random.cpp

加密解密,安全工具！很有意思的代码

#include "random.h"
#include "sha1.h"
#include <stdlib.h>
#include <string.h>

char random_cpp[]="$Id: random.cpp,v 1.3 2002/10/29 07:11:46 crypt Rel-1.6-3 $";

RNGRESULT SHA1RandomAllocate( sSHA1Random **sRandom )
{
	*sRandom = ( sSHA1Random * ) malloc( sizeof ( sSHA1Random ) );

	if ( *sRandom == 0 )
		return RNG_MALLOC_ERROR;

	SHA1RandomInit( *sRandom );

	return RNG_OK;
}

void SHA1RandomInit( sSHA1Random *sRandom )
{
	memset( sRandom , 0 , sizeof ( *sRandom ) );
}

void SHA1RandomUpdate(
	sSHA1Random *sRandom ,
	byte *seedBuffer ,
	int seedBufferSize )
{

	SHA1Context *SHA_ctx;
	SHA1Allocate( (void**)&SHA_ctx );

	memset( sRandom , 0 , sizeof ( *sRandom ) );

	SHA1Init( SHA_ctx , 0 , 0 );

	SHA1Process( SHA_ctx , seedBuffer , seedBufferSize );

	SHA1Final( SHA_ctx ,  sRandom->state );

	SHA1Free( (void**)&SHA_ctx );
    
}

//
//	SHA1RandomUpdateEx...
//	Main difference is, it uses SHA1Process with current sRandom->state.
//
void SHA1RandomUpdateEx(
	sSHA1Random *sRandom ,
	byte *seedBuffer ,
	int seedBufferSize )
{

	SHA1Context *SHA_ctx;
	SHA1Allocate( (void**)&SHA_ctx );

	SHA1Init( SHA_ctx , 0 , 0 );

	SHA1Process( SHA_ctx , sRandom->state , sizeof( sRandom->state ) );
	SHA1Process( SHA_ctx , seedBuffer , seedBufferSize );

	SHA1Final( SHA_ctx ,  sRandom->state );

	SHA1Free( (void**)&SHA_ctx );
	
}

static void SHA1RandomReGenerate ( sSHA1Random *sRandom )
{
	int i;

	SHA1Context *SHA_ctx;

/* Generate new data */

	SHA1Allocate( (void**)&SHA_ctx );

	SHA1Init( SHA_ctx , 0 , 0 ); 

	SHA1Process( SHA_ctx , sRandom->state , sizeof(sRandom->state) );

	SHA1Final( SHA_ctx, sRandom->data ); /* FinalDigest array must be >= 20 bytes */

	SHA1Free( (void**)&SHA_ctx );

/* Increment current state */
	for (i = sizeof(sRandom->state) ; i-- ; )
		if (sRandom->state[i]++)
			break;

	sRandom->residue = sizeof( sRandom->data );
}

void SHA1RandomGenerateBytes(
	sSHA1Random *sRandom,
	unsigned char *buffer ,
	unsigned int bufferSize)
{
	while ( bufferSize > sRandom->residue )
	{
		memcpy( 
			buffer ,
			&( sRandom->data[ sizeof(sRandom->data) - sRandom->residue ] ),
			sRandom->residue );

		bufferSize	-= sRandom->residue;
		buffer		+= sRandom->residue;

		SHA1RandomReGenerate( sRandom );
	}
	
	memcpy( 
		buffer ,
		& ( sRandom->data[ sizeof(sRandom->data) - sRandom->residue ] ),
		bufferSize );

	sRandom->residue -= bufferSize;
}

void SHA1RandomFinal( sSHA1Random **sRandom )
{
	free( *sRandom );
	*sRandom = 0;
}

extern "C" RNGRESULT SHA1RandomGenerate(
	byte *byteBuffer ,
	size_t byteBufferSize ,
	byte *seedBuffer ,
	size_t seedBufferSize )
{
	sSHA1Random *sRandom;
	RNGRESULT result; 

	result = SHA1RandomAllocate ( &sRandom );

	if ( result != RNG_OK )
		return result;

	SHA1RandomInit( sRandom );

	SHA1RandomUpdate( sRandom , seedBuffer , seedBufferSize );

	SHA1RandomGenerateBytes( sRandom , byteBuffer , byteBufferSize );

	SHA1RandomFinal ( &sRandom );

	return RNG_OK;
}

void SHA1RandomGenerateBytesEx(
	sSHA1Random *sRandom,
	byte *buffer ,
	size_t bufferSize,
	byte *seedBuffer ,
	size_t seedBufferSize )
{
	SHA1RandomUpdate( sRandom , seedBuffer , seedBufferSize );

	while ( bufferSize > sRandom->residue )
	{
		memcpy( 
			buffer ,
			& ( sRandom->data[ sizeof(sRandom->data) - sRandom->residue ] ),
			sRandom->residue );

		bufferSize	-= sRandom->residue;
		buffer		+= sRandom->residue;

        SHA1RandomReGenerate( sRandom );
		SHA1RandomUpdateEx( sRandom , seedBuffer , seedBufferSize );
    }
	
	memcpy( 
		buffer ,
		& ( sRandom->data[ sizeof(sRandom->data) - sRandom->residue ] ),
		bufferSize );

	sRandom->residue -= bufferSize;
}

//
//	Main difference in random generation is,
//	SHA1RandomGenerateBytesEx does not use 
//		the SHA1RandomReGenerate ( the function simple increments sRandom->state ),
//		SHA1RandomGenerateBytesEx processes current state first and 
//		then processes all seed again.
extern "C" RNGRESULT SHA1RandomGenerateKey(
	byte *byteBuffer ,
	size_t byteBufferSize ,
	byte *seedBuffer ,
	size_t seedBufferSize )
{
	sSHA1Random *sRandom;
	RNGRESULT result; 

	result = SHA1RandomAllocate ( &sRandom );

	if ( result != RNG_OK )
		return result;

	SHA1RandomInit( sRandom );

	SHA1RandomGenerateBytesEx( sRandom , byteBuffer , byteBufferSize, seedBuffer , seedBufferSize  );

	SHA1RandomFinal ( &sRandom );

	return RNG_OK;
}