aes_decrypt.rs

// rustc aes_decrypt.rs -o aes_decrypt
// ./aes_decrypt

#[cfg_attr(rustfmt, rustfmt_skip)]
static S: [u8; 16 * 16] = [
    0x63, 0x7c, 0x77, 0x7b, 0xf2, 0x6b, 0x6f, 0xc5, 0x30, 0x01, 0x67, 0x2b, 0xfe, 0xd7, 0xab, 0x76,
    0xca, 0x82, 0xc9, 0x7d, 0xfa, 0x59, 0x47, 0xf0, 0xad, 0xd4, 0xa2, 0xaf, 0x9c, 0xa4, 0x72, 0xc0,
    0xb7, 0xfd, 0x93, 0x26, 0x36, 0x3f, 0xf7, 0xcc, 0x34, 0xa5, 0xe5, 0xf1, 0x71, 0xd8, 0x31, 0x15,
    0x04, 0xc7, 0x23, 0xc3, 0x18, 0x96, 0x05, 0x9a, 0x07, 0x12, 0x80, 0xe2, 0xeb, 0x27, 0xb2, 0x75,
    0x09, 0x83, 0x2c, 0x1a, 0x1b, 0x6e, 0x5a, 0xa0, 0x52, 0x3b, 0xd6, 0xb3, 0x29, 0xe3, 0x2f, 0x84,
    0x53, 0xd1, 0x00, 0xed, 0x20, 0xfc, 0xb1, 0x5b, 0x6a, 0xcb, 0xbe, 0x39, 0x4a, 0x4c, 0x58, 0xcf,
    0xd0, 0xef, 0xaa, 0xfb, 0x43, 0x4d, 0x33, 0x85, 0x45, 0xf9, 0x02, 0x7f, 0x50, 0x3c, 0x9f, 0xa8,
    0x51, 0xa3, 0x40, 0x8f, 0x92, 0x9d, 0x38, 0xf5, 0xbc, 0xb6, 0xda, 0x21, 0x10, 0xff, 0xf3, 0xd2,
    0xcd, 0x0c, 0x13, 0xec, 0x5f, 0x97, 0x44, 0x17, 0xc4, 0xa7, 0x7e, 0x3d, 0x64, 0x5d, 0x19, 0x73,
    0x60, 0x81, 0x4f, 0xdc, 0x22, 0x2a, 0x90, 0x88, 0x46, 0xee, 0xb8, 0x14, 0xde, 0x5e, 0x0b, 0xdb,
    0xe0, 0x32, 0x3a, 0x0a, 0x49, 0x06, 0x24, 0x5c, 0xc2, 0xd3, 0xac, 0x62, 0x91, 0x95, 0xe4, 0x79,
    0xe7, 0xc8, 0x37, 0x6d, 0x8d, 0xd5, 0x4e, 0xa9, 0x6c, 0x56, 0xf4, 0xea, 0x65, 0x7a, 0xae, 0x08,
    0xba, 0x78, 0x25, 0x2e, 0x1c, 0xa6, 0xb4, 0xc6, 0xe8, 0xdd, 0x74, 0x1f, 0x4b, 0xbd, 0x8b, 0x8a,
    0x70, 0x3e, 0xb5, 0x66, 0x48, 0x03, 0xf6, 0x0e, 0x61, 0x35, 0x57, 0xb9, 0x86, 0xc1, 0x1d, 0x9e,
    0xe1, 0xf8, 0x98, 0x11, 0x69, 0xd9, 0x8e, 0x94, 0x9b, 0x1e, 0x87, 0xe9, 0xce, 0x55, 0x28, 0xdf,
    0x8c, 0xa1, 0x89, 0x0d, 0xbf, 0xe6, 0x42, 0x68, 0x41, 0x99, 0x2d, 0x0f, 0xb0, 0x54, 0xbb, 0x16
];

#[cfg_attr(rustfmt, rustfmt_skip)]
static SInv: [u8; 16 * 16] = [
    0x52, 0x09, 0x6a, 0xd5, 0x30, 0x36, 0xa5, 0x38, 0xbf, 0x40, 0xa3, 0x9e, 0x81, 0xf3, 0xd7, 0xfb,
    0x7c, 0xe3, 0x39, 0x82, 0x9b, 0x2f, 0xff, 0x87, 0x34, 0x8e, 0x43, 0x44, 0xc4, 0xde, 0xe9, 0xcb,
    0x54, 0x7b, 0x94, 0x32, 0xa6, 0xc2, 0x23, 0x3d, 0xee, 0x4c, 0x95, 0x0b, 0x42, 0xfa, 0xc3, 0x4e,
    0x08, 0x2e, 0xa1, 0x66, 0x28, 0xd9, 0x24, 0xb2, 0x76, 0x5b, 0xa2, 0x49, 0x6d, 0x8b, 0xd1, 0x25,
    0x72, 0xf8, 0xf6, 0x64, 0x86, 0x68, 0x98, 0x16, 0xd4, 0xa4, 0x5c, 0xcc, 0x5d, 0x65, 0xb6, 0x92,
    0x6c, 0x70, 0x48, 0x50, 0xfd, 0xed, 0xb9, 0xda, 0x5e, 0x15, 0x46, 0x57, 0xa7, 0x8d, 0x9d, 0x84,
    0x90, 0xd8, 0xab, 0x00, 0x8c, 0xbc, 0xd3, 0x0a, 0xf7, 0xe4, 0x58, 0x05, 0xb8, 0xb3, 0x45, 0x06,
    0xd0, 0x2c, 0x1e, 0x8f, 0xca, 0x3f, 0x0f, 0x02, 0xc1, 0xaf, 0xbd, 0x03, 0x01, 0x13, 0x8a, 0x6b,
    0x3a, 0x91, 0x11, 0x41, 0x4f, 0x67, 0xdc, 0xea, 0x97, 0xf2, 0xcf, 0xce, 0xf0, 0xb4, 0xe6, 0x73,
    0x96, 0xac, 0x74, 0x22, 0xe7, 0xad, 0x35, 0x85, 0xe2, 0xf9, 0x37, 0xe8, 0x1c, 0x75, 0xdf, 0x6e,
    0x47, 0xf1, 0x1a, 0x71, 0x1d, 0x29, 0xc5, 0x89, 0x6f, 0xb7, 0x62, 0x0e, 0xaa, 0x18, 0xbe, 0x1b,
    0xfc, 0x56, 0x3e, 0x4b, 0xc6, 0xd2, 0x79, 0x20, 0x9a, 0xdb, 0xc0, 0xfe, 0x78, 0xcd, 0x5a, 0xf4,
    0x1f, 0xdd, 0xa8, 0x33, 0x88, 0x07, 0xc7, 0x31, 0xb1, 0x12, 0x10, 0x59, 0x27, 0x80, 0xec, 0x5f,
    0x60, 0x51, 0x7f, 0xa9, 0x19, 0xb5, 0x4a, 0x0d, 0x2d, 0xe5, 0x7a, 0x9f, 0x93, 0xc9, 0x9c, 0xef,
    0xa0, 0xe0, 0x3b, 0x4d, 0xae, 0x2a, 0xf5, 0xb0, 0xc8, 0xeb, 0xbb, 0x3c, 0x83, 0x53, 0x99, 0x61,
    0x17, 0x2b, 0x04, 0x7e, 0xba, 0x77, 0xd6, 0x26, 0xe1, 0x69, 0x14, 0x63, 0x55, 0x21, 0x0c, 0x7d
];

fn s_box(s: &[u8; 16 * 16], input: u8) -> u8 {
    let x = (input >> 4) & 0xF;
    let y = input & 0xF;
    s[x as usize * 16 + y as usize]
}

fn g(x: u32, rc: u8) -> u32 {
    let mut y = [0u8; 4];
    y[3] = ((x >> 24) & 0xFF) as _;
    y[0] = ((x >> 16) & 0xFF) as _;
    y[1] = ((x >> 8) & 0xFF) as _;
    y[2] = (x & 0xFF) as _;

    for a in &mut y {
        *a = s_box(&S, *a);
    }

    (y[3] as u32) | (y[2] as u32) << 8 | (y[1] as u32) << 16 | ((y[0] ^ rc) as u32) << 24
}

fn aes_keygen_128(input: [u32; 4], rc: u8) -> [u32; 4] {
    let mut out = [0u32; 4];

    out[0] = input[0] ^ g(input[3], rc);
    out[1] = input[1] ^ out[0];
    out[2] = input[2] ^ out[1];
    out[3] = input[3] ^ out[2];

    out
}

fn key_add(a: &[u32; 4], b: &[u32; 4]) -> [u32; 4] {
    let mut ret = [0; 4];

    for (x, (y, z)) in ret.iter_mut().zip(a.iter().zip(b.iter())) {
        *x = y ^ z;
    }

    ret
}

macro_rules! bit_set{
    ($i:expr, $x:expr, $v:expr) => {
        $x ^= ($v & 1) << $i;
    }
}

macro_rules! bit_get{
    ($i:expr, $v:expr) => {
        {($v & (1 << $i)) >> $i}
    }
}

// * (x) mod P(x)
fn mul_x(i: u8) -> u8 {
    let mut ret = i << 1;

    bit_set!(4, ret, bit_get!(7, i));
    bit_set!(3, ret, bit_get!(7, i));
    bit_set!(1, ret, bit_get!(7, i));
    bit_set!(0, ret, bit_get!(7, i));

    ret
}

// * (x^2) mod P(x)
fn mul_x_pow_2(i: u8) -> u8 {
    let mut ret = i << 2;

    bit_set!(5, ret, bit_get!(7, i));
    bit_set!(4, ret, bit_get!(7, i) ^ bit_get!(6, i));
    bit_set!(3, ret, bit_get!(6, i));
    bit_set!(2, ret, bit_get!(7, i));
    bit_set!(1, ret, bit_get!(7, i) ^ bit_get!(6, i));
    bit_set!(0, ret, bit_get!(6, i));

    ret
}

// * (x^3) mod P(x)
fn mul_x_pow_3(i: u8) -> u8 {
    let mut ret = i << 3;

    bit_set!(6, ret, bit_get!(7, i));
    bit_set!(5, ret, bit_get!(7, i) ^ bit_get!(6, i));
    bit_set!(4, ret, bit_get!(6, i) ^ bit_get!(5, i));
    bit_set!(3, ret, bit_get!(7, i) ^ bit_get!(5, i));
    bit_set!(2, ret, bit_get!(7, i) ^ bit_get!(6, i));
    bit_set!(1, ret, bit_get!(6, i) ^ bit_get!(5, i));
    bit_set!(0, ret, bit_get!(5, i));

    ret
}

// * (x^3 + 1)
fn mul9(i: u8) -> u8 {
    mul_x_pow_3(i) ^ i
}

// * (x^3 + x + 1)
fn mulb(i: u8) -> u8 {
    mul_x_pow_3(i) ^ mul_x(i) ^ i
}

// * (x^3 + x^2 + 1)
fn muld(i: u8) -> u8 {
    mul_x_pow_3(i) ^ mul_x_pow_2(i) ^ i
}

// * (x^3 + x^2 + x)
fn mule(i: u8) -> u8 {
    mul_x_pow_3(i) ^ mul_x_pow_2(i) ^ mul_x(i)
}

fn mix_columns(i: u32) -> u32 {
    let mut ret = 0;

    let i0 = ((i >> 24) & 0xFF) as u8;
    let i1 = ((i >> 16) & 0xFF) as u8;
    let i2 = ((i >> 8) & 0xFF) as u8;
    let i3 = ((i >> 0) & 0xFF) as u8;

    ret |= ((mule(i0) ^ mulb(i1) ^ muld(i2) ^ mul9(i3)) as u32) << 24;
    ret |= ((mul9(i0) ^ mule(i1) ^ mulb(i2) ^ muld(i3)) as u32) << 16;
    ret |= ((muld(i0) ^ mul9(i1) ^ mule(i2) ^ mulb(i3)) as u32) << 8;
    ret |= ((mulb(i0) ^ muld(i1) ^ mul9(i2) ^ mule(i3)) as u32) << 0;

    ret
}

macro_rules! shift {
    (@left, $v:expr, $i:expr) => {
        ($v & 0xFF) << $i
    };
    (@right, $v:expr, $i:expr) => {
        ($v >> $i) & 0xFF
    };
}

fn inv_shift_rows(i: &[u32; 4]) -> [u32; 4] {
    let mut ret = [0; 4];

    // first row
    ret[0] |= shift!(@left, shift!(@right, i[0], 24), 24);
    ret[1] |= shift!(@left, shift!(@right, i[1], 24), 24);
    ret[2] |= shift!(@left, shift!(@right, i[2], 24), 24);
    ret[3] |= shift!(@left, shift!(@right, i[3], 24), 24);

    // second row
    ret[0] |= shift!(@left, shift!(@right, i[3], 16), 16);
    ret[1] |= shift!(@left, shift!(@right, i[0], 16), 16);
    ret[2] |= shift!(@left, shift!(@right, i[1], 16), 16);
    ret[3] |= shift!(@left, shift!(@right, i[2], 16), 16);

    // third row
    ret[0] |= shift!(@left, shift!(@right, i[2], 8), 8);
    ret[1] |= shift!(@left, shift!(@right, i[3], 8), 8);
    ret[2] |= shift!(@left, shift!(@right, i[0], 8), 8);
    ret[3] |= shift!(@left, shift!(@right, i[1], 8), 8);

    // fourth row
    ret[0] |= shift!(@left, shift!(@right, i[1], 0), 0);
    ret[1] |= shift!(@left, shift!(@right, i[2], 0), 0);
    ret[2] |= shift!(@left, shift!(@right, i[3], 0), 0);
    ret[3] |= shift!(@left, shift!(@right, i[0], 0), 0);

    ret
}

fn inv_sbox(i: &[u32; 4]) -> [u32; 4] {
    let mut ret = [0; 4];

    for (r, &i) in ret.iter_mut().zip(i.iter()) {
        *r |= shift!(@left, s_box(&SInv, shift!(@right, i, 24) as u8) as u32, 24);
        *r |= shift!(@left, s_box(&SInv, shift!(@right, i, 16) as u8) as u32, 16);
        *r |= shift!(@left, s_box(&SInv, shift!(@right, i, 8) as u8) as u32, 8);
        *r |= shift!(@left, s_box(&SInv, shift!(@right, i, 0) as u8) as u32, 0);
    }

    ret
}

fn print(text: &str, a: &[u32]) {
    println!("\\text{{{}}} &= ", text);

    println!("\\left( \\begin{{matrix}}");

    print!("{:02X} & ", shift!(@right, a[0], 24));
    print!("{:02X} & ", shift!(@right, a[1], 24));
    print!("{:02X} & ", shift!(@right, a[2], 24));
    println!("{:02X} \\\\ ", shift!(@right, a[3], 24));

    print!("{:02X} & ", shift!(@right, a[0], 16));
    print!("{:02X} & ", shift!(@right, a[1], 16));
    print!("{:02X} & ", shift!(@right, a[2], 16));
    println!("{:02X} \\\\ ", shift!(@right, a[3], 16));

    print!("{:02X} & ", shift!(@right, a[0], 8));
    print!("{:02X} & ", shift!(@right, a[1], 8));
    print!("{:02X} & ", shift!(@right, a[2], 8));
    println!("{:02X} \\\\ ", shift!(@right, a[3], 8));

    print!("{:02X} & ", shift!(@right, a[0], 0));
    print!("{:02X} & ", shift!(@right, a[1], 0));
    print!("{:02X} & ", shift!(@right, a[2], 0));
    println!("{:02X} \\\\ ", shift!(@right, a[3], 0));

    println!("\\end{{matrix}} \\right)");

    println!("\\\\");
}

fn main() {
    let round_input = [0x54015CFC, 0x8752C1E6, 0x61EF26F9, 0xE2A6E5D4];
    let k0 = [0xF2A02596, 0x96EF693C, 0xA7102B8D, 0xB5253A3F];
    let k1 = aes_keygen_128(k0, 0b1);

    println!("$");
    println!("\\begin{{aligned}}[t]");

    print("$k_1$", &k1);

    let after_key_add = key_add(&round_input, &k1);
    print("Zustand nach dem Key Addition Layer $k_1$", &after_key_add);

    let after_mix_columns = [
        mix_columns(after_key_add[0]),
        mix_columns(after_key_add[1]),
        mix_columns(after_key_add[2]),
        mix_columns(after_key_add[3]),
    ];
    print(
        "Zustand nach dem inversen MixColumns Layer",
        &after_mix_columns,
    );

    let after_shift_rows = inv_shift_rows(&after_mix_columns);
    print(
        "Zustand nach dem inversen ShiftRows Layer",
        &after_shift_rows,
    );

    let after_inv_sbox = inv_sbox(&after_shift_rows);
    print(
        "Zustand nach der inversen Byte Substitution",
        &after_inv_sbox,
    );

    let after_final_add = key_add(&after_inv_sbox, &k0);
    print(
        "Zustand nach dem Key Addition Layer $k_0$",
        &after_final_add,
    );

    print("AES Klartext", &after_final_add);

    println!("\\end{{aligned}}");
    println!("$");
}