Does AES64ESM use floating-point or vector registers?
No. These scalar crypto extension instructions use integer X registers.
AES64ESM
RISC-V AES64ESM Instruction Details
Instruction ManualR-typeAES middle-round encrypt (RV64): two 64-bit source registers represent the full state and apply ShiftRows/SubBytes/MixColumns
Instruction Syntax
aes64esm rd, rs1, rs2
Operand Breakdown
rd: receives one 64-bit half of the next AES state.
rs1 and rs2: together represent the complete 128-bit AES state; the official operation uses them as aes_rv64_shiftrows_fwd(rs2, rs1).
One execution produces one half only; the official paired sequence swaps rs1 and rs2 to produce the other half. This middle-round form applies MixColumns to two 32-bit words and does not imply a round-key XOR.
ZkneCrypto & Security
Instruction Behavior
aes64esm is an RV64 AES encrypt middle-round instruction in Zkne. It uses rs1 and rs2 as two 64-bit source registers representing the full 128-bit AES state, applies ShiftRows, SubBytes, and MixColumns, and writes half of the next-round output to rd. The full 128-bit output is normally produced by executing the official paired instruction with reversed source-register order; round-key XOR is not implicitly performed by this AES64 round instruction.
AES64ESM Decode And Execute Animation
Bounded teaching inputs follow the local official ISA formulas; this does not model a complete AES round, round-key XOR, or microarchitecture.
aes64esm
Execution Context
XLEN is fixed at 64; rs1 and rs2 jointly represent the complete 128-bit state. A destination that is not a source starts at 0; sources are read before writeback.
fixed funct7
source state
source state
fixed
destination
OP
31..25
0011011
24..20
rs2=x12
19..15
rs1=x11
14..12
000
11..7
rd=x10
6..0
0110011
Execution Data Path
rs1[63:0]
0x0011223344556677
rs2[63:0]
0x8899AABBCCDDEEFF
aes_rv64_shiftrows_fwd
0x4499EE3388DD2277
forward SubBytes
0x1BEE28C3C4C193F5
two aes_mixcolumn_fwd words
0xAE01A110C5A8545A
Current Step
Decode AES64 fixed OP fields
funct7=0011011, funct3=000, and OP=0110011; this encoding is RV64-only.
encoding: 0x36C58533
syntax: aes64esm a0(x10), a1(x11), a2(x12)
syntax: aes64esm a0(x10), a1(x11), a2(x12)
Architectural Result
a0(x10) = 0x0000000000000000
This animation shows only official ISA fields and architectural state, not a particular CPU pipeline, cache, or timing implementation.
Quick Understanding & Search Notes
AES64ESM is a Zkne scalar cryptography instruction for AES middle-round encrypt half-block.
RV64 instruction: rs1/rs2 together represent the full AES state, and the instruction produces half of the next-round output; compute the other half with reversed source-register order.
Scalar crypto instructions use integer X registers, and the official spec requires the relevant crypto instructions to be implemented with data-independent execution latency.
aes64* forms are defined only for RV64.
Common Usage Scenarios
Crypto & Security
Understand this scenario with real code like «aes64esm a0, a1, a2».
Data Protection
Understand this scenario with real code like «aes64esm a0, a1, a2».
Pre-Use Checklist
Syntax Check
- RV64 only; register operands select integer x0–x31, with no rs3. Verify availability of the Zkne or Zknd extension listed on this page.
- There is no assembly immediate; fixed encoding fields undergo no arithmetic-immediate sign extension.
Semantic Check
- aes64esm is an RV64 AES encrypt middle-round instruction in Zkne. It uses rs1 and rs2 as two 64-bit source registers representing the full 128-bit AES state, applies ShiftRows, SubBytes, and MixColumns, and writes half of the next-round output to rd. The full 128-bit output is normally produced by executing the official paired instruction with reversed source-register order; round-key XOR is not implicitly performed by this AES64 round instruction.
- Overlapping operands read source values before writeback; one source register has one value, x0 is always zero, and writes to x0 are discarded.
Pitfalls / Common Confusions
RV64 only; this AES64 form is not available on RV32.
rs1 and rs2 are the two 64-bit halves of the current AES state; do not describe rs2 as a fixed round-key operand.
AES64ESM includes MixColumns; AES64ES final-round form does not include MixColumns.
One execution produces only half of the 128-bit state output; compute the other half using the official reversed source-register order.
FAQ
Is AES64ESM a complete algorithm implementation?
No. It performs one architecturally defined AES half-state step; software still combines instructions and round keys in algorithm order.