aesd

AES Decrypt (A64)

AESD <Vd>.16B, <Vm>.16B

AES single round decryption (AArch64 NEON).

Pseudocode Operation

state ← Vd.B[0:15]
key ← Vm.B[0:15]
state ← InvSubBytes(state)
state ← InvShiftRows(state)
state ← InvMixColumns(state)
state ← state ⊕ key
Vd.B[0:15] ← state

Example

AESD v0.4s.16B, v2.4s.16B

Encoding

Binary Layout

01001110

31:24

00

23:22

101000010

21:13

1

12

10

11:10

Rn

9:5

Rd

4:0

 

Format Crypto

Opcode 0x4E285800

Extension Crypto

Operands

• Vd
  State
• Vm
  Key

Related

Other forms of aesd

• aesd AES Decrypt (A32)
• aesd AES Decrypt

More in Crypto

Reference

View in Arm A64 ISA Reference ↗ Arm A64 ISA

Instruction Forms

Encoding	Instruction		ISA		Bit pattern
0x4E285800	AESD <Vd>.16B, <Vn>.16B		A64		01001110 | 00 | 101000010 | 1 | 10 | Rn | Rd
0x4522E400	AESD <Zdn>.B, <Zdn>.B, <Zm>.B		A64		01000101 | 0 | 0 | 10001 | 0 | 11100 | 1 | Zm | Zdn

Description

AES single round decryption.

Operation

AArch64.CheckFPAdvSIMDEnabled();

bits(128) operand1 = V[d, 128];
bits(128) operand2 = V[n, 128];
bits(128) result;
result = operand1 EOR operand2;
result = AESInvSubBytes(AESInvShiftRows(result));
V[d, 128] = result;