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
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569
570
571
572
573
574
575
576
577
578
579
580
581
582
583
584
585
586
587
588
589
590
591
592
593
594
595
596
597
598
599
600
601
602
603
604
605
606
607
608
609
610
611
612
613
614
615
616
617
618
619
620
621
622
623
624
625
626
627
628
629
630
631
632
633
634
635
636
637
638
639
640
641
642
643
644
645
646
647
use core::fmt::Debug;
#[cfg(feature = "std")]
use rand::Rng;
use digest::BlockInput;
use digest::Digest;
use digest::Input;
use digest::FixedOutput;
use generic_array::typenum::U64;
use curve25519_dalek::constants;
use curve25519_dalek::curve::CompressedEdwardsY;
use curve25519_dalek::curve::ExtendedPoint;
use curve25519_dalek::scalar::Scalar;
use subtle::slices_equal;
pub const SIGNATURE_LENGTH: usize = 64;
pub const SECRET_KEY_LENGTH: usize = 32;
pub const PUBLIC_KEY_LENGTH: usize = 32;
#[derive(Copy)]
#[repr(C)]
pub struct Signature(pub [u8; SIGNATURE_LENGTH]);
impl Clone for Signature {
fn clone(&self) -> Self { *self }
}
impl Debug for Signature {
fn fmt(&self, f: &mut ::core::fmt::Formatter) -> ::core::fmt::Result {
write!(f, "Signature([{:?}])", &self.0[..])
}
}
impl Eq for Signature {}
impl PartialEq for Signature {
fn eq(&self, other: &Signature) -> bool {
let mut equal: u8 = 0;
for i in 0..64 {
equal |= self.0[i] ^ other.0[i];
}
if equal == 0 {
return true;
} else {
return false;
}
}
}
impl Signature {
#[inline]
pub fn to_bytes(&self) -> [u8; SIGNATURE_LENGTH] {
self.0
}
#[inline]
pub fn as_bytes<'a>(&'a self) -> &'a [u8; SIGNATURE_LENGTH] {
&self.0
}
#[inline]
pub fn from_bytes(bytes: &[u8]) -> Signature {
Signature(*array_ref!(bytes, 0, SIGNATURE_LENGTH))
}
}
#[repr(C)]
pub struct SecretKey(pub [u8; SECRET_KEY_LENGTH]);
impl Debug for SecretKey {
fn fmt(&self, f: &mut ::core::fmt::Formatter) -> ::core::fmt::Result {
write!(f, "SecretKey: {:?}", &self.0[..])
}
}
impl SecretKey {
#[inline]
pub fn to_bytes(&self) -> [u8; SECRET_KEY_LENGTH] {
self.0
}
#[inline]
pub fn as_bytes<'a>(&'a self) -> &'a [u8; SECRET_KEY_LENGTH] {
&self.0
}
#[inline]
pub fn from_bytes(bytes: &[u8]) -> SecretKey {
SecretKey(*array_ref!(bytes, 0, SECRET_KEY_LENGTH))
}
#[cfg(feature = "std")]
pub fn generate(csprng: &mut Rng) -> SecretKey {
let mut sk: SecretKey = SecretKey([0u8; 32]);
csprng.fill_bytes(&mut sk.0);
sk
}
}
#[derive(Copy, Clone)]
#[repr(C)]
pub struct PublicKey(pub CompressedEdwardsY);
impl Debug for PublicKey {
fn fmt(&self, f: &mut ::core::fmt::Formatter) -> ::core::fmt::Result {
write!(f, "PublicKey( CompressedPoint( {:?} ))", self.0)
}
}
impl PublicKey {
#[inline]
pub fn to_bytes(&self) -> [u8; PUBLIC_KEY_LENGTH] {
self.0.to_bytes()
}
#[inline]
pub fn as_bytes<'a>(&'a self) -> &'a [u8; PUBLIC_KEY_LENGTH] {
&(self.0).0
}
#[inline]
pub fn from_bytes(bytes: &[u8]) -> PublicKey {
PublicKey(CompressedEdwardsY(*array_ref!(bytes, 0, 32)))
}
#[inline]
fn decompress(&self) -> Option<ExtendedPoint> {
self.0.decompress()
}
#[cfg(feature = "std")]
#[allow(unused_assignments)]
pub fn from_secret<D>(secret_key: &SecretKey) -> PublicKey
where D: Digest<OutputSize = U64> + Default {
let mut h: D = D::default();
let mut hash: [u8; 64] = [0u8; 64];
let pk: [u8; 32];
let mut digest: &mut [u8; 32];
h.input(secret_key.as_bytes());
hash.copy_from_slice(h.fixed_result().as_slice());
digest = array_mut_ref!(&mut hash, 0, 32);
digest[0] &= 248;
digest[31] &= 127;
digest[31] |= 64;
pk = (&Scalar(*digest) * &constants::ED25519_BASEPOINT).compress_edwards().to_bytes();
PublicKey(CompressedEdwardsY(pk))
}
pub fn verify<D>(&self, message: &[u8], signature: &Signature) -> bool
where D: Digest<OutputSize = U64> + Default {
let mut h: D = D::default();
let mut a: ExtendedPoint;
let ao: Option<ExtendedPoint>;
let r: ExtendedPoint;
let digest: [u8; 64];
let digest_reduced: Scalar;
if signature.0[63] & 224 != 0 {
return false;
}
ao = self.decompress();
if ao.is_some() {
a = ao.unwrap();
} else {
return false;
}
a = -(&a);
let top_half: &[u8; 32] = array_ref!(&signature.0, 32, 32);
let bottom_half: &[u8; 32] = array_ref!(&signature.0, 0, 32);
h.input(&bottom_half[..]);
h.input(&self.to_bytes());
h.input(&message);
let digest_bytes = h.fixed_result();
digest = *array_ref!(digest_bytes, 0, 64);
digest_reduced = Scalar::reduce(&digest);
r = &(&digest_reduced * &a) + &(&Scalar(*top_half) * &constants::ED25519_BASEPOINT);
if slices_equal(bottom_half, &r.compress_edwards().to_bytes()) == 1 {
return true
} else {
return false
}
}
}
#[derive(Debug)]
#[repr(C)]
pub struct Keypair {
pub public: PublicKey,
pub secret: SecretKey,
}
impl Keypair {
pub fn from_bytes<'a>(public: &'a [u8; 32], secret: &'a [u8; 32]) -> Keypair {
Keypair{ public: PublicKey::from_bytes(public),
secret: SecretKey::from_bytes(secret), }
}
#[cfg(feature = "std")]
pub fn generate<D>(csprng: &mut Rng) -> Keypair
where D: Digest<OutputSize = U64> + Default {
let sk: SecretKey = SecretKey::generate(csprng);
let pk: PublicKey = PublicKey::from_secret::<D>(&sk);
Keypair{ public: pk, secret: sk }
}
pub fn sign<D>(&self, message: &[u8]) -> Signature
where D: Digest<OutputSize = U64> + Default {
let mut h: D = D::default();
let mut hash: [u8; 64] = [0u8; 64];
let mut signature_bytes: [u8; 64] = [0u8; SIGNATURE_LENGTH];
let mut expanded_key_secret: Scalar;
let mesg_digest: Scalar;
let hram_digest: Scalar;
let r: ExtendedPoint;
let s: Scalar;
let t: CompressedEdwardsY;
let secret_key: &[u8; 32] = self.secret.as_bytes();
let public_key: &[u8; 32] = self.public.as_bytes();
h.input(secret_key);
hash.copy_from_slice(h.fixed_result().as_slice());
expanded_key_secret = Scalar(*array_ref!(&hash, 0, 32));
expanded_key_secret[0] &= 248;
expanded_key_secret[31] &= 63;
expanded_key_secret[31] |= 64;
h = D::default();
h.input(&hash[32..]);
h.input(&message);
hash.copy_from_slice(h.fixed_result().as_slice());
mesg_digest = Scalar::reduce(&hash);
r = &mesg_digest * &constants::ED25519_BASEPOINT;
h = D::default();
h.input(&r.compress_edwards().to_bytes()[..]);
h.input(public_key);
h.input(&message);
hash.copy_from_slice(h.fixed_result().as_slice());
hram_digest = Scalar::reduce(&hash);
s = Scalar::multiply_add(&hram_digest, &expanded_key_secret, &mesg_digest);
t = r.compress_edwards();
signature_bytes[..32].copy_from_slice(&t.0);
signature_bytes[32..64].copy_from_slice(&s.0);
Signature(*array_ref!(&signature_bytes, 0, 64))
}
pub fn verify<D>(&self, message: &[u8], signature: &Signature) -> bool
where D: FixedOutput<OutputSize = U64> + BlockInput + Default + Input {
self.public.verify::<D>(message, signature)
}
}
#[cfg(test)]
mod test {
use std::io::BufReader;
use std::io::BufRead;
use std::fs::File;
use std::string::String;
use std::vec::Vec;
use curve25519_dalek::curve::ExtendedPoint;
use rand::OsRng;
use rustc_serialize::hex::FromHex;
use sha2::Sha512;
use super::*;
#[test]
fn unmarshal_marshal() {
let mut cspring: OsRng;
let mut keypair: Keypair;
let mut x: Option<ExtendedPoint>;
let a: ExtendedPoint;
let public: PublicKey;
cspring = OsRng::new().unwrap();
loop {
keypair = Keypair::generate::<Sha512>(&mut cspring);
x = keypair.public.decompress();
if x.is_some() {
a = x.unwrap();
break;
}
}
public = PublicKey(a.compress_edwards());
assert!(keypair.public.0 == public.0);
}
#[test]
fn sign_verify() {
let mut cspring: OsRng;
let keypair: Keypair;
let good_sig: Signature;
let bad_sig: Signature;
let good: &[u8] = "test message".as_bytes();
let bad: &[u8] = "wrong message".as_bytes();
cspring = OsRng::new().unwrap();
keypair = Keypair::generate::<Sha512>(&mut cspring);
good_sig = keypair.sign::<Sha512>(&good);
bad_sig = keypair.sign::<Sha512>(&bad);
assert!(keypair.verify::<Sha512>(&good, &good_sig) == true,
"Verification of a valid signature failed!");
assert!(keypair.verify::<Sha512>(&good, &bad_sig) == false,
"Verification of a signature on a different message passed!");
assert!(keypair.verify::<Sha512>(&bad, &good_sig) == false,
"Verification of a signature on a different message passed!");
}
#[cfg(test)]
#[cfg(not(release))]
#[test]
fn golden() {
let mut line: String;
let mut lineno: usize = 0;
let f = File::open("TESTVECTORS");
if f.is_err() {
println!("This test is only available when the code has been cloned \
from the git repository, since the TESTVECTORS file is large \
and is therefore not included within the distributed crate.");
panic!();
}
let file = BufReader::new(f.unwrap());
for l in file.lines() {
lineno += 1;
line = l.unwrap();
let parts: Vec<&str> = line.split(':').collect();
assert_eq!(parts.len(), 5, "wrong number of fields in line {}", lineno);
let sec_bytes: &[u8] = &parts[0].from_hex().unwrap();
let pub_bytes: &[u8] = &parts[1].from_hex().unwrap();
let message: &[u8] = &parts[2].from_hex().unwrap();
let sig_bytes: &[u8] = &parts[3].from_hex().unwrap();
let sig1: Signature = Signature::from_bytes(sig_bytes);
let keypair: Keypair = Keypair::from_bytes(
array_ref!(*pub_bytes, 0, PUBLIC_KEY_LENGTH),
array_ref!(*sec_bytes, 0, SECRET_KEY_LENGTH));
let sig2: Signature = keypair.sign::<Sha512>(&message);
assert!(sig1 == sig2, "Signature bytes not equal on line {}", lineno);
assert!(keypair.verify::<Sha512>(&message, &sig2),
"Signature verification failed on line {}", lineno);
}
}
}
#[cfg(all(test, feature = "bench"))]
mod bench {
use test::Bencher;
use rand::OsRng;
use sha2::Sha512;
use super::*;
struct ZeroRng;
impl ZeroRng {
pub fn new() -> ZeroRng {
ZeroRng
}
}
impl Rng for ZeroRng {
fn next_u32(&mut self) -> u32 { 0u32 }
fn fill_bytes(&mut self, bytes: &mut [u8]) {
for i in 0 .. bytes.len() {
bytes[i] = 0;
}
}
}
#[bench]
fn sign(b: &mut Bencher) {
let mut cspring: OsRng = OsRng::new().unwrap();
let keypair: Keypair = Keypair::generate::<Sha512>(&mut cspring);
let msg: &[u8] = b"";
b.iter(| | keypair.sign::<Sha512>(msg));
}
#[bench]
fn verify(b: &mut Bencher) {
let mut cspring: OsRng = OsRng::new().unwrap();
let keypair: Keypair = Keypair::generate::<Sha512>(&mut cspring);
let msg: &[u8] = b"";
let sig: Signature = keypair.sign::<Sha512>(msg);
b.iter(| | keypair.verify::<Sha512>(msg, &sig));
}
#[bench]
fn key_generation(b: &mut Bencher) {
let mut rng: ZeroRng = ZeroRng::new();
b.iter(| | Keypair::generate::<Sha512>(&mut rng));
}
}