Crate barebones_x509 

A low-level X.509 parsing and certificate signature verification library.

barebones-x509 can verify the signatures of X.509 certificates, as well as certificates made by their private keys. It can also verify that a certificate is valid for the given time. However, it is (by design) very low-level: it does not know about any X.509 extensions, and does not parse distinguished names at all. It also provides no path-building facilities. As such, it is not intended for use with the web PKI; use webpki for that.

barebones-x509’s flexibiity is a double-edged sword: it allows it to be used in situations where webpki cannot be used, but it also makes it significantly more dangerous. As a general rule, barebones-x509 will accept any certificate that webpki will, but it will also accept certificates that webpki will reject. If you find a certificate that barebones-x509 rejects and webpki rejects, please report it as a bug.

barebones-x509 was developed for use with libp2p, which uses certificates that webpki cannot handle. Its bare-bones design ensures that it can handle almost any conforming X.509 certificate, but it also means that the application is responsible for ensuring that the certificate has valid X.509 extensions. barebones-x509 cannot distinguish between a certificate valid for mozilla.org and one for evilmalware.com! However, barebones-x509 does provide the hooks needed for higher-level libraries to be built on top of it.

Like webpki, barebones-x509 is zero-copy and #![no_std] friendly. If built without the alloc feature, barebones-x509 will not rely on features of ring that require heap allocation, specifically RSA.

barebones-x509 should never panic on any input, regardless of its configuration options. If it does panic, it is considered a security vulnerability and will be fixed with the highest priority.

Features

barebones-x509 is highly configurable by means of compile-time options. Code that is not used by most users is off by default and must be enabled by means of a cargo feature. This reduces the attack surface of normal builds.

The following features are available:

• legacy-certificates: Allows parsing legacy v1 and v2 certificates. This is off by default.
• obsolete-unique-ids: Allows parsing certificates containing the obsolete subjectUniqueId and issuerUniqueId fields. This is off by default. The subjectUniqueId and issuerUniqueId fields available as the unique_id field on the X509Certificate struct. This feature is made available so that barebones-x509 can claim to be able to parse any valid X.509 certificate. If you do need to enable it, please e-mail me at demiobenour@gmail.com explaining the reason.

Structs

ASN1Time

An ASN.1 timestamp.

DataAlgorithmSignature

A data-algorithm-signature structure

ExtensionIterator

An iterator over X.509 extensions.

SequenceIterator

An iterator over X.509 sequences.

SubjectPublicKeyInfo

A PKIX SubjectPublicKeyInfo struct

X509Certificate

A parsed (but not validated) X.509 version 3 certificate.

Enums

ErrorNon-webpki

Errors that can be produced when parsing a certificate or validating a signature.

Restrictions

Restrictions on allowed signature algorithms

SignatureScheme

A signature scheme supported by this library

Version

X509 certificate version

Constants

MAX_ASN1_TIMESTAMP

The largest timestamp that an ASN.1 GeneralizedTime can represent.

MIN_ASN1_TIMESTAMP

The smallest timestamp that an ASN.1 GeneralizedTime can represent.

Functions

days_from_ymd

We use our own version, instead of chrono, because:

parse_algorithmid

Parse the ASN.1 DER-encoded algorithm identifier in asn1 into a SignatureScheme. This will fail if asn1 is not a known signature scheme.

parse_certificate

Extracts the algorithm id and public key from a certificate

seconds_from_hms

Convert an (hour, minute, second) tuple to a number of seconds since midnight or an error.