int_api.c

cryptlib安全工具包

/****************************************************************************
*																			*
*							cryptlib Internal API							*
*						Copyright Peter Gutmann 1992-2007					*
*																			*
****************************************************************************/

/* A generic module that implements a rug under which all problems not
   solved elsewhere are swept */

#if defined( INC_ALL )
  #include "crypt.h"
  #include "stream.h"
#else
  #include "crypt.h"
  #include "io/stream.h"
#endif /* Compiler-specific includes */

/* Perform the FIPS-140 statistical checks that are feasible on a byte
   string.  The full suite of tests assumes that an infinite source of
   values (and time) is available, the following is a scaled-down version
   used to sanity-check keys and other short random data blocks.  Note that
   this check requires at least 64 bits of data in order to produce useful
   results */

CHECK_RETVAL STDC_NONNULL_ARG( ( 1 ) ) \
BOOLEAN checkEntropy( IN_BUFFER( dataLength ) const BYTE *data, 
					  IN_LENGTH_SHORT_MIN( MIN_KEYSIZE ) const int dataLength )
	{
	const int delta = ( dataLength < 16 ) ? 1 : 0;
	int bitCount[ 4 + 8 ] = { 0 }, noOnes, i;

	assert( isReadPtr( data, dataLength ) );
	
	REQUIRES_B( dataLength >= MIN_KEYSIZE && dataLength < MAX_INTLENGTH_SHORT );

	for( i = 0; i < dataLength; i++ )
		{
		const int value = data[ i ];

		bitCount[ value & 3 ]++;
		bitCount[ ( value >> 2 ) & 3 ]++;
		bitCount[ ( value >> 4 ) & 3 ]++;
		bitCount[ ( value >> 6 ) & 3 ]++;
		}

	/* Monobit test: Make sure that at least 1/4 of the bits are ones and 1/4
	   are zeroes */
	noOnes = bitCount[ 1 ] + bitCount[ 2 ] + ( 2 * bitCount[ 3 ] );
	if( noOnes < dataLength * 2 || noOnes > dataLength * 6 )
		return( FALSE );

	/* Poker test (almost): Make sure that each bit pair is present at least
	   1/16 of the time.  The FIPS 140 version uses 4-bit values but the
	   numer of samples available from the keys is far too small for this so
	   we can only use 2-bit values.

	   This isn't precisely 1/16, for short samples (< 128 bits) we adjust
	   the count by one because of the small sample size and for odd-length
	   data we're getting four more samples so the actual figure is slightly
	   less than 1/16 */
	if( ( bitCount[ 0 ] + delta < dataLength / 2 ) || \
		( bitCount[ 1 ] + delta < dataLength / 2 ) || \
		( bitCount[ 2 ] + delta < dataLength / 2 ) || \
		( bitCount[ 3 ] + delta < dataLength / 2 ) )
		return( FALSE );

	return( TRUE );
	}

/* Copy a string attribute to external storage, with various range checks
   to follow the cryptlib semantics (these will already have been done by
   the caller, this is just a backup check).  There are two forms for this
   function, one that takes a MESSAGE_DATA parameter containing all of the 
   result parameters in one place and the other that takes distinct result
   parameters, typically because they've been passed down through several
   levels of function call beyond the point where they were in a 
   MESSAGE_DATA */

CHECK_RETVAL STDC_NONNULL_ARG( ( 3, 4 ) ) \
int attributeCopyParams( OUT_BUFFER_OPT( destMaxLength, \
										 *destLength ) void *dest, 
						 IN_LENGTH_SHORT_Z const int destMaxLength, 
						 OUT_LENGTH_SHORT_Z int *destLength, 
						 IN_BUFFER( sourceLength ) const void *source, 
						 IN_LENGTH_SHORT_Z const int sourceLength )
	{
	assert( ( dest == NULL && destMaxLength == 0 ) || \
			( isWritePtr( dest, destMaxLength ) ) );
	assert( isWritePtr( destLength, sizeof( int ) ) );
	assert( ( source == NULL && sourceLength == 0 ) || \
			isReadPtr( source, sourceLength ) );

	REQUIRES( ( dest == NULL && destMaxLength == 0 ) || \
			  ( dest != NULL && \
				destMaxLength > 0 && \
				destMaxLength < MAX_INTLENGTH_SHORT ) );
	REQUIRES( ( source == NULL && sourceLength == 0 ) || \
			  ( source != NULL && \
			    sourceLength > 0 && \
				sourceLength < MAX_INTLENGTH_SHORT ) );

	/* Clear return value */
	*destLength = 0;

	if( sourceLength <= 0 )
		return( CRYPT_ERROR_NOTFOUND );
	if( dest != NULL )
		{
		assert( isReadPtr( source, sourceLength ) );

		if( sourceLength > destMaxLength || \
			!isWritePtr( dest, sourceLength ) )
			return( CRYPT_ERROR_OVERFLOW );
		memcpy( dest, source, sourceLength );
		}
	*destLength = sourceLength;

	return( CRYPT_OK );
	}

CHECK_RETVAL STDC_NONNULL_ARG( ( 1, 2 ) ) \
int attributeCopy( INOUT MESSAGE_DATA *msgData, 
				   IN_BUFFER( attributeLength ) const void *attribute, 
				   IN_LENGTH_SHORT_Z const int attributeLength )
	{
	assert( isWritePtr( msgData, sizeof( MESSAGE_DATA ) ) );
	assert( attributeLength == 0 || \
			isReadPtr( attribute, attributeLength ) );

	REQUIRES( attributeLength >= 0 && \
			  attributeLength < MAX_INTLENGTH_SHORT );

	return( attributeCopyParams( msgData->data, msgData->length, 
								 &msgData->length, attribute, 
								 attributeLength ) );
	}

/* Check whether a given algorithm is available */

CHECK_RETVAL_BOOL \
BOOLEAN algoAvailable( IN_ALGO const CRYPT_ALGO_TYPE cryptAlgo )
	{
	CRYPT_QUERY_INFO queryInfo;

	REQUIRES_B( cryptAlgo > CRYPT_ALGO_NONE && \
				cryptAlgo < CRYPT_ALGO_LAST );

	return( cryptStatusOK( krnlSendMessage( SYSTEM_OBJECT_HANDLE,
									IMESSAGE_DEV_QUERYCAPABILITY, &queryInfo,
									cryptAlgo ) ) ? TRUE : FALSE );
	}

/* For a given algorithm pair, check whether the first is stronger than the
   second.  For hashes the order is:

	SHA2 > RIPEMD160 > SHA-1 > all others */

CHECK_RETVAL_BOOL \
BOOLEAN isStrongerHash( IN_ALGO const CRYPT_ALGO_TYPE algorithm1,
						IN_ALGO const CRYPT_ALGO_TYPE algorithm2 )
	{
	static const CRYPT_ALGO_TYPE algoPrecedence[] = {
		CRYPT_ALGO_SHA2, CRYPT_ALGO_RIPEMD160, CRYPT_ALGO_SHA1,
		CRYPT_ALGO_NONE, CRYPT_ALGO_NONE };
	int algo1index, algo2index;

	REQUIRES_B( algorithm1 >= CRYPT_ALGO_FIRST_HASH && \
				algorithm1 <= CRYPT_ALGO_LAST_HASH );
	REQUIRES_B( algorithm2 >= CRYPT_ALGO_FIRST_HASH && \
				algorithm2 <= CRYPT_ALGO_LAST_HASH );

	/* Find the relative positions on the scale of the two algorithms */
	for( algo1index = 0; 
		 algoPrecedence[ algo1index ] != algorithm1 && \
			algo1index < FAILSAFE_ARRAYSIZE( algoPrecedence, CRYPT_ALGO_TYPE );
		 algo1index++ )
		{
		/* If we've reached an unrated algorithm, it can't be stronger than 
		   the other one */
		if( algoPrecedence[ algo1index ] == CRYPT_ALGO_NONE )
			return( FALSE );
		}
	ENSURES_B( algo1index < FAILSAFE_ARRAYSIZE( algoPrecedence, \
												CRYPT_ALGO_TYPE ) );
	for( algo2index = 0; 
		 algoPrecedence[ algo2index ] != algorithm2 && \
			algo2index < FAILSAFE_ARRAYSIZE( algoPrecedence, CRYPT_ALGO_TYPE );
		 algo2index++ )
		{
		/* If we've reached an unrated algorithm, it's weaker than the other 
		   one */
		if( algoPrecedence[ algo2index ] == CRYPT_ALGO_NONE )
			return( TRUE );
		}
	ENSURES_B( algo2index < FAILSAFE_ARRAYSIZE( algoPrecedence, \
												CRYPT_ALGO_TYPE ) );

	/* If the first algorithm has a smaller index than the second, it's a
	   stronger algorithm */
	return( ( algo1index < algo2index ) ? TRUE : FALSE );
	}

/* Map one value to another, used to map values from one representation 
   (e.g. PGP algorithms or HMAC algorithms) to another (cryptlib algorithms
   or the underlying hash used for the HMAC algorithm) */

CHECK_RETVAL STDC_NONNULL_ARG( ( 2, 3 ) ) \
int mapValue( IN_INT_SHORT_Z const int srcValue,
			  OUT_INT_SHORT_Z int *destValue,
			  IN_ARRAY( mapTblSize ) const MAP_TABLE *mapTbl,
			  IN_LENGTH_SHORT const int mapTblSize )
	{
	int i;

	assert( isWritePtr( destValue, sizeof( int ) ) );
	assert( isReadPtr( mapTbl, mapTblSize * sizeof( MAP_TABLE ) ) );

	REQUIRES( srcValue >= 0 && srcValue < MAX_INTLENGTH_SHORT );
	REQUIRES( mapTblSize > 0 && mapTblSize < 100 );

	/* Clear return value */
	*destValue = 0;

	/* Convert the hash algorithm into the equivalent HMAC algorithm */
	for( i = 0; mapTbl[ i ].source != CRYPT_ERROR && i < mapTblSize; i++ )
		{
		if( mapTbl[ i ].source == srcValue )
			{
			*destValue = mapTbl[ i ].destination;

			return( CRYPT_OK );
			}
		}
	ENSURES( i < mapTblSize );

	return( CRYPT_ERROR_NOTAVAIL );
	}

/****************************************************************************
*																			*
*							Checksum/Hash Functions							*
*																			*
****************************************************************************/

/* Calculate a 16-bit Fletcher-like checksum of a block of data.  This isn't
   quite a pure Fletcher checksum because we don't bother keeping the
   accumulators at 8 bits and also don't need to set the initial value to
   nonzero since we'll never see a sequence of zero bytes.  This isn't a big
   deal since all we need is consistent results for identical data, the 
   value itself is never communicated externally.  In addition we don't 
   bother with masking to 16 bits during the calculation process (although 
   we mask at the end to avoid potential problems with sign bits) since it's 
   not being used as a true checksum */

RETVAL_RANGE( MAX_ERROR, 0xFFFF ) STDC_NONNULL_ARG( ( 1 ) ) \
int checksumData( IN_BUFFER( dataLength ) const void *data, 
				  IN_LENGTH const int dataLength )
	{
	const BYTE *dataPtr = data;
	int sum1 = 0, sum2 = 0, i;

	assert( isReadPtr( data, dataLength ) );

	REQUIRES( data != NULL );
	REQUIRES( dataLength > 0 && dataLength < MAX_INTLENGTH )

	for( i = 0; i < dataLength; i++ )
		{
		sum1 += dataPtr[ i ];
		sum2 += sum1;
		}

	return( sum2 & 0xFFFF );
	}

/* Calculate the hash of a block of data.  We use SHA-1 because it's the 
   built-in default, but any algorithm will do since we're only using it
   to transform a variable-length value to a fixed-length one for easy
   comparison purposes */

STDC_NONNULL_ARG( ( 1, 3 ) ) \
void hashData( OUT_BUFFER_FIXED( hashMaxLength ) BYTE *hash, 
			   IN_LENGTH_HASH const int hashMaxLength, 
			   IN_BUFFER( dataLength ) const void *data, 
			   IN_LENGTH const int dataLength )
	{
	static HASHFUNCTION_ATOMIC hashFunctionAtomic = NULL;
	static int hashSize;
	BYTE hashBuffer[ CRYPT_MAX_HASHSIZE + 8 ];

	assert( isWritePtr( hash, hashMaxLength ) );
	assert( hashMaxLength >= 16 && \
			hashMaxLength <= CRYPT_MAX_HASHSIZE );
	assert( isReadPtr( data, dataLength ) );
	assert( dataLength > 0 && dataLength < MAX_INTLENGTH );

	/* Get the hash algorithm information if necessary */
	if( hashFunctionAtomic == NULL )
		getHashAtomicParameters( CRYPT_ALGO_SHA1, &hashFunctionAtomic, 
								 &hashSize );

	/* Error handling: If there's a problem, return a zero hash.  We use 
	   this strategy since this is a void function and so the usual 
	   REQUIRES() predicate won't be effective.  Note that this can lead to 
	   a false-positive match if we're called multiple times with invalid 
	   input, in theory we could fill the return buffer with nonce data to 
	   ensure that we never get a false-positive match but since this is a 
	   should-never-occur condition anyway it's not certain whether forcing 
	   a match or forcing a non-match is the preferred behaviour */
	if( data == NULL || dataLength <= 0 || dataLength >= MAX_INTLENGTH || \
		hashMaxLength < 16 || hashMaxLength > hashSize || \
		hashMaxLength > CRYPT_MAX_HASHSIZE || hashFunctionAtomic == NULL )
		{
		memset( hash, 0, hashMaxLength );
		retIntError_Void();
		}

	/* Hash the data and copy as many bytes as the caller has requested to
	   the output.  Typically they'll require only a subset of the full 
	   amount since all that we're doing is transforming a variable-length
	   value to a fixed-length value for easy comparison purposes */
	hashFunctionAtomic( hashBuffer, 20, data, dataLength );
	memcpy( hash, hashBuffer, hashMaxLength );
	zeroise( hashBuffer, 20 );
	}

/****************************************************************************
*																			*
*							Stream Export/Import Routines					*
*																			*
****************************************************************************/

/* Export attribute or certificate data to a stream.  In theory we would
   have to export this via a dynbuf and then write it to the stream but we 
   can save some overhead by writing it directly to the stream's buffer.
   
   Some attributes have a user-defined size (e.g. 
   CRYPT_IATTRIBUTE_RANDOM_NONCE) so we allow the caller to specify an 
   optional length parameter indicating how much of the attribute should be 
   exported */

CHECK_RETVAL STDC_NONNULL_ARG( ( 1 ) ) \
static int exportAttr( INOUT STREAM *stream, 
					   IN_HANDLE const CRYPT_HANDLE cryptHandle,
					   IN_ATTRIBUTE const CRYPT_ATTRIBUTE_TYPE attributeType,
					   IN_LENGTH_INDEF const int length )
							/* Declared as LENGTH_INDEF because SHORT_INDEF
							   doesn't make sense */
	{
	MESSAGE_DATA msgData;