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
873
874
875
876
877
878
879
880
881
882
883
//! This crate provides types for representing X.509 certificates, keys and other types as
//! commonly used in the rustls ecosystem. It is intended to be used by crates that need to work
//! with such X.509 types, such as [rustls](https://crates.io/crates/rustls),
//! [rustls-webpki](https://crates.io/crates/rustls-webpki),
//! [rustls-pemfile](https://crates.io/crates/rustls-pemfile), and others.
//!
//! Some of these crates used to define their own trivial wrappers around DER-encoded bytes.
//! However, in order to avoid inconvenient dependency edges, these were all disconnected. By
//! using a common low-level crate of types with long-term stable API, we hope to avoid the
//! downsides of unnecessary dependency edges while providing good interoperability between crates.
//!
//! ## DER and PEM
//!
//! Many of the types defined in this crate represent DER-encoded data. DER is a binary encoding of
//! the ASN.1 format commonly used in web PKI specifications. It is a binary encoding, so it is
//! relatively compact when stored in memory. However, as a binary format, it is not very easy to
//! work with for humans and in contexts where binary data is inconvenient. For this reason,
//! many tools and protocols use a ASCII-based encoding of DER, called PEM. In addition to the
//! base64-encoded DER, PEM objects are delimited by header and footer lines which indicate the type
//! of object contained in the PEM blob.
//!
//! The [rustls-pemfile](https://docs.rs/rustls-pemfile) crate can be used to parse PEM files.
//!
//! ## Creating new certificates and keys
//!
//! This crate does not provide any functionality for creating new certificates or keys. However,
//! the [rcgen](https://docs.rs/rcgen) crate can be used to create new certificates and keys.
//!
//! ## Cloning private keys
//!
//! This crate intentionally **does not** implement `Clone` on private key types in
//! order to minimize the exposure of private key data in memory.
//!
//! If you want to extend the lifetime of a `PrivateKeyDer<'_>`, consider [`PrivateKeyDer::clone_key()`].
//! Alternatively  since these types are immutable, consider wrapping the `PrivateKeyDer<'_>` in a [`Rc`]
//! or an [`Arc`].
//!
//! [`Rc`]: https://doc.rust-lang.org/std/rc/struct.Rc.html
//! [`Arc`]: https://doc.rust-lang.org/std/sync/struct.Arc.html
//! [`PrivateKeyDer::clone_key()`]: https://docs.rs/rustls-pki-types/latest/rustls_pki_types/enum.PrivateKeyDer.html#method.clone_key
//!
//! ## Target `wasm32-unknown-unknown` with the `web` feature
//!
//! [`std::time::SystemTime`](https://doc.rust-lang.org/std/time/struct.SystemTime.html)
//! is unavailable in `wasm32-unknown-unknown` targets, so calls to
//! [`UnixTime::now()`](https://docs.rs/rustls-pki-types/latest/rustls_pki_types/struct.UnixTime.html#method.now),
//! otherwise enabled by the [`std`](https://docs.rs/crate/rustls-pki-types/latest/features#std) feature,
//! require building instead with the [`web`](https://docs.rs/crate/rustls-pki-types/latest/features#web)
//! feature. It gets time by calling [`Date.now()`](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Date/now)
//! in the browser.

#![cfg_attr(not(feature = "std"), no_std)]
#![warn(unreachable_pub, clippy::use_self)]
#![deny(missing_docs)]
#![cfg_attr(docsrs, feature(doc_cfg, doc_auto_cfg))]

#[cfg(feature = "alloc")]
extern crate alloc;

#[cfg(feature = "alloc")]
use alloc::vec::Vec;
use core::fmt;
use core::ops::Deref;
use core::time::Duration;
#[cfg(all(
    feature = "std",
    not(all(target_family = "wasm", target_os = "unknown"))
))]
use std::time::SystemTime;
#[cfg(all(target_family = "wasm", target_os = "unknown", feature = "web"))]
use web_time::SystemTime;

mod server_name;
pub use server_name::{
    AddrParseError, DnsName, InvalidDnsNameError, IpAddr, Ipv4Addr, Ipv6Addr, ServerName,
};

/// A DER-encoded X.509 private key, in one of several formats
///
/// See variant inner types for more detailed information.
#[non_exhaustive]
#[derive(Debug, PartialEq, Eq)]
pub enum PrivateKeyDer<'a> {
    /// An RSA private key
    Pkcs1(PrivatePkcs1KeyDer<'a>),
    /// A Sec1 private key
    Sec1(PrivateSec1KeyDer<'a>),
    /// A PKCS#8 private key
    Pkcs8(PrivatePkcs8KeyDer<'a>),
}

impl<'a> PrivateKeyDer<'a> {
    /// Clone the private key to a `'static` value
    #[cfg(feature = "alloc")]
    pub fn clone_key(&self) -> PrivateKeyDer<'static> {
        use PrivateKeyDer::*;
        match self {
            Pkcs1(key) => Pkcs1(key.clone_key()),
            Sec1(key) => Sec1(key.clone_key()),
            Pkcs8(key) => Pkcs8(key.clone_key()),
        }
    }

    /// Yield the DER-encoded bytes of the private key
    pub fn secret_der(&self) -> &[u8] {
        match self {
            PrivateKeyDer::Pkcs1(key) => key.secret_pkcs1_der(),
            PrivateKeyDer::Sec1(key) => key.secret_sec1_der(),
            PrivateKeyDer::Pkcs8(key) => key.secret_pkcs8_der(),
        }
    }
}

impl<'a> From<PrivatePkcs1KeyDer<'a>> for PrivateKeyDer<'a> {
    fn from(key: PrivatePkcs1KeyDer<'a>) -> Self {
        Self::Pkcs1(key)
    }
}

impl<'a> From<PrivateSec1KeyDer<'a>> for PrivateKeyDer<'a> {
    fn from(key: PrivateSec1KeyDer<'a>) -> Self {
        Self::Sec1(key)
    }
}

impl<'a> From<PrivatePkcs8KeyDer<'a>> for PrivateKeyDer<'a> {
    fn from(key: PrivatePkcs8KeyDer<'a>) -> Self {
        Self::Pkcs8(key)
    }
}

impl<'a> TryFrom<&'a [u8]> for PrivateKeyDer<'a> {
    type Error = &'static str;

    fn try_from(key: &'a [u8]) -> Result<Self, Self::Error> {
        const SHORT_FORM_LEN_MAX: u8 = 128;
        const TAG_SEQUENCE: u8 = 0x30;
        const TAG_INTEGER: u8 = 0x02;

        // We expect all key formats to begin with a SEQUENCE, which requires at least 2 bytes
        // in the short length encoding.
        if key.first() != Some(&TAG_SEQUENCE) || key.len() < 2 {
            return Err(INVALID_KEY_DER_ERR);
        }

        // The length of the SEQUENCE is encoded in the second byte. We must skip this many bytes.
        let skip_len = match key[1] >= SHORT_FORM_LEN_MAX {
            // 1 byte for SEQUENCE tag, 1 byte for short-form len
            false => 2,
            // 1 byte for SEQUENCE tag, 1 byte for start of len, remaining bytes encoded
            // in key[1].
            true => 2 + (key[1] - SHORT_FORM_LEN_MAX) as usize,
        };
        let key_bytes = key.get(skip_len..).ok_or(INVALID_KEY_DER_ERR)?;

        // PKCS#8 (https://www.rfc-editor.org/rfc/rfc5208) describes the PrivateKeyInfo
        // structure as:
        //   PrivateKeyInfo ::= SEQUENCE {
        //      version Version,
        //      privateKeyAlgorithm AlgorithmIdentifier {{PrivateKeyAlgorithms}},
        //      privateKey PrivateKey,
        //      attributes [0] Attributes OPTIONAL
        //   }
        // PKCS#5 (https://www.rfc-editor.org/rfc/rfc8018) describes the AlgorithmIdentifier
        // as a SEQUENCE.
        //
        // Therefore, we consider the outer SEQUENCE, a version number, and the start of
        // an AlgorithmIdentifier to be enough to identify a PKCS#8 key. If it were PKCS#1 or SEC1
        // the version would not be followed by a SEQUENCE.
        if matches!(key_bytes, [TAG_INTEGER, 0x01, _, TAG_SEQUENCE, ..]) {
            return Ok(Self::Pkcs8(key.into()));
        }

        // PKCS#1 (https://www.rfc-editor.org/rfc/rfc8017) describes the RSAPrivateKey structure
        // as:
        //  RSAPrivateKey ::= SEQUENCE {
        //              version           Version,
        //              modulus           INTEGER,  -- n
        //              publicExponent    INTEGER,  -- e
        //              privateExponent   INTEGER,  -- d
        //              prime1            INTEGER,  -- p
        //              prime2            INTEGER,  -- q
        //              exponent1         INTEGER,  -- d mod (p-1)
        //              exponent2         INTEGER,  -- d mod (q-1)
        //              coefficient       INTEGER,  -- (inverse of q) mod p
        //              otherPrimeInfos   OtherPrimeInfos OPTIONAL
        //          }
        //
        // Therefore, we consider the outer SEQUENCE and a Version of 0 to be enough to identify
        // a PKCS#1 key. If it were PKCS#8, the version would be followed by a SEQUENCE. If it
        // were SEC1, the VERSION would have been 1.
        if key_bytes.starts_with(&[TAG_INTEGER, 0x01, 0x00]) {
            return Ok(Self::Pkcs1(key.into()));
        }

        // SEC1 (https://www.rfc-editor.org/rfc/rfc5915) describes the ECPrivateKey structure as:
        //   ECPrivateKey ::= SEQUENCE {
        //      version        INTEGER { ecPrivkeyVer1(1) } (ecPrivkeyVer1),
        //      privateKey     OCTET STRING,
        //      parameters [0] ECParameters {{ NamedCurve }} OPTIONAL,
        //      publicKey  [1] BIT STRING OPTIONAL
        //   }
        //
        // Therefore, we consider the outer SEQUENCE and an INTEGER of 1 to be enough to
        // identify a SEC1 key. If it were PKCS#8 or PKCS#1, the version would have been 0.
        if key_bytes.starts_with(&[TAG_INTEGER, 0x01, 0x01]) {
            return Ok(Self::Sec1(key.into()));
        }

        Err(INVALID_KEY_DER_ERR)
    }
}

static INVALID_KEY_DER_ERR: &str = "unknown or invalid key format";

#[cfg(feature = "alloc")]
impl<'a> TryFrom<Vec<u8>> for PrivateKeyDer<'a> {
    type Error = &'static str;

    fn try_from(key: Vec<u8>) -> Result<Self, Self::Error> {
        Ok(match PrivateKeyDer::try_from(&key[..])? {
            PrivateKeyDer::Pkcs1(_) => Self::Pkcs1(key.into()),
            PrivateKeyDer::Sec1(_) => Self::Sec1(key.into()),
            PrivateKeyDer::Pkcs8(_) => Self::Pkcs8(key.into()),
        })
    }
}

/// A DER-encoded plaintext RSA private key; as specified in PKCS#1/RFC 3447
///
/// RSA private keys are identified in PEM context as `RSA PRIVATE KEY` and when stored in a
/// file usually use a `.pem` or `.key` extension. For more on PEM files, refer to the crate
/// documentation.
#[derive(PartialEq, Eq)]
pub struct PrivatePkcs1KeyDer<'a>(Der<'a>);

impl PrivatePkcs1KeyDer<'_> {
    /// Clone the private key to a `'static` value
    #[cfg(feature = "alloc")]
    pub fn clone_key(&self) -> PrivatePkcs1KeyDer<'static> {
        PrivatePkcs1KeyDer::from(self.0.as_ref().to_vec())
    }

    /// Yield the DER-encoded bytes of the private key
    pub fn secret_pkcs1_der(&self) -> &[u8] {
        self.0.as_ref()
    }
}

impl<'a> From<&'a [u8]> for PrivatePkcs1KeyDer<'a> {
    fn from(slice: &'a [u8]) -> Self {
        Self(Der(BytesInner::Borrowed(slice)))
    }
}

#[cfg(feature = "alloc")]
impl<'a> From<Vec<u8>> for PrivatePkcs1KeyDer<'a> {
    fn from(vec: Vec<u8>) -> Self {
        Self(Der(BytesInner::Owned(vec)))
    }
}

impl fmt::Debug for PrivatePkcs1KeyDer<'_> {
    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
        f.debug_tuple("PrivatePkcs1KeyDer")
            .field(&"[secret key elided]")
            .finish()
    }
}

/// A Sec1-encoded plaintext private key; as specified in RFC 5915
///
/// Sec1 private keys are identified in PEM context as `EC PRIVATE KEY` and when stored in a
/// file usually use a `.pem` or `.key` extension. For more on PEM files, refer to the crate
/// documentation.
#[derive(PartialEq, Eq)]
pub struct PrivateSec1KeyDer<'a>(Der<'a>);

impl PrivateSec1KeyDer<'_> {
    /// Clone the private key to a `'static` value
    #[cfg(feature = "alloc")]
    pub fn clone_key(&self) -> PrivateSec1KeyDer<'static> {
        PrivateSec1KeyDer::from(self.0.as_ref().to_vec())
    }

    /// Yield the DER-encoded bytes of the private key
    pub fn secret_sec1_der(&self) -> &[u8] {
        self.0.as_ref()
    }
}

impl<'a> From<&'a [u8]> for PrivateSec1KeyDer<'a> {
    fn from(slice: &'a [u8]) -> Self {
        Self(Der(BytesInner::Borrowed(slice)))
    }
}

#[cfg(feature = "alloc")]
impl<'a> From<Vec<u8>> for PrivateSec1KeyDer<'a> {
    fn from(vec: Vec<u8>) -> Self {
        Self(Der(BytesInner::Owned(vec)))
    }
}

impl fmt::Debug for PrivateSec1KeyDer<'_> {
    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
        f.debug_tuple("PrivateSec1KeyDer")
            .field(&"[secret key elided]")
            .finish()
    }
}

/// A DER-encoded plaintext private key; as specified in PKCS#8/RFC 5958
///
/// PKCS#8 private keys are identified in PEM context as `PRIVATE KEY` and when stored in a
/// file usually use a `.pem` or `.key` extension. For more on PEM files, refer to the crate
/// documentation.
#[derive(PartialEq, Eq)]
pub struct PrivatePkcs8KeyDer<'a>(Der<'a>);

impl PrivatePkcs8KeyDer<'_> {
    /// Clone the private key to a `'static` value
    #[cfg(feature = "alloc")]
    pub fn clone_key(&self) -> PrivatePkcs8KeyDer<'static> {
        PrivatePkcs8KeyDer::from(self.0.as_ref().to_vec())
    }

    /// Yield the DER-encoded bytes of the private key
    pub fn secret_pkcs8_der(&self) -> &[u8] {
        self.0.as_ref()
    }
}

impl<'a> From<&'a [u8]> for PrivatePkcs8KeyDer<'a> {
    fn from(slice: &'a [u8]) -> Self {
        Self(Der(BytesInner::Borrowed(slice)))
    }
}

#[cfg(feature = "alloc")]
impl<'a> From<Vec<u8>> for PrivatePkcs8KeyDer<'a> {
    fn from(vec: Vec<u8>) -> Self {
        Self(Der(BytesInner::Owned(vec)))
    }
}

impl fmt::Debug for PrivatePkcs8KeyDer<'_> {
    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
        f.debug_tuple("PrivatePkcs8KeyDer")
            .field(&"[secret key elided]")
            .finish()
    }
}

/// A trust anchor (a.k.a. root CA)
///
/// Traditionally, certificate verification libraries have represented trust anchors as full X.509
/// root certificates. However, those certificates contain a lot more data than is needed for
/// verifying certificates. The [`TrustAnchor`] representation allows an application to store
/// just the essential elements of trust anchors.
///
/// The most common way to get one of these is to call [`rustls_webpki::anchor_from_trusted_cert()`].
///
/// [`rustls_webpki::anchor_from_trusted_cert()`]: https://docs.rs/rustls-webpki/latest/webpki/fn.anchor_from_trusted_cert.html
#[derive(Clone, Debug, PartialEq, Eq)]
pub struct TrustAnchor<'a> {
    /// Value of the `subject` field of the trust anchor
    pub subject: Der<'a>,
    /// Value of the `subjectPublicKeyInfo` field of the trust anchor
    pub subject_public_key_info: Der<'a>,
    /// Value of DER-encoded `NameConstraints`, containing name constraints to the trust anchor, if any
    pub name_constraints: Option<Der<'a>>,
}

impl TrustAnchor<'_> {
    /// Yield a `'static` lifetime of the `TrustAnchor` by allocating owned `Der` variants
    #[cfg(feature = "alloc")]
    pub fn to_owned(&self) -> TrustAnchor<'static> {
        #[cfg(not(feature = "std"))]
        use alloc::borrow::ToOwned;
        TrustAnchor {
            subject: self.subject.as_ref().to_owned().into(),
            subject_public_key_info: self.subject_public_key_info.as_ref().to_owned().into(),
            name_constraints: self
                .name_constraints
                .as_ref()
                .map(|nc| nc.as_ref().to_owned().into()),
        }
    }
}

/// A Certificate Revocation List; as specified in RFC 5280
///
/// Certificate revocation lists are identified in PEM context as `X509 CRL` and when stored in a
/// file usually use a `.crl` extension. For more on PEM files, refer to the crate documentation.
#[derive(Clone, Debug, PartialEq, Eq)]
pub struct CertificateRevocationListDer<'a>(Der<'a>);

impl AsRef<[u8]> for CertificateRevocationListDer<'_> {
    fn as_ref(&self) -> &[u8] {
        self.0.as_ref()
    }
}

impl Deref for CertificateRevocationListDer<'_> {
    type Target = [u8];

    fn deref(&self) -> &Self::Target {
        self.as_ref()
    }
}

impl<'a> From<&'a [u8]> for CertificateRevocationListDer<'a> {
    fn from(slice: &'a [u8]) -> Self {
        Self(Der::from(slice))
    }
}

#[cfg(feature = "alloc")]
impl<'a> From<Vec<u8>> for CertificateRevocationListDer<'a> {
    fn from(vec: Vec<u8>) -> Self {
        Self(Der::from(vec))
    }
}

/// A Certificate Signing Request; as specified in RFC 2986
///
/// Certificate signing requests are identified in PEM context as `CERTIFICATE REQUEST` and when stored in a
/// file usually use a `.csr` extension. For more on PEM files, refer to the crate documentation.
#[derive(Clone, Debug, PartialEq, Eq)]
pub struct CertificateSigningRequestDer<'a>(Der<'a>);

impl AsRef<[u8]> for CertificateSigningRequestDer<'_> {
    fn as_ref(&self) -> &[u8] {
        self.0.as_ref()
    }
}

impl Deref for CertificateSigningRequestDer<'_> {
    type Target = [u8];

    fn deref(&self) -> &Self::Target {
        self.as_ref()
    }
}

impl<'a> From<&'a [u8]> for CertificateSigningRequestDer<'a> {
    fn from(slice: &'a [u8]) -> Self {
        Self(Der::from(slice))
    }
}

#[cfg(feature = "alloc")]
impl<'a> From<Vec<u8>> for CertificateSigningRequestDer<'a> {
    fn from(vec: Vec<u8>) -> Self {
        Self(Der::from(vec))
    }
}

/// A DER-encoded X.509 certificate; as specified in RFC 5280
///
/// Certificates are identified in PEM context as `CERTIFICATE` and when stored in a
/// file usually use a `.pem`, `.cer` or `.crt` extension. For more on PEM files, refer to the
/// crate documentation.
#[derive(Clone, Debug, PartialEq, Eq)]
pub struct CertificateDer<'a>(Der<'a>);

impl AsRef<[u8]> for CertificateDer<'_> {
    fn as_ref(&self) -> &[u8] {
        self.0.as_ref()
    }
}

impl Deref for CertificateDer<'_> {
    type Target = [u8];

    fn deref(&self) -> &Self::Target {
        self.as_ref()
    }
}

impl<'a> From<&'a [u8]> for CertificateDer<'a> {
    fn from(slice: &'a [u8]) -> Self {
        Self(Der::from(slice))
    }
}

#[cfg(feature = "alloc")]
impl<'a> From<Vec<u8>> for CertificateDer<'a> {
    fn from(vec: Vec<u8>) -> Self {
        Self(Der::from(vec))
    }
}

impl CertificateDer<'_> {
    /// Converts this certificate into its owned variant, unfreezing borrowed content (if any)
    #[cfg(feature = "alloc")]
    pub fn into_owned(self) -> CertificateDer<'static> {
        CertificateDer(Der(self.0 .0.into_owned()))
    }
}

/// A DER-encoded SubjectPublicKeyInfo (SPKI), as specified in RFC 5280.
#[deprecated(since = "1.7.0", note = "Prefer `SubjectPublicKeyInfoDer` instead")]
pub type SubjectPublicKeyInfo<'a> = SubjectPublicKeyInfoDer<'a>;

/// A DER-encoded SubjectPublicKeyInfo (SPKI), as specified in RFC 5280.
#[derive(Clone, Debug, PartialEq, Eq)]
pub struct SubjectPublicKeyInfoDer<'a>(Der<'a>);

impl AsRef<[u8]> for SubjectPublicKeyInfoDer<'_> {
    fn as_ref(&self) -> &[u8] {
        self.0.as_ref()
    }
}

impl Deref for SubjectPublicKeyInfoDer<'_> {
    type Target = [u8];

    fn deref(&self) -> &Self::Target {
        self.as_ref()
    }
}

impl<'a> From<&'a [u8]> for SubjectPublicKeyInfoDer<'a> {
    fn from(slice: &'a [u8]) -> Self {
        Self(Der::from(slice))
    }
}

#[cfg(feature = "alloc")]
impl<'a> From<Vec<u8>> for SubjectPublicKeyInfoDer<'a> {
    fn from(vec: Vec<u8>) -> Self {
        Self(Der::from(vec))
    }
}

impl SubjectPublicKeyInfoDer<'_> {
    /// Converts this SubjectPublicKeyInfo into its owned variant, unfreezing borrowed content (if any)
    #[cfg(feature = "alloc")]
    pub fn into_owned(self) -> SubjectPublicKeyInfoDer<'static> {
        SubjectPublicKeyInfoDer(Der(self.0 .0.into_owned()))
    }
}

/// A TLS-encoded Encrypted Client Hello (ECH) configuration list (`ECHConfigList`); as specified in
/// [draft-ietf-tls-esni-18 ยง4](https://datatracker.ietf.org/doc/html/draft-ietf-tls-esni-18#section-4)
#[derive(Clone, Eq, PartialEq)]
pub struct EchConfigListBytes<'a>(BytesInner<'a>);

impl EchConfigListBytes<'_> {
    /// Converts this config into its owned variant, unfreezing borrowed content (if any)
    #[cfg(feature = "alloc")]
    pub fn into_owned(self) -> EchConfigListBytes<'static> {
        EchConfigListBytes(self.0.into_owned())
    }
}

impl fmt::Debug for EchConfigListBytes<'_> {
    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
        hex(f, self.as_ref())
    }
}

impl AsRef<[u8]> for EchConfigListBytes<'_> {
    fn as_ref(&self) -> &[u8] {
        self.0.as_ref()
    }
}

impl Deref for EchConfigListBytes<'_> {
    type Target = [u8];

    fn deref(&self) -> &Self::Target {
        self.as_ref()
    }
}

impl<'a> From<&'a [u8]> for EchConfigListBytes<'a> {
    fn from(slice: &'a [u8]) -> Self {
        Self(BytesInner::Borrowed(slice))
    }
}

#[cfg(feature = "alloc")]
impl<'a> From<Vec<u8>> for EchConfigListBytes<'a> {
    fn from(vec: Vec<u8>) -> Self {
        Self(BytesInner::Owned(vec))
    }
}

/// An abstract signature verification algorithm.
///
/// One of these is needed per supported pair of public key type (identified
/// with `public_key_alg_id()`) and `signatureAlgorithm` (identified with
/// `signature_alg_id()`).  Note that both of these `AlgorithmIdentifier`s include
/// the parameters encoding, so separate `SignatureVerificationAlgorithm`s are needed
/// for each possible public key or signature parameters.
///
/// Debug implementations should list the public key algorithm identifier and
/// signature algorithm identifier in human friendly form (i.e. not encoded bytes),
/// along with the name of the implementing library (to distinguish different
/// implementations of the same algorithms).
pub trait SignatureVerificationAlgorithm: Send + Sync + fmt::Debug {
    /// Verify a signature.
    ///
    /// `public_key` is the `subjectPublicKey` value from a `SubjectPublicKeyInfo` encoding
    /// and is untrusted.  The key's `subjectPublicKeyInfo` matches the [`AlgorithmIdentifier`]
    /// returned by `public_key_alg_id()`.
    ///
    /// `message` is the data over which the signature was allegedly computed.
    /// It is not hashed; implementations of this trait function must do hashing
    /// if that is required by the algorithm they implement.
    ///
    /// `signature` is the signature allegedly over `message`.
    ///
    /// Return `Ok(())` only if `signature` is a valid signature on `message`.
    ///
    /// Return `Err(InvalidSignature)` if the signature is invalid, including if the `public_key`
    /// encoding is invalid.  There is no need or opportunity to produce errors
    /// that are more specific than this.
    fn verify_signature(
        &self,
        public_key: &[u8],
        message: &[u8],
        signature: &[u8],
    ) -> Result<(), InvalidSignature>;

    /// Return the `AlgorithmIdentifier` that must equal a public key's
    /// `subjectPublicKeyInfo` value for this `SignatureVerificationAlgorithm`
    /// to be used for signature verification.
    fn public_key_alg_id(&self) -> AlgorithmIdentifier;

    /// Return the `AlgorithmIdentifier` that must equal the `signatureAlgorithm` value
    /// on the data to be verified for this `SignatureVerificationAlgorithm` to be used
    /// for signature verification.
    fn signature_alg_id(&self) -> AlgorithmIdentifier;

    /// Return `true` if this is backed by a FIPS-approved implementation.
    fn fips(&self) -> bool {
        false
    }
}

/// A detail-less error when a signature is not valid.
#[derive(Debug, Copy, Clone)]
pub struct InvalidSignature;

/// A DER encoding of the PKIX AlgorithmIdentifier type:
///
/// ```ASN.1
/// AlgorithmIdentifier  ::=  SEQUENCE  {
///     algorithm               OBJECT IDENTIFIER,
///     parameters              ANY DEFINED BY algorithm OPTIONAL  }
///                                -- contains a value of the type
///                                -- registered for use with the
///                                -- algorithm object identifier value
/// ```
/// (from <https://www.rfc-editor.org/rfc/rfc5280#section-4.1.1.2>)
///
/// The outer sequence encoding is *not included*, so this is the DER encoding
/// of an OID for `algorithm` plus the `parameters` value.
///
/// For example, this is the `rsaEncryption` algorithm:
///
/// ```
/// let rsa_encryption = rustls_pki_types::AlgorithmIdentifier::from_slice(
///     &[
///         // algorithm: 1.2.840.113549.1.1.1
///         0x06, 0x09, 0x2a, 0x86, 0x48, 0x86, 0xf7, 0x0d, 0x01, 0x01, 0x01,
///         // parameters: NULL
///         0x05, 0x00
///     ]
/// );
/// ```
#[derive(Clone, Copy, PartialEq, Eq)]
pub struct AlgorithmIdentifier(&'static [u8]);

impl AlgorithmIdentifier {
    /// Makes a new `AlgorithmIdentifier` from a static octet slice.
    ///
    /// This does not validate the contents of the slice.
    pub const fn from_slice(bytes: &'static [u8]) -> Self {
        Self(bytes)
    }
}

impl AsRef<[u8]> for AlgorithmIdentifier {
    fn as_ref(&self) -> &[u8] {
        self.0
    }
}

impl fmt::Debug for AlgorithmIdentifier {
    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
        hex(f, self.0)
    }
}

impl Deref for AlgorithmIdentifier {
    type Target = [u8];

    fn deref(&self) -> &Self::Target {
        self.as_ref()
    }
}

/// A timestamp, tracking the number of non-leap seconds since the Unix epoch.
///
/// The Unix epoch is defined January 1, 1970 00:00:00 UTC.
#[derive(Debug, Clone, Copy, PartialEq, Eq, PartialOrd)]
pub struct UnixTime(u64);

impl UnixTime {
    /// The current time, as a `UnixTime`
    #[cfg(any(
        all(
            feature = "std",
            not(all(target_family = "wasm", target_os = "unknown"))
        ),
        all(target_family = "wasm", target_os = "unknown", feature = "web")
    ))]
    pub fn now() -> Self {
        Self::since_unix_epoch(
            SystemTime::now()
                .duration_since(SystemTime::UNIX_EPOCH)
                .unwrap(), // Safe: this code did not exist before 1970.
        )
    }

    /// Convert a `Duration` since the start of 1970 to a `UnixTime`
    ///
    /// The `duration` must be relative to the Unix epoch.
    pub fn since_unix_epoch(duration: Duration) -> Self {
        Self(duration.as_secs())
    }

    /// Number of seconds since the Unix epoch
    pub fn as_secs(&self) -> u64 {
        self.0
    }
}

/// DER-encoded data, either owned or borrowed
///
/// This wrapper type is used to represent DER-encoded data in a way that is agnostic to whether
/// the data is owned (by a `Vec<u8>`) or borrowed (by a `&[u8]`). Support for the owned
/// variant is only available when the `alloc` feature is enabled.
#[derive(Clone, Eq, PartialEq)]
pub struct Der<'a>(BytesInner<'a>);

impl<'a> Der<'a> {
    /// A const constructor to create a `Der` from a borrowed slice
    pub const fn from_slice(der: &'a [u8]) -> Self {
        Self(BytesInner::Borrowed(der))
    }
}

impl AsRef<[u8]> for Der<'_> {
    fn as_ref(&self) -> &[u8] {
        self.0.as_ref()
    }
}

impl Deref for Der<'_> {
    type Target = [u8];

    fn deref(&self) -> &Self::Target {
        self.as_ref()
    }
}

impl<'a> From<&'a [u8]> for Der<'a> {
    fn from(slice: &'a [u8]) -> Self {
        Self(BytesInner::Borrowed(slice))
    }
}

#[cfg(feature = "alloc")]
impl From<Vec<u8>> for Der<'static> {
    fn from(vec: Vec<u8>) -> Self {
        Self(BytesInner::Owned(vec))
    }
}

impl fmt::Debug for Der<'_> {
    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
        hex(f, self.as_ref())
    }
}

#[derive(Debug, Clone)]
enum BytesInner<'a> {
    #[cfg(feature = "alloc")]
    Owned(Vec<u8>),
    Borrowed(&'a [u8]),
}

#[cfg(feature = "alloc")]
impl BytesInner<'_> {
    fn into_owned(self) -> BytesInner<'static> {
        BytesInner::Owned(match self {
            Self::Owned(vec) => vec,
            Self::Borrowed(slice) => slice.to_vec(),
        })
    }
}

impl AsRef<[u8]> for BytesInner<'_> {
    fn as_ref(&self) -> &[u8] {
        match &self {
            #[cfg(feature = "alloc")]
            BytesInner::Owned(vec) => vec.as_ref(),
            BytesInner::Borrowed(slice) => slice,
        }
    }
}

impl PartialEq for BytesInner<'_> {
    fn eq(&self, other: &Self) -> bool {
        self.as_ref() == other.as_ref()
    }
}

impl Eq for BytesInner<'_> {}

// Format an iterator of u8 into a hex string
fn hex<'a>(f: &mut fmt::Formatter<'_>, payload: impl IntoIterator<Item = &'a u8>) -> fmt::Result {
    for (i, b) in payload.into_iter().enumerate() {
        if i == 0 {
            write!(f, "0x")?;
        }
        write!(f, "{:02x}", b)?;
    }
    Ok(())
}

#[cfg(all(test, feature = "std"))]
mod tests {
    use super::*;

    #[test]
    fn der_debug() {
        let der = Der::from_slice(&[0x01, 0x02, 0x03]);
        assert_eq!(format!("{:?}", der), "0x010203");
    }

    #[test]
    fn alg_id_debug() {
        let alg_id = AlgorithmIdentifier::from_slice(&[0x01, 0x02, 0x03]);
        assert_eq!(format!("{:?}", alg_id), "0x010203");
    }

    #[test]
    fn bytes_inner_equality() {
        let owned_a = BytesInner::Owned(vec![1, 2, 3]);
        let owned_b = BytesInner::Owned(vec![4, 5]);
        let borrowed_a = BytesInner::Borrowed(&[1, 2, 3]);
        let borrowed_b = BytesInner::Borrowed(&[99]);

        // Self-equality.
        assert_eq!(owned_a, owned_a);
        assert_eq!(owned_b, owned_b);
        assert_eq!(borrowed_a, borrowed_a);
        assert_eq!(borrowed_b, borrowed_b);

        // Borrowed vs Owned equality
        assert_eq!(owned_a, borrowed_a);
        assert_eq!(borrowed_a, owned_a);

        // Owned inequality
        assert_ne!(owned_a, owned_b);
        assert_ne!(owned_b, owned_a);

        // Borrowed inequality
        assert_ne!(borrowed_a, borrowed_b);
        assert_ne!(borrowed_b, borrowed_a);

        // Borrowed vs Owned inequality
        assert_ne!(owned_a, borrowed_b);
        assert_ne!(borrowed_b, owned_a);
    }
}