image/svg+xmlAESDEC256KL—Perform 14 Rounds of AES Decryption Flow with Key Locker Using 256-Bit KeyInstruction Operand EncodingDescriptionThe AESDEC256KL1 instruction performs 14 rounds of AES to decrypt the first operand using the 256-bit key indi-cated by the handle from the second operand. It stores the result in the first operand if the operation succeeds (e.g., does not run into a handle violation failure).OperationAESDEC256KL Handle := UnalignedLoad of 512 bit (SRC); // Load is not guaranteed to be atomic.Illegal Handle = (HandleReservedBitSet (Handle) ||(Handle[0] AND (CPL > 0)) ||Handle [2] ||HandleKeyType (Handle) != HANDLE_KEY_TYPE_AES256);IF (Illegal Handle) THEN RFLAGS.ZF := 1;ELSE (UnwrappedKey, Authentic) := UnwrapKeyAndAuthenticate512 (Handle[511:0], IWKey);IF (Authentic == 0) THEN RFLAGS.ZF := 1;ELSE DEST := AES256Decrypt (DEST, UnwrappedKey) ;RFLAGS.ZF := 0;FI;FI;RFLAGS.OF, SF, AF, PF, CF := 0;Flags AffectedZF is set to 0 if the operation succeeded and set to 1 if the operation failed due to a handle violation. The other arithmetic flags (OF, SF, AF, PF, CF) are cleared to 0.Intel C/C++ Compiler Intrinsic EquivalentAESDEC256KLunsigned char _mm_aesdec256kl_u8(__m128i* odata, __m128i idata, const void* h);Opcode/InstructionOp/ En64/32-bit ModeCPUID Feature FlagDescriptionF3 0F 38 DF !(11):rrr:bbb AESDEC256KL xmm, m512AV/VAESKLEDecrypt xmm using 256-bit AES key indicated by han-dle at m512 and store result in xmm.Op/EnTupleOperand 1Operand 2Operand 3Operand 4ANAModRM:reg (r, w)ModRM:r/m (r)NANA1.Further details on Key Locker and usage of this instruction can be found here:https://software.intel.com/content/www/us/en/develop/download/intel-key-locker-specification.html.

image/svg+xmlExceptions (All Operating Modes)#UD If the LOCK prefix is used.If CPUID.07H:ECX.KL [bit 23] = 0.If CR4.KL = 0.If CPUID.19H:EBX.AESKLE [bit 0] = 0.If CR0.EM = 1.If CR4.OSFXSR = 0.#NM If CR0.TS = 1.#PF If a page fault occurs.#GP(0) If a memory operand effective address is outside the CS, DS, ES, FS, or GS segment limit.If the DS, ES, FS, or GS register is used to access memory and it contains a NULL segment selector.If the memory address is in a non-canonical form.#SS(0) If a memory operand effective address is outside the SS segment limit.If a memory address referencing the SS segment is in a non-canonical form.

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