Create README.txt

Author: sirdarckcat

block1/README.txt

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+README.txt
+Last updated:  1/04/2006
+
+This file is intended to supplement the code found in block1.c.
+
+%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
+Building the Executable
+%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
+
+To build the binary, just type 'make' at the command line, or use the command
+
+        gcc -O3 -march=pentium4 block1.c -o block1
+
+where the '-march=' flag is changed to the appropriate value.  On the
+Pentium 4, use of this flag makes the code roughly twice as fast compared
+to a binary compiled without specifying the architecture.  You can also
+use the build.sh script supplied to build the entire toolkit.
+
+
+%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
+Usage
+%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
+
+The code can either use the default IV for MD5, or it can take the
+IV as a paramter.  In the former case, the code is invoked by
+
+        ./block1
+
+and in the latter case the code is invoked by
+
+        ./block 1 <IV>
+
+where IV is any hex value of length 32.  As an example, one might invoke the
+code as follows:
+
+        ./block1 d41d8cd98f00b204e9800998ecf8427e
+
+
+%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
+Output
+%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
+
+The output to the program consists of three parts: the output of the
+MD5 compression function on the first of two messages, M and M', and
+then the two 512-bit messages M and M' themselves,
+represented as a 16-tuple of 32-bit hex values.
+
+As an example run, we obtained the following output:
+
+    Chaining value for M:
+    ef5f6cf37991e593628c40e6794a54b9
+    M = {   87e85516, 9f820a2d, 1d2c1ea0, 891cc06e, 
+            b50347ae, 364a887c, 3ada98ae, 62468e31, 
+            05352d45, 21333bfe, 8c9ef6b7, 269a3354, 
+            6043a0c7, 3f98a2f4, ab400728, 3a995dcd }
+
+    M' = {  87e85516, 9f820a2d, 1d2c1ea0, 891cc06e, 
+            350347ae, 364a887c, 3ada98ae, 62468e31, 
+            05352d45, 21333bfe, 8c9ef6b7, 269ab354, 
+            6043a0c7, 3f98a2f4, 2b400728, 3a995dcd }
+
+This output is a pair of first-blocks of what will be a pair of two-block
+messages that collide under MD5.  The differential is the Wang-differential,
+but several more conditions were specified to speed up the algorithm as
+described in the accompanying paper (and see below).
+
+The chaining value for M is all that is needed in order to produce a pair
+of second-blocks to complete the collision-pair.  The chaining value above
+is given to a separate program (aptly named 'block2') to accomplish this.
+When M from this program is prepended to M from the block2 program we get
+a two-block message X.  When M' from this program is prepended to M' from
+the block2 program, we get a distinct two-block message Y.  X and Y will
+collide under MD5.
+
+%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
+md5cond_1.txt
+%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
+
+This file contains the list of conditions on the step values computed during
+the computation of the MD5 compression function.  For 'normal' use of the
+code, no modifications of md5cond_1.txt are necessary.  That is, the file
+contains an encoding of all the conditions present in the associated
+paper.  One may wish to change md5cond_1.txt only to experiment with
+new conditions or to examine the effect on code running-time when various
+conditions are manipulated, created, or removed.
+
+Format:
+Each line of the file encodes one condition and is composed of five
+space-delimited numbers.  The first number denotes the step number of the
+condition, with acceptable values of 0-63 (68-71 are used for the conditions
+on the chaining values).  The second number denotes the index of the bit of
+the condition (values 0-31).  The third value denotes either the value of
+that bit (-2 means that bit should be zero, and -1 means that bit should be
+one) or the index of the step value that it should be compared to.  The
+fourth and fifth values are used only when the condition refers to another
+step value and they represent the bit index and additive constant to that
+value, respectively.
+
+Examples:
+3 5 -2 0 0
+Bit 5 on step value 3 should be 0.
+
+27 31 -1 0 0
+Bit 31 on step value 27 should be 1.
+
+15 31 14 31 0
+Bit 31 on step value 15 should be the same as bit 31 on step value 14.
+
+63 31 61 31 1
+Bit 31 on step value 63 should be the opposite of bit 31 on step value 61.