Block

pub const Block = struct

File

Code

pub const Block = struct {
    const Repr = @Vector(2, u64);

    pub const block_length: usize = 16;

    /// Internal representation of a block.
    repr: Repr,

    /// Convert a byte sequence into an internal representation.
    pub fn fromBytes(bytes: *const [16]u8) Block {
        const repr = mem.bytesToValue(Repr, bytes);
        return Block{ .repr = repr };
    }

    /// Convert the internal representation of a block into a byte sequence.
    pub fn toBytes(block: Block) [16]u8 {
        return mem.toBytes(block.repr);
    }

    /// XOR the block with a byte sequence.
    pub fn xorBytes(block: Block, bytes: *const [16]u8) [16]u8 {
        const x = block.repr ^ fromBytes(bytes).repr;
        return mem.toBytes(x);
    }

    const zero = @Vector(2, u64){ 0, 0 };

    /// Encrypt a block with a round key.
    pub fn encrypt(block: Block, round_key: Block) Block {
        return Block{
            .repr = (asm (
                \\ mov   %[out].16b, %[in].16b
                \\ aese  %[out].16b, %[zero].16b
                \\ aesmc %[out].16b, %[out].16b
                : [out] "=&x" (-> Repr),
                : [in] "x" (block.repr),
                  [zero] "x" (zero),
            )) ^ round_key.repr,
        };
    }

    /// Encrypt a block with the last round key.
    pub fn encryptLast(block: Block, round_key: Block) Block {
        return Block{
            .repr = (asm (
                \\ mov   %[out].16b, %[in].16b
                \\ aese  %[out].16b, %[zero].16b
                : [out] "=&x" (-> Repr),
                : [in] "x" (block.repr),
                  [zero] "x" (zero),
            )) ^ round_key.repr,
        };
    }

    /// Decrypt a block with a round key.
    pub fn decrypt(block: Block, inv_round_key: Block) Block {
        return Block{
            .repr = (asm (
                \\ mov   %[out].16b, %[in].16b
                \\ aesd  %[out].16b, %[zero].16b
                \\ aesimc %[out].16b, %[out].16b
                : [out] "=&x" (-> Repr),
                : [in] "x" (block.repr),
                  [zero] "x" (zero),
            )) ^ inv_round_key.repr,
        };
    }

    /// Decrypt a block with the last round key.
    pub fn decryptLast(block: Block, inv_round_key: Block) Block {
        return Block{
            .repr = (asm (
                \\ mov   %[out].16b, %[in].16b
                \\ aesd  %[out].16b, %[zero].16b
                : [out] "=&x" (-> Repr),
                : [in] "x" (block.repr),
                  [zero] "x" (zero),
            )) ^ inv_round_key.repr,
        };
    }

    /// Apply the bitwise XOR operation to the content of two blocks.
    pub fn xorBlocks(block1: Block, block2: Block) Block {
        return Block{ .repr = block1.repr ^ block2.repr };
    }

    /// Apply the bitwise AND operation to the content of two blocks.
    pub fn andBlocks(block1: Block, block2: Block) Block {
        return Block{ .repr = block1.repr & block2.repr };
    }

    /// Apply the bitwise OR operation to the content of two blocks.
    pub fn orBlocks(block1: Block, block2: Block) Block {
        return Block{ .repr = block1.repr | block2.repr };
    }

    /// Apply the inverse MixColumns operation to a block.
    pub fn invMixColumns(block: Block) Block {
        return Block{
            .repr = asm (
                \\ aesimc %[out].16b, %[in].16b
                : [out] "=x" (-> Repr),
                : [in] "x" (block.repr),
            ),
        };
    }

    /// Perform operations on multiple blocks in parallel.
    pub const parallel = struct {
        /// The recommended number of AES encryption/decryption to perform in parallel for the chosen implementation.
        pub const optimal_parallel_blocks = 6;

        /// Encrypt multiple blocks in parallel, each their own round key.
        pub fn encryptParallel(comptime count: usize, blocks: [count]Block, round_keys: [count]Block) [count]Block {
            comptime var i = 0;
            var out: [count]Block = undefined;
            inline while (i < count) : (i += 1) {
                out[i] = blocks[i].encrypt(round_keys[i]);
            }
            return out;
        }

        /// Decrypt multiple blocks in parallel, each their own round key.
        pub fn decryptParallel(comptime count: usize, blocks: [count]Block, round_keys: [count]Block) [count]Block {
            comptime var i = 0;
            var out: [count]Block = undefined;
            inline while (i < count) : (i += 1) {
                out[i] = blocks[i].decrypt(round_keys[i]);
            }
            return out;
        }

        /// Encrypt multiple blocks in parallel with the same round key.
        pub fn encryptWide(comptime count: usize, blocks: [count]Block, round_key: Block) [count]Block {
            comptime var i = 0;
            var out: [count]Block = undefined;
            inline while (i < count) : (i += 1) {
                out[i] = blocks[i].encrypt(round_key);
            }
            return out;
        }

        /// Decrypt multiple blocks in parallel with the same round key.
        pub fn decryptWide(comptime count: usize, blocks: [count]Block, round_key: Block) [count]Block {
            comptime var i = 0;
            var out: [count]Block = undefined;
            inline while (i < count) : (i += 1) {
                out[i] = blocks[i].decrypt(round_key);
            }
            return out;
        }

        /// Encrypt multiple blocks in parallel with the same last round key.
        pub fn encryptLastWide(comptime count: usize, blocks: [count]Block, round_key: Block) [count]Block {
            comptime var i = 0;
            var out: [count]Block = undefined;
            inline while (i < count) : (i += 1) {
                out[i] = blocks[i].encryptLast(round_key);
            }
            return out;
        }

        /// Decrypt multiple blocks in parallel with the same last round key.
        pub fn decryptLastWide(comptime count: usize, blocks: [count]Block, round_key: Block) [count]Block {
            comptime var i = 0;
            var out: [count]Block = undefined;
            inline while (i < count) : (i += 1) {
                out[i] = blocks[i].decryptLast(round_key);
            }
            return out;
        }
    };
}