hashx/
lib.rs

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1#![cfg_attr(docsrs, feature(doc_auto_cfg, doc_cfg))]
2#![doc = include_str!("../README.md")]
3// @@ begin lint list maintained by maint/add_warning @@
4#![allow(renamed_and_removed_lints)] // @@REMOVE_WHEN(ci_arti_stable)
5#![allow(unknown_lints)] // @@REMOVE_WHEN(ci_arti_nightly)
6#![warn(missing_docs)]
7#![warn(noop_method_call)]
8#![warn(unreachable_pub)]
9#![warn(clippy::all)]
10#![deny(clippy::await_holding_lock)]
11#![deny(clippy::cargo_common_metadata)]
12#![deny(clippy::cast_lossless)]
13#![deny(clippy::checked_conversions)]
14#![warn(clippy::cognitive_complexity)]
15#![deny(clippy::debug_assert_with_mut_call)]
16#![deny(clippy::exhaustive_enums)]
17#![deny(clippy::exhaustive_structs)]
18#![deny(clippy::expl_impl_clone_on_copy)]
19#![deny(clippy::fallible_impl_from)]
20#![deny(clippy::implicit_clone)]
21#![deny(clippy::large_stack_arrays)]
22#![warn(clippy::manual_ok_or)]
23#![deny(clippy::missing_docs_in_private_items)]
24#![warn(clippy::needless_borrow)]
25#![warn(clippy::needless_pass_by_value)]
26#![warn(clippy::option_option)]
27#![deny(clippy::print_stderr)]
28#![deny(clippy::print_stdout)]
29#![warn(clippy::rc_buffer)]
30#![deny(clippy::ref_option_ref)]
31#![warn(clippy::semicolon_if_nothing_returned)]
32#![warn(clippy::trait_duplication_in_bounds)]
33#![deny(clippy::unchecked_duration_subtraction)]
34#![deny(clippy::unnecessary_wraps)]
35#![warn(clippy::unseparated_literal_suffix)]
36#![deny(clippy::unwrap_used)]
37#![deny(clippy::mod_module_files)]
38#![allow(clippy::let_unit_value)] // This can reasonably be done for explicitness
39#![allow(clippy::uninlined_format_args)]
40#![allow(clippy::significant_drop_in_scrutinee)] // arti/-/merge_requests/588/#note_2812945
41#![allow(clippy::result_large_err)] // temporary workaround for arti#587
42#![allow(clippy::needless_raw_string_hashes)] // complained-about code is fine, often best
43#![allow(clippy::needless_lifetimes)] // See arti#1765
44#![allow(mismatched_lifetime_syntaxes)] // temporary workaround for arti#2060
45//! <!-- @@ end lint list maintained by maint/add_warning @@ -->
46
47mod compiler;
48mod constraints;
49mod err;
50mod generator;
51mod program;
52mod rand;
53mod register;
54mod scheduler;
55mod siphash;
56
57use crate::compiler::{Architecture, Executable};
58use crate::program::Program;
59use rand_core::RngCore;
60
61pub use crate::err::{CompilerError, Error};
62pub use crate::rand::SipRand;
63pub use crate::siphash::SipState;
64
65/// Option for selecting a HashX runtime
66#[derive(Default, Debug, Copy, Clone, Eq, PartialEq)]
67#[non_exhaustive]
68pub enum RuntimeOption {
69    /// Choose the interpreted runtime, without trying the compiler at all.
70    InterpretOnly,
71    /// Choose the compiled runtime only, and fail if it experiences any errors.
72    CompileOnly,
73    /// Always try the compiler first but fall back to the interpreter on error.
74    /// (This is the default)
75    #[default]
76    TryCompile,
77}
78
79/// Effective HashX runtime for a constructed program
80#[derive(Debug, Copy, Clone, Eq, PartialEq)]
81#[non_exhaustive]
82pub enum Runtime {
83    /// The interpreted runtime is active.
84    Interpret,
85    /// The compiled runtime is active.
86    Compiled,
87}
88
89/// Pre-built hash program that can be rapidly computed with different inputs
90///
91/// The program and initial state representation are not specified in this
92/// public interface, but [`std::fmt::Debug`] can describe program internals.
93#[derive(Debug)]
94pub struct HashX {
95    /// Keys used to generate an initial register state from the hash input
96    ///
97    /// Half of the key material generated from seed bytes go into the random
98    /// program generator, and the other half are saved here for use in each
99    /// hash invocation.
100    register_key: SipState,
101
102    /// A prepared randomly generated hash program
103    ///
104    /// In compiled runtimes this will be executable code, and in the
105    /// interpreter it's a list of instructions. There is no stable API for
106    /// program information, but the Debug trait will list programs in either
107    /// format.
108    program: RuntimeProgram,
109}
110
111/// Combination of [`Runtime`] and the actual program info used by that runtime
112///
113/// All variants of [`RuntimeProgram`] use some kind of inner heap allocation
114/// to store the program data.
115#[derive(Debug)]
116enum RuntimeProgram {
117    /// Select the interpreted runtime, and hold a Program for it to run.
118    Interpret(Program),
119    /// Select the compiled runtime, and hold an executable code page.
120    Compiled(Executable),
121}
122
123impl HashX {
124    /// The maximum available output size for [`Self::hash_to_bytes()`]
125    pub const FULL_SIZE: usize = 32;
126
127    /// Generate a new hash function with the supplied seed.
128    pub fn new(seed: &[u8]) -> Result<Self, Error> {
129        HashXBuilder::new().build(seed)
130    }
131
132    /// Check which actual program runtime is in effect.
133    ///
134    /// By default we try to generate code at runtime to accelerate the hash
135    /// function, but we fall back to an interpreter if this fails. The compiler
136    /// can be disabled entirely using [`RuntimeOption::InterpretOnly`] and
137    /// [`HashXBuilder`].
138    pub fn runtime(&self) -> Runtime {
139        match &self.program {
140            RuntimeProgram::Interpret(_) => Runtime::Interpret,
141            RuntimeProgram::Compiled(_) => Runtime::Compiled,
142        }
143    }
144
145    /// Calculate the first 64-bit word of the hash, without converting to bytes.
146    pub fn hash_to_u64(&self, input: u64) -> u64 {
147        self.hash_to_regs(input).digest(self.register_key)[0]
148    }
149
150    /// Calculate the hash function at its full output width, returning a fixed
151    /// size byte array.
152    pub fn hash_to_bytes(&self, input: u64) -> [u8; Self::FULL_SIZE] {
153        let words = self.hash_to_regs(input).digest(self.register_key);
154        let mut bytes = [0_u8; Self::FULL_SIZE];
155        for word in 0..words.len() {
156            bytes[word * 8..(word + 1) * 8].copy_from_slice(&words[word].to_le_bytes());
157        }
158        bytes
159    }
160
161    /// Common setup for hashes with any output format
162    #[inline(always)]
163    fn hash_to_regs(&self, input: u64) -> register::RegisterFile {
164        let mut regs = register::RegisterFile::new(self.register_key, input);
165        match &self.program {
166            RuntimeProgram::Interpret(program) => program.interpret(&mut regs),
167            RuntimeProgram::Compiled(executable) => executable.invoke(&mut regs),
168        }
169        regs
170    }
171}
172
173/// Builder for creating [`HashX`] instances with custom settings
174#[derive(Default, Debug, Clone, Eq, PartialEq)]
175pub struct HashXBuilder {
176    /// Current runtime() setting for this builder
177    runtime: RuntimeOption,
178}
179
180impl HashXBuilder {
181    /// Create a new [`HashXBuilder`] with default settings.
182    ///
183    /// Immediately calling [`Self::build()`] would be equivalent to using
184    /// [`HashX::new()`].
185    pub fn new() -> Self {
186        Default::default()
187    }
188
189    /// Select a new [`RuntimeOption`].
190    pub fn runtime(&mut self, runtime: RuntimeOption) -> &mut Self {
191        self.runtime = runtime;
192        self
193    }
194
195    /// Build a [`HashX`] instance with a seed and the selected options.
196    pub fn build(&self, seed: &[u8]) -> Result<HashX, Error> {
197        let (key0, key1) = SipState::pair_from_seed(seed);
198        let mut rng = SipRand::new(key0);
199        self.build_from_rng(&mut rng, key1)
200    }
201
202    /// Build a [`HashX`] instance from an arbitrary [`RngCore`] and
203    /// a [`SipState`] key used for initializing the register file.
204    pub fn build_from_rng<R: RngCore>(
205        &self,
206        rng: &mut R,
207        register_key: SipState,
208    ) -> Result<HashX, Error> {
209        let program = Program::generate(rng)?;
210        self.build_from_program(program, register_key)
211    }
212
213    /// Build a [`HashX`] instance from an already-generated [`Program`] and
214    /// [`SipState`] key.
215    ///
216    /// The program is either stored as-is or compiled, depending on the current
217    /// [`RuntimeOption`]. Requires a program as well as a [`SipState`] to be
218    /// used for initializing the register file.
219    fn build_from_program(&self, program: Program, register_key: SipState) -> Result<HashX, Error> {
220        Ok(HashX {
221            register_key,
222            program: match self.runtime {
223                RuntimeOption::InterpretOnly => RuntimeProgram::Interpret(program),
224                RuntimeOption::CompileOnly => {
225                    RuntimeProgram::Compiled(Architecture::compile((&program).into())?)
226                }
227                RuntimeOption::TryCompile => match Architecture::compile((&program).into()) {
228                    Ok(exec) => RuntimeProgram::Compiled(exec),
229                    Err(_) => RuntimeProgram::Interpret(program),
230                },
231            },
232        })
233    }
234}
hashx/lib.rs

hashx/
lib.rs
