FreeBSD/Linux Kernel Cross Reference
sys/crypto/serpent/serpent.c

     
     // Copyright in this code is held by Dr B.R. Gladman but free direct or
     // derivative use is permitted subject to acknowledgement of its origin
     // and subject to any constraints placed on the use of the algorithm by
     // its designers (if such constraints may exist, this will be indicated
     // below).
     //
     // Dr. B. R. Gladman                               . 25th January 2000.
     //
    // This is an implementation of Serpent, an encryption algorithm designed
    // by Anderson, Biham and Knudsen and submitted as a candidate for the
    // Advanced Encryption Standard programme of the US National Institute of
    // Standards and Technology.
    //
    // The designers of Serpent have not placed any constraints on the use of
    // this algorithm.
    
    #include <sys/types.h>
    #include <sys/endian.h>
    
    #include <crypto/serpent/serpent.h>
    
    // Partially optimised Serpent S Box boolean functions derived
    // using a recursive descent analyser but without a full search
    // of all subtrees. This set of S boxes is the result of work
    // by Sam Simpson and Brian Gladman using the spare time on a
    // cluster of high capacity servers to search for S boxes with
    // this customised search engine.
    //
    // Copyright:   Dr B. R Gladman (gladman@seven77.demon.co.uk)
    //              and Sam Simpson (s.simpson@mia.co.uk)
    //              17th December 1998
    //
    // We hereby give permission for information in this file to be
    // used freely subject only to acknowledgement of its origin
    
    // 15 terms
    
    #define rotr(x,n)   (((x) >> ((int)((n) & 0x1f))) | ((x) << ((int)((32 - ((n) & 0x1f))))))
    #define rotl(x,n)   (((x) << ((int)((n) & 0x1f))) | ((x) >> ((int)((32 - ((n) & 0x1f))))))
    
    #define sb0(a,b,c,d,e,f,g,h)    \
    {   t1 = a ^ d;     \
        t2 = a & d;     \
        t3 = c ^ t1;    \
        t6 = b & t1;    \
        t4 = b ^ t3;    \
        t10 = ~t3;      \
        h = t2 ^ t4;    \
        t7 = a ^ t6;    \
        t14 = ~t7;      \
        t8 = c | t7;    \
        t11 = t3 ^ t7;  \
        g = t4 ^ t8;    \
        t12 = h & t11;  \
        f = t10 ^ t12;  \
        e = t12 ^ t14;  \
    }
    // 15 terms
    
    #define ib0(a,b,c,d,e,f,g,h)    \
    {   t1 = ~a;        \
        t2 = a ^ b;     \
        t3 = t1 | t2;   \
        t4 = d ^ t3;    \
        t7 = d & t2;    \
        t5 = c ^ t4;    \
        t8 = t1 ^ t7;   \
        g = t2 ^ t5;    \
        t11 = a & t4;   \
        t9 = g & t8;    \
        t14 = t5 ^ t8;  \
        f = t4 ^ t9;    \
        t12 = t5 | f;   \
        h = t11 ^ t12;  \
        e = h ^ t14;    \
    }
    
    // 14 terms!
    
    #define sb1(a,b,c,d,e,f,g,h)    \
    {   t1 = ~a;        \
        t2 = b ^ t1;    \
        t3 = a | t2;    \
        t4 = d | t2;    \
        t5 = c ^ t3;    \
        g = d ^ t5;     \
        t7 = b ^ t4;    \
        t8 = t2 ^ g;    \
        t9 = t5 & t7;   \
        h = t8 ^ t9;    \
        t11 = t5 ^ t7;  \
        f = h ^ t11;    \
        t13 = t8 & t11; \
        e = t5 ^ t13;   \
    }
    
    // 17 terms
    
   #define ib1(a,b,c,d,e,f,g,h)    \
   {   t1 = a ^ d;     \
       t2 = a & b;     \
       t3 = b ^ c;     \
       t4 = a ^ t3;    \
       t5 = b | d;     \
       t7 = c | t1;    \
       h = t4 ^ t5;    \
       t8 = b ^ t7;    \
       t11 = ~t2;      \
       t9 = t4 & t8;   \
       f = t1 ^ t9;    \
       t13 = t9 ^ t11; \
       t12 = h & f;    \
       g = t12 ^ t13;  \
       t15 = a & d;    \
       t16 = c ^ t13;  \
       e = t15 ^ t16;  \
   }
   
   // 16 terms
   
   #define sb2(a,b,c,d,e,f,g,h)    \
   {   t1 = ~a;        \
       t2 = b ^ d;     \
       t3 = c & t1;    \
       t13 = d | t1;   \
       e = t2 ^ t3;    \
       t5 = c ^ t1;    \
       t6 = c ^ e;     \
       t7 = b & t6;    \
       t10 = e | t5;   \
       h = t5 ^ t7;    \
       t9 = d | t7;    \
       t11 = t9 & t10; \
       t14 = t2 ^ h;   \
       g = a ^ t11;    \
       t15 = g ^ t13;  \
       f = t14 ^ t15;  \
   }
   
   // 16 terms
   
   #define ib2(a,b,c,d,e,f,g,h)    \
   {   t1 = b ^ d;     \
       t2 = ~t1;       \
       t3 = a ^ c;     \
       t4 = c ^ t1;    \
       t7 = a | t2;    \
       t5 = b & t4;    \
       t8 = d ^ t7;    \
       t11 = ~t4;      \
       e = t3 ^ t5;    \
       t9 = t3 | t8;   \
       t14 = d & t11;  \
       h = t1 ^ t9;    \
       t12 = e | h;    \
       f = t11 ^ t12;  \
       t15 = t3 ^ t12; \
       g = t14 ^ t15;  \
   }
   
   // 17 terms
   
   #define sb3(a,b,c,d,e,f,g,h)    \
   {   t1 = a ^ c;     \
       t2 = d ^ t1;    \
       t3 = a & t2;    \
       t4 = d ^ t3;    \
       t5 = b & t4;    \
       g = t2 ^ t5;    \
       t7 = a | g;     \
       t8 = b | d;     \
       t11 = a | d;    \
       t9 = t4 & t7;   \
       f = t8 ^ t9;    \
       t12 = b ^ t11;  \
       t13 = g ^ t9;   \
       t15 = t3 ^ t8;  \
       h = t12 ^ t13;  \
       t16 = c & t15;  \
       e = t12 ^ t16;  \
   }
   
   // 16 term solution that performs less well than 17 term one
   // in my environment (PPro/PII)
   
   #if 0
   
   #define sb3(a,b,c,d,e,f,g,h)    \
   {   t1 = a ^ b;     \
       t2 = a & c;     \
       t3 = a | d;     \
       t4 = c ^ d;     \
       t5 = t1 & t3;   \
       t6 = t2 | t5;   \
       g = t4 ^ t6;    \
       t8 = b ^ t3;    \
       t9 = t6 ^ t8;   \
       t10 = t4 & t9;  \
       e = t1 ^ t10;   \
       t12 = g & e;    \
       f = t9 ^ t12;   \
       t14 = b | d;    \
       t15 = t4 ^ t12; \
       h = t14 ^ t15;  \
   }
   
   #endif
   
   // 17 terms
   
   #define ib3(a,b,c,d,e,f,g,h)    \
   {   t1 = b ^ c;     \
       t2 = b | c;     \
       t3 = a ^ c;     \
       t7 = a ^ d;     \
       t4 = t2 ^ t3;   \
       t5 = d | t4;    \
       t9 = t2 ^ t7;   \
       e = t1 ^ t5;    \
       t8 = t1 | t5;   \
       t11 = a & t4;   \
       g = t8 ^ t9;    \
       t12 = e | t9;   \
       f = t11 ^ t12;  \
       t14 = a & g;    \
       t15 = t2 ^ t14; \
       t16 = e & t15;  \
       h = t4 ^ t16;   \
   }
   
   // 15 terms
   
   #define sb4(a,b,c,d,e,f,g,h)    \
   {   t1 = a ^ d;     \
       t2 = d & t1;    \
       t3 = c ^ t2;    \
       t4 = b | t3;    \
       h = t1 ^ t4;    \
       t6 = ~b;        \
       t7 = t1 | t6;   \
       e = t3 ^ t7;    \
       t9 = a & e;     \
       t10 = t1 ^ t6;  \
       t11 = t4 & t10; \
       g = t9 ^ t11;   \
       t13 = a ^ t3;   \
       t14 = t10 & g;  \
       f = t13 ^ t14;  \
   }
   
   // 17 terms
   
   #define ib4(a,b,c,d,e,f,g,h)    \
   {   t1 = c ^ d;     \
       t2 = c | d;     \
       t3 = b ^ t2;    \
       t4 = a & t3;    \
       f = t1 ^ t4;    \
       t6 = a ^ d;     \
       t7 = b | d;     \
       t8 = t6 & t7;   \
       h = t3 ^ t8;    \
       t10 = ~a;       \
       t11 = c ^ h;    \
       t12 = t10 | t11;\
       e = t3 ^ t12;   \
       t14 = c | t4;   \
       t15 = t7 ^ t14; \
       t16 = h | t10;  \
       g = t15 ^ t16;  \
   }
   
   // 16 terms
   
   #define sb5(a,b,c,d,e,f,g,h)    \
   {   t1 = ~a;        \
       t2 = a ^ b;     \
       t3 = a ^ d;     \
       t4 = c ^ t1;    \
       t5 = t2 | t3;   \
       e = t4 ^ t5;    \
       t7 = d & e;     \
       t8 = t2 ^ e;    \
       t10 = t1 | e;   \
       f = t7 ^ t8;    \
       t11 = t2 | t7;  \
       t12 = t3 ^ t10; \
       t14 = b ^ t7;   \
       g = t11 ^ t12;  \
       t15 = f & t12;  \
       h = t14 ^ t15;  \
   }
   
   // 16 terms
   
   #define ib5(a,b,c,d,e,f,g,h)    \
   {   t1 = ~c;        \
       t2 = b & t1;    \
       t3 = d ^ t2;    \
       t4 = a & t3;    \
       t5 = b ^ t1;    \
       h = t4 ^ t5;    \
       t7 = b | h;     \
       t8 = a & t7;    \
       f = t3 ^ t8;    \
       t10 = a | d;    \
       t11 = t1 ^ t7;  \
       e = t10 ^ t11;  \
       t13 = a ^ c;    \
       t14 = b & t10;  \
       t15 = t4 | t13; \
       g = t14 ^ t15;  \
   }
   
   // 15 terms
   
   #define sb6(a,b,c,d,e,f,g,h)    \
   {   t1 = ~a;        \
       t2 = a ^ d;     \
       t3 = b ^ t2;    \
       t4 = t1 | t2;   \
       t5 = c ^ t4;    \
       f = b ^ t5;     \
       t13 = ~t5;      \
       t7 = t2 | f;    \
       t8 = d ^ t7;    \
       t9 = t5 & t8;   \
       g = t3 ^ t9;    \
       t11 = t5 ^ t8;  \
       e = g ^ t11;    \
       t14 = t3 & t11; \
       h = t13 ^ t14;  \
   }
   
   // 15 terms
   
   #define ib6(a,b,c,d,e,f,g,h)    \
   {   t1 = ~a;        \
       t2 = a ^ b;     \
       t3 = c ^ t2;    \
       t4 = c | t1;    \
       t5 = d ^ t4;    \
       t13 = d & t1;   \
       f = t3 ^ t5;    \
       t7 = t3 & t5;   \
       t8 = t2 ^ t7;   \
       t9 = b | t8;    \
       h = t5 ^ t9;    \
       t11 = b | h;    \
       e = t8 ^ t11;   \
       t14 = t3 ^ t11; \
       g = t13 ^ t14;  \
   }
   
   // 17 terms
   
   #define sb7(a,b,c,d,e,f,g,h)    \
   {   t1 = ~c;        \
       t2 = b ^ c;     \
       t3 = b | t1;    \
       t4 = d ^ t3;    \
       t5 = a & t4;    \
       t7 = a ^ d;     \
       h = t2 ^ t5;    \
       t8 = b ^ t5;    \
       t9 = t2 | t8;   \
       t11 = d & t3;   \
       f = t7 ^ t9;    \
       t12 = t5 ^ f;   \
       t15 = t1 | t4;  \
       t13 = h & t12;  \
       g = t11 ^ t13;  \
       t16 = t12 ^ g;  \
       e = t15 ^ t16;  \
   }
   
   // 17 terms
   
   #define ib7(a,b,c,d,e,f,g,h)    \
   {   t1 = a & b;     \
       t2 = a | b;     \
       t3 = c | t1;    \
       t4 = d & t2;    \
       h = t3 ^ t4;    \
       t6 = ~d;        \
       t7 = b ^ t4;    \
       t8 = h ^ t6;    \
       t11 = c ^ t7;   \
       t9 = t7 | t8;   \
       f = a ^ t9;     \
       t12 = d | f;    \
       e = t11 ^ t12;  \
       t14 = a & h;    \
       t15 = t3 ^ f;   \
       t16 = e ^ t14;  \
       g = t15 ^ t16;  \
   }
   
   #define k_xor(r,a,b,c,d)             \
   {   a ^= ctx->l_key[4 * r +  8]; \
       b ^= ctx->l_key[4 * r +  9]; \
       c ^= ctx->l_key[4 * r + 10]; \
       d ^= ctx->l_key[4 * r + 11]; \
   }
   
   #define k_set(r,a,b,c,d)             \
   {   a = ctx->l_key[4 * r +  8];  \
       b = ctx->l_key[4 * r +  9];  \
       c = ctx->l_key[4 * r + 10];  \
       d = ctx->l_key[4 * r + 11];  \
   }
   
   #define k_get(r,a,b,c,d)    \
   {   ctx->l_key[4 * r +  8] = a;  \
       ctx->l_key[4 * r +  9] = b;  \
       ctx->l_key[4 * r + 10] = c;  \
       ctx->l_key[4 * r + 11] = d;  \
   }
   
   // the linear transformation and its inverse
   
   #define rot(a,b,c,d)    \
   {   a = rotl(a, 13);    \
       c = rotl(c, 3);     \
       d ^= c ^ (a << 3);  \
       b ^= a ^ c;         \
       d = rotl(d, 7);     \
       b = rotl(b, 1);     \
       a ^= b ^ d;         \
       c ^= d ^ (b << 7);  \
       a = rotl(a, 5);     \
       c = rotl(c, 22);    \
   }
   
   #define irot(a,b,c,d)   \
   {   c = rotr(c, 22);    \
       a = rotr(a, 5);     \
       c ^= d ^ (b << 7);  \
       a ^= b ^ d;         \
       d = rotr(d, 7);     \
       b = rotr(b, 1);     \
       d ^= c ^ (a << 3);  \
       b ^= a ^ c;         \
       c = rotr(c, 3);     \
       a = rotr(a, 13);    \
   }
   
   // initialise the key schedule from the user supplied key
   
   void serpent_set_key(serpent_ctx *ctx, const u_int8_t in_key[], int key_len)
   {
       u_int32_t  i,lk,a,b,c,d,e,f,g,h;
       u_int32_t  t1,t2,t3,t4,t5,t6,t7,t8,t9,t10,t11,t12,t13,t14,t15,t16;
   
       if(key_len > 256)
           return;
   
       i = 0; lk = (key_len + 31) / 32;
   
       while(i < lk)
       {
           ctx->l_key[i] = htole32(*((const u_int32_t *)(in_key + 4 * i))); i++;
       }
   
       if(key_len < 256)
       {
           while(i < 8)
   
               ctx->l_key[i++] = 0;
   
           i = key_len / 32; lk = 1 << key_len % 32;
   
           ctx->l_key[i] = (ctx->l_key[i] & (lk - 1)) | lk;
       }
   
       t1 = ctx->l_key[2] ^ ctx->l_key[4] ^ ctx->l_key[6] ^ 0x9e3779b9;
       t2 = ctx->l_key[3] ^ ctx->l_key[5] ^ ctx->l_key[7] ^ 0x9e3779b9;
   
       for(i = 0; i < 132; i += 2)
       {
           ctx->l_key[i + 8] = rotr(i ^ ctx->l_key[i] ^ t2, 21);
   
           t1 ^= ctx->l_key[i + 2] ^ ctx->l_key[i + 8];
   
           ctx->l_key[i + 9] = rotr((i + 1) ^ ctx->l_key[i + 1] ^ t1, 21);
   
           t2 ^= ctx->l_key[i + 3] ^ ctx->l_key[i + 9];
       }
   
       k_set( 0,a,b,c,d);sb3(a,b,c,d,e,f,g,h);k_get( 0,e,f,g,h);
       k_set( 1,a,b,c,d);sb2(a,b,c,d,e,f,g,h);k_get( 1,e,f,g,h);
       k_set( 2,a,b,c,d);sb1(a,b,c,d,e,f,g,h);k_get( 2,e,f,g,h);
       k_set( 3,a,b,c,d);sb0(a,b,c,d,e,f,g,h);k_get( 3,e,f,g,h);
       k_set( 4,a,b,c,d);sb7(a,b,c,d,e,f,g,h);k_get( 4,e,f,g,h);
       k_set( 5,a,b,c,d);sb6(a,b,c,d,e,f,g,h);k_get( 5,e,f,g,h);
       k_set( 6,a,b,c,d);sb5(a,b,c,d,e,f,g,h);k_get( 6,e,f,g,h);
       k_set( 7,a,b,c,d);sb4(a,b,c,d,e,f,g,h);k_get( 7,e,f,g,h);
       k_set( 8,a,b,c,d);sb3(a,b,c,d,e,f,g,h);k_get( 8,e,f,g,h);
       k_set( 9,a,b,c,d);sb2(a,b,c,d,e,f,g,h);k_get( 9,e,f,g,h);
       k_set(10,a,b,c,d);sb1(a,b,c,d,e,f,g,h);k_get(10,e,f,g,h);
       k_set(11,a,b,c,d);sb0(a,b,c,d,e,f,g,h);k_get(11,e,f,g,h);
       k_set(12,a,b,c,d);sb7(a,b,c,d,e,f,g,h);k_get(12,e,f,g,h);
       k_set(13,a,b,c,d);sb6(a,b,c,d,e,f,g,h);k_get(13,e,f,g,h);
       k_set(14,a,b,c,d);sb5(a,b,c,d,e,f,g,h);k_get(14,e,f,g,h);
       k_set(15,a,b,c,d);sb4(a,b,c,d,e,f,g,h);k_get(15,e,f,g,h);
       k_set(16,a,b,c,d);sb3(a,b,c,d,e,f,g,h);k_get(16,e,f,g,h);
       k_set(17,a,b,c,d);sb2(a,b,c,d,e,f,g,h);k_get(17,e,f,g,h);
       k_set(18,a,b,c,d);sb1(a,b,c,d,e,f,g,h);k_get(18,e,f,g,h);
       k_set(19,a,b,c,d);sb0(a,b,c,d,e,f,g,h);k_get(19,e,f,g,h);
       k_set(20,a,b,c,d);sb7(a,b,c,d,e,f,g,h);k_get(20,e,f,g,h);
       k_set(21,a,b,c,d);sb6(a,b,c,d,e,f,g,h);k_get(21,e,f,g,h);
       k_set(22,a,b,c,d);sb5(a,b,c,d,e,f,g,h);k_get(22,e,f,g,h);
       k_set(23,a,b,c,d);sb4(a,b,c,d,e,f,g,h);k_get(23,e,f,g,h);
       k_set(24,a,b,c,d);sb3(a,b,c,d,e,f,g,h);k_get(24,e,f,g,h);
       k_set(25,a,b,c,d);sb2(a,b,c,d,e,f,g,h);k_get(25,e,f,g,h);
       k_set(26,a,b,c,d);sb1(a,b,c,d,e,f,g,h);k_get(26,e,f,g,h);
       k_set(27,a,b,c,d);sb0(a,b,c,d,e,f,g,h);k_get(27,e,f,g,h);
       k_set(28,a,b,c,d);sb7(a,b,c,d,e,f,g,h);k_get(28,e,f,g,h);
       k_set(29,a,b,c,d);sb6(a,b,c,d,e,f,g,h);k_get(29,e,f,g,h);
       k_set(30,a,b,c,d);sb5(a,b,c,d,e,f,g,h);k_get(30,e,f,g,h);
       k_set(31,a,b,c,d);sb4(a,b,c,d,e,f,g,h);k_get(31,e,f,g,h);
       k_set(32,a,b,c,d);sb3(a,b,c,d,e,f,g,h);k_get(32,e,f,g,h);
   
       return;
   }
   
   // encrypt a block of text
   
   void serpent_encrypt(serpent_ctx *ctx, const u_int8_t in_blk[],
                        u_int8_t out_blk[])
   {
       u_int32_t  a,b,c,d,e,f,g,h;
       u_int32_t  t1,t2,t3,t4,t5,t6,t7,t8,t9,t10,t11,t12,t13,t14,t15,t16;
   
       a = htole32(*((const u_int32_t *)(in_blk     )));
       b = htole32(*((const u_int32_t *)(in_blk + 4 )));
       c = htole32(*((const u_int32_t *)(in_blk + 8 )));
       d = htole32(*((const u_int32_t *)(in_blk + 12)));
   
       k_xor( 0,a,b,c,d); sb0(a,b,c,d,e,f,g,h); rot(e,f,g,h);
       k_xor( 1,e,f,g,h); sb1(e,f,g,h,a,b,c,d); rot(a,b,c,d);
       k_xor( 2,a,b,c,d); sb2(a,b,c,d,e,f,g,h); rot(e,f,g,h);
       k_xor( 3,e,f,g,h); sb3(e,f,g,h,a,b,c,d); rot(a,b,c,d);
       k_xor( 4,a,b,c,d); sb4(a,b,c,d,e,f,g,h); rot(e,f,g,h);
       k_xor( 5,e,f,g,h); sb5(e,f,g,h,a,b,c,d); rot(a,b,c,d);
       k_xor( 6,a,b,c,d); sb6(a,b,c,d,e,f,g,h); rot(e,f,g,h);
       k_xor( 7,e,f,g,h); sb7(e,f,g,h,a,b,c,d); rot(a,b,c,d);
       k_xor( 8,a,b,c,d); sb0(a,b,c,d,e,f,g,h); rot(e,f,g,h);
       k_xor( 9,e,f,g,h); sb1(e,f,g,h,a,b,c,d); rot(a,b,c,d);
       k_xor(10,a,b,c,d); sb2(a,b,c,d,e,f,g,h); rot(e,f,g,h);
       k_xor(11,e,f,g,h); sb3(e,f,g,h,a,b,c,d); rot(a,b,c,d);
       k_xor(12,a,b,c,d); sb4(a,b,c,d,e,f,g,h); rot(e,f,g,h);
       k_xor(13,e,f,g,h); sb5(e,f,g,h,a,b,c,d); rot(a,b,c,d);
       k_xor(14,a,b,c,d); sb6(a,b,c,d,e,f,g,h); rot(e,f,g,h);
       k_xor(15,e,f,g,h); sb7(e,f,g,h,a,b,c,d); rot(a,b,c,d);
       k_xor(16,a,b,c,d); sb0(a,b,c,d,e,f,g,h); rot(e,f,g,h);
       k_xor(17,e,f,g,h); sb1(e,f,g,h,a,b,c,d); rot(a,b,c,d);
       k_xor(18,a,b,c,d); sb2(a,b,c,d,e,f,g,h); rot(e,f,g,h);
       k_xor(19,e,f,g,h); sb3(e,f,g,h,a,b,c,d); rot(a,b,c,d);
       k_xor(20,a,b,c,d); sb4(a,b,c,d,e,f,g,h); rot(e,f,g,h);
       k_xor(21,e,f,g,h); sb5(e,f,g,h,a,b,c,d); rot(a,b,c,d);
       k_xor(22,a,b,c,d); sb6(a,b,c,d,e,f,g,h); rot(e,f,g,h);
       k_xor(23,e,f,g,h); sb7(e,f,g,h,a,b,c,d); rot(a,b,c,d);
       k_xor(24,a,b,c,d); sb0(a,b,c,d,e,f,g,h); rot(e,f,g,h);
       k_xor(25,e,f,g,h); sb1(e,f,g,h,a,b,c,d); rot(a,b,c,d);
       k_xor(26,a,b,c,d); sb2(a,b,c,d,e,f,g,h); rot(e,f,g,h);
       k_xor(27,e,f,g,h); sb3(e,f,g,h,a,b,c,d); rot(a,b,c,d);
       k_xor(28,a,b,c,d); sb4(a,b,c,d,e,f,g,h); rot(e,f,g,h);
       k_xor(29,e,f,g,h); sb5(e,f,g,h,a,b,c,d); rot(a,b,c,d);
       k_xor(30,a,b,c,d); sb6(a,b,c,d,e,f,g,h); rot(e,f,g,h);
       k_xor(31,e,f,g,h); sb7(e,f,g,h,a,b,c,d); k_xor(32,a,b,c,d);
   
       *((u_int32_t *)(out_blk     )) = le32toh(a);
       *((u_int32_t *)(out_blk +  4)) = le32toh(b);
       *((u_int32_t *)(out_blk +  8)) = le32toh(c);
       *((u_int32_t *)(out_blk + 12)) = le32toh(d);
   }
   
   // decrypt a block of text
   
   void serpent_decrypt(serpent_ctx *ctx, const u_int8_t in_blk[],
                        u_int8_t out_blk[])
   {
       u_int32_t  a,b,c,d,e,f,g,h;
       u_int32_t  t1,t2,t3,t4,t5,t6,t7,t8,t9,t10,t11,t12,t13,t14,t15,t16;
   
       a = htole32(*((const u_int32_t *)(in_blk     )));
       b = htole32(*((const u_int32_t *)(in_blk + 4 )));
       c = htole32(*((const u_int32_t *)(in_blk + 8 )));
       d = htole32(*((const u_int32_t *)(in_blk + 12)));
   
       k_xor(32,a,b,c,d); ib7(a,b,c,d,e,f,g,h); k_xor(31,e,f,g,h);
       irot(e,f,g,h); ib6(e,f,g,h,a,b,c,d); k_xor(30,a,b,c,d);
       irot(a,b,c,d); ib5(a,b,c,d,e,f,g,h); k_xor(29,e,f,g,h);
       irot(e,f,g,h); ib4(e,f,g,h,a,b,c,d); k_xor(28,a,b,c,d);
       irot(a,b,c,d); ib3(a,b,c,d,e,f,g,h); k_xor(27,e,f,g,h);
       irot(e,f,g,h); ib2(e,f,g,h,a,b,c,d); k_xor(26,a,b,c,d);
       irot(a,b,c,d); ib1(a,b,c,d,e,f,g,h); k_xor(25,e,f,g,h);
       irot(e,f,g,h); ib0(e,f,g,h,a,b,c,d); k_xor(24,a,b,c,d);
       irot(a,b,c,d); ib7(a,b,c,d,e,f,g,h); k_xor(23,e,f,g,h);
       irot(e,f,g,h); ib6(e,f,g,h,a,b,c,d); k_xor(22,a,b,c,d);
       irot(a,b,c,d); ib5(a,b,c,d,e,f,g,h); k_xor(21,e,f,g,h);
       irot(e,f,g,h); ib4(e,f,g,h,a,b,c,d); k_xor(20,a,b,c,d);
       irot(a,b,c,d); ib3(a,b,c,d,e,f,g,h); k_xor(19,e,f,g,h);
       irot(e,f,g,h); ib2(e,f,g,h,a,b,c,d); k_xor(18,a,b,c,d);
       irot(a,b,c,d); ib1(a,b,c,d,e,f,g,h); k_xor(17,e,f,g,h);
       irot(e,f,g,h); ib0(e,f,g,h,a,b,c,d); k_xor(16,a,b,c,d);
       irot(a,b,c,d); ib7(a,b,c,d,e,f,g,h); k_xor(15,e,f,g,h);
       irot(e,f,g,h); ib6(e,f,g,h,a,b,c,d); k_xor(14,a,b,c,d);
       irot(a,b,c,d); ib5(a,b,c,d,e,f,g,h); k_xor(13,e,f,g,h);
       irot(e,f,g,h); ib4(e,f,g,h,a,b,c,d); k_xor(12,a,b,c,d);
       irot(a,b,c,d); ib3(a,b,c,d,e,f,g,h); k_xor(11,e,f,g,h);
       irot(e,f,g,h); ib2(e,f,g,h,a,b,c,d); k_xor(10,a,b,c,d);
       irot(a,b,c,d); ib1(a,b,c,d,e,f,g,h); k_xor( 9,e,f,g,h);
       irot(e,f,g,h); ib0(e,f,g,h,a,b,c,d); k_xor( 8,a,b,c,d);
       irot(a,b,c,d); ib7(a,b,c,d,e,f,g,h); k_xor( 7,e,f,g,h);
       irot(e,f,g,h); ib6(e,f,g,h,a,b,c,d); k_xor( 6,a,b,c,d);
       irot(a,b,c,d); ib5(a,b,c,d,e,f,g,h); k_xor( 5,e,f,g,h);
       irot(e,f,g,h); ib4(e,f,g,h,a,b,c,d); k_xor( 4,a,b,c,d);
       irot(a,b,c,d); ib3(a,b,c,d,e,f,g,h); k_xor( 3,e,f,g,h);
       irot(e,f,g,h); ib2(e,f,g,h,a,b,c,d); k_xor( 2,a,b,c,d);
       irot(a,b,c,d); ib1(a,b,c,d,e,f,g,h); k_xor( 1,e,f,g,h);
       irot(e,f,g,h); ib0(e,f,g,h,a,b,c,d); k_xor( 0,a,b,c,d);
   
       *((u_int32_t *)(out_blk     )) = le32toh(a);
       *((u_int32_t *)(out_blk +  4)) = le32toh(b);
       *((u_int32_t *)(out_blk +  8)) = le32toh(c);
       *((u_int32_t *)(out_blk + 12)) = le32toh(d);
   }
   

Cache object: 726b2f5694fbfed588b44a44868dd9cc