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des.cpp

// des.cpp - modified by Wei Dai from Phil Karn's des.c
// The original code and all modifications are in the public domain.

/*
 * This is a major rewrite of my old public domain DES code written
 * circa 1987, which in turn borrowed heavily from Jim Gillogly's 1977
 * public domain code. I pretty much kept my key scheduling code, but
 * the actual encrypt/decrypt routines are taken from from Richard
 * Outerbridge's DES code as printed in Schneier's "Applied Cryptography."
 *
 * This code is in the public domain. I would appreciate bug reports and
 * enhancements.
 *
 * Phil Karn KA9Q, karn@unix.ka9q.ampr.org, August 1994.
 */

#include "pch.h"
#include "misc.h"
#include "des.h"

NAMESPACE_BEGIN(CryptoPP)

static inline bool CheckParity(byte b)
{
        unsigned int a = b ^ (b >> 4);
        return ((a ^ (a>>1) ^ (a>>2) ^ (a>>3)) & 1) == 1;
}

bool DES_CheckKeyParityBits(const byte *key)
{
        for (unsigned int i=0; i<8; i++)
                if (!CheckParity(key[i]))
                        return false;
        return true;
}

void DES_CorrectKeyParityBits(byte *key)
{
        for (unsigned int i=0; i<8; i++)
                if (!CheckParity(key[i]))
                        key[i] ^= 1;
}

/* Tables defined in the Data Encryption Standard documents
 * Three of these tables, the initial permutation, the final
 * permutation and the expansion operator, are regular enough that
 * for speed, we hard-code them. They're here for reference only.
 * Also, the S and P boxes are used by a separate program, gensp.c,
 * to build the combined SP box, Spbox[]. They're also here just
 * for reference.
 */
#ifdef notdef
/* initial permutation IP */
static byte ip[] = {
           58, 50, 42, 34, 26, 18, 10,  2,
           60, 52, 44, 36, 28, 20, 12,  4,
           62, 54, 46, 38, 30, 22, 14,  6,
           64, 56, 48, 40, 32, 24, 16,  8,
           57, 49, 41, 33, 25, 17,  9,  1,
           59, 51, 43, 35, 27, 19, 11,  3,
           61, 53, 45, 37, 29, 21, 13,  5,
           63, 55, 47, 39, 31, 23, 15,  7
};

/* final permutation IP^-1 */
static byte fp[] = {
           40,  8, 48, 16, 56, 24, 64, 32,
           39,  7, 47, 15, 55, 23, 63, 31,
           38,  6, 46, 14, 54, 22, 62, 30,
           37,  5, 45, 13, 53, 21, 61, 29,
           36,  4, 44, 12, 52, 20, 60, 28,
           35,  3, 43, 11, 51, 19, 59, 27,
           34,  2, 42, 10, 50, 18, 58, 26,
           33,  1, 41,  9, 49, 17, 57, 25
};
/* expansion operation matrix */
static byte ei[] = {
           32,  1,  2,  3,  4,  5,
                4,  5,  6,  7,  8,  9,
                8,  9, 10, 11, 12, 13,
           12, 13, 14, 15, 16, 17,
           16, 17, 18, 19, 20, 21,
           20, 21, 22, 23, 24, 25,
           24, 25, 26, 27, 28, 29,
           28, 29, 30, 31, 32,  1
};
/* The (in)famous S-boxes */
static byte sbox[8][64] = {
           /* S1 */
           14,  4, 13,  1,  2, 15, 11,  8,  3, 10,  6, 12,  5,  9,  0,  7,
                0, 15,  7,  4, 14,  2, 13,  1, 10,  6, 12, 11,  9,  5,  3,  8,
                4,  1, 14,  8, 13,  6,  2, 11, 15, 12,  9,  7,  3, 10,  5,  0,
           15, 12,  8,  2,  4,  9,  1,  7,  5, 11,  3, 14, 10,  0,  6, 13,

           /* S2 */
           15,  1,  8, 14,  6, 11,  3,  4,  9,  7,  2, 13, 12,  0,  5, 10,
                3, 13,  4,  7, 15,  2,  8, 14, 12,  0,  1, 10,  6,  9, 11,  5,
                0, 14,  7, 11, 10,  4, 13,  1,  5,  8, 12,  6,  9,  3,  2, 15,
           13,  8, 10,  1,  3, 15,  4,  2, 11,  6,  7, 12,  0,  5, 14,  9,

           /* S3 */
           10,  0,  9, 14,  6,  3, 15,  5,  1, 13, 12,  7, 11,  4,  2,  8,
           13,  7,  0,  9,  3,  4,  6, 10,  2,  8,  5, 14, 12, 11, 15,  1,
           13,  6,  4,  9,  8, 15,  3,  0, 11,  1,  2, 12,  5, 10, 14,  7,
                1, 10, 13,  0,  6,  9,  8,  7,  4, 15, 14,  3, 11,  5,  2, 12,

           /* S4 */
                7, 13, 14,  3,  0,  6,  9, 10,  1,  2,  8,  5, 11, 12,  4, 15,
           13,  8, 11,  5,  6, 15,  0,  3,  4,  7,  2, 12,  1, 10, 14,  9,
           10,  6,  9,  0, 12, 11,  7, 13, 15,  1,  3, 14,  5,  2,  8,  4,
                3, 15,  0,  6, 10,  1, 13,  8,  9,  4,  5, 11, 12,  7,  2, 14,

           /* S5 */
                2, 12,  4,  1,  7, 10, 11,  6,  8,  5,  3, 15, 13,  0, 14,  9,
           14, 11,  2, 12,  4,  7, 13,  1,  5,  0, 15, 10,  3,  9,  8,  6,
                4,  2,  1, 11, 10, 13,  7,  8, 15,  9, 12,  5,  6,  3,  0, 14,
           11,  8, 12,  7,  1, 14,  2, 13,  6, 15,  0,  9, 10,  4,  5,  3,

           /* S6 */
           12,  1, 10, 15,  9,  2,  6,  8,  0, 13,  3,  4, 14,  7,  5, 11,
           10, 15,  4,  2,  7, 12,  9,  5,  6,  1, 13, 14,  0, 11,  3,  8,
                9, 14, 15,  5,  2,  8, 12,  3,  7,  0,  4, 10,  1, 13, 11,  6,
                4,  3,  2, 12,  9,  5, 15, 10, 11, 14,  1,  7,  6,  0,  8, 13,

           /* S7 */
                4, 11,  2, 14, 15,  0,  8, 13,  3, 12,  9,  7,  5, 10,  6,  1,
           13,  0, 11,  7,  4,  9,  1, 10, 14,  3,  5, 12,  2, 15,  8,  6,
                1,  4, 11, 13, 12,  3,  7, 14, 10, 15,  6,  8,  0,  5,  9,  2,
                6, 11, 13,  8,  1,  4, 10,  7,  9,  5,  0, 15, 14,  2,  3, 12,

           /* S8 */
           13,  2,  8,  4,  6, 15, 11,  1, 10,  9,  3, 14,  5,  0, 12,  7,
                1, 15, 13,  8, 10,  3,  7,  4, 12,  5,  6, 11,  0, 14,  9,  2,
                7, 11,  4,  1,  9, 12, 14,  2,  0,  6, 10, 13, 15,  3,  5,  8,
                2,  1, 14,  7,  4, 10,  8, 13, 15, 12,  9,  0,  3,  5,  6, 11
};

/* 32-bit permutation function P used on the output of the S-boxes */
static byte p32i[] = {
           16,  7, 20, 21,
           29, 12, 28, 17,
                1, 15, 23, 26,
                5, 18, 31, 10,
                2,  8, 24, 14,
           32, 27,  3,  9,
           19, 13, 30,  6,
           22, 11,  4, 25
};
#endif

/* permuted choice table (key) */
static const byte pc1[] = {
           57, 49, 41, 33, 25, 17,  9,
                1, 58, 50, 42, 34, 26, 18,
           10,  2, 59, 51, 43, 35, 27,
           19, 11,  3, 60, 52, 44, 36,

           63, 55, 47, 39, 31, 23, 15,
                7, 62, 54, 46, 38, 30, 22,
           14,  6, 61, 53, 45, 37, 29,
           21, 13,  5, 28, 20, 12,  4
};

/* number left rotations of pc1 */
static const byte totrot[] = {
           1,2,4,6,8,10,12,14,15,17,19,21,23,25,27,28
};

/* permuted choice key (table) */
static const byte pc2[] = {
           14, 17, 11, 24,  1,  5,
                3, 28, 15,  6, 21, 10,
           23, 19, 12,  4, 26,  8,
           16,  7, 27, 20, 13,  2,
           41, 52, 31, 37, 47, 55,
           30, 40, 51, 45, 33, 48,
           44, 49, 39, 56, 34, 53,
           46, 42, 50, 36, 29, 32
};

/* End of DES-defined tables */

/* bit 0 is left-most in byte */
static const int bytebit[] = {
           0200,0100,040,020,010,04,02,01
};

/* Set key (initialize key schedule array) */
DES::DES(const byte *key, CipherDir dir)
        : k(32)
{
           SecByteBlock buffer(56+56+8);
           byte *const pc1m=buffer;                 /* place to modify pc1 into */
           byte *const pcr=pc1m+56;                 /* place to rotate pc1 into */
           byte *const ks=pcr+56;
           register int i,j,l;
           int m;

           for (j=0; j<56; j++) {          /* convert pc1 to bits of key */
                           l=pc1[j]-1;             /* integer bit location  */
                           m = l & 07;             /* find bit              */
                           pc1m[j]=(key[l>>3] &    /* find which key byte l is in */
                                           bytebit[m])     /* and which bit of that byte */
                                           ? 1 : 0;        /* and store 1-bit result */
           }
           for (i=0; i<16; i++) {          /* key chunk for each iteration */
                           memset(ks,0,8);         /* Clear key schedule */
                           for (j=0; j<56; j++)    /* rotate pc1 the right amount */
                                           pcr[j] = pc1m[(l=j+totrot[i])<(j<28? 28 : 56) ? l: l-28];
                                           /* rotate left and right halves independently */
                           for (j=0; j<48; j++){   /* select bits individually */
                                           /* check bit that goes to ks[j] */
                                           if (pcr[pc2[j]-1]){
                                                           /* mask it in if it's there */
                                                           l= j % 6;
                                                           ks[j/6] |= bytebit[l] >> 2;
                                           }
                           }
                           /* Now convert to odd/even interleaved form for use in F */
                           k[2*i] = ((word32)ks[0] << 24)
                                | ((word32)ks[2] << 16)
                                | ((word32)ks[4] << 8)
                                | ((word32)ks[6]);
                           k[2*i+1] = ((word32)ks[1] << 24)
                                | ((word32)ks[3] << 16)
                                | ((word32)ks[5] << 8)
                                | ((word32)ks[7]);
           }

        if (dir==DECRYPTION)     // reverse key schedule order
                for (i=0; i<16; i+=2)
                {
                        std::swap(k[i], k[32-2-i]);
                        std::swap(k[i+1], k[32-1-i]);
                }
}

// Richard Outerbridge's initial permutation algorithm
/*
inline void IPERM(word32 &left, word32 &right)
{
        word32 work;

        work = ((left >> 4) ^ right) & 0x0f0f0f0f;
        right ^= work;
        left ^= work << 4;
        work = ((left >> 16) ^ right) & 0xffff;
        right ^= work;
        left ^= work << 16;
        work = ((right >> 2) ^ left) & 0x33333333;
        left ^= work;
        right ^= (work << 2);
        work = ((right >> 8) ^ left) & 0xff00ff;
        left ^= work;
        right ^= (work << 8);
        right = rotl(right, 1);
        work = (left ^ right) & 0xaaaaaaaa;
        left ^= work;
        right ^= work;
        left = rotl(left, 1);
}
inline void FPERM(word32 &left, word32 &right)
{
        word32 work;

        right = rotr(right, 1);
        work = (left ^ right) & 0xaaaaaaaa;
        left ^= work;
        right ^= work;
        left = rotr(left, 1);
        work = ((left >> 8) ^ right) & 0xff00ff;
        right ^= work;
        left ^= work << 8;
        work = ((left >> 2) ^ right) & 0x33333333;
        right ^= work;
        left ^= work << 2;
        work = ((right >> 16) ^ left) & 0xffff;
        left ^= work;
        right ^= work << 16;
        work = ((right >> 4) ^ left) & 0x0f0f0f0f;
        left ^= work;
        right ^= work << 4;
}
*/

// Wei Dai's modification to Richard Outerbridge's initial permutation 
// algorithm, this one is faster if you have access to rotate instructions 
// (like in MSVC)
static inline void IPERM(word32 &left, word32 &right)
{
        word32 work;

        right = rotlFixed(right, 4U);
        work = (left ^ right) & 0xf0f0f0f0;
        left ^= work;
        right = rotrFixed(right^work, 20U);
        work = (left ^ right) & 0xffff0000;
        left ^= work;
        right = rotrFixed(right^work, 18U);
        work = (left ^ right) & 0x33333333;
        left ^= work;
        right = rotrFixed(right^work, 6U);
        work = (left ^ right) & 0x00ff00ff;
        left ^= work;
        right = rotlFixed(right^work, 9U);
        work = (left ^ right) & 0xaaaaaaaa;
        left = rotlFixed(left^work, 1U);
        right ^= work;
}

static inline void FPERM(word32 &left, word32 &right)
{
        word32 work;

        right = rotrFixed(right, 1U);
        work = (left ^ right) & 0xaaaaaaaa;
        right ^= work;
        left = rotrFixed(left^work, 9U);
        work = (left ^ right) & 0x00ff00ff;
        right ^= work;
        left = rotlFixed(left^work, 6U);
        work = (left ^ right) & 0x33333333;
        right ^= work;
        left = rotlFixed(left^work, 18U);
        work = (left ^ right) & 0xffff0000;
        right ^= work;
        left = rotlFixed(left^work, 20U);
        work = (left ^ right) & 0xf0f0f0f0;
        right ^= work;
        left = rotrFixed(left^work, 4U);
}

void DES::RawProcessBlock(word32 &l_, word32 &r_) const
{
        word32 l = l_, r = r_;
        const word32 *kptr=k;

        for (unsigned i=0; i<8; i++)
        {
                word32 work = rotrFixed(r, 4U) ^ kptr[4*i+0];
                l ^= Spbox[6][(work) & 0x3f]
                  ^  Spbox[4][(work >> 8) & 0x3f]
                  ^  Spbox[2][(work >> 16) & 0x3f]
                  ^  Spbox[0][(work >> 24) & 0x3f];
                work = r ^ kptr[4*i+1];
                l ^= Spbox[7][(work) & 0x3f]
                  ^  Spbox[5][(work >> 8) & 0x3f]
                  ^  Spbox[3][(work >> 16) & 0x3f]
                  ^  Spbox[1][(work >> 24) & 0x3f];

                work = rotrFixed(l, 4U) ^ kptr[4*i+2];
                r ^= Spbox[6][(work) & 0x3f]
                  ^  Spbox[4][(work >> 8) & 0x3f]
                  ^  Spbox[2][(work >> 16) & 0x3f]
                  ^  Spbox[0][(work >> 24) & 0x3f];
                work = l ^ kptr[4*i+3];
                r ^= Spbox[7][(work) & 0x3f]
                  ^  Spbox[5][(work >> 8) & 0x3f]
                  ^  Spbox[3][(work >> 16) & 0x3f]
                  ^  Spbox[1][(work >> 24) & 0x3f];
        }

        l_ = l; r_ = r;
}

// Encrypt or decrypt a block of data in ECB mode
void DES::ProcessBlock(const byte *inBlock, byte * outBlock) const
{
        word32 l,r;
        GetBlockBigEndian(inBlock, l, r);
        IPERM(l,r);

        const word32 *kptr=k;

        for (unsigned i=0; i<8; i++)
        {
                word32 work = rotrFixed(r, 4U) ^ kptr[4*i+0];
                l ^= Spbox[6][(work) & 0x3f]
                  ^  Spbox[4][(work >> 8) & 0x3f]
                  ^  Spbox[2][(work >> 16) & 0x3f]
                  ^  Spbox[0][(work >> 24) & 0x3f];
                work = r ^ kptr[4*i+1];
                l ^= Spbox[7][(work) & 0x3f]
                  ^  Spbox[5][(work >> 8) & 0x3f]
                  ^  Spbox[3][(work >> 16) & 0x3f]
                  ^  Spbox[1][(work >> 24) & 0x3f];

                work = rotrFixed(l, 4U) ^ kptr[4*i+2];
                r ^= Spbox[6][(work) & 0x3f]
                  ^  Spbox[4][(work >> 8) & 0x3f]
                  ^  Spbox[2][(work >> 16) & 0x3f]
                  ^  Spbox[0][(work >> 24) & 0x3f];
                work = l ^ kptr[4*i+3];
                r ^= Spbox[7][(work) & 0x3f]
                  ^  Spbox[5][(work >> 8) & 0x3f]
                  ^  Spbox[3][(work >> 16) & 0x3f]
                  ^  Spbox[1][(work >> 24) & 0x3f];
        }

        FPERM(l,r);
        PutBlockBigEndian(outBlock, r, l);
}

void DES_EDE2_Encryption::ProcessBlock(const byte *inBlock, byte *outBlock) const
{
        word32 l,r;
        GetBlockBigEndian(inBlock, l, r);
        IPERM(l,r);
        e.RawProcessBlock(l, r);
        d.RawProcessBlock(r, l);
        e.RawProcessBlock(l, r);
        FPERM(l,r);
        PutBlockBigEndian(outBlock, r, l);
}

void DES_EDE2_Decryption::ProcessBlock(const byte *inBlock, byte *outBlock) const
{
        word32 l,r;
        GetBlockBigEndian(inBlock, l, r);
        IPERM(l,r);
        d.RawProcessBlock(l, r);
        e.RawProcessBlock(r, l);
        d.RawProcessBlock(l, r);
        FPERM(l,r);
        PutBlockBigEndian(outBlock, r, l);
}

void DES_EDE3_Encryption::ProcessBlock(const byte *inBlock, byte *outBlock) const
{
        word32 l,r;
        GetBlockBigEndian(inBlock, l, r);
        IPERM(l,r);
        e1.RawProcessBlock(l, r);
        d2.RawProcessBlock(r, l);
        e3.RawProcessBlock(l, r);
        FPERM(l,r);
        PutBlockBigEndian(outBlock, r, l);
}

void DES_EDE3_Decryption::ProcessBlock(const byte *inBlock, byte *outBlock) const
{
        word32 l,r;
        GetBlockBigEndian(inBlock, l, r);
        IPERM(l,r);
        d3.RawProcessBlock(l, r);
        e2.RawProcessBlock(r, l);
        d1.RawProcessBlock(l, r);
        FPERM(l,r);
        PutBlockBigEndian(outBlock, r, l);
}

void DES_XEX3_Encryption::ProcessBlock(const byte *inBlock, byte *outBlock) const
{
        xorbuf(outBlock, inBlock, x1, BLOCKSIZE);
        e2.ProcessBlock(outBlock);
        xorbuf(outBlock, x3, BLOCKSIZE);
}

void DES_XEX3_Decryption::ProcessBlock(const byte *inBlock, byte *outBlock) const
{
        xorbuf(outBlock, inBlock, x3, BLOCKSIZE);
        d2.ProcessBlock(outBlock);
        xorbuf(outBlock, x1, BLOCKSIZE);
}

NAMESPACE_END

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