AesEncryptCtx

pub fn AesEncryptCtx(comptime Aes: type) type

File

Code

pub fn AesEncryptCtx(comptime Aes: type) type {
    std.debug.assert(Aes.key_bits == 128 or Aes.key_bits == 256);
    const rounds = Aes.rounds;

    return struct {
        const Self = @This();
        pub const block = Aes.block;
        pub const block_length = block.block_length;
        key_schedule: KeySchedule(Aes),

        /// Create a new encryption context with the given key.
        pub fn init(key: [Aes.key_bits / 8]u8) Self {
            const key_schedule = KeySchedule(Aes).expandKey(key);
            return Self{
                .key_schedule = key_schedule,
            };
        }

        /// Encrypt a single block.
        pub fn encrypt(ctx: Self, dst: *[16]u8, src: *const [16]u8) void {
            const round_keys = ctx.key_schedule.round_keys;
            var t = Block.fromBytes(src).xorBlocks(round_keys[0]);
            comptime var i = 1;
            if (side_channels_mitigations == .full) {
                inline while (i < rounds) : (i += 1) {
                    t = t.encrypt(round_keys[i]);
                }
            } else {
                inline while (i < 5) : (i += 1) {
                    t = t.encrypt(round_keys[i]);
                }
                inline while (i < rounds - 1) : (i += 1) {
                    t = t.encryptUnprotected(round_keys[i]);
                }
                t = t.encrypt(round_keys[i]);
            }
            t = t.encryptLast(round_keys[rounds]);
            dst.* = t.toBytes();
        }

        /// Encrypt+XOR a single block.
        pub fn xor(ctx: Self, dst: *[16]u8, src: *const [16]u8, counter: [16]u8) void {
            const round_keys = ctx.key_schedule.round_keys;
            var t = Block.fromBytes(&counter).xorBlocks(round_keys[0]);
            comptime var i = 1;
            if (side_channels_mitigations == .full) {
                inline while (i < rounds) : (i += 1) {
                    t = t.encrypt(round_keys[i]);
                }
            } else {
                inline while (i < 5) : (i += 1) {
                    t = t.encrypt(round_keys[i]);
                }
                inline while (i < rounds - 1) : (i += 1) {
                    t = t.encryptUnprotected(round_keys[i]);
                }
                t = t.encrypt(round_keys[i]);
            }
            t = t.encryptLast(round_keys[rounds]);
            dst.* = t.xorBytes(src);
        }

        /// Encrypt multiple blocks, possibly leveraging parallelization.
        pub fn encryptWide(ctx: Self, comptime count: usize, dst: *[16 * count]u8, src: *const [16 * count]u8) void {
            var i: usize = 0;
            while (i < count) : (i += 1) {
                ctx.encrypt(dst[16 * i .. 16 * i + 16][0..16], src[16 * i .. 16 * i + 16][0..16]);
            }
        }

        /// Encrypt+XOR multiple blocks, possibly leveraging parallelization.
        pub fn xorWide(ctx: Self, comptime count: usize, dst: *[16 * count]u8, src: *const [16 * count]u8, counters: [16 * count]u8) void {
            var i: usize = 0;
            while (i < count) : (i += 1) {
                ctx.xor(dst[16 * i .. 16 * i + 16][0..16], src[16 * i .. 16 * i + 16][0..16], counters[16 * i .. 16 * i + 16][0..16].*);
            }
        }
    };
}