//

// xtsaes_pattern.c

//

// Copyright (c) Microsoft Corporation. Licensed under the MIT license.

//

VOID

SYMCRYPT_CALL

SYMCRYPT_XtsAesXxx(

    _In_                                    PCSYMCRYPT_XTS_AES_EXPANDED_KEY pExpandedKey,

                                            SIZE_T                          cbDataUnit,

    _In_reads_( SYMCRYPT_AES_BLOCK_SIZE )   PCBYTE                          pbTweak,

    _In_reads_( cbData )                    PCBYTE                          pbSrc,

    _Out_writes_( cbData )                  PBYTE                           pbDst,

                                            SIZE_T                          cbData,

                                            BOOLEAN                         bOverflow )

{

    SYMCRYPT_XTS_AES_LOCALSCRATCH_DEFN;

    // SYMCRYPT_ALIGN BYTE localScratch[N_PARALLEL_TWEAKS * SYMCRYPT_AES_BLOCK_SIZE];

    // or

    // /* Defining localScratch as a buffer of __m128is ensures there is required 16B alignment on x86 */

    // __m128i localScratch[ N_PARALLEL_TWEAKS + 16 ];

    // Note that the extra 16 __m128i space is used for internal scratch space for SymCryptXtsAesEncryptDataUnitXmm

    // This allows modified tweak generation to be performed in scalar registers in parallel with AES in Xmm register

    // which reduces register pressure and increases throughput

    PBYTE   tweakBuf    = (PBYTE) &localScratch[0];

    SIZE_T  i, tweakBytes;

    UINT64  tweakLow64  = SYMCRYPT_LOAD_LSBFIRST64(pbTweak);

    UINT64  tweakHigh64 = SYMCRYPT_LOAD_LSBFIRST64(pbTweak+8);

    UINT64  previousTweakLow64;

    SYMCRYPT_ASSERT( cbData % cbDataUnit == 0 );

    while( cbData >= cbDataUnit )

    {

        //

        // We encrypt the tweaks of many data units in parallel for best performance.

        // In the first loop we build the tweaks and decrement cbData.

        // In the second loop we use up all the tweaks, and update the pointers.

        // Both loops are executed the same number of times.

        //

        tweakBytes = 0;

        previousTweakLow64 = tweakLow64;

        do // do-while because we know we are going to go through at least once.

        {

            SYMCRYPT_STORE_LSBFIRST64(&tweakBuf[tweakBytes    ], tweakLow64);

            SYMCRYPT_STORE_LSBFIRST64(&tweakBuf[tweakBytes + 8], tweakHigh64);

            tweakLow64++;

            cbData -= cbDataUnit;

            tweakBytes += SYMCRYPT_AES_BLOCK_SIZE;

        } while( cbData >= cbDataUnit && tweakBytes < SYMCRYPT_AES_BLOCK_SIZE * N_PARALLEL_TWEAKS );

        if( bOverflow && previousTweakLow64 > tweakLow64 )

        {

            // Very rare fix-up of tweaks if tweakLow64 overflowed, and should have incremented tweakHigh64

            // bOverflow=FALSE allows backwards compatibility with old API which wrapped around at 64-bits

            SYMCRYPT_ASSERT( tweakLow64 < N_PARALLEL_TWEAKS );

            // Increment tweakHigh64 and store new value in high half of the previous tweakLow64 tweaks

            tweakHigh64++;

            for( i=0; i<tweakLow64; i++)

            {

                SYMCRYPT_STORE_LSBFIRST64(&tweakBuf[tweakBytes - (16*i) - 8], tweakHigh64);

            }

        }

        SYMCRYPT_AesEcbEncryptXxx( &pExpandedKey->key2, &tweakBuf[0], &tweakBuf[0], tweakBytes );

        i = 0;

        while( i < tweakBytes )

        {

            SYMCRYPT_XTSAESDATAUNIT_INVOKE;

            // SymCryptXtsAesXxcryptDataUnitXxx( &pExpandedKey->key1, &tweakBuf[i], pbSrc, pbDst, cbDataUnit );

            // or

            // SymCryptXtsAesXxcryptDataUnitXxx( &pExpandedKey->key1, &tweakBuf[i], (PBYTE) &localScratch[N_PARALLEL_TWEAKS], pbSrc, pbDst, cbDataUnit );

            // Note that the scratch space being provided to the DataUnit function is an offset into the localScratch buffer

            pbSrc += cbDataUnit;

            pbDst += cbDataUnit;

            i += SYMCRYPT_AES_BLOCK_SIZE;

        }

    }

    SymCryptWipeKnownSize( localScratch, sizeof( localScratch ) );

}

Unexecuted instantiation: SymCryptXtsAesEncryptInternalC

Unexecuted instantiation: SymCryptXtsAesDecryptInternalC

Unexecuted instantiation: SymCryptXtsAesEncryptInternalAsm

Unexecuted instantiation: SymCryptXtsAesDecryptInternalAsm

Unexecuted instantiation: SymCryptXtsAesEncryptInternalXmm

Unexecuted instantiation: SymCryptXtsAesDecryptInternalXmm

Unexecuted instantiation: SymCryptXtsAesEncryptInternalYmm

Unexecuted instantiation: SymCryptXtsAesDecryptInternalYmm