Date: Sun, 18 Dec 2011 06:38:13 +0530 From: piyush mittal <piyush.cse29@...il.com> To: john-dev@...ts.openwall.com Subject: Re: Bit slice implementation of DES based hashes > > You really don't need salts and iterations of DES_bs_crypt(). You need > different ones, which you may implement externally to your slight > revision of DES_bs_crypt_LM(). > Yes *Of course.*May be today I will be able to finish out the whole work*.* Thanks On Sun, Dec 18, 2011 at 3:54 AM, Solar Designer <solar@...nwall.com> wrote: > On Sat, Dec 17, 2011 at 10:01:24PM +0530, piyush mittal wrote: > > Yes, that is true that we can call DES_bs_set_key() with same fixed key > > for all layers.But what about different plain text that we need i.e if we > > see into struct fmt_main initialisation it sends all stored list of > > password through method set_key(). > > Just because the format method is named set_key() doesn't imply that it > has to call DES_bs_set_key(). In your case, it sounds like it should not. > Instead, according to what you're saying, it should either initialize a > bit layer in B or it should save the password as-is e.g. in a > saved_key entry (like some formats do) and then have crypt_all() > process those passwords into their bit layers in B before calling a > revision of DES_bs_crypt_LM(). > > > > As I suggested, DES_bs_crypt_LM() is a closer match. DES_bs_crypt() > > > adds salts and iterations, which you don't need. > > > > No.Salt and iterations also exist in oracle.Salt here is user name and we > > need two iterations. > > You really don't need salts and iterations of DES_bs_crypt(). You need > different ones, which you may implement externally to your slight > revision of DES_bs_crypt_LM(). > > > Let me summarise you what actually going on. > > > > 1.Concatenate user name(i.e salt) and password to get plain text > string(i.e > > input plain text for DES). > > 2.Encrypt plain text string in CBC mode using fixed key > 0x0123456789ABCDEF. > > 3.Encrypt the plain text string again in CBC mode but using the last > block > > of o/p of previous step as the encryption key. > > > > so if I will apply DES_bs_crypt_LM() then step 2 can be done but step 3 > > again needs number of modifications > > Please don't worry about efficiency for your initial implementation. > When you don't worry about efficiency, you can just use a trivial > revision of DES_bs_crypt_LM() (with B initialization removed) for both > step 2 and step 3 above. You will need to replace K between steps 2 and > 3, but you can do it externally to the function. > > Of course, the goal of bitslicing is to improve performance, so you will > need to worry about it at some point, but initially your goal is just to > get things working. > > Thanks, > > Alexander > -- Piyush Mittal Department of Computer Science and Engineering National Institute of Technology,Rourkela INDIA Content of type "text/html" skipped
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