pub fn Pkcs7(comptime N: comptime_int) type {
    comptime {
        if (N >= 256)
            @compileError("pkcs#7 mod should be smaller than 256");
    }

    return struct {
        pub fn outLen(in: []const u8) usize {
            return (in.len / N + 1) * N;
        }

        pub fn pad(out: []u8, in: []const u8) !void {
            if (out.len != (in.len / N + 1) * N) {
                return error.ShortBuffer;
            }

            std.mem.copyForwards(u8, out[0..in.len], in);

            @memset(out[in.len..], @as(u8, @intCast(N - (in.len % N))));
        }
    };
}