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      1 Newsgroups: sci.crypt,alt.security,comp.security.misc,alt.privacy
      2 Path: ghost.dsi.unimi.it!univ-lyon1.fr!jussieu.fr!zaphod.crihan.fr!warwick!clyde.open.ac.uk!strath-cs!bnr.co.uk!bt!pipex!howland.reston.ans.net!europa.eng.gtefsd.com!MathWorks.Com!yeshua.marcam.com!charnel.ecst.csuchico.edu!csusac!csus.edu!netcom.com!sterndark
      3 From: sterndark (a] netcom.com (David Sterndark)
      4 Subject: RC4 Algorithm revealed.
      5 Message-ID: <sternCvKL4B.Hyy (a] netcom.com>
      6 Sender: sterndark (a] netcom.com 
      7 Organization: NETCOM On-line Communication Services (408 261-4700 guest)
      8 X-Newsreader: TIN [version 1.2 PL1]
      9 Date: Wed, 14 Sep 1994 06:35:31 GMT
     10 Lines: 263
     11 Xref: ghost.dsi.unimi.it sci.crypt:27332 alt.security:14732 comp.security.misc:11701 alt.privacy:16026
     12 
     13 I am shocked,  shocked, I tell you,  shocked, to discover
     14 that the cypherpunks have illegaly and criminally revealed
     15 a crucial RSA trade secret and harmed the security of
     16 America by reverse engineering the RC4 algorithm and
     17 publishing it to the world.
     18  
     19 On Saturday morning an anonymous cypherpunk wrote:
     20  
     21  
     22    SUBJECT:  RC4 Source Code
     23  
     24  
     25    I've tested this.  It is compatible with the RC4 object module
     26    that comes in the various RSA toolkits.  
     27  
     28    /* rc4.h */
     29    typedef struct rc4_key
     30    {      
     31         unsigned char state[256];       
     32         unsigned char x;        
     33         unsigned char y;
     34    } rc4_key;
     35    void prepare_key(unsigned char *key_data_ptr,int key_data_len,
     36    rc4_key *key);
     37    void rc4(unsigned char *buffer_ptr,int buffer_len,rc4_key * key);
     38    
     39    
     40    /*rc4.c */
     41    #include "rc4.h"
     42    static void swap_byte(unsigned char *a, unsigned char *b);
     43    void prepare_key(unsigned char *key_data_ptr, int key_data_len,
     44    rc4_key *key)
     45    {
     46         unsigned char swapByte;
     47         unsigned char index1;
     48         unsigned char index2;
     49         unsigned char* state;
     50         short counter;     
     51         
     52         state = &key->state[0];         
     53         for(counter = 0; counter < 256; counter++)              
     54         state[counter] = counter;               
     55         key->x = 0;     
     56         key->y = 0;     
     57         index1 = 0;     
     58         index2 = 0;             
     59         for(counter = 0; counter < 256; counter++)      
     60         {               
     61              index2 = (key_data_ptr[index1] + state[counter] +
     62                 index2) % 256;                
     63              swap_byte(&state[counter], &state[index2]);            
     64    
     65              index1 = (index1 + 1) % key_data_len;  
     66         }       
     67     }
     68     
     69     void rc4(unsigned char *buffer_ptr, int buffer_len, rc4_key *key)
     70     { 
     71         unsigned char x;
     72         unsigned char y;
     73         unsigned char* state;
     74         unsigned char xorIndex;
     75         short counter;              
     76         
     77         x = key->x;     
     78         y = key->y;     
     79         
     80         state = &key->state[0];         
     81         for(counter = 0; counter < buffer_len; counter ++)      
     82         {               
     83              x = (x + 1) % 256;                      
     84              y = (state[x] + y) % 256;               
     85              swap_byte(&state[x], &state[y]);                        
     86                   
     87              xorIndex = (state[x] + state[y]) % 256;                 
     88                   
     89              buffer_ptr[counter] ^= state[xorIndex];         
     90          }               
     91          key->x = x;     
     92          key->y = y;
     93     }
     94     
     95     static void swap_byte(unsigned char *a, unsigned char *b)
     96     {
     97         unsigned char swapByte; 
     98         
     99         swapByte = *a; 
    100         *a = *b;      
    101         *b = swapByte;
    102     }
    103  
    104  
    105  
    106 Another cypherpunk, this one not anonymous, tested the
    107 output from this algorithm against the output from
    108 official RC4 object code
    109  
    110  
    111    Date: Tue, 13 Sep 94 18:37:56 PDT
    112    From: ekr (a] eit.COM (Eric Rescorla)
    113    Message-Id: <9409140137.AA17743 (a] eitech.eit.com>
    114    Subject: RC4 compatibility testing
    115    Cc: cypherpunks (a] toad.com
    116    
    117    One data point:
    118    
    119    I can't say anything about the internals of RC4 versus the
    120    algorithm that Bill Sommerfeld is rightly calling 'Alleged RC4',
    121    since I don't know anything about RC4's internals. 
    122    
    123    However, I do have a (legitimately acquired) copy of BSAFE2 and
    124    so I'm able to compare the output of this algorithm to the output
    125    of genuine RC4 as found in BSAFE. I chose a set of test vectors
    126    and ran them through both algorithms. The algorithms appear to
    127    give identical results, at least with these key/plaintext pairs.
    128    
    129    I note that this is the algorithm _without_ Hal Finney's
    130    proposed modification
    131    
    132    (see <199409130605.XAA24133 (a] jobe.shell.portal.com>).
    133    
    134    The vectors I used (together with the ciphertext they produce)
    135    follow at the end of this message.
    136    
    137    -Ekr
    138    
    139    Disclaimer: This posting does not reflect the opinions of EIT.
    140    
    141    --------------------results follow--------------
    142    Test vector 0
    143    Key: 0x01 0x23 0x45 0x67 0x89 0xab 0xcd 0xef 
    144    Input: 0x01 0x23 0x45 0x67 0x89 0xab 0xcd 0xef 
    145    0 Output: 0x75 0xb7 0x87 0x80 0x99 0xe0 0xc5 0x96 
    146    
    147    Test vector 1
    148    Key: 0x01 0x23 0x45 0x67 0x89 0xab 0xcd 0xef 
    149    Input: 0x00 0x00 0x00 0x00 0x00 0x00 0x00 0x00 
    150    0 Output: 0x74 0x94 0xc2 0xe7 0x10 0x4b 0x08 0x79 
    151    
    152    Test vector 2
    153    Key: 0x00 0x00 0x00 0x00 0x00 0x00 0x00 0x00 
    154    Input: 0x00 0x00 0x00 0x00 0x00 0x00 0x00 0x00 
    155    0 Output: 0xde 0x18 0x89 0x41 0xa3 0x37 0x5d 0x3a 
    156    
    157    Test vector 3
    158    Key: 0xef 0x01 0x23 0x45 
    159    Input: 0x00 0x00 0x00 0x00 0x00 0x00 0x00 0x00 0x00 0x00 
    160    0 Output: 0xd6 0xa1 0x41 0xa7 0xec 0x3c 0x38 0xdf 0xbd 0x61 
    161    
    162    Test vector 4
    163    Key: 0x01 0x23 0x45 0x67 0x89 0xab 0xcd 0xef 
    164    Input: 0x01 0x01 0x01 0x01 0x01 0x01 0x01 0x01 0x01 0x01 0x01 
    165    0x01 0x01 0x01 0x01 0x01 0x01 0x01 0x01 0x01 0x01 
    166    0x01 0x01 0x01 0x01 0x01 0x01 0x01 0x01 0x01 0x01 
    167    0x01 0x01 0x01 0x01 0x01 0x01 0x01 0x01 0x01 0x01 
    168    0x01 0x01 0x01 0x01 0x01 0x01 0x01 0x01 0x01 0x01 
    169    0x01 0x01 0x01 0x01 0x01 0x01 0x01 0x01 0x01 0x01 
    170    0x01 0x01 0x01 0x01 0x01 0x01 0x01 0x01 0x01 0x01 
    171    0x01 0x01 0x01 0x01 0x01 0x01 0x01 0x01 0x01 0x01 
    172    0x01 0x01 0x01 0x01 0x01 0x01 0x01 0x01 0x01 0x01 
    173    0x01 0x01 0x01 0x01 0x01 0x01 0x01 0x01 0x01 0x01 
    174    0x01 0x01 0x01 0x01 0x01 0x01 0x01 0x01 0x01 0x01 
    175    0x01 0x01 0x01 0x01 0x01 0x01 0x01 0x01 0x01 0x01 
    176    0x01 0x01 0x01 0x01 0x01 0x01 0x01 0x01 0x01 0x01 
    177    0x01 0x01 0x01 0x01 0x01 0x01 0x01 0x01 0x01 0x01 
    178    0x01 0x01 0x01 0x01 0x01 0x01 0x01 0x01 0x01 0x01 
    179    0x01 0x01 0x01 0x01 0x01 0x01 0x01 0x01 0x01 0x01 
    180    0x01 0x01 0x01 0x01 0x01 0x01 0x01 0x01 0x01 0x01 
    181    0x01 0x01 0x01 0x01 0x01 0x01 0x01 0x01 0x01 0x01 
    182    0x01 0x01 0x01 0x01 0x01 0x01 0x01 0x01 0x01 0x01 
    183    0x01 0x01 0x01 0x01 0x01 0x01 0x01 0x01 0x01 0x01 
    184    0x01 0x01 0x01 0x01 0x01 0x01 0x01 0x01 0x01 0x01 
    185    0x01 0x01 0x01 0x01 0x01 0x01 0x01 0x01 0x01 0x01 
    186    0x01 0x01 0x01 0x01 0x01 0x01 0x01 0x01 0x01 0x01 
    187    0x01 0x01 0x01 0x01 0x01 0x01 0x01 0x01 0x01 0x01 
    188    0x01 0x01 0x01 0x01 0x01 0x01 0x01 0x01 0x01 0x01 
    189    0x01 0x01 0x01 0x01 0x01 0x01 0x01 0x01 0x01 0x01 
    190    0x01 0x01 0x01 0x01 0x01 0x01 0x01 0x01 0x01 0x01 
    191    0x01 0x01 0x01 0x01 0x01 0x01 0x01 0x01 0x01 0x01 
    192    0x01 0x01 0x01 0x01 0x01 0x01 0x01 0x01 0x01 0x01 
    193    0x01 0x01 0x01 0x01 0x01 0x01 0x01 0x01 0x01 0x01 
    194    0x01 0x01 0x01 0x01 0x01 0x01 0x01 0x01 0x01 0x01 
    195    0x01 0x01 0x01 0x01 0x01 0x01 0x01 0x01 0x01 0x01 
    196    0x01 0x01 0x01 0x01 0x01 0x01 0x01 0x01 0x01 0x01 
    197    0x01 0x01 0x01 0x01 0x01 0x01 0x01 0x01 0x01 0x01 
    198    0x01 0x01 0x01 0x01 0x01 0x01 0x01 0x01 0x01 0x01 
    199    0x01 0x01 0x01 0x01 0x01 0x01 0x01 0x01 0x01 0x01 
    200    0x01 0x01 0x01 0x01 0x01 0x01 0x01 0x01 0x01 0x01 
    201    0x01 0x01 0x01 0x01 0x01 0x01 0x01 0x01 0x01 0x01 
    202    0x01 0x01 0x01 0x01 0x01 0x01 0x01 0x01 0x01 0x01 
    203    0x01 0x01 0x01 0x01 0x01 0x01 0x01 0x01 0x01 0x01 
    204    0x01 0x01 0x01 0x01 0x01 0x01 0x01 0x01 0x01 0x01 
    205    0x01 0x01 0x01 0x01 0x01 0x01 0x01 0x01 0x01 0x01 
    206    0x01 0x01 0x01 0x01 0x01 0x01 0x01 0x01 0x01 0x01 
    207    0x01 0x01 0x01 0x01 0x01 0x01 0x01 0x01 0x01 0x01 
    208    0x01 0x01 0x01 0x01 0x01 0x01 0x01 0x01 0x01 0x01 
    209    0x01 0x01 0x01 0x01 0x01 0x01 0x01 0x01 0x01 0x01 
    210    0x01 0x01 0x01 0x01 0x01 0x01 0x01 0x01 0x01 0x01 
    211    0x01 0x01 0x01 0x01 0x01 0x01 0x01 0x01 0x01 0x01 
    212    0x01 0x01 0x01 0x01 0x01 0x01 0x01 0x01 0x01 0x01 
    213    0x01 0x01 0x01 0x01 0x01 0x01 0x01 0x01 0x01 0x01 
    214    0x01 0x01 0x01 0x01 0x01 0x01 0x01 0x01 0x01 0x01 
    215    0x01 
    216    0 Output: 0x75 0x95 0xc3 0xe6 0x11 0x4a 0x09 0x78 0x0c 0x4a 0xd4 
    217    0x52 0x33 0x8e 0x1f 0xfd 0x9a 0x1b 0xe9 0x49 0x8f 
    218    0x81 0x3d 0x76 0x53 0x34 0x49 0xb6 0x77 0x8d 0xca 
    219    0xd8 0xc7 0x8a 0x8d 0x2b 0xa9 0xac 0x66 0x08 0x5d 
    220    0x0e 0x53 0xd5 0x9c 0x26 0xc2 0xd1 0xc4 0x90 0xc1 
    221    0xeb 0xbe 0x0c 0xe6 0x6d 0x1b 0x6b 0x1b 0x13 0xb6 
    222    0xb9 0x19 0xb8 0x47 0xc2 0x5a 0x91 0x44 0x7a 0x95 
    223    0xe7 0x5e 0x4e 0xf1 0x67 0x79 0xcd 0xe8 0xbf 0x0a 
    224    0x95 0x85 0x0e 0x32 0xaf 0x96 0x89 0x44 0x4f 0xd3 
    225    0x77 0x10 0x8f 0x98 0xfd 0xcb 0xd4 0xe7 0x26 0x56 
    226    0x75 0x00 0x99 0x0b 0xcc 0x7e 0x0c 0xa3 0xc4 0xaa 
    227    0xa3 0x04 0xa3 0x87 0xd2 0x0f 0x3b 0x8f 0xbb 0xcd 
    228    0x42 0xa1 0xbd 0x31 0x1d 0x7a 0x43 0x03 0xdd 0xa5 
    229    0xab 0x07 0x88 0x96 0xae 0x80 0xc1 0x8b 0x0a 0xf6 
    230    0x6d 0xff 0x31 0x96 0x16 0xeb 0x78 0x4e 0x49 0x5a 
    231    0xd2 0xce 0x90 0xd7 0xf7 0x72 0xa8 0x17 0x47 0xb6 
    232    0x5f 0x62 0x09 0x3b 0x1e 0x0d 0xb9 0xe5 0xba 0x53 
    233    0x2f 0xaf 0xec 0x47 0x50 0x83 0x23 0xe6 0x71 0x32 
    234    0x7d 0xf9 0x44 0x44 0x32 0xcb 0x73 0x67 0xce 0xc8 
    235    0x2f 0x5d 0x44 0xc0 0xd0 0x0b 0x67 0xd6 0x50 0xa0 
    236    0x75 0xcd 0x4b 0x70 0xde 0xdd 0x77 0xeb 0x9b 0x10 
    237    0x23 0x1b 0x6b 0x5b 0x74 0x13 0x47 0x39 0x6d 0x62 
    238    0x89 0x74 0x21 0xd4 0x3d 0xf9 0xb4 0x2e 0x44 0x6e 
    239    0x35 0x8e 0x9c 0x11 0xa9 0xb2 0x18 0x4e 0xcb 0xef 
    240    0x0c 0xd8 0xe7 0xa8 0x77 0xef 0x96 0x8f 0x13 0x90 
    241    0xec 0x9b 0x3d 0x35 0xa5 0x58 0x5c 0xb0 0x09 0x29 
    242    0x0e 0x2f 0xcd 0xe7 0xb5 0xec 0x66 0xd9 0x08 0x4b 
    243    0xe4 0x40 0x55 0xa6 0x19 0xd9 0xdd 0x7f 0xc3 0x16 
    244    0x6f 0x94 0x87 0xf7 0xcb 0x27 0x29 0x12 0x42 0x64 
    245    0x45 0x99 0x85 0x14 0xc1 0x5d 0x53 0xa1 0x8c 0x86 
    246    0x4c 0xe3 0xa2 0xb7 0x55 0x57 0x93 0x98 0x81 0x26 
    247    0x52 0x0e 0xac 0xf2 0xe3 0x06 0x6e 0x23 0x0c 0x91 
    248    0xbe 0xe4 0xdd 0x53 0x04 0xf5 0xfd 0x04 0x05 0xb3 
    249    0x5b 0xd9 0x9c 0x73 0x13 0x5d 0x3d 0x9b 0xc3 0x35 
    250    0xee 0x04 0x9e 0xf6 0x9b 0x38 0x67 0xbf 0x2d 0x7b 
    251    0xd1 0xea 0xa5 0x95 0xd8 0xbf 0xc0 0x06 0x6f 0xf8 
    252    0xd3 0x15 0x09 0xeb 0x0c 0x6c 0xaa 0x00 0x6c 0x80 
    253    0x7a 0x62 0x3e 0xf8 0x4c 0x3d 0x33 0xc1 0x95 0xd2 
    254    0x3e 0xe3 0x20 0xc4 0x0d 0xe0 0x55 0x81 0x57 0xc8 
    255    0x22 0xd4 0xb8 0xc5 0x69 0xd8 0x49 0xae 0xd5 0x9d 
    256    0x4e 0x0f 0xd7 0xf3 0x79 0x58 0x6b 0x4b 0x7f 0xf6 
    257    0x84 0xed 0x6a 0x18 0x9f 0x74 0x86 0xd4 0x9b 0x9c 
    258    0x4b 0xad 0x9b 0xa2 0x4b 0x96 0xab 0xf9 0x24 0x37 
    259    0x2c 0x8a 0x8f 0xff 0xb1 0x0d 0x55 0x35 0x49 0x00 
    260    0xa7 0x7a 0x3d 0xb5 0xf2 0x05 0xe1 0xb9 0x9f 0xcd 
    261    0x86 0x60 0x86 0x3a 0x15 0x9a 0xd4 0xab 0xe4 0x0f 
    262    0xa4 0x89 0x34 0x16 0x3d 0xdd 0xe5 0x42 0xa6 0x58 
    263    0x55 0x40 0xfd 0x68 0x3c 0xbf 0xd8 0xc0 0x0f 0x12 
    264    0x12 0x9a 0x28 0x4d 0xea 0xcc 0x4c 0xde 0xfe 0x58 
    265    0xbe 0x71 0x37 0x54 0x1c 0x04 0x71 0x26 0xc8 0xd4 
    266    0x9e 0x27 0x55 0xab 0x18 0x1a 0xb7 0xe9 0x40 0xb0 
    267    0xc0 
    268    
    269 
    270 
    271 -- 
    272  ---------------------------------------------------------------------
    273 We have the right to defend ourselves and our
    274 property, because of the kind of animals that we              James A. Donald
    275 are.  True law derives from this right, not from
    276 the arbitrary power of the omnipotent state.                jamesd (a] netcom.com
    277 
    278 
    279