1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 142 143 144 145 146 147 148 149 150 151 152 153 154 155 156 157 158 159 160 161 162 163 164 165 166 167 168 169 170 171 172 173 174 175 176 177 178 179 180 181 182 183 184 185 186 187 188 189 190 191 192 193 194 195 196 197 198 199 200 201 202 203 204 205 206 207 208 209 210 211 212 213 214 215 216 217 218 219 220 221 222 223 224 225 226 227 228 229 230 231 232 233 234 235 236 237 238 239 240 241 242 243 244 245 246 247 248 249 250 251 252 253 254 255 256 257 258 259 260 261 262 263 264 265 266 267 268 269 270 271 272 273 274 275 276 277 278 279 280 281 282 283 284 285 286 287 288 289 290 291 292 293 294 295 296 297 298 299 300 301 302 303 304 305 306 307 308 309 310 311 312 313 314 315 316 317 318 319 320 321 322 323 324 325 326 327 328 329 330 331 332 333 334 335 336 337 338 339 340 341 342 343 344 345 346 347 348 349 350 351 352 353 354 355 356 357 358 359 360 361 362 363 364 365 366 367 368 369 370 371 372 373 374 375 376 377 378 379 380 381 382 383 384 385 386 387 388 389 390 391 392 393 394 395 396 397 398 399 400 401 402 403 404 405 406 407 408 409 410 411 412 413 414 415 416 417 418 419 420 421 422 423 424 425 426 427 428 429 430 431 432 433 434 435 436 437 438 439 440 441 442 443 444 445 446 447 448 449 450 451 452 453 454 455 456 457 458 459 460 461 462 463 464 465 466 467 468 469 470 471 472 473 474 475 476 477 478 479 480 481 482 483 484 485 486 487 488 489 490 491 492 493 494 495 496 497 498 499 500 501 502 503 504 505 506 507 508 509 510 511 512 513 514 515 516 517 518 519 520 521 522 523 524 525 526 527 528 529 530 531 532 533 534 535 536 537 538 539
//! # Public-key signatures
//!
//! This module implements libsodium's public-key signature functions. The
//! signatures are based on Ed25519 (EdDSA). It provides both a
//! [single-part](SigningKeyPair::sign) and [multi-part](IncrementalSigner)
//! interface.
//!
//! The single-part interface is convenient for short
//! messages, such as those small enough to fit in memory. The multi-part
//! interface may be more appropriate for lengthy messages, those which don't
//! fit in memory, or those for which the entire message isn't known at once
//! (i.e., during network communication, or reading a large file).
//!
//! The single-part and multi-part variants use slightly different algorithms,
//! and thus they are not compatible with each other.
//!
//! You should use a this module when you want to:
//!
//! * share a message with other parties, and provide a proof that the message
//! is authentic
//! * verify that the message from another party was signed using their secret
//! key, without having knowledge of the original secret
//!
//! The public key of the signer must be known to the verifier.
//!
//! One should take note that keys used for signing and encryption should remain
//! separate. While it's possible to convert Ed25519 keys to X25519 keys (or
//! derive them from the same seed), one is cautioned against doing so.
//!
//! ## Rustaceous API example, single-part
//!
//! ```
//! use dryoc::sign::*;
//!
//! // Generate a random keypair, using default types
//! let keypair = SigningKeyPair::gen_with_defaults();
//! let message = b"Fair is foul, and foul is fair: Hover through the fog and filthy air.";
//!
//! // Sign the message, using default types (stack-allocated byte array, Vec<u8>)
//! let signed_message = keypair.sign_with_defaults(message).expect("signing failed");
//!
//! // Verify the message signature
//! signed_message
//! .verify(&keypair.public_key)
//! .expect("verification failed");
//! ```
//!
//! ## Incremental (multi-part) interface
//!
//! ```
//! use dryoc::sign::*;
//!
//! // Generate a random keypair, using default types
//! let keypair = SigningKeyPair::gen_with_defaults();
//!
//! // Initialize the incremental signer interface
//! let mut signer = IncrementalSigner::new();
//! signer.update(b"This above all: to thine ownself be true.");
//! signer.update(b"And it must follow, as the night the day,");
//! signer.update(b"Thou canst not then be false to any man.");
//!
//! let signature: Signature = signer
//! .finalize(&keypair.secret_key)
//! .expect("signing failed");
//! ```
//!
//! ## Additional resources
//!
//! * See <https://libsodium.gitbook.io/doc/public-key_cryptography/public-key_signatures>
//! for additional details on public-key signatures
//! * For secret-key based encryption, see
//! [`DryocSecretBox`](crate::dryocsecretbox)
//! * For stream encryption, see [`DryocStream`](crate::dryocstream)
//! * See the [protected] mod for an example using the protected memory features
#[cfg(feature = "serde")]
use serde::{Deserialize, Serialize};
use subtle::ConstantTimeEq;
use zeroize::{Zeroize, ZeroizeOnDrop};
use crate::classic::crypto_sign::{
crypto_sign_detached, crypto_sign_final_create, crypto_sign_final_verify, crypto_sign_init,
crypto_sign_keypair_inplace, crypto_sign_seed_keypair_inplace, crypto_sign_update,
crypto_sign_verify_detached, SignerState,
};
use crate::constants::{
CRYPTO_SIGN_BYTES, CRYPTO_SIGN_PUBLICKEYBYTES, CRYPTO_SIGN_SECRETKEYBYTES,
CRYPTO_SIGN_SEEDBYTES,
};
use crate::error::Error;
use crate::types::*;
/// Stack-allocated public key for message signing.
pub type PublicKey = StackByteArray<CRYPTO_SIGN_PUBLICKEYBYTES>;
/// Stack-allocated secret key for message signing.
pub type SecretKey = StackByteArray<CRYPTO_SIGN_SECRETKEYBYTES>;
/// Stack-allocated signature for message signing.
pub type Signature = StackByteArray<CRYPTO_SIGN_BYTES>;
/// Heap-allocated message for message signing.
pub type Message = Vec<u8>;
#[cfg_attr(
feature = "serde",
derive(Zeroize, ZeroizeOnDrop, Serialize, Deserialize, Debug, Clone)
)]
#[cfg_attr(not(feature = "serde"), derive(Zeroize, ZeroizeOnDrop, Debug, Clone))]
/// An Ed25519 keypair for public-key signatures
pub struct SigningKeyPair<
PublicKey: ByteArray<CRYPTO_SIGN_PUBLICKEYBYTES> + Zeroize,
SecretKey: ByteArray<CRYPTO_SIGN_SECRETKEYBYTES> + Zeroize,
> {
/// Public key
pub public_key: PublicKey,
/// Secret key
pub secret_key: SecretKey,
}
impl<
PublicKey: NewByteArray<CRYPTO_SIGN_PUBLICKEYBYTES> + Zeroize,
SecretKey: NewByteArray<CRYPTO_SIGN_SECRETKEYBYTES> + Zeroize,
> SigningKeyPair<PublicKey, SecretKey>
{
/// Creates a new, empty signing keypair.
pub fn new() -> Self {
Self {
public_key: PublicKey::new_byte_array(),
secret_key: SecretKey::new_byte_array(),
}
}
/// Generates a random signing keypair.
pub fn gen() -> Self {
let mut public_key = PublicKey::new_byte_array();
let mut secret_key = SecretKey::new_byte_array();
crypto_sign_keypair_inplace(public_key.as_mut_array(), secret_key.as_mut_array());
Self {
public_key,
secret_key,
}
}
/// Derives a signing keypair from `secret_key`, and consumes it, returning
/// a new keypair.
pub fn from_secret_key(secret_key: SecretKey) -> Self {
let mut seed = [0u8; 32];
seed.copy_from_slice(&secret_key.as_slice()[..32]);
Self::from_seed(&seed)
}
/// Derives a signing keypair from `seed`, returning
/// a new keypair.
pub fn from_seed<Seed: ByteArray<CRYPTO_SIGN_SEEDBYTES>>(seed: &Seed) -> Self {
let mut public_key = PublicKey::new_byte_array();
let mut secret_key = SecretKey::new_byte_array();
crypto_sign_seed_keypair_inplace(
public_key.as_mut_array(),
secret_key.as_mut_array(),
seed.as_array(),
);
Self {
public_key,
secret_key,
}
}
}
impl
SigningKeyPair<
StackByteArray<CRYPTO_SIGN_PUBLICKEYBYTES>,
StackByteArray<CRYPTO_SIGN_SECRETKEYBYTES>,
>
{
/// Randomly generates a new signing keypair, using default types
/// (stack-allocated byte arrays). Provided for convenience.
pub fn gen_with_defaults() -> Self {
Self::gen()
}
}
impl<
'a,
PublicKey: ByteArray<CRYPTO_SIGN_PUBLICKEYBYTES> + std::convert::TryFrom<&'a [u8]> + Zeroize,
SecretKey: ByteArray<CRYPTO_SIGN_SECRETKEYBYTES> + std::convert::TryFrom<&'a [u8]> + Zeroize,
> SigningKeyPair<PublicKey, SecretKey>
{
/// Constructs a new signing keypair from key slices, consuming them. Does
/// not check validity or authenticity of keypair.
pub fn from_slices(public_key: &'a [u8], secret_key: &'a [u8]) -> Result<Self, Error> {
Ok(Self {
public_key: PublicKey::try_from(public_key)
.map_err(|_e| dryoc_error!("invalid public key"))?,
secret_key: SecretKey::try_from(secret_key)
.map_err(|_e| dryoc_error!("invalid secret key"))?,
})
}
}
#[cfg(any(feature = "nightly", all(doc, not(doctest))))]
#[cfg_attr(all(feature = "nightly", doc), doc(cfg(feature = "nightly")))]
pub mod protected {
//! # Protected memory for [`SigningKeyPair`] and [`SignedMessage`].
//!
//! ## Example
//! ```
//! use dryoc::sign::protected::*;
//! use dryoc::sign::SigningKeyPair;
//!
//! // Generate a random keypair, using default types
//! let keypair = SigningKeyPair::gen_locked_keypair().expect("keypair gen failed");
//! let message = Message::from_slice_into_locked(
//! b"Fair is foul, and foul is fair: Hover through the fog and filthy air.",
//! )
//! .expect("message lock failed");
//!
//! // Sign the message, using default types (stack-allocated byte array, Vec<u8>)
//! let signed_message: LockedSignedMessage = keypair.sign(message).expect("signing failed");
//!
//! // Verify the message signature
//! signed_message
//! .verify(&keypair.public_key)
//! .expect("verification failed");
//! ```
use super::*;
pub use crate::protected::*;
/// Heap-allocated, page-aligned public-key for signed messages,
/// for use with protected memory.
pub type PublicKey = HeapByteArray<CRYPTO_SIGN_PUBLICKEYBYTES>;
/// Heap-allocated, page-aligned secret-key for signed messages,
/// for use with protected memory.
pub type SecretKey = HeapByteArray<CRYPTO_SIGN_SECRETKEYBYTES>;
/// Heap-allocated, page-aligned signature for signed messages,
/// for use with protected memory.
pub type Signature = HeapByteArray<CRYPTO_SIGN_BYTES>;
/// Heap-allocated, page-aligned message for signed messages,
/// for use with protected memory.
pub type Message = HeapBytes;
/// Heap-allocated, page-aligned public/secret keypair for message signing,
/// for use with protected memory.
pub type LockedSigningKeyPair = SigningKeyPair<Locked<PublicKey>, Locked<SecretKey>>;
/// Heap-allocated, page-aligned signed message, for use with protected
/// memory.
pub type LockedSignedMessage = SignedMessage<Locked<Signature>, Locked<Message>>;
impl
SigningKeyPair<
Locked<HeapByteArray<CRYPTO_SIGN_PUBLICKEYBYTES>>,
Locked<HeapByteArray<CRYPTO_SIGN_SECRETKEYBYTES>>,
>
{
/// Returns a new locked signing keypair.
pub fn new_locked_keypair() -> Result<Self, std::io::Error> {
Ok(Self {
public_key: HeapByteArray::<CRYPTO_SIGN_PUBLICKEYBYTES>::new_locked()?,
secret_key: HeapByteArray::<CRYPTO_SIGN_SECRETKEYBYTES>::new_locked()?,
})
}
/// Returns a new randomly generated locked signing keypair.
pub fn gen_locked_keypair() -> Result<Self, std::io::Error> {
let mut res = Self::new_locked_keypair()?;
crypto_sign_keypair_inplace(
res.public_key.as_mut_array(),
res.secret_key.as_mut_array(),
);
Ok(res)
}
}
impl
SigningKeyPair<
LockedRO<HeapByteArray<CRYPTO_SIGN_PUBLICKEYBYTES>>,
LockedRO<HeapByteArray<CRYPTO_SIGN_SECRETKEYBYTES>>,
>
{
/// Returns a new randomly generated locked, read-only signing keypair.
pub fn gen_readonly_locked_keypair() -> Result<Self, std::io::Error> {
let mut public_key = HeapByteArray::<CRYPTO_SIGN_PUBLICKEYBYTES>::new_locked()?;
let mut secret_key = HeapByteArray::<CRYPTO_SIGN_SECRETKEYBYTES>::new_locked()?;
crypto_sign_keypair_inplace(public_key.as_mut_array(), secret_key.as_mut_array());
let public_key = public_key.mprotect_readonly()?;
let secret_key = secret_key.mprotect_readonly()?;
Ok(Self {
public_key,
secret_key,
})
}
}
}
#[cfg_attr(
feature = "serde",
derive(Zeroize, Clone, Debug, Serialize, Deserialize)
)]
#[cfg_attr(not(feature = "serde"), derive(Zeroize, Clone, Debug))]
/// A signed message, for use with [`SigningKeyPair`].
pub struct SignedMessage<
Signature: ByteArray<CRYPTO_SIGN_BYTES> + Zeroize,
Message: Bytes + Zeroize,
> {
signature: Signature,
message: Message,
}
/// [Vec]-based signed message.
pub type VecSignedMessage = SignedMessage<Signature, Vec<u8>>;
impl<
PublicKey: ByteArray<CRYPTO_SIGN_PUBLICKEYBYTES> + Zeroize,
SecretKey: ByteArray<CRYPTO_SIGN_SECRETKEYBYTES> + Zeroize,
> SigningKeyPair<PublicKey, SecretKey>
{
/// Signs `message` using this keypair, consuming the message, and returning
/// a new [`SignedMessage`]. The type of `message` should match that of the
/// target signed message.
pub fn sign<Signature: NewByteArray<CRYPTO_SIGN_BYTES> + Zeroize, Message: Bytes + Zeroize>(
&self,
message: Message,
) -> Result<SignedMessage<Signature, Message>, Error> {
let mut signature = Signature::new_byte_array();
crypto_sign_detached(
signature.as_mut_array(),
message.as_slice(),
self.secret_key.as_array(),
)?;
Ok(SignedMessage::<Signature, Message> { signature, message })
}
/// Signs `message`, putting the result into a [`Vec`]. Convenience wrapper
/// for [`SigningKeyPair::sign`].
pub fn sign_with_defaults<Message: Bytes>(
&self,
message: Message,
) -> Result<SignedMessage<StackByteArray<CRYPTO_SIGN_BYTES>, Vec<u8>>, Error> {
self.sign(Vec::from(message.as_slice()))
}
}
impl Default for SigningKeyPair<PublicKey, SecretKey> {
fn default() -> Self {
Self::new()
}
}
/// Multi-part (incremental) interface for [`SigningKeyPair`].
pub struct IncrementalSigner {
state: SignerState,
}
impl IncrementalSigner {
/// Returns a new incremental signer instance.
pub fn new() -> Self {
Self {
state: crypto_sign_init(),
}
}
/// Updates the state for this incremental signer with `message`.
pub fn update<Message: Bytes>(&mut self, message: &Message) {
crypto_sign_update(&mut self.state, message.as_slice())
}
/// Finalizes this incremental signer, returning the signature upon
/// success.
pub fn finalize<
Signature: NewByteArray<CRYPTO_SIGN_BYTES>,
SecretKey: ByteArray<CRYPTO_SIGN_SECRETKEYBYTES>,
>(
self,
secret_key: &SecretKey,
) -> Result<Signature, Error> {
let mut signature = Signature::new_byte_array();
crypto_sign_final_create(self.state, signature.as_mut_array(), secret_key.as_array())?;
Ok(signature)
}
/// Verifies `signature` as a valid signature for this signer.
pub fn verify<
Signature: ByteArray<CRYPTO_SIGN_BYTES>,
PublicKey: ByteArray<CRYPTO_SIGN_PUBLICKEYBYTES>,
>(
self,
signature: &Signature,
public_key: &PublicKey,
) -> Result<(), Error> {
crypto_sign_final_verify(self.state, signature.as_array(), public_key.as_array())?;
Ok(())
}
}
impl Default for IncrementalSigner {
fn default() -> Self {
Self::new()
}
}
impl<Signature: ByteArray<CRYPTO_SIGN_BYTES> + Zeroize, Message: Bytes + Zeroize>
SignedMessage<Signature, Message>
{
/// Verifies that this signed message is valid for `public_key`.
pub fn verify<PublicKey: ByteArray<CRYPTO_SIGN_PUBLICKEYBYTES>>(
&self,
public_key: &PublicKey,
) -> Result<(), Error> {
crypto_sign_verify_detached(
self.signature.as_array(),
self.message.as_slice(),
public_key.as_array(),
)
}
}
impl<
'a,
Signature: ByteArray<CRYPTO_SIGN_BYTES> + std::convert::TryFrom<&'a [u8]> + Zeroize,
Message: Bytes + From<&'a [u8]> + Zeroize,
> SignedMessage<Signature, Message>
{
/// Initializes a [`SignedMessage`] from a slice. Expects the first
/// [`CRYPTO_SIGN_BYTES`] bytes to contain the message signature,
/// with the remaining bytes containing the message.
pub fn from_bytes(bytes: &'a [u8]) -> Result<Self, Error> {
if bytes.len() < CRYPTO_SIGN_BYTES {
Err(dryoc_error!(format!(
"bytes of len {} less than expected minimum of {}",
bytes.len(),
CRYPTO_SIGN_BYTES
)))
} else {
let (signature, message) = bytes.split_at(CRYPTO_SIGN_BYTES);
Ok(Self {
signature: Signature::try_from(signature)
.map_err(|_e| dryoc_error!("invalid signature"))?,
message: Message::from(message),
})
}
}
}
impl<Signature: ByteArray<CRYPTO_SIGN_BYTES> + Zeroize, Message: Bytes + Zeroize>
SignedMessage<Signature, Message>
{
/// Returns a new box with `tag`, `data` and (optional) `ephemeral_pk`,
/// consuming each.
pub fn from_parts(signature: Signature, message: Message) -> Self {
Self { signature, message }
}
/// Copies `self` into a new [`Vec`]
pub fn to_vec(&self) -> Vec<u8> {
self.to_bytes()
}
/// Moves the tag, data, and (optional) ephemeral public key out of this
/// instance, returning them as a tuple.
pub fn into_parts(self) -> (Signature, Message) {
(self.signature, self.message)
}
/// Copies `self` into the target. Can be used with protected memory.
pub fn to_bytes<Bytes: NewBytes + ResizableBytes>(&self) -> Bytes {
let mut data = Bytes::new_bytes();
data.resize(self.signature.len() + self.message.len(), 0);
let s = data.as_mut_slice();
s[..CRYPTO_SIGN_BYTES].copy_from_slice(self.signature.as_slice());
s[CRYPTO_SIGN_BYTES..].copy_from_slice(self.message.as_slice());
data
}
}
impl<
PublicKey: ByteArray<CRYPTO_SIGN_PUBLICKEYBYTES> + Zeroize,
SecretKey: ByteArray<CRYPTO_SIGN_SECRETKEYBYTES> + Zeroize,
> PartialEq<SigningKeyPair<PublicKey, SecretKey>> for SigningKeyPair<PublicKey, SecretKey>
{
fn eq(&self, other: &Self) -> bool {
self.public_key
.as_slice()
.ct_eq(other.public_key.as_slice())
.unwrap_u8()
== 1
&& self
.secret_key
.as_slice()
.ct_eq(other.secret_key.as_slice())
.unwrap_u8()
== 1
}
}
impl<Signature: ByteArray<CRYPTO_SIGN_BYTES> + Zeroize, Message: Bytes + Zeroize>
PartialEq<SignedMessage<Signature, Message>> for SignedMessage<Signature, Message>
{
fn eq(&self, other: &Self) -> bool {
self.signature
.as_slice()
.ct_eq(other.signature.as_slice())
.unwrap_u8()
== 1
&& self
.message
.as_slice()
.ct_eq(other.message.as_slice())
.unwrap_u8()
== 1
}
}
#[cfg(test)]
mod tests {
use super::*;
#[test]
fn test_message_signing() {
let keypair = SigningKeyPair::gen_with_defaults();
let message = b"hello my frens";
let signed_message = keypair.sign_with_defaults(message).expect("signing failed");
signed_message
.verify(&keypair.public_key)
.expect("verification failed");
}
}