randpool.cpp

来自「各种加密算法的集合」· C++ 代码 · 共 96 行

// The algorithm in this module comes from PGP's randpool.c 

#include "randpool.h" 
#include "mdc.h" 
#include "md5.h" 
#include "modes.h" 
#include <assert.h> 

typedef MDC<MD5> RandomPoolCipher; 

RandomPool::RandomPool(unsigned int poolSize) 
: pool(poolSize), key(RandomPoolCipher::KEYLENGTH) 
{ 
assert(poolSize > key.size); 

addPos=0; 
getPos=poolSize; 
memset(pool, 0, poolSize); 
memset(key, 0, key.size); 
} 

void RandomPool::Stir() 
{ 
// add these lines to be compatible with PGP's randpool.c 
// byteReverse((word32 *)pool.ptr, (word32 *)pool.ptr, pool.size); 
for (int i=0; i<2; i++) 
{ 
RandomPoolCipher cipher(key); 
CFBEncryption cfb(cipher, pool+pool.size-cipher.BlockSize()); 
cfb.ProcessString(pool, pool.size); 
memcpy(key, pool, key.size); 
} 
// byteReverse((word32 *)pool.ptr, (word32 *)pool.ptr, pool.size); 

addPos = 0; 
getPos = key.size; 
} 

void RandomPool::Put(byte inByte) 
{ 
if (addPos == pool.size) 
Stir(); 

pool[addPos++] ^= inByte; 
getPos = pool.size; // Force stir on get 
} 

void RandomPool::Put(const byte *inString, unsigned int length) 
{ 
unsigned t; 

while (length > (t = pool.size - addPos)) 
{ 
xorbuf(pool+addPos, inString, t); 
inString += t; 
length -= t; 
Stir(); 
} 

if (length) 
{ 
xorbuf(pool+addPos, inString, length); 
addPos += length; 
getPos = pool.size; // Force stir on get 
} 
} 

int RandomPool::Get(byte &amt;outByte) 
{ 
if (getPos == pool.size) 
Stir(); 

outByte = pool[getPos++]; 
return 1; 
} 

unsigned int RandomPool::Get(byte *outString, unsigned int getMax) 
{ 
unsigned t; 
unsigned int length = getMax; 

while (length > (t = pool.size - getPos)) 
{ 
memcpy(outString, pool+getPos, t); 
outString += t; 
length -= t; 
Stir(); 
} 

if (length) 
{ 
memcpy(outString, pool+getPos, length); 
getPos += length; 
} 
return getMax; 
}