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SM4EKEY

SM4 key updates.

The SM4EKEY instruction reads four rounds of 32-bit input key values from each 128-bit segment of the first source vector, along with four rounds of 32-bit constants from the corresponding 128-bit segment of the second source vector. The four rounds of output key values are derived in accordance with the SM4 standard, and placed in the corresponding segments of the destination vector. This instruction is unpredicated.

ID_AA64ZFR0_EL1.SM4 indicates whether this instruction is implemented.

313029282726252423222120191817161514131211109876543210
01000101001Zm111100ZnZd
size<1>size<0>

SM4EKEY <Zd>.S, <Zn>.S, <Zm>.S

if !HaveSVE2SM4() then UNDEFINED;
integer n = UInt(Zn);
integer m = UInt(Zm);
integer d = UInt(Zd);

Assembler Symbols

<Zd>

Is the name of the destination scalable vector register, encoded in the "Zd" field.

<Zn>

Is the name of the first source scalable vector register, encoded in the "Zn" field.

<Zm>

Is the name of the second source scalable vector register, encoded in the "Zm" field.

Operation

CheckSVEEnabled();
integer segments = VL DIV 128;
bits(VL) operand1 = Z[n];
bits(VL) operand2 = Z[m];
bits(VL) result;

for s = 0 to segments-1
    bits(128) source = Elem[operand2, s, 128];
    bits(32) intval;
    bits(8) sboxout;
    bits(32) const;
    bits(128) roundresult = Elem[operand1, s, 128];

    for index = 0 to 3
        const = Elem[source, index, 32];
        intval = roundresult<127:96> EOR roundresult<95:64> EOR roundresult<63:32> EOR const;
        for i = 0 to 3
            Elem[intval, i, 8] = Sbox(Elem[intval, i, 8]);

        intval = intval EOR ROL(intval, 13) EOR ROL(intval, 23);
        intval = intval EOR roundresult<31:0>;

        roundresult<31:0> = roundresult<63:32>;
        roundresult<63:32> = roundresult<95:64>;
        roundresult<95:64> = roundresult<127:96>;
        roundresult<127:96> = intval;

    Elem[result, s, 128] = roundresult;

Z[d] = result;

Operational information

If PSTATE.DIT is 1:

  • The execution time of this instruction is independent of:
    • The values of the data supplied in any of its registers.
    • The values of the NZCV flags.
  • The response of this instruction to asynchronous exceptions does not vary based on:
    • The values of the data supplied in any of its registers.
    • The values of the NZCV flags.