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
648
649
650
651
652
653
654
655
656
657
658
659
660
661
662
663
664
665
666
667
668
669
670
671
672
673
674
675
676
677
678
679
680
681
682
683
684
685
686
687
688
689
690
691
692
693
694
695
696
697
698
699
700
701
702
703
704
705
706
707
708
709
710
711
712
713
714
715
716
717
718
719
720
721
722
723
724
725
726
727
728
729
730
731
732
733
734
735
736
737
738
739
740
741
742
743
744
745
746
747
748
749
750
751
752
753
754
755
756
757
758
759
760
761
762
763
764
765
766
767
768
769
770
771
772
773
774
775
776
777
778
779
780
781
782
783
784
785
786
787
788
789
790
791
792
793
794
795
796
797
798
799
800
801
802
803
804
805
806
807
808
809
810
811
812
813
814
815
816
817
818
819
820
821
822
823
824
825
826
827
828
829
830
831
832
833
834
835
836
837
838
839
840
841
842
843
844
845
846
847
848
849
850
851
852
853
854
855
856
857
858
859
860
861
862
863
864
865
866
867
868
869
870
871
872
//! Message signatures.
//!
//! The `Signer` allows for the computation of cryptographic signatures of
//! data given a private key. The `Verifier` can then be used with the
//! corresponding public key to verify the integrity and authenticity of that
//! data given the signature.
//!
//! # Examples
//!
//! Sign and verify data given an RSA keypair:
//!
//! ```rust
//! use openssl::sign::{Signer, Verifier};
//! use openssl::rsa::Rsa;
//! use openssl::pkey::PKey;
//! use openssl::hash::MessageDigest;
//!
//! // Generate a keypair
//! let keypair = Rsa::generate(2048).unwrap();
//! let keypair = PKey::from_rsa(keypair).unwrap();
//!
//! let data = b"hello, world!";
//! let data2 = b"hola, mundo!";
//!
//! // Sign the data
//! let mut signer = Signer::new(MessageDigest::sha256(), &keypair).unwrap();
//! signer.update(data).unwrap();
//! signer.update(data2).unwrap();
//! let signature = signer.sign_to_vec().unwrap();
//!
//! // Verify the data
//! let mut verifier = Verifier::new(MessageDigest::sha256(), &keypair).unwrap();
//! verifier.update(data).unwrap();
//! verifier.update(data2).unwrap();
//! assert!(verifier.verify(&signature).unwrap());
//! ```
//!
//! Compute an HMAC:
//!
//! ```rust
//! use openssl::hash::MessageDigest;
//! use openssl::memcmp;
//! use openssl::pkey::PKey;
//! use openssl::sign::Signer;
//!
//! // Create a PKey
//! let key = PKey::hmac(b"my secret").unwrap();
//!
//! let data = b"hello, world!";
//! let data2 = b"hola, mundo!";
//!
//! // Compute the HMAC
//! let mut signer = Signer::new(MessageDigest::sha256(), &key).unwrap();
//! signer.update(data).unwrap();
//! signer.update(data2).unwrap();
//! let hmac = signer.sign_to_vec().unwrap();
//!
//! // `Verifier` cannot be used with HMACs; use the `memcmp::eq` function instead
//! //
//! // Do not simply check for equality with `==`!
//! # let target = hmac.clone();
//! assert!(memcmp::eq(&hmac, &target));
//! ```
use ffi;
use foreign_types::ForeignTypeRef;
use libc::c_int;
use std::io::{self, Write};
use std::marker::PhantomData;
use std::ptr;

use error::ErrorStack;
use hash::MessageDigest;
use pkey::{HasPrivate, HasPublic, PKeyRef};
use rsa::Padding;
use {cvt, cvt_p};

cfg_if! {
    if #[cfg(ossl110)] {
        use ffi::{EVP_MD_CTX_free, EVP_MD_CTX_new};
    } else {
        use ffi::{EVP_MD_CTX_create as EVP_MD_CTX_new, EVP_MD_CTX_destroy as EVP_MD_CTX_free};
    }
}

/// Salt lengths that must be used with `set_rsa_pss_saltlen`.
pub struct RsaPssSaltlen(c_int);

impl RsaPssSaltlen {
    /// Returns the integer representation of `RsaPssSaltlen`.
    fn as_raw(&self) -> c_int {
        self.0
    }

    /// Sets the salt length to the given value.
    pub fn custom(val: c_int) -> RsaPssSaltlen {
        RsaPssSaltlen(val)
    }

    /// The salt length is set to the digest length.
    /// Corresponds to the special value `-1`.
    pub const DIGEST_LENGTH: RsaPssSaltlen = RsaPssSaltlen(-1);
    /// The salt length is set to the maximum permissible value.
    /// Corresponds to the special value `-2`.
    pub const MAXIMUM_LENGTH: RsaPssSaltlen = RsaPssSaltlen(-2);
}

/// A type which computes cryptographic signatures of data.
pub struct Signer<'a> {
    md_ctx: *mut ffi::EVP_MD_CTX,
    pctx: *mut ffi::EVP_PKEY_CTX,
    _p: PhantomData<&'a ()>,
}

unsafe impl<'a> Sync for Signer<'a> {}
unsafe impl<'a> Send for Signer<'a> {}

impl<'a> Drop for Signer<'a> {
    fn drop(&mut self) {
        // pkey_ctx is owned by the md_ctx, so no need to explicitly free it.
        unsafe {
            EVP_MD_CTX_free(self.md_ctx);
        }
    }
}

#[allow(clippy::len_without_is_empty)]
impl<'a> Signer<'a> {
    /// Creates a new `Signer`.
    ///
    /// This cannot be used with Ed25519 or Ed448 keys. Please refer to
    /// `new_without_digest`.
    ///
    /// OpenSSL documentation at [`EVP_DigestSignInit`].
    ///
    /// [`EVP_DigestSignInit`]: https://www.openssl.org/docs/manmaster/man3/EVP_DigestSignInit.html
    pub fn new<T>(type_: MessageDigest, pkey: &'a PKeyRef<T>) -> Result<Signer<'a>, ErrorStack>
    where
        T: HasPrivate,
    {
        Self::new_intern(Some(type_), pkey)
    }

    /// Creates a new `Signer` without a digest.
    ///
    /// This is the only way to create a `Verifier` for Ed25519 or Ed448 keys.
    /// It can also be used to create a CMAC.
    ///
    /// OpenSSL documentation at [`EVP_DigestSignInit`].
    ///
    /// [`EVP_DigestSignInit`]: https://www.openssl.org/docs/manmaster/man3/EVP_DigestSignInit.html
    pub fn new_without_digest<T>(pkey: &'a PKeyRef<T>) -> Result<Signer<'a>, ErrorStack>
    where
        T: HasPrivate,
    {
        Self::new_intern(None, pkey)
    }

    fn new_intern<T>(
        type_: Option<MessageDigest>,
        pkey: &'a PKeyRef<T>,
    ) -> Result<Signer<'a>, ErrorStack>
    where
        T: HasPrivate,
    {
        unsafe {
            ffi::init();

            let ctx = cvt_p(EVP_MD_CTX_new())?;
            let mut pctx: *mut ffi::EVP_PKEY_CTX = ptr::null_mut();
            let r = ffi::EVP_DigestSignInit(
                ctx,
                &mut pctx,
                type_.map(|t| t.as_ptr()).unwrap_or(ptr::null()),
                ptr::null_mut(),
                pkey.as_ptr(),
            );
            if r != 1 {
                EVP_MD_CTX_free(ctx);
                return Err(ErrorStack::get());
            }

            assert!(!pctx.is_null());

            Ok(Signer {
                md_ctx: ctx,
                pctx,
                _p: PhantomData,
            })
        }
    }

    /// Returns the RSA padding mode in use.
    ///
    /// This is only useful for RSA keys.
    ///
    /// This corresponds to `EVP_PKEY_CTX_get_rsa_padding`.
    pub fn rsa_padding(&self) -> Result<Padding, ErrorStack> {
        unsafe {
            let mut pad = 0;
            cvt(ffi::EVP_PKEY_CTX_get_rsa_padding(self.pctx, &mut pad))
                .map(|_| Padding::from_raw(pad))
        }
    }

    /// Sets the RSA padding mode.
    ///
    /// This is only useful for RSA keys.
    ///
    /// This corresponds to [`EVP_PKEY_CTX_set_rsa_padding`].
    ///
    /// [`EVP_PKEY_CTX_set_rsa_padding`]: https://www.openssl.org/docs/man1.1.0/crypto/EVP_PKEY_CTX_set_rsa_padding.html
    pub fn set_rsa_padding(&mut self, padding: Padding) -> Result<(), ErrorStack> {
        unsafe {
            cvt(ffi::EVP_PKEY_CTX_set_rsa_padding(
                self.pctx,
                padding.as_raw(),
            ))
            .map(|_| ())
        }
    }

    /// Sets the RSA PSS salt length.
    ///
    /// This is only useful for RSA keys.
    ///
    /// This corresponds to [`EVP_PKEY_CTX_set_rsa_pss_saltlen`].
    ///
    /// [`EVP_PKEY_CTX_set_rsa_pss_saltlen`]: https://www.openssl.org/docs/man1.1.0/crypto/EVP_PKEY_CTX_set_rsa_pss_saltlen.html
    pub fn set_rsa_pss_saltlen(&mut self, len: RsaPssSaltlen) -> Result<(), ErrorStack> {
        unsafe {
            cvt(ffi::EVP_PKEY_CTX_set_rsa_pss_saltlen(
                self.pctx,
                len.as_raw(),
            ))
            .map(|_| ())
        }
    }

    /// Sets the RSA MGF1 algorithm.
    ///
    /// This is only useful for RSA keys.
    ///
    /// This corresponds to [`EVP_PKEY_CTX_set_rsa_mgf1_md`].
    ///
    /// [`EVP_PKEY_CTX_set_rsa_mgf1_md`]: https://www.openssl.org/docs/manmaster/man7/RSA-PSS.html
    pub fn set_rsa_mgf1_md(&mut self, md: MessageDigest) -> Result<(), ErrorStack> {
        unsafe {
            cvt(ffi::EVP_PKEY_CTX_set_rsa_mgf1_md(
                self.pctx,
                md.as_ptr() as *mut _,
            ))
            .map(|_| ())
        }
    }

    /// Feeds more data into the `Signer`.
    ///
    /// Please note that PureEdDSA (Ed25519 and Ed448 keys) do not support streaming.
    /// Use `sign_oneshot` instead.
    ///
    /// OpenSSL documentation at [`EVP_DigestUpdate`].
    ///
    /// [`EVP_DigestUpdate`]: https://www.openssl.org/docs/manmaster/man3/EVP_DigestInit.html
    pub fn update(&mut self, buf: &[u8]) -> Result<(), ErrorStack> {
        unsafe {
            cvt(ffi::EVP_DigestUpdate(
                self.md_ctx,
                buf.as_ptr() as *const _,
                buf.len(),
            ))
            .map(|_| ())
        }
    }

    /// Computes an upper bound on the signature length.
    ///
    /// The actual signature may be shorter than this value. Check the return value of
    /// `sign` to get the exact length.
    ///
    /// OpenSSL documentation at [`EVP_DigestSignFinal`].
    ///
    /// [`EVP_DigestSignFinal`]: https://www.openssl.org/docs/man1.1.0/crypto/EVP_DigestSignFinal.html
    pub fn len(&self) -> Result<usize, ErrorStack> {
        self.len_intern()
    }

    #[cfg(not(ossl111))]
    fn len_intern(&self) -> Result<usize, ErrorStack> {
        unsafe {
            let mut len = 0;
            cvt(ffi::EVP_DigestSignFinal(
                self.md_ctx,
                ptr::null_mut(),
                &mut len,
            ))?;
            Ok(len)
        }
    }

    #[cfg(ossl111)]
    fn len_intern(&self) -> Result<usize, ErrorStack> {
        unsafe {
            let mut len = 0;
            cvt(ffi::EVP_DigestSign(
                self.md_ctx,
                ptr::null_mut(),
                &mut len,
                ptr::null(),
                0,
            ))?;
            Ok(len)
        }
    }

    /// Writes the signature into the provided buffer, returning the number of bytes written.
    ///
    /// This method will fail if the buffer is not large enough for the signature. Use the `len`
    /// method to get an upper bound on the required size.
    ///
    /// OpenSSL documentation at [`EVP_DigestSignFinal`].
    ///
    /// [`EVP_DigestSignFinal`]: https://www.openssl.org/docs/man1.1.0/crypto/EVP_DigestSignFinal.html
    pub fn sign(&self, buf: &mut [u8]) -> Result<usize, ErrorStack> {
        unsafe {
            let mut len = buf.len();
            cvt(ffi::EVP_DigestSignFinal(
                self.md_ctx,
                buf.as_mut_ptr() as *mut _,
                &mut len,
            ))?;
            Ok(len)
        }
    }

    /// Returns the signature.
    ///
    /// This is a simple convenience wrapper over `len` and `sign`.
    pub fn sign_to_vec(&self) -> Result<Vec<u8>, ErrorStack> {
        let mut buf = vec![0; self.len()?];
        let len = self.sign(&mut buf)?;
        // The advertised length is not always equal to the real length for things like DSA
        buf.truncate(len);
        Ok(buf)
    }

    /// Signs the data in data_buf and writes the signature into the buffer sig_buf, returning the
    /// number of bytes written.
    ///
    /// For PureEdDSA (Ed25519 and Ed448 keys) this is the only way to sign data.
    ///
    /// This method will fail if the buffer is not large enough for the signature. Use the `len`
    /// method to get an upper bound on the required size.
    ///
    /// OpenSSL documentation at [`EVP_DigestSign`].
    ///
    /// [`EVP_DigestSign`]: https://www.openssl.org/docs/man1.1.1/man3/EVP_DigestSign.html
    #[cfg(ossl111)]
    pub fn sign_oneshot(
        &mut self,
        sig_buf: &mut [u8],
        data_buf: &[u8],
    ) -> Result<usize, ErrorStack> {
        unsafe {
            let mut sig_len = sig_buf.len();
            cvt(ffi::EVP_DigestSign(
                self.md_ctx,
                sig_buf.as_mut_ptr() as *mut _,
                &mut sig_len,
                data_buf.as_ptr() as *const _,
                data_buf.len(),
            ))?;
            Ok(sig_len)
        }
    }

    /// Returns the signature.
    ///
    /// This is a simple convenience wrapper over `len` and `sign_oneshot`.
    #[cfg(ossl111)]
    pub fn sign_oneshot_to_vec(&mut self, data_buf: &[u8]) -> Result<Vec<u8>, ErrorStack> {
        let mut sig_buf = vec![0; self.len()?];
        let len = self.sign_oneshot(&mut sig_buf, data_buf)?;
        // The advertised length is not always equal to the real length for things like DSA
        sig_buf.truncate(len);
        Ok(sig_buf)
    }
}

impl<'a> Write for Signer<'a> {
    fn write(&mut self, buf: &[u8]) -> io::Result<usize> {
        self.update(buf)?;
        Ok(buf.len())
    }

    fn flush(&mut self) -> io::Result<()> {
        Ok(())
    }
}

pub struct Verifier<'a> {
    md_ctx: *mut ffi::EVP_MD_CTX,
    pctx: *mut ffi::EVP_PKEY_CTX,
    pkey_pd: PhantomData<&'a ()>,
}

unsafe impl<'a> Sync for Verifier<'a> {}
unsafe impl<'a> Send for Verifier<'a> {}

impl<'a> Drop for Verifier<'a> {
    fn drop(&mut self) {
        // pkey_ctx is owned by the md_ctx, so no need to explicitly free it.
        unsafe {
            EVP_MD_CTX_free(self.md_ctx);
        }
    }
}

/// A type which verifies cryptographic signatures of data.
impl<'a> Verifier<'a> {
    /// Creates a new `Verifier`.
    ///
    /// This cannot be used with Ed25519 or Ed448 keys. Please refer to
    /// `new_without_digest`.
    ///
    /// OpenSSL documentation at [`EVP_DigestVerifyInit`].
    ///
    /// [`EVP_DigestVerifyInit`]: https://www.openssl.org/docs/manmaster/man3/EVP_DigestVerifyInit.html
    pub fn new<T>(type_: MessageDigest, pkey: &'a PKeyRef<T>) -> Result<Verifier<'a>, ErrorStack>
    where
        T: HasPublic,
    {
        Verifier::new_intern(Some(type_), pkey)
    }

    /// Creates a new `Verifier` without a digest.
    ///
    /// This is the only way to create a `Verifier` for Ed25519 or Ed448 keys.
    ///
    /// OpenSSL documentation at [`EVP_DigestVerifyInit`].
    ///
    /// [`EVP_DigestVerifyInit`]: https://www.openssl.org/docs/manmaster/man3/EVP_DigestVerifyInit.html
    pub fn new_without_digest<T>(pkey: &'a PKeyRef<T>) -> Result<Verifier<'a>, ErrorStack>
    where
        T: HasPublic,
    {
        Verifier::new_intern(None, pkey)
    }

    fn new_intern<T>(
        type_: Option<MessageDigest>,
        pkey: &'a PKeyRef<T>,
    ) -> Result<Verifier<'a>, ErrorStack>
    where
        T: HasPublic,
    {
        unsafe {
            ffi::init();

            let ctx = cvt_p(EVP_MD_CTX_new())?;
            let mut pctx: *mut ffi::EVP_PKEY_CTX = ptr::null_mut();
            let r = ffi::EVP_DigestVerifyInit(
                ctx,
                &mut pctx,
                type_.map(|t| t.as_ptr()).unwrap_or(ptr::null()),
                ptr::null_mut(),
                pkey.as_ptr(),
            );
            if r != 1 {
                EVP_MD_CTX_free(ctx);
                return Err(ErrorStack::get());
            }

            assert!(!pctx.is_null());

            Ok(Verifier {
                md_ctx: ctx,
                pctx,
                pkey_pd: PhantomData,
            })
        }
    }

    /// Returns the RSA padding mode in use.
    ///
    /// This is only useful for RSA keys.
    ///
    /// This corresponds to `EVP_PKEY_CTX_get_rsa_padding`.
    pub fn rsa_padding(&self) -> Result<Padding, ErrorStack> {
        unsafe {
            let mut pad = 0;
            cvt(ffi::EVP_PKEY_CTX_get_rsa_padding(self.pctx, &mut pad))
                .map(|_| Padding::from_raw(pad))
        }
    }

    /// Sets the RSA padding mode.
    ///
    /// This is only useful for RSA keys.
    ///
    /// This corresponds to [`EVP_PKEY_CTX_set_rsa_padding`].
    ///
    /// [`EVP_PKEY_CTX_set_rsa_padding`]: https://www.openssl.org/docs/man1.1.0/crypto/EVP_PKEY_CTX_set_rsa_padding.html
    pub fn set_rsa_padding(&mut self, padding: Padding) -> Result<(), ErrorStack> {
        unsafe {
            cvt(ffi::EVP_PKEY_CTX_set_rsa_padding(
                self.pctx,
                padding.as_raw(),
            ))
            .map(|_| ())
        }
    }

    /// Sets the RSA PSS salt length.
    ///
    /// This is only useful for RSA keys.
    ///
    /// This corresponds to [`EVP_PKEY_CTX_set_rsa_pss_saltlen`].
    ///
    /// [`EVP_PKEY_CTX_set_rsa_pss_saltlen`]: https://www.openssl.org/docs/man1.1.0/crypto/EVP_PKEY_CTX_set_rsa_pss_saltlen.html
    pub fn set_rsa_pss_saltlen(&mut self, len: RsaPssSaltlen) -> Result<(), ErrorStack> {
        unsafe {
            cvt(ffi::EVP_PKEY_CTX_set_rsa_pss_saltlen(
                self.pctx,
                len.as_raw(),
            ))
            .map(|_| ())
        }
    }

    /// Sets the RSA MGF1 algorithm.
    ///
    /// This is only useful for RSA keys.
    ///
    /// This corresponds to [`EVP_PKEY_CTX_set_rsa_mgf1_md`].
    ///
    /// [`EVP_PKEY_CTX_set_rsa_mgf1_md`]: https://www.openssl.org/docs/manmaster/man7/RSA-PSS.html
    pub fn set_rsa_mgf1_md(&mut self, md: MessageDigest) -> Result<(), ErrorStack> {
        unsafe {
            cvt(ffi::EVP_PKEY_CTX_set_rsa_mgf1_md(
                self.pctx,
                md.as_ptr() as *mut _,
            ))
            .map(|_| ())
        }
    }

    /// Feeds more data into the `Verifier`.
    ///
    /// Please note that PureEdDSA (Ed25519 and Ed448 keys) do not support streaming.
    /// Use `verify_oneshot` instead.
    ///
    /// OpenSSL documentation at [`EVP_DigestUpdate`].
    ///
    /// [`EVP_DigestUpdate`]: https://www.openssl.org/docs/manmaster/man3/EVP_DigestInit.html
    pub fn update(&mut self, buf: &[u8]) -> Result<(), ErrorStack> {
        unsafe {
            cvt(ffi::EVP_DigestUpdate(
                self.md_ctx,
                buf.as_ptr() as *const _,
                buf.len(),
            ))
            .map(|_| ())
        }
    }

    /// Determines if the data fed into the `Verifier` matches the provided signature.
    ///
    /// OpenSSL documentation at [`EVP_DigestVerifyFinal`].
    ///
    /// [`EVP_DigestVerifyFinal`]: https://www.openssl.org/docs/manmaster/man3/EVP_DigestVerifyFinal.html
    pub fn verify(&self, signature: &[u8]) -> Result<bool, ErrorStack> {
        unsafe {
            let r =
                EVP_DigestVerifyFinal(self.md_ctx, signature.as_ptr() as *mut _, signature.len());
            match r {
                1 => Ok(true),
                0 => {
                    ErrorStack::get(); // discard error stack
                    Ok(false)
                }
                _ => Err(ErrorStack::get()),
            }
        }
    }

    /// Determines if the data given in buf matches the provided signature.
    ///
    /// OpenSSL documentation at [`EVP_DigestVerify`].
    ///
    /// [`EVP_DigestVerify`]: https://www.openssl.org/docs/man1.1.1/man3/EVP_DigestVerify.html
    #[cfg(ossl111)]
    pub fn verify_oneshot(&mut self, signature: &[u8], buf: &[u8]) -> Result<bool, ErrorStack> {
        unsafe {
            let r = ffi::EVP_DigestVerify(
                self.md_ctx,
                signature.as_ptr() as *const _,
                signature.len(),
                buf.as_ptr() as *const _,
                buf.len(),
            );
            match r {
                1 => Ok(true),
                0 => {
                    ErrorStack::get();
                    Ok(false)
                }
                _ => Err(ErrorStack::get()),
            }
        }
    }
}

impl<'a> Write for Verifier<'a> {
    fn write(&mut self, buf: &[u8]) -> io::Result<usize> {
        self.update(buf)?;
        Ok(buf.len())
    }

    fn flush(&mut self) -> io::Result<()> {
        Ok(())
    }
}

#[cfg(not(ossl101))]
use ffi::EVP_DigestVerifyFinal;

#[cfg(ossl101)]
#[allow(bad_style)]
unsafe fn EVP_DigestVerifyFinal(
    ctx: *mut ffi::EVP_MD_CTX,
    sigret: *const ::libc::c_uchar,
    siglen: ::libc::size_t,
) -> ::libc::c_int {
    ffi::EVP_DigestVerifyFinal(ctx, sigret as *mut _, siglen)
}

#[cfg(test)]
mod test {
    use hex::{self, FromHex};
    use std::iter;

    use ec::{EcGroup, EcKey};
    use hash::MessageDigest;
    use nid::Nid;
    use pkey::PKey;
    use rsa::{Padding, Rsa};
    use sign::{RsaPssSaltlen, Signer, Verifier};

    const INPUT: &str =
        "65794a68624763694f694a53557a49314e694a392e65794a7063334d694f694a71623255694c41304b49434a6c\
         654841694f6a457a4d4441344d546b7a4f44417344516f67496d6830644841364c79396c654746746347786c4c\
         6d4e76625339706331397962323930496a7030636e566c6651";

    const SIGNATURE: &str =
        "702e218943e88fd11eb5d82dbf7845f34106ae1b81fff7731116add1717d83656d420afd3c96eedd73a2663e51\
         66687b000b87226e0187ed1073f945e582adfcef16d85a798ee8c66ddb3db8975b17d09402beedd5d9d9700710\
         8db28160d5f8040ca7445762b81fbe7ff9d92e0ae76f24f25b33bbe6f44ae61eb1040acb20044d3ef9128ed401\
         30795bd4bd3b41eecad066ab651981fde48df77f372dc38b9fafdd3befb18b5da3cc3c2eb02f9e3a41d612caad\
         15911273a05f23b9e838faaf849d698429ef5a1e88798236c3d40e604522a544c8f27a7a2db80663d16cf7caea\
         56de405cb2215a45b2c25566b55ac1a748a070dfc8a32a469543d019eefb47";

    #[test]
    fn rsa_sign() {
        let key = include_bytes!("../test/rsa.pem");
        let private_key = Rsa::private_key_from_pem(key).unwrap();
        let pkey = PKey::from_rsa(private_key).unwrap();

        let mut signer = Signer::new(MessageDigest::sha256(), &pkey).unwrap();
        assert_eq!(signer.rsa_padding().unwrap(), Padding::PKCS1);
        signer.set_rsa_padding(Padding::PKCS1).unwrap();
        signer.update(&Vec::from_hex(INPUT).unwrap()).unwrap();
        let result = signer.sign_to_vec().unwrap();

        assert_eq!(hex::encode(result), SIGNATURE);
    }

    #[test]
    fn rsa_verify_ok() {
        let key = include_bytes!("../test/rsa.pem");
        let private_key = Rsa::private_key_from_pem(key).unwrap();
        let pkey = PKey::from_rsa(private_key).unwrap();

        let mut verifier = Verifier::new(MessageDigest::sha256(), &pkey).unwrap();
        assert_eq!(verifier.rsa_padding().unwrap(), Padding::PKCS1);
        verifier.update(&Vec::from_hex(INPUT).unwrap()).unwrap();
        assert!(verifier.verify(&Vec::from_hex(SIGNATURE).unwrap()).unwrap());
    }

    #[test]
    fn rsa_verify_invalid() {
        let key = include_bytes!("../test/rsa.pem");
        let private_key = Rsa::private_key_from_pem(key).unwrap();
        let pkey = PKey::from_rsa(private_key).unwrap();

        let mut verifier = Verifier::new(MessageDigest::sha256(), &pkey).unwrap();
        verifier.update(&Vec::from_hex(INPUT).unwrap()).unwrap();
        verifier.update(b"foobar").unwrap();
        assert!(!verifier.verify(&Vec::from_hex(SIGNATURE).unwrap()).unwrap());
    }

    fn test_hmac(ty: MessageDigest, tests: &[(Vec<u8>, Vec<u8>, Vec<u8>)]) {
        for &(ref key, ref data, ref res) in tests.iter() {
            let pkey = PKey::hmac(key).unwrap();
            let mut signer = Signer::new(ty, &pkey).unwrap();
            signer.update(data).unwrap();
            assert_eq!(signer.sign_to_vec().unwrap(), *res);
        }
    }

    #[test]
    fn hmac_md5() {
        // test vectors from RFC 2202
        let tests: [(Vec<u8>, Vec<u8>, Vec<u8>); 7] = [
            (
                iter::repeat(0x0b_u8).take(16).collect(),
                b"Hi There".to_vec(),
                Vec::from_hex("9294727a3638bb1c13f48ef8158bfc9d").unwrap(),
            ),
            (
                b"Jefe".to_vec(),
                b"what do ya want for nothing?".to_vec(),
                Vec::from_hex("750c783e6ab0b503eaa86e310a5db738").unwrap(),
            ),
            (
                iter::repeat(0xaa_u8).take(16).collect(),
                iter::repeat(0xdd_u8).take(50).collect(),
                Vec::from_hex("56be34521d144c88dbb8c733f0e8b3f6").unwrap(),
            ),
            (
                Vec::from_hex("0102030405060708090a0b0c0d0e0f10111213141516171819").unwrap(),
                iter::repeat(0xcd_u8).take(50).collect(),
                Vec::from_hex("697eaf0aca3a3aea3a75164746ffaa79").unwrap(),
            ),
            (
                iter::repeat(0x0c_u8).take(16).collect(),
                b"Test With Truncation".to_vec(),
                Vec::from_hex("56461ef2342edc00f9bab995690efd4c").unwrap(),
            ),
            (
                iter::repeat(0xaa_u8).take(80).collect(),
                b"Test Using Larger Than Block-Size Key - Hash Key First".to_vec(),
                Vec::from_hex("6b1ab7fe4bd7bf8f0b62e6ce61b9d0cd").unwrap(),
            ),
            (
                iter::repeat(0xaa_u8).take(80).collect(),
                b"Test Using Larger Than Block-Size Key \
              and Larger Than One Block-Size Data"
                    .to_vec(),
                Vec::from_hex("6f630fad67cda0ee1fb1f562db3aa53e").unwrap(),
            ),
        ];

        test_hmac(MessageDigest::md5(), &tests);
    }

    #[test]
    fn hmac_sha1() {
        // test vectors from RFC 2202
        let tests: [(Vec<u8>, Vec<u8>, Vec<u8>); 7] = [
            (
                iter::repeat(0x0b_u8).take(20).collect(),
                b"Hi There".to_vec(),
                Vec::from_hex("b617318655057264e28bc0b6fb378c8ef146be00").unwrap(),
            ),
            (
                b"Jefe".to_vec(),
                b"what do ya want for nothing?".to_vec(),
                Vec::from_hex("effcdf6ae5eb2fa2d27416d5f184df9c259a7c79").unwrap(),
            ),
            (
                iter::repeat(0xaa_u8).take(20).collect(),
                iter::repeat(0xdd_u8).take(50).collect(),
                Vec::from_hex("125d7342b9ac11cd91a39af48aa17b4f63f175d3").unwrap(),
            ),
            (
                Vec::from_hex("0102030405060708090a0b0c0d0e0f10111213141516171819").unwrap(),
                iter::repeat(0xcd_u8).take(50).collect(),
                Vec::from_hex("4c9007f4026250c6bc8414f9bf50c86c2d7235da").unwrap(),
            ),
            (
                iter::repeat(0x0c_u8).take(20).collect(),
                b"Test With Truncation".to_vec(),
                Vec::from_hex("4c1a03424b55e07fe7f27be1d58bb9324a9a5a04").unwrap(),
            ),
            (
                iter::repeat(0xaa_u8).take(80).collect(),
                b"Test Using Larger Than Block-Size Key - Hash Key First".to_vec(),
                Vec::from_hex("aa4ae5e15272d00e95705637ce8a3b55ed402112").unwrap(),
            ),
            (
                iter::repeat(0xaa_u8).take(80).collect(),
                b"Test Using Larger Than Block-Size Key \
              and Larger Than One Block-Size Data"
                    .to_vec(),
                Vec::from_hex("e8e99d0f45237d786d6bbaa7965c7808bbff1a91").unwrap(),
            ),
        ];

        test_hmac(MessageDigest::sha1(), &tests);
    }

    #[test]
    #[cfg(ossl110)]
    fn test_cmac() {
        let cipher = ::symm::Cipher::aes_128_cbc();
        let key = Vec::from_hex("9294727a3638bb1c13f48ef8158bfc9d").unwrap();
        let pkey = PKey::cmac(&cipher, &key).unwrap();
        let mut signer = Signer::new_without_digest(&pkey).unwrap();

        let data = b"Hi There";
        signer.update(data as &[u8]).unwrap();

        let expected = vec![
            136, 101, 61, 167, 61, 30, 248, 234, 124, 166, 196, 157, 203, 52, 171, 19,
        ];
        assert_eq!(signer.sign_to_vec().unwrap(), expected);
    }

    #[test]
    fn ec() {
        let group = EcGroup::from_curve_name(Nid::X9_62_PRIME256V1).unwrap();
        let key = EcKey::generate(&group).unwrap();
        let key = PKey::from_ec_key(key).unwrap();

        let mut signer = Signer::new(MessageDigest::sha256(), &key).unwrap();
        signer.update(b"hello world").unwrap();
        let signature = signer.sign_to_vec().unwrap();

        let mut verifier = Verifier::new(MessageDigest::sha256(), &key).unwrap();
        verifier.update(b"hello world").unwrap();
        assert!(verifier.verify(&signature).unwrap());
    }

    #[test]
    #[cfg(ossl111)]
    fn eddsa() {
        let key = PKey::generate_ed25519().unwrap();

        let mut signer = Signer::new_without_digest(&key).unwrap();
        let signature = signer.sign_oneshot_to_vec(b"hello world").unwrap();

        let mut verifier = Verifier::new_without_digest(&key).unwrap();
        assert!(verifier.verify_oneshot(&signature, b"hello world").unwrap());
    }

    #[test]
    #[cfg(ossl111)]
    fn rsa_sign_verify() {
        let key = include_bytes!("../test/rsa.pem");
        let private_key = Rsa::private_key_from_pem(key).unwrap();
        let pkey = PKey::from_rsa(private_key).unwrap();

        let mut signer = Signer::new(MessageDigest::sha256(), &pkey).unwrap();
        signer.set_rsa_padding(Padding::PKCS1_PSS).unwrap();
        assert_eq!(signer.rsa_padding().unwrap(), Padding::PKCS1_PSS);
        signer
            .set_rsa_pss_saltlen(RsaPssSaltlen::DIGEST_LENGTH)
            .unwrap();
        signer.set_rsa_mgf1_md(MessageDigest::sha256()).unwrap();
        signer.update(&Vec::from_hex(INPUT).unwrap()).unwrap();
        let signature = signer.sign_to_vec().unwrap();

        let mut verifier = Verifier::new(MessageDigest::sha256(), &pkey).unwrap();
        verifier.set_rsa_padding(Padding::PKCS1_PSS).unwrap();
        verifier
            .set_rsa_pss_saltlen(RsaPssSaltlen::DIGEST_LENGTH)
            .unwrap();
        verifier.set_rsa_mgf1_md(MessageDigest::sha256()).unwrap();
        verifier.update(&Vec::from_hex(INPUT).unwrap()).unwrap();
        assert!(verifier.verify(&signature).unwrap());
    }
}