Zig 0.17.0-dev (Split by item)

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generateSbox

soft.generateSbox

fn generateSbox(invert: bool) [256]u8

File

lib/std/crypto/aes/soft.zig:738

Code

fn generateSbox(invert: bool) [256]u8 {
    @setEvalBranchQuota(10000);

    var sbox: [256]u8 = undefined;

    var p: u8 = 1;
    var q: u8 = 1;
    for (sbox) |_| {
        p = mul(p, 3);
        q = mul(q, 0xf6); // divide by 3

        var value: u8 = q ^ 0x63;
        value ^= math.rotl(u8, q, 1);
        value ^= math.rotl(u8, q, 2);
        value ^= math.rotl(u8, q, 3);
        value ^= math.rotl(u8, q, 4);

        if (invert) {
            sbox[value] = p;
        } else {
            sbox[p] = value;
        }
    }

    if (invert) {
        sbox[0x63] = 0x00;
    } else {
        sbox[0x00] = 0x63;
    }

    return sbox;
}