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AESENC256KL

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Henk-Jan Lebbink edited this page Jun 4, 2026 · 1 revision

AESENC256KL — Perform 14 Rounds of AES Encryption Flow with Key Locker Using 256-Bit Key

Opcode/ Instruction Op/ En 64/32-bit Mode CPUID Feature Flag Description
F3 0F 38 DE !(11):rrr:bbb AESENC256KL xmm, m512 A V/V AESKLE Encrypt xmm using 256-bit AES key indicated by handle at m512 and store result in xmm.

Instruction Operand Encoding

Op/En Tuple Operand 1 Operand 2 Operand 3 Operand 4
A N/A ModRM:reg (r, w) ModRM:r/m (r) N/A N/A

Description

1 The AESENC256KL instruction performs 14 rounds of AES to encrypt the first operand using the 256-bit key indicated 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).

Operation

AESENC256KL

Handle ← UnalignedLoad of 512 bit (SRC);
                            // Load is not guaranteed to be atomic.
Illegal Handle = (
                HandleReservedBitSet (Handle) ||
                (Handle[0] AND (CPL > 0)) ||
                Handle [1] ||
                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 ← AES256Encrypt (DEST, UnwrappedKey) ;
                RFLAGS.ZF ← 0;
        FI;
FI;
RFLAGS.OF, SF, AF, PF, CF ← 0;

Flags Affected

ZF 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 Equivalent

AESENC256KL unsigned char _mm_aesenc256kl_u8(__m128i* odata, __m128i idata, const void* h);
1. 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.

Exceptions (All Operating Modes)

#UD If the LOCK prefix is used. If CPUID.07H.00H:ECX.KEY_LOCKER[23] = 0. If CR4.KL = 0. If CPUID.19H:EBX.AESKLE[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.

Source: Intel® 64 and IA-32 Architectures Software Developer's Manual, Combined Volumes (Order Number 325462-091US, March 2026)
Generated: 7-6-2026

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