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Annotation of truecrypt/common/xts.c, revision 1.1

1.1     ! root        1: /*
        !             2:  Copyright (c) 2008 TrueCrypt Foundation. All rights reserved.
        !             3: 
        !             4:  Governed by the TrueCrypt License 2.4 the full text of which is contained
        !             5:  in the file License.txt included in TrueCrypt binary and source code
        !             6:  distribution packages.
        !             7: */
        !             8: 
        !             9: /* For low-memory environments, define XTS_LOW_RESOURCE_VERSION, which will save 
        !            10: 0.5 KB of RAM, but the speed will be 15-20% lower. However, on multi-core CPUs,
        !            11: the XTS_LOW_RESOURCE_VERSION code might eventually be faster when parallelized,
        !            12: because it processes the buffer continuously as a whole -- it does not divide the
        !            13: buffer into data units (nevertheless, note that GenerateWhiteningValues supports
        !            14: more than one data unit). 
        !            15: 
        !            16: Note that when TC_NO_COMPILER_INT64 is defined, XTS_LOW_RESOURCE_VERSION is implicitly
        !            17: defined as well (because the non-low-resource version needs 64-bit types). 
        !            18: 
        !            19: For big-endian platforms (PowerPC, SPARC, etc.) define BYTE_ORDER as BIG_ENDIAN. */
        !            20: 
        !            21: 
        !            22: #ifdef TC_MINIMIZE_CODE_SIZE
        !            23: #      define XTS_LOW_RESOURCE_VERSION
        !            24: #endif
        !            25: 
        !            26: #ifdef TC_NO_COMPILER_INT64
        !            27: #      ifndef XTS_LOW_RESOURCE_VERSION
        !            28: #              define XTS_LOW_RESOURCE_VERSION
        !            29: #      endif
        !            30: #endif
        !            31: 
        !            32: 
        !            33: #include "Xts.h"
        !            34: 
        !            35: 
        !            36: #ifndef XTS_LOW_RESOURCE_VERSION
        !            37: 
        !            38: // length: number of bytes to encrypt; may be larger than one data unit and must be divisible by the cipher block size
        !            39: // ks: the primary key schedule
        !            40: // ks2: the secondary key schedule
        !            41: // startDataUnitNo: The sequential number of the data unit with which the buffer starts.
        !            42: // startCipherBlockNo: The sequential number of the first plaintext block to encrypt inside the data unit startDataUnitNo.
        !            43: //                     When encrypting the data unit from its first block, startCipherBlockNo is 0. 
        !            44: //                     The startCipherBlockNo value applies only to the first data unit in the buffer; each successive
        !            45: //                     data unit is encrypted from its first block. The start of the buffer does not have to be
        !            46: //                     aligned with the start of a data unit. If it is aligned, startCipherBlockNo must be 0; if it
        !            47: //                     is not aligned, startCipherBlockNo must reflect the misalignment accordingly.
        !            48: void EncryptBufferXTS (unsigned __int8 *buffer,
        !            49:                                           TC_LARGEST_COMPILER_UINT length,
        !            50:                                           const UINT64_STRUCT *startDataUnitNo,
        !            51:                                           unsigned int startCipherBlockNo,
        !            52:                                           unsigned __int8 *ks,
        !            53:                                           unsigned __int8 *ks2,
        !            54:                                           int cipher)
        !            55: {
        !            56:        unsigned __int8 finalCarry;
        !            57:        unsigned __int8 whiteningValues [ENCRYPTION_DATA_UNIT_SIZE];
        !            58:        unsigned __int8 whiteningValue [BYTES_PER_XTS_BLOCK];
        !            59:        unsigned __int8 byteBufUnitNo [BYTES_PER_XTS_BLOCK];
        !            60:        unsigned __int64 *whiteningValuesPtr64 = (unsigned __int64 *) whiteningValues;
        !            61:        unsigned __int64 *whiteningValuePtr64 = (unsigned __int64 *) whiteningValue;
        !            62:        unsigned __int64 *bufPtr = (unsigned __int64 *) buffer;
        !            63:        unsigned int startBlock = startCipherBlockNo, endBlock, block;
        !            64:        unsigned __int64 *const finalInt64WhiteningValuesPtr = whiteningValuesPtr64 + sizeof (whiteningValues) / sizeof (*whiteningValuesPtr64) - 1;
        !            65:        TC_LARGEST_COMPILER_UINT blockCount, dataUnitNo;
        !            66: 
        !            67:        /* The encrypted data unit number (i.e. the resultant ciphertext block) is to be multiplied in the
        !            68:        finite field GF(2^128) by j-th power of n, where j is the sequential plaintext/ciphertext block
        !            69:        number and n is 2, a primitive element of GF(2^128). This can be (and is) simplified and implemented
        !            70:        as a left shift of the preceding whitening value by one bit (with carry propagating). In addition, if
        !            71:        the shift of the highest byte results in a carry, 135 is XORed into the lowest byte. The value 135 is
        !            72:        derived from the modulus of the Galois Field (x^128+x^7+x^2+x+1). */
        !            73: 
        !            74:        // Convert the 64-bit data unit number into a little-endian 16-byte array. 
        !            75:        // Note that as we are converting a 64-bit number into a 16-byte array we can always zero the last 8 bytes.
        !            76:        dataUnitNo = startDataUnitNo->Value;
        !            77:        *((unsigned __int64 *) byteBufUnitNo) = LE64 (dataUnitNo);
        !            78:        *((unsigned __int64 *) byteBufUnitNo + 1) = 0;
        !            79: 
        !            80:        if (length % BYTES_PER_XTS_BLOCK)
        !            81:                TC_THROW_FATAL_EXCEPTION;
        !            82: 
        !            83:        blockCount = length / BYTES_PER_XTS_BLOCK;
        !            84: 
        !            85:        // Process all blocks in the buffer
        !            86:        // When length > ENCRYPTION_DATA_UNIT_SIZE, this can be parallelized (one data unit per core)
        !            87:        while (blockCount > 0)
        !            88:        {
        !            89:                if (blockCount < BLOCKS_PER_XTS_DATA_UNIT)
        !            90:                        endBlock = startBlock + (unsigned int) blockCount;
        !            91:                else
        !            92:                        endBlock = BLOCKS_PER_XTS_DATA_UNIT;
        !            93: 
        !            94:                whiteningValuesPtr64 = finalInt64WhiteningValuesPtr;
        !            95:                whiteningValuePtr64 = (unsigned __int64 *) whiteningValue;
        !            96: 
        !            97:                // Encrypt the data unit number using the secondary key (in order to generate the first 
        !            98:                // whitening value for this data unit)
        !            99:                *whiteningValuePtr64 = *((unsigned __int64 *) byteBufUnitNo);
        !           100:                *(whiteningValuePtr64 + 1) = 0;
        !           101:                EncipherBlock (cipher, whiteningValue, ks2);
        !           102: 
        !           103:                // Generate subsequent whitening values for blocks in this data unit. Note that all generated 128-bit
        !           104:                // whitening values are stored in memory as a sequence of 64-bit integers in reverse order.
        !           105:                for (block = 0; block < endBlock; block++)
        !           106:                {
        !           107:                        if (block >= startBlock)
        !           108:                        {
        !           109:                                *whiteningValuesPtr64-- = *whiteningValuePtr64++;
        !           110:                                *whiteningValuesPtr64-- = *whiteningValuePtr64;
        !           111:                        }
        !           112:                        else
        !           113:                                whiteningValuePtr64++;
        !           114: 
        !           115:                        // Derive the next whitening value
        !           116: 
        !           117: #if BYTE_ORDER == LITTLE_ENDIAN
        !           118: 
        !           119:                        // Little-endian platforms (Intel, AMD, etc.)
        !           120: 
        !           121:                        finalCarry = 
        !           122:                                (*whiteningValuePtr64 & 0x8000000000000000) ?
        !           123:                                135 : 0;
        !           124: 
        !           125:                        *whiteningValuePtr64-- <<= 1;
        !           126: 
        !           127:                        if (*whiteningValuePtr64 & 0x8000000000000000)
        !           128:                                *(whiteningValuePtr64 + 1) |= 1;        
        !           129: 
        !           130:                        *whiteningValuePtr64 <<= 1;
        !           131: 
        !           132: #else
        !           133:                        // Big-endian platforms (PowerPC, Motorola, etc.)
        !           134: 
        !           135:                        finalCarry = 
        !           136:                                (*whiteningValuePtr64 & 0x80) ?
        !           137:                                135 : 0;
        !           138: 
        !           139:                        *whiteningValuePtr64 = LE64 (LE64 (*whiteningValuePtr64) << 1);
        !           140: 
        !           141:                        whiteningValuePtr64--;
        !           142: 
        !           143:                        if (*whiteningValuePtr64 & 0x80)
        !           144:                                *(whiteningValuePtr64 + 1) |= 0x0100000000000000;       
        !           145: 
        !           146:                        *whiteningValuePtr64 = LE64 (LE64 (*whiteningValuePtr64) << 1);
        !           147: #endif
        !           148: 
        !           149:                        whiteningValue[0] ^= finalCarry;
        !           150:                }
        !           151: 
        !           152:                whiteningValuesPtr64 = finalInt64WhiteningValuesPtr;
        !           153: 
        !           154:                // Encrypt all blocks in this data unit
        !           155:                // TO DO: This should be parallelized (one block per core)
        !           156:                for (block = startBlock; block < endBlock; block++)
        !           157:                {
        !           158:                        // Pre-whitening
        !           159:                        *bufPtr++ ^= *whiteningValuesPtr64--;
        !           160:                        *bufPtr-- ^= *whiteningValuesPtr64++;
        !           161: 
        !           162:                        // Actual encryption
        !           163:                        EncipherBlock (cipher, bufPtr, ks);
        !           164: 
        !           165:                        // Post-whitening
        !           166:                        *bufPtr++ ^= *whiteningValuesPtr64--;
        !           167:                        *bufPtr++ ^= *whiteningValuesPtr64--;
        !           168: 
        !           169:                        blockCount--;
        !           170:                }
        !           171: 
        !           172:                startBlock = 0;
        !           173: 
        !           174:                dataUnitNo++;
        !           175: 
        !           176:                *((unsigned __int64 *) byteBufUnitNo) = LE64 (dataUnitNo);
        !           177:        }
        !           178: 
        !           179:        FAST_ERASE64 (whiteningValue, sizeof(whiteningValue));
        !           180:        FAST_ERASE64 (whiteningValues, sizeof(whiteningValues));
        !           181: }
        !           182: 
        !           183: 
        !           184: // For descriptions of the input parameters, see EncryptBufferXTS().
        !           185: void DecryptBufferXTS (unsigned __int8 *buffer,
        !           186:                                           TC_LARGEST_COMPILER_UINT length,
        !           187:                                           const UINT64_STRUCT *startDataUnitNo,
        !           188:                                           unsigned int startCipherBlockNo,
        !           189:                                           unsigned __int8 *ks,
        !           190:                                           unsigned __int8 *ks2,
        !           191:                                           int cipher)
        !           192: {
        !           193:        unsigned __int8 finalCarry;
        !           194:        unsigned __int8 whiteningValues [ENCRYPTION_DATA_UNIT_SIZE];
        !           195:        unsigned __int8 whiteningValue [BYTES_PER_XTS_BLOCK];
        !           196:        unsigned __int8 byteBufUnitNo [BYTES_PER_XTS_BLOCK];
        !           197:        unsigned __int64 *whiteningValuesPtr64 = (unsigned __int64 *) whiteningValues;
        !           198:        unsigned __int64 *whiteningValuePtr64 = (unsigned __int64 *) whiteningValue;
        !           199:        unsigned __int64 *bufPtr = (unsigned __int64 *) buffer;
        !           200:        unsigned int startBlock = startCipherBlockNo, endBlock, block;
        !           201:        unsigned __int64 *const finalInt64WhiteningValuesPtr = whiteningValuesPtr64 + sizeof (whiteningValues) / sizeof (*whiteningValuesPtr64) - 1;
        !           202:        TC_LARGEST_COMPILER_UINT blockCount, dataUnitNo;
        !           203:        
        !           204:        // Convert the 64-bit data unit number into a little-endian 16-byte array. 
        !           205:        // Note that as we are converting a 64-bit number into a 16-byte array we can always zero the last 8 bytes.
        !           206:        dataUnitNo = startDataUnitNo->Value;
        !           207:        *((unsigned __int64 *) byteBufUnitNo) = LE64 (dataUnitNo);
        !           208:        *((unsigned __int64 *) byteBufUnitNo + 1) = 0;
        !           209: 
        !           210:        if (length % BYTES_PER_XTS_BLOCK)
        !           211:                TC_THROW_FATAL_EXCEPTION;
        !           212: 
        !           213:        blockCount = length / BYTES_PER_XTS_BLOCK;
        !           214: 
        !           215:        // Process all blocks in the buffer
        !           216:        // When length > ENCRYPTION_DATA_UNIT_SIZE, this can be parallelized (one data unit per core)
        !           217:        while (blockCount > 0)
        !           218:        {
        !           219:                if (blockCount < BLOCKS_PER_XTS_DATA_UNIT)
        !           220:                        endBlock = startBlock + (unsigned int) blockCount;
        !           221:                else
        !           222:                        endBlock = BLOCKS_PER_XTS_DATA_UNIT;
        !           223: 
        !           224:                whiteningValuesPtr64 = finalInt64WhiteningValuesPtr;
        !           225:                whiteningValuePtr64 = (unsigned __int64 *) whiteningValue;
        !           226: 
        !           227:                // Encrypt the data unit number using the secondary key (in order to generate the first 
        !           228:                // whitening value for this data unit)
        !           229:                *whiteningValuePtr64 = *((unsigned __int64 *) byteBufUnitNo);
        !           230:                *(whiteningValuePtr64 + 1) = 0;
        !           231:                EncipherBlock (cipher, whiteningValue, ks2);
        !           232: 
        !           233:                // Generate subsequent whitening values for blocks in this data unit. Note that all generated 128-bit
        !           234:                // whitening values are stored in memory as a sequence of 64-bit integers in reverse order.
        !           235:                for (block = 0; block < endBlock; block++)
        !           236:                {
        !           237:                        if (block >= startBlock)
        !           238:                        {
        !           239:                                *whiteningValuesPtr64-- = *whiteningValuePtr64++;
        !           240:                                *whiteningValuesPtr64-- = *whiteningValuePtr64;
        !           241:                        }
        !           242:                        else
        !           243:                                whiteningValuePtr64++;
        !           244: 
        !           245:                        // Derive the next whitening value
        !           246: 
        !           247: #if BYTE_ORDER == LITTLE_ENDIAN
        !           248: 
        !           249:                        // Little-endian platforms (Intel, AMD, etc.)
        !           250: 
        !           251:                        finalCarry = 
        !           252:                                (*whiteningValuePtr64 & 0x8000000000000000) ?
        !           253:                                135 : 0;
        !           254: 
        !           255:                        *whiteningValuePtr64-- <<= 1;
        !           256: 
        !           257:                        if (*whiteningValuePtr64 & 0x8000000000000000)
        !           258:                                *(whiteningValuePtr64 + 1) |= 1;        
        !           259: 
        !           260:                        *whiteningValuePtr64 <<= 1;
        !           261: 
        !           262: #else
        !           263:                        // Big-endian platforms (PowerPC, Motorola, etc.)
        !           264: 
        !           265:                        finalCarry = 
        !           266:                                (*whiteningValuePtr64 & 0x80) ?
        !           267:                                135 : 0;
        !           268: 
        !           269:                        *whiteningValuePtr64 = LE64 (LE64 (*whiteningValuePtr64) << 1);
        !           270: 
        !           271:                        whiteningValuePtr64--;
        !           272: 
        !           273:                        if (*whiteningValuePtr64 & 0x80)
        !           274:                                *(whiteningValuePtr64 + 1) |= 0x0100000000000000;       
        !           275: 
        !           276:                        *whiteningValuePtr64 = LE64 (LE64 (*whiteningValuePtr64) << 1);
        !           277: #endif
        !           278: 
        !           279:                        whiteningValue[0] ^= finalCarry;
        !           280:                }
        !           281: 
        !           282:                whiteningValuesPtr64 = finalInt64WhiteningValuesPtr;
        !           283: 
        !           284:                // Decrypt blocks in this data unit
        !           285:                // TO DO: This should be parallelized (one block per core)
        !           286:                for (block = startBlock; block < endBlock; block++)
        !           287:                {
        !           288:                        *bufPtr++ ^= *whiteningValuesPtr64--;
        !           289:                        *bufPtr-- ^= *whiteningValuesPtr64++;
        !           290: 
        !           291:                        DecipherBlock (cipher, bufPtr, ks);
        !           292: 
        !           293:                        *bufPtr++ ^= *whiteningValuesPtr64--;
        !           294:                        *bufPtr++ ^= *whiteningValuesPtr64--;
        !           295: 
        !           296:                        blockCount--;
        !           297:                }
        !           298: 
        !           299:                startBlock = 0;
        !           300: 
        !           301:                dataUnitNo++;
        !           302: 
        !           303:                *((unsigned __int64 *) byteBufUnitNo) = LE64 (dataUnitNo);
        !           304:        }
        !           305: 
        !           306:        FAST_ERASE64 (whiteningValue, sizeof(whiteningValue));
        !           307:        FAST_ERASE64 (whiteningValues, sizeof(whiteningValues));
        !           308: }
        !           309: 
        !           310: 
        !           311: #if 0  // The following function is currently unused but may be useful in future
        !           312: 
        !           313: // Generates XTS whitening values. Use this function if you need to generate whitening values for more than
        !           314: // one data unit in one pass (the value 'length' may be greater than the data unit size). 'buffer' must point
        !           315: // to the LAST 8 bytes of the buffer for the whitening values. Note that the generated 128-bit whitening values
        !           316: // are stored in memory as a sequence of 64-bit integers in reverse order. For descriptions of the input
        !           317: // parameters, see EncryptBufferXTS().
        !           318: static void GenerateWhiteningValues (unsigned __int64 *bufPtr64,
        !           319:                                                        TC_LARGEST_COMPILER_UINT length,
        !           320:                                                        const UINT64_STRUCT *startDataUnitNo,
        !           321:                                                        unsigned int startBlock,
        !           322:                                                        unsigned __int8 *ks2,
        !           323:                                                        int cipher)
        !           324: {
        !           325:        unsigned int block;
        !           326:        unsigned int endBlock;
        !           327:        unsigned __int8 byteBufUnitNo [BYTES_PER_XTS_BLOCK];
        !           328:        unsigned __int8 whiteningValue [BYTES_PER_XTS_BLOCK];
        !           329:        unsigned __int64 *whiteningValuePtr64 = (unsigned __int64 *) whiteningValue;
        !           330:        unsigned __int8 finalCarry;
        !           331:        unsigned __int64 *const finalInt64WhiteningValuePtr = whiteningValuePtr64 + sizeof (whiteningValue) / sizeof (*whiteningValuePtr64) - 1;
        !           332:        TC_LARGEST_COMPILER_UINT blockCount, dataUnitNo;
        !           333: 
        !           334:        dataUnitNo = startDataUnitNo->Value;
        !           335: 
        !           336:        blockCount = length / BYTES_PER_XTS_BLOCK;
        !           337: 
        !           338:        // Convert the 64-bit data unit number into a little-endian 16-byte array. 
        !           339:        // Note that as we are converting a 64-bit number into a 16-byte array we can always zero the last 8 bytes.
        !           340:        *((unsigned __int64 *) byteBufUnitNo) = LE64 (dataUnitNo);
        !           341:        *((unsigned __int64 *) byteBufUnitNo + 1) = 0;
        !           342: 
        !           343:        // Generate the whitening values. 
        !           344:        // When length > ENCRYPTION_DATA_UNIT_SIZE, this can be parallelized (one data unit per core)
        !           345:        while (blockCount > 0)
        !           346:        {
        !           347:                if (blockCount < BLOCKS_PER_XTS_DATA_UNIT)
        !           348:                        endBlock = startBlock + (unsigned int) blockCount;
        !           349:                else
        !           350:                        endBlock = BLOCKS_PER_XTS_DATA_UNIT;
        !           351: 
        !           352:                // Encrypt the data unit number using the secondary key (in order to generate the first 
        !           353:                // whitening value for this data unit)
        !           354:                memcpy (whiteningValue, byteBufUnitNo, BYTES_PER_XTS_BLOCK);
        !           355:                EncipherBlock (cipher, whiteningValue, ks2);
        !           356: 
        !           357:                // Process all blocks in this data unit
        !           358:                for (block = 0; block < endBlock; block++)
        !           359:                {
        !           360:                        if (block >= startBlock)
        !           361:                        {
        !           362:                                whiteningValuePtr64 = (unsigned __int64 *) whiteningValue;
        !           363: 
        !           364:                                *bufPtr64-- = *whiteningValuePtr64++;
        !           365:                                *bufPtr64-- = *whiteningValuePtr64;
        !           366: 
        !           367:                                blockCount--;
        !           368:                        }
        !           369: 
        !           370:                        // Derive the next whitening value
        !           371: 
        !           372:                        whiteningValuePtr64 = finalInt64WhiteningValuePtr;
        !           373: 
        !           374: #if BYTE_ORDER == LITTLE_ENDIAN
        !           375: 
        !           376:                        // Little-endian platforms (Intel, AMD, etc.)
        !           377: 
        !           378:                        finalCarry = 
        !           379:                                (*whiteningValuePtr64 & 0x8000000000000000) ?
        !           380:                                135 : 0;
        !           381: 
        !           382:                        *whiteningValuePtr64-- <<= 1;
        !           383: 
        !           384:                        if (*whiteningValuePtr64 & 0x8000000000000000)
        !           385:                                *(whiteningValuePtr64 + 1) |= 1;        
        !           386: 
        !           387:                        *whiteningValuePtr64 <<= 1;
        !           388: 
        !           389: #else
        !           390:                        // Big-endian platforms (PowerPC, Motorola, etc.)
        !           391: 
        !           392:                        finalCarry = 
        !           393:                                (*whiteningValuePtr64 & 0x80) ?
        !           394:                                135 : 0;
        !           395: 
        !           396:                        *whiteningValuePtr64 = LE64 (LE64 (*whiteningValuePtr64) << 1);
        !           397: 
        !           398:                        whiteningValuePtr64--;
        !           399: 
        !           400:                        if (*whiteningValuePtr64 & 0x80)
        !           401:                                *(whiteningValuePtr64 + 1) |= 0x0100000000000000;       
        !           402: 
        !           403:                        *whiteningValuePtr64 = LE64 (LE64 (*whiteningValuePtr64) << 1);
        !           404: #endif
        !           405: 
        !           406:                        whiteningValue[0] ^= finalCarry;
        !           407:                }
        !           408: 
        !           409:                startBlock = 0;
        !           410: 
        !           411:                dataUnitNo++;
        !           412: 
        !           413:                // Convert the 64-bit data unit number into a little-endian 16-byte array. 
        !           414:                *((unsigned __int64 *) byteBufUnitNo) = LE64 (dataUnitNo);
        !           415:        }
        !           416: 
        !           417:        FAST_ERASE64 (whiteningValue, sizeof(whiteningValue));
        !           418: }
        !           419: #endif // #if 0
        !           420: 
        !           421: 
        !           422: #else  // XTS_LOW_RESOURCE_VERSION
        !           423: 
        !           424: 
        !           425: #if BYTE_ORDER == BIG_ENDIAN
        !           426: #error XTS_LOW_RESOURCE_VERSION is not compatible with big-endian platforms
        !           427: #endif 
        !           428: 
        !           429: 
        !           430: // Increases a 64-bit value by one in a way compatible with non-64-bit environments/platforms
        !           431: static void IncUint64Struct (UINT64_STRUCT *uint64Struct)
        !           432: {
        !           433: #ifdef TC_NO_COMPILER_INT64
        !           434:        if (!++uint64Struct->LowPart)
        !           435:        {
        !           436:                uint64Struct->HighPart++;
        !           437:        }
        !           438: #else
        !           439:        uint64Struct->Value++;
        !           440: #endif
        !           441: }
        !           442: 
        !           443: 
        !           444: // Converts a 64-bit unsigned integer (passed as two 32-bit integers for compatibility with non-64-bit
        !           445: // environments/platforms) into a little-endian 16-byte array.
        !           446: static void Uint64ToLE16ByteArray (unsigned __int8 *byteBuf, unsigned __int32 highInt32, unsigned __int32 lowInt32)
        !           447: {
        !           448:        unsigned __int32 *bufPtr32 = (unsigned __int32 *) byteBuf;
        !           449: 
        !           450:        *bufPtr32++ = lowInt32;
        !           451:        *bufPtr32++ = highInt32;
        !           452: 
        !           453:        // We're converting a 64-bit number into a little-endian 16-byte array so we can zero the last 8 bytes
        !           454:        *bufPtr32++ = 0;
        !           455:        *bufPtr32 = 0;
        !           456: }
        !           457: 
        !           458: 
        !           459: // Generates and XORs XTS whitening values into blocks in the buffer.
        !           460: // For descriptions of the input parameters, see EncryptBufferXTS().
        !           461: static void WhiteningPass (unsigned __int8 *buffer,
        !           462:                                                        TC_LARGEST_COMPILER_UINT length,
        !           463:                                                        const UINT64_STRUCT *startDataUnitNo,
        !           464:                                                        unsigned int startBlock,
        !           465:                                                        unsigned __int8 *ks2,
        !           466:                                                        int cipher)
        !           467: {
        !           468:        TC_LARGEST_COMPILER_UINT blockCount;
        !           469:        UINT64_STRUCT dataUnitNo;
        !           470:        unsigned int block;
        !           471:        unsigned int endBlock;
        !           472:        unsigned __int8 byteBufUnitNo [BYTES_PER_XTS_BLOCK];
        !           473:        unsigned __int8 whiteningValue [BYTES_PER_XTS_BLOCK];
        !           474:        unsigned __int32 *bufPtr32 = (unsigned __int32 *) buffer;
        !           475:        unsigned __int32 *whiteningValuePtr32 = (unsigned __int32 *) whiteningValue;
        !           476:        unsigned __int8 finalCarry;
        !           477:        unsigned __int32 *const finalDwordWhiteningValuePtr = whiteningValuePtr32 + sizeof (whiteningValue) / sizeof (*whiteningValuePtr32) - 1;
        !           478: 
        !           479:        // Store the 64-bit data unit number in a way compatible with non-64-bit environments/platforms
        !           480:        dataUnitNo.HighPart = startDataUnitNo->HighPart;
        !           481:        dataUnitNo.LowPart = startDataUnitNo->LowPart;
        !           482: 
        !           483:        blockCount = length / BYTES_PER_XTS_BLOCK;
        !           484: 
        !           485:        // Convert the 64-bit data unit number into a little-endian 16-byte array. 
        !           486:        // (Passed as two 32-bit integers for compatibility with non-64-bit environments/platforms.)
        !           487:        Uint64ToLE16ByteArray (byteBufUnitNo, dataUnitNo.HighPart, dataUnitNo.LowPart);
        !           488: 
        !           489:        // Generate whitening values for all blocks in the buffer
        !           490:        while (blockCount > 0)
        !           491:        {
        !           492:                if (blockCount < BLOCKS_PER_XTS_DATA_UNIT)
        !           493:                        endBlock = startBlock + (unsigned int) blockCount;
        !           494:                else
        !           495:                        endBlock = BLOCKS_PER_XTS_DATA_UNIT;
        !           496: 
        !           497:                // Encrypt the data unit number using the secondary key (in order to generate the first 
        !           498:                // whitening value for this data unit)
        !           499:                memcpy (whiteningValue, byteBufUnitNo, BYTES_PER_XTS_BLOCK);
        !           500:                EncipherBlock (cipher, whiteningValue, ks2);
        !           501: 
        !           502:                // Generate subsequent whitening values and XOR each whitening value into corresponding
        !           503:                // ciphertext/plaintext block
        !           504: 
        !           505:                for (block = 0; block < endBlock; block++)
        !           506:                {
        !           507:                        if (block >= startBlock)
        !           508:                        {
        !           509:                                whiteningValuePtr32 = (unsigned __int32 *) whiteningValue;
        !           510: 
        !           511:                                // XOR the whitening value into this ciphertext/plaintext block
        !           512:                                *bufPtr32++ ^= *whiteningValuePtr32++;
        !           513:                                *bufPtr32++ ^= *whiteningValuePtr32++;
        !           514:                                *bufPtr32++ ^= *whiteningValuePtr32++;
        !           515:                                *bufPtr32++ ^= *whiteningValuePtr32;
        !           516: 
        !           517:                                blockCount--;
        !           518:                        }
        !           519: 
        !           520:                        // Derive the next whitening value
        !           521: 
        !           522:                        finalCarry = 0;
        !           523: 
        !           524:                        for (whiteningValuePtr32 = finalDwordWhiteningValuePtr;
        !           525:                                whiteningValuePtr32 >= (unsigned __int32 *) whiteningValue;
        !           526:                                whiteningValuePtr32--)
        !           527:                        {
        !           528:                                if (*whiteningValuePtr32 & 0x80000000)  // If the following shift results in a carry
        !           529:                                {
        !           530:                                        if (whiteningValuePtr32 != finalDwordWhiteningValuePtr) // If not processing the highest double word
        !           531:                                        {
        !           532:                                                // A regular carry
        !           533:                                                *(whiteningValuePtr32 + 1) |= 1;
        !           534:                                        }
        !           535:                                        else 
        !           536:                                        {
        !           537:                                                // The highest byte shift will result in a carry
        !           538:                                                finalCarry = 135;
        !           539:                                        }
        !           540:                                }
        !           541: 
        !           542:                                *whiteningValuePtr32 <<= 1;
        !           543:                        }
        !           544: 
        !           545:                        whiteningValue[0] ^= finalCarry;
        !           546:                }
        !           547: 
        !           548:                startBlock = 0;
        !           549: 
        !           550:                // Increase the data unit number by one
        !           551:                IncUint64Struct (&dataUnitNo);
        !           552: 
        !           553:                // Convert the 64-bit data unit number into a little-endian 16-byte array. 
        !           554:                Uint64ToLE16ByteArray (byteBufUnitNo, dataUnitNo.HighPart, dataUnitNo.LowPart);
        !           555:        }
        !           556: 
        !           557:        FAST_ERASE64 (whiteningValue, sizeof(whiteningValue));
        !           558: }
        !           559: 
        !           560: 
        !           561: // length: number of bytes to encrypt; may be larger than one data unit and must be divisible by the cipher block size
        !           562: // ks: the primary key schedule
        !           563: // ks2: the secondary key schedule
        !           564: // dataUnitNo: The sequential number of the data unit with which the buffer starts.
        !           565: // startCipherBlockNo: The sequential number of the first plaintext block to encrypt inside the data unit dataUnitNo.
        !           566: //                     When encrypting the data unit from its first block, startCipherBlockNo is 0. 
        !           567: //                     The startCipherBlockNo value applies only to the first data unit in the buffer; each successive
        !           568: //                     data unit is encrypted from its first block. The start of the buffer does not have to be
        !           569: //                     aligned with the start of a data unit. If it is aligned, startCipherBlockNo must be 0; if it
        !           570: //                     is not aligned, startCipherBlockNo must reflect the misalignment accordingly.
        !           571: void EncryptBufferXTS (unsigned __int8 *buffer,
        !           572:                                           TC_LARGEST_COMPILER_UINT length,
        !           573:                                           const UINT64_STRUCT *dataUnitNo,
        !           574:                                           unsigned int startCipherBlockNo,
        !           575:                                           unsigned __int8 *ks,
        !           576:                                           unsigned __int8 *ks2,
        !           577:                                           int cipher)
        !           578: {
        !           579:        TC_LARGEST_COMPILER_UINT blockCount;
        !           580:        unsigned __int8 *bufPtr = buffer;
        !           581: 
        !           582:        if (length % BYTES_PER_XTS_BLOCK)
        !           583:                TC_THROW_FATAL_EXCEPTION;
        !           584: 
        !           585:        // Pre-whitening (all plaintext blocks in the buffer)
        !           586:        WhiteningPass (buffer, length, dataUnitNo, startCipherBlockNo, ks2, cipher);
        !           587: 
        !           588:        // Encrypt all plaintext blocks in the buffer
        !           589:        for (blockCount = 0; blockCount < length / BYTES_PER_XTS_BLOCK; blockCount++)
        !           590:        {
        !           591:                EncipherBlock (cipher, bufPtr, ks);
        !           592:                bufPtr += BYTES_PER_XTS_BLOCK;
        !           593:        }
        !           594: 
        !           595:        // Post-whitening (all ciphertext blocks in the buffer)
        !           596:        WhiteningPass (buffer, length, dataUnitNo, startCipherBlockNo, ks2, cipher);
        !           597: }
        !           598: 
        !           599: 
        !           600: // For descriptions of the input parameters, see EncryptBufferXTS().
        !           601: void DecryptBufferXTS (unsigned __int8 *buffer,
        !           602:                                           TC_LARGEST_COMPILER_UINT length,
        !           603:                                           const UINT64_STRUCT *dataUnitNo,
        !           604:                                           unsigned int startCipherBlockNo,
        !           605:                                           unsigned __int8 *ks,
        !           606:                                           unsigned __int8 *ks2,
        !           607:                                           int cipher)
        !           608: {
        !           609:        TC_LARGEST_COMPILER_UINT blockCount;
        !           610:        unsigned __int8 *bufPtr = buffer;
        !           611: 
        !           612:        if (length % BYTES_PER_XTS_BLOCK)
        !           613:                TC_THROW_FATAL_EXCEPTION;
        !           614: 
        !           615:        WhiteningPass (buffer, length, dataUnitNo, startCipherBlockNo, ks2, cipher);
        !           616: 
        !           617:        for (blockCount = 0; blockCount < length / BYTES_PER_XTS_BLOCK; blockCount++)
        !           618:        {
        !           619:                DecipherBlock (cipher, bufPtr, ks);
        !           620:                bufPtr += BYTES_PER_XTS_BLOCK;
        !           621:        }
        !           622: 
        !           623:        WhiteningPass (buffer, length, dataUnitNo, startCipherBlockNo, ks2, cipher);
        !           624: }
        !           625: 
        !           626: #endif // XTS_LOW_RESOURCE_VERSION

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