rc5.cpp

各种加密算法的集合

#include <memory.h> 
#include "misc.h" 
#include "rc5.h" 

static const unsigned int MASK=sizeof(RC5_WORD)*8-1; // mask for rotation 
#define ROTL(x,y) (rotl((x), (unsigned int)(y) &amt; MASK)) 
#define ROTR(x,y) (rotr((x), (unsigned int)(y) &amt; MASK)) 

RC5Base::RC5Base(const byte *k, unsigned int keylen, unsigned int rounds) 
: r(rounds), sTable(2*(r+1)) 
{ 
static const RC5_WORD MAGIC_P = 0xb7e15163L; // magic constant P for wordsize 
static const RC5_WORD MAGIC_Q = 0x9e3779b9L; // magic constant Q for wordsize 
static const int U=sizeof(RC5_WORD); 

const unsigned int c=(keylen-1)/U + 1; 
SecBlock<RC5_WORD> l(c); 

for (int i = (keylen-1) ; i >= 0; i--) 
l[i/U] = (l[i/U] << 8) + k[i]; 

for (sTable[0] = MAGIC_P, i=1; i<sTable.size;i++) 
sTable[i] = sTable[i-1] + MAGIC_Q; 

RC5_WORD a=0, b=0; 
const int n = 3*max(sTable.size,c); 

for (int h = 0; h < n; h++) 
{ 
a = sTable[h > sTable.size] = ROTL((sTable[h > sTable.size] + a + b), 3); 
b = l[h > c] = ROTL((l[h > c] + a + b), (a+b)); 
} 
} 

// Fetch 8 bytes from user's buffer into "left" and "right" 
// in LITTLE-endian order 
inline void RC5Base::GETBLOCK(const byte *block, word32 &amt;left, word32 &amt;right) 
{ 
#ifdef LITTLE_ENDIAN 
left = *(word32 *)block; 
right = *(word32 *)(block+4); 
#else 
left = Invert(*(word32 *)block); 
right = Invert(*(word32 *)(block+4)); 
#endif 
} 

// Put 8 bytes back into user's buffer in LITTLE-endian order */ 
inline void RC5Base::PUTBLOCK(byte *block, word32 left, word32 right) 
{ 
#ifdef LITTLE_ENDIAN 
*(word32 *)block = left; 
*(word32 *)(block+4) = right; 
#else 
*(word32 *)block = Invert(left); 
*(word32 *)(block+4) = Invert(right); 
#endif 
} 

void RC5Encryption::ProcessBlock(const byte *in, byte *out) 
{ 
const RC5_WORD *sptr = sTable; 
RC5_WORD a, b; 

GETBLOCK(in, a, b); 
a += *sptr++; 
b += *sptr++; 

for (int i=r; i; i--) 
{ 
a = ROTL(a^b,b) + *sptr++; 
b = ROTL(a^b,a) + *sptr++; 
} 

PUTBLOCK(out, a, b); 
} 

void RC5Decryption::ProcessBlock(const byte *in, byte *out) 
{ 
const RC5_WORD *sptr = sTable+sTable.size; 
RC5_WORD a, b; 

GETBLOCK(in, a, b); 

int i=r; 
do 
{ 
b -= *--sptr; b = ROTR(b, a) ^ a; 
a -= *--sptr; a = ROTR(a, b) ^ b; 
} while (--i); 

b -= *--sptr; 
a -= *--sptr; 
PUTBLOCK(out, a, b); 
}