p></p></div><div><p class=MsoNormal><o:p> </o:p></p></div><div><p class=MsoNormal>Anyway.... I do need encrypt/decrypt and it should be fast. I have just tried ARC4 and seems to be fast. I have a few questions:<o:p></o:p></p></div><div><p class=MsoNormal><o:p> </o:p></p></div><div><p class=MsoNormal>- If I make the ARC4 key larger is it likely to be safer? <o:p></o:p></p></div><div><p class=MsoNormal><span style='color:#1F497D'>Safer depends mostly on how you use store the key and how you transfer secrets. I gave you the largest key for ARC4 so making it larger is not really an option. Oops Sorry no I didn’t (this is a good example of why crypto needs to be simple to be used properly!) use nextBytes: not nextBits for a larger key. You may want to use a 40 bit key, see below.<o:p></o:p></span></p><p class=MsoNormal><span style='color:#1F497D'><o:p> </o:p></span></p><p class=MsoNormal><span style='color:#1F497D'>Some of the things you need to do are salt your data. This allows you to store a different value each and every time the data in encrypted even if the data itself doesn’t change. Never send the key in the open, it should also be encrypted (so that the same network packets sent again never open any locks). <o:p></o:p></span></p><p class=MsoNormal><span style='color:#1F497D'><o:p> </o:p></span></p><p class=MsoNormal><span style='color:#1F497D'>How you store the key is important, but only as important as your security profile. For example if you wanted to protect the data against governments, you are out of luck. If you wanted to protect your data against large powerful actors, then you would need to store your password in memory only, and change it a multiple times a second (by re-salting and encrypting). If the program is tampered with or shuts down all the data is permanently lost in memory. You could have a master key (stored offline) to recover from disk. Now that is an extreme example, but you have to keep in mind that your program is only as good as your key storage. If you can store your key offline and start your system with it, then salt and stretch it for regular operations, you are pretty secure. If you just add your key to an ivar on a class running in smalltalk, you are probably not very secure. Your security profile will probably be in between the extremes but it is definitely worth thinking about. Two way auth is also a good way to go (like google authenticator). I personally like SAML. It allows you to handle authentication externally and your program doesn’t need to handle secrets. AD is also another way to add good security to your system without having to throw the solution all yourself. <o:p></o:p></span></p><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'><o:p> </o:p></span></p><p class=MsoNormal>- How does ARC4 compare to blowfish from security point of view? Is blowfish much more secure or not that much?<o:p></o:p></p></div><div><p class=MsoNormal> <o:p></o:p></p><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'>If you really care about the cipher use Rijndael instead. That is our implementation of AES. Blowfish was a contender for AES but was not picked. It’s a very good program but it’s not as well reviewed as AES. When AES was selected it of course went through a huge amount of review. It also is the current back bone of SSL (TLS).<o:p></o:p></span></p><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'><o:p> </o:p></span></p><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'>RC2 is best if you plan to export your security code (use 40 bit key size). It is also vulnerable to some attacks but it’s still good for most uses (which is why it’s a good choice for export). Governments like encryption they can break. <o:p></o:p></span></p><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'><o:p> </o:p></span></p><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'>If you can use approved software instead writing your own, you are much better off. Using cryptography is not the same thing as implementing it. Implementing it requires government restrictions, registration, and regulations.<o:p></o:p></span></p><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'><o:p> </o:p></span></p><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'>Hope that helps and doesn’t scare you off. Cryptography is really fun, and very cool. Just be careful to follow the rules and do things properly.<o:p></o:p></span></p><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'><o:p> </o:p></span></p></div><div><p class=MsoNormal>Thanks in advance!<o:p></o:p></p><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'><o:p> </o:p></span></p><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'><o:p> </o:p></span></p></div><div><p class=MsoNormal><o:p> </o:p></p></div><blockquote style='border:none;border-left:solid #CCCCCC 1.0pt;padding:0in 0in 0in 6.0pt;margin-left:4.8pt;margin-right:0in'><div><div><p class=MsoNormal style='mso-margin-top-alt:auto;mso-margin-bottom-alt:auto'><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'>If you are looking for a simple cypher for something other than a password how about ARC4 from <a href="http://www.squeaksrouce.com/Cryptography" target="_blank">www.squeaksrouce.com/Cryptography</a> </span><o:p></o:p></p><p class=MsoNormal style='mso-margin-top-alt:auto;mso-margin-bottom-alt:auto'><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'> </span><o:p></o:p></p><p class=MsoNormal style='mso-margin-top-alt:auto;mso-margin-bottom-alt:auto'><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'>|key cText pText|</span><o:p></o:p></p><p class=MsoNormal style='mso-margin-top-alt:auto;mso-margin-bottom-alt:auto'><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'>key := SecureRandom picker nextBits: 254. </span><o:p></o:p></p><p class=MsoNormal style='mso-margin-top-alt:auto;mso-margin-bottom-alt:auto'><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'>cText := (ARC4 new key: key) encrypt: 'This is a very secure but meaningless string' asByteArray.</span><o:p></o:p></p><p class=MsoNormal style='mso-margin-top-alt:auto;mso-margin-bottom-alt:auto'><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'>pText := (ARC4 new key: key) decrypt: cText.</span><o:p></o:p></p><p class=MsoNormal style='mso-margin-top-alt:auto;mso-margin-bottom-alt:auto'><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'>^pText asString</span><o:p></o:p></p><p class=MsoNormal style='mso-margin-top-alt:auto;mso-margin-bottom-alt:auto'><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'>'This is a very secure but meaningless string'</span><o:p></o:p></p><p class=MsoNormal style='mso-margin-top-alt:auto;mso-margin-bottom-alt:auto'><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'> </span><o:p></o:p></p><p class=MsoNormal style='mso-margin-top-alt:auto;mso-margin-bottom-alt:auto'><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'>It’s pretty simple. To get the plainText back all you need is the key. </span><o:p></o:p></p><p class=MsoNormal style='mso-margin-top-alt:auto;mso-margin-bottom-alt:auto'><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'> </span><o:p></o:p></p><p class=MsoNormal style='mso-margin-top-alt:auto;mso-margin-bottom-alt:auto'><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'>All the best,</span><o:p></o:p></p><p class=MsoNormal style='mso-margin-top-alt:auto;mso-margin-bottom-alt:auto'><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'> </span><o:p></o:p></p><p class=MsoNormal style='mso-margin-top-alt:auto;mso-margin-bottom-alt:auto'><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'>Ron Teitelbaum</span><o:p></o:p></p><p class=MsoNormal style='mso-margin-top-alt:auto;mso-margin-bottom-alt:auto'><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'> </span><o:p></o:p></p><div style='border:none;border-left:solid blue 1.5pt;padding:0in 0in 0in 4.0pt'><div><div style='border:none;border-top:solid #B5C4DF 1.0pt;padding:3.0pt 0in 0in 0in'><p class=MsoNormal style='mso-margin-top-alt:auto;mso-margin-bottom-alt:auto'><b><span style='font-size:10.0pt;font-family:"Tahoma","sans-serif"'>From:</span></b><span style='font-size:10.0pt;font-family:"Tahoma","sans-serif"'> Pharo-dev [mailto:<a href="mailto:pharo-dev-bounces@lists.pharo.org" target="_blank">pharo-dev-bounces@lists.pharo.org</a>] <b>On Behalf Of </b>Mariano Martinez Peck<br><b>Sent:</b> Monday, February 17, 2014 4:17 PM<br><b>To:</b> Pharo Development List; <a href="mailto:glass@lists.gemtalksystems.com" target="_blank">glass@lists.gemtalksystems.com</a>; The general-purpose Squeak developers list<br><b>Subject:</b> [Pharo-dev] FFI blowfish for encrypting / decrypting [WAS] Re: How to encrypt a password?</span><o:p></o:p></p></div></div><div><div><p class=MsoNormal style='mso-margin-top-alt:auto;mso-margin-bottom-alt:auto'> <o:p></o:p></p><div><div><p class=MsoNormal style='mso-margin-top-alt:auto;margin-bottom:12.0pt'> <o:p></o:p></p><div><p class=MsoNormal style='mso-margin-top-alt:auto;mso-margin-bottom-alt:auto'>On Thu, Nov 21, 2013 at 3:53 PM, Paul DeBruicker <<a href="mailto:pdebruic@gmail.com" target="_blank">pdebruic@gmail.com</a>> wrote:<o:p></o:p></p><p class=MsoNormal style='mso-margin-top-alt:auto;mso-margin-bottom-alt:auto'>Mariano Martinez Peck wrote<o:p></o:p></p><div><p class=MsoNormal style='mso-margin-top-alt:auto;mso-margin-bottom-alt:auto'>> Hi Paul, and just to be sure I understand...none of them could work as a<br>> two-way encryption, right?<br>> The only one is your Pharo's version of Blowfish but that only works with<br>> 8<br>> chars long. Is it like this? Or is there any other two-way encryption?<br>><br>> Thanks!<br>><o:p></o:p></p></div><p class=MsoNormal style='mso-margin-top-alt:auto;margin-bottom:12.0pt'>> --<br>> Mariano<br>> <a href="http://marianopeck.wordpress.com" target="_blank">http://marianopeck.wordpress.com</a><br><br><br>Yes that's right. The PasswordHashingFFI stuff is all one way encryption.<br>Blowfish is two way, and the current implementation only works for 8 byte<br>chunks. I stopped working on it when the Smalltalk bcrypt implementation I<br>wanted proved to be 5000x times slower than the FFI version. Someone needs<br>to add the CBC part to Blowfish to encrypt longer strings. I do not know of<br>another in image two way encryption scheme, but there may be something in<br>the Cryptography repo. I'm not sure.<o:p></o:p></p><div><p class=MsoNormal style='mso-margin-top-alt:auto;mso-margin-bottom-alt:auto'> <o:p></o:p></p></div><div><p class=MsoNormal style='mso-margin-top-alt:auto;mso-margin-bottom-alt:auto'>Hi Paul,<o:p></o:p></p></div><div><p class=MsoNormal style='mso-margin-top-alt:auto;mso-margin-bottom-alt:auto'> <o:p></o:p></p></div><div><p class=MsoNormal style='mso-margin-top-alt:auto;mso-margin-bottom-alt:auto'>Sorry for the cross posting. <o:p></o:p></p></div><div><p class=MsoNormal style='mso-margin-top-alt:auto;mso-margin-bottom-alt:auto'> <o:p></o:p></p></div><div><p class=MsoNormal style='mso-margin-top-alt:auto;mso-margin-bottom-alt:auto'>I was using the Smalltalk version of the Blowfish you did to encrypt and decrypt things. But now I realize it is very very slow for the usage I need. You seem to have faced the same problem. <o:p></o:p></p></div><div><p class=MsoNormal style='mso-margin-top-alt:auto;mso-margin-bottom-alt:auto'> <o:p></o:p></p></div><div><p class=MsoNormal style='mso-margin-top-alt:auto;mso-margin-bottom-alt:auto'>I am encrypting pieces of 8 characters long. But I wonder if the <b>decryption</b> is available as well in FFI version? I see #ffiCrypt:with: but nothing to decrypt...<o:p></o:p></p></div><div><p class=MsoNormal style='mso-margin-top-alt:auto;mso-margin-bottom-alt:auto'> <o:p></o:p></p></div><div><p class=MsoNormal style='mso-margin-top-alt:auto;mso-margin-bottom-alt:auto'>Thanks in advance <o:p></o:p></p></div></div><p class=MsoNormal style='mso-margin-top-alt:auto;mso-margin-bottom-alt:auto'><br clear=all><o:p></o:p></p><div><p class=MsoNormal style='mso-margin-top-alt:auto;mso-margin-bottom-alt:auto'> <o:p></o:p></p></div><p class=MsoNormal style='mso-margin-top-alt:auto;mso-margin-bottom-alt:auto'>-- <br>Mariano<br><a href="http://marianopeck.wordpress.com" target="_blank">http://marianopeck.wordpress.com</a><o:p></o:p></p></div></div></div></div></div></div></div></blockquote></div><p class=MsoNormal><br><br clear=all><o:p></o:p></p><div><p class=MsoNormal><o:p> </o:p></p></div><p class=MsoNormal>-- <br>Mariano<br><a href="http://marianopeck.wordpress.com" target="_blank">http://marianopeck.wordpress.com</a><o:p></o:p></p></div></div></div></div></body></html>