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81-471: In a typical public-key infrastructure (PKI) scheme, the certificate issuer is a certificate authority (CA), usually a company that charges customers a fee to issue certificates for them. By contrast, in a web of trust scheme, individuals sign each other's keys directly, in a format that performs a similar function to a public key certificate. In case of key compromise, a certificate may need to be revoked . The most common format for public key certificates

162-453: A cryptographically authenticated statement of revocation. For distributing revocation information to clients, timeliness of the discovery of revocation (and hence the window for an attacker to exploit a compromised certificate) trades off against resource usage in querying revocation statuses and privacy concerns. If revocation information is unavailable (either due to accident or an attack), clients must decide whether to fail-hard and treat

243-445: A root certificate is a public key certificate that identifies a root certificate authority (CA). Root certificates are self-signed (and it is possible for a certificate to have multiple trust paths, say if the certificate was issued by a root that was cross-signed) and form the basis of an X.509 -based public key infrastructure (PKI). Either it has matched Authority Key Identifier with Subject Key Identifier, in some cases there

324-535: A server is secure. The protocol requires the server to present a digital certificate, proving that it is the intended destination. The connecting client conducts certification path validation , ensuring that: The Subject field of the certificate must identify the primary hostname of the server as the Common Name . The hostname must be publicly accessible, not using private addresses or reserved domains . A certificate may be valid for multiple hostnames (e.g.,

405-554: A wildcard certificate . Once the certification path validation is successful, the client can establish an encrypted connection with the server. Internet-facing servers, such as public web servers , must obtain their certificates from a trusted, public certificate authority (CA). Client certificates authenticate the client connecting to a TLS service, for instance to provide access control. Because most services provide access to individuals, rather than devices, most client certificates contain an email address or personal name rather than

486-427: A PKI is an arrangement that binds public keys with respective identities of entities (like people and organizations). The binding is established through a process of registration and issuance of certificates at and by a certificate authority (CA). Depending on the assurance level of the binding, this may be carried out by an automated process or under human supervision. When done over a network, this requires using

567-433: A PKI is to facilitate the secure electronic transfer of information for a range of network activities such as e-commerce, internet banking and confidential email. It is required for activities where simple passwords are an inadequate authentication method and more rigorous proof is required to confirm the identity of the parties involved in the communication and to validate the information being transferred. In cryptography ,

648-440: A certificate as if it is revoked (and so degrade availability ) or to fail-soft and treat it as unrevoked (and allow attackers to sidestep revocation). Due to the cost of revocation checks and the availability impact from potentially-unreliable remote services, Web browsers limit the revocation checks they will perform, and will fail-soft where they do. Certificate revocation lists are too bandwidth-costly for routine use, and

729-401: A certificate is not "flat" but contains these fields nested in various structures within the certificate. This is an example of a decoded SSL/TLS certificate retrieved from SSL.com's website. The issuer's common name (CN) is shown as SSL.com EV SSL Intermediate CA RSA R3 , identifying this as an Extended Validation (EV) certificate. Validated information about the website's owner (SSL Corp)

810-457: A collection of certifying signatures from other people, with the expectation that anyone receiving it will trust at least one or two of the signatures. This will cause the emergence of a decentralized fault-tolerant web of confidence for all public keys. Another alternative, which does not deal with public authentication of public key information, is the simple public key infrastructure (SPKI), which grew out of three independent efforts to overcome

891-550: A domain and its subdomains). Such certificates are commonly called Subject Alternative Name (SAN) certificates or Unified Communications Certificates (UCC) . These certificates contain the Subject Alternative Name field, though many CAs also put them into the Subject Common Name field for backward compatibility. If some of the hostnames contain an asterisk (*), a certificate may also be called

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972-627: A further consequence of that, for ways in which users could be sure with whom they were actually interacting. Assorted cryptographic protocols were invented and analyzed within which the new cryptographic primitives could be effectively used. With the invention of the World Wide Web and its rapid spread, the need for authentication and secure communication became still more acute. Commercial reasons alone (e.g., e-commerce , online access to proprietary databases from web browsers ) were sufficient. Taher Elgamal and others at Netscape developed

1053-448: A good example of this is an air-gapped network in an office. Decentralized identifiers (DIDs) eliminate dependence on centralized registries for identifiers as well as centralized certificate authorities for key management, which is the standard in hierarchical PKI. In cases where the DID registry is a distributed ledger , each entity can serve as its own root authority. This architecture

1134-456: A hostname. In addition, the certificate authority that issues the client certificate is usually the service provider to which client connects because it is the provider that needs to perform authentication. Some service providers even offer free SSL certificates as part of their packages. While most web browsers support client certificates, the most common form of authentication on the Internet

1215-506: A label as a "partial wildcard" according to early specifications However, use of "partial-wildcard" certs is not recommended. As of 2011, partial wildcard support is optional, and is explicitly disallowed in SubjectAltName headers that are required for multi-name certificates. All major browsers have deliberately removed support for partial-wildcard certificates; they will result in a "SSL_ERROR_BAD_CERT_DOMAIN" error. Similarly, it

1296-483: A public certificate. During web browsing, this public certificate is served to any web browser that connects to the web site and proves to the web browser that the provider believes it has issued a certificate to the owner of the web site. As an example, when a user connects to https://www.example.com/ with their browser, if the browser does not give any certificate warning message, then the user can be theoretically sure that interacting with https://www.example.com/

1377-439: A qualified trust service provider and signature creation device) are given the same power as a physical signature. In the X.509 trust model, a certificate authority (CA) is responsible for signing certificates. These certificates act as an introduction between two parties, which means that a CA acts as a trusted third party. A CA processes requests from people or organizations requesting certificates (called subscribers), verifies

1458-432: A relatively small community, like a business, and are distributed by other mechanisms like Windows Group Policy . Certificate authorities are also responsible for maintaining up-to-date revocation information about certificates they have issued, indicating whether certificates are still valid. They provide this information through Online Certificate Status Protocol (OCSP) and/or Certificate Revocation Lists (CRLs). Some of

1539-412: A secure certificate enrollment or certificate management protocol such as CMP . The PKI role that may be delegated by a CA to assure valid and correct registration is called a registration authority (RA). An RA is responsible for accepting requests for digital certificates and authenticating the entity making the request. The Internet Engineering Task Force 's RFC 3647 defines an RA as "An entity that

1620-472: A self-signed certificate, called a root certificate , trust anchor , or trust root . A certificate authority self-signs a root certificate to be able to sign other certificates. An intermediate certificate has a similar purpose to the root certificate – its only use is to sign other certificates. However, an intermediate certificate is not self-signed. A root certificate or another intermediate certificate needs to sign it. An end-entity or leaf certificate

1701-430: A server that acts as an offline certificate authority within a single sign-on system. A single sign-on server will issue digital certificates into the client system, but never stores them. Users can execute programs, etc. with the temporary certificate. It is common to find this solution variety with X.509 -based certificates. Starting Sep 2020, TLS Certificate Validity reduced to 13 Months. An alternative approach to

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1782-500: A signature that can be verified by its own public key. Self-signed certificates have their own limited uses. They have full trust value when the issuer and the sole user are the same entity. For example, the Encrypting File System on Microsoft Windows issues a self-signed certificate on behalf of the encrypting user and uses it to transparently decrypt data on the fly. The digital certificate chain of trust starts with

1863-429: A single certificate for all main domains and subdomains and reduce cost. Because the wildcard only covers one level of subdomains (the asterisk doesn't match full stops), these domains would not be valid for the certificates: Note possible exceptions by CAs, for example wildcard-plus cert by DigiCert contains an automatic "Plus" property for the naked domain example.com . Only a single level of subdomain matching

1944-483: A top-level domain is not allowed. Too general and should not be allowed. International domain names encoded in ASCII (A-label) are labels that are ASCII-encoded and begin with xn-- . URLs with international labels cannot contain wildcards. These are some of the most common fields in certificates. Most certificates contain a number of fields not listed here. Note that in terms of a certificate's X.509 representation,

2025-431: A web server using a password. The latter is termed client-side authentication - sometimes used when authenticating using a smart card (hosting a digital certificate and private key). Public-key cryptography is a cryptographic technique that enables entities to securely communicate on an insecure public network, and reliably verify the identity of an entity via digital signatures . A public key infrastructure (PKI)

2106-444: Is a capability underpinning the security of data in transit, i.e. during transmission. A classic example of TLS for confidentiality is when using an internet browser to log on to a service hosted on an internet based web site by entering a password. Integrity: Assurance that if an entity changed (tampered) with transmitted data in the slightest way, it would be obvious it happened as its integrity would have been compromised. Often it

2187-462: Is a system for the creation, storage, and distribution of digital certificates which are used to verify that a particular public key belongs to a certain entity. The PKI creates digital certificates which map public keys to entities, securely stores these certificates in a central repository and revokes them if needed. A PKI consists of: The primary role of the CA is to digitally sign and publish

2268-480: Is a username and password pair. Client certificates are more common in virtual private networks (VPN) and Remote Desktop Services , where they authenticate devices. In accordance with the S/MIME protocol, email certificates can both establish the message integrity and encrypt messages. To establish encrypted email communication, the communicating parties must have their digital certificates in advance. Each must send

2349-481: Is an important part of a public key infrastructure. Revocation is performed by the issuing certificate authority , which produces a cryptographically authenticated statement of revocation. For distributing revocation information to clients, timeliness of the discovery of revocation (and hence the window for an attacker to exploit a compromised certificate) trades off against resource usage in querying revocation statuses and privacy concerns. If revocation information

2430-546: Is any certificate that cannot sign other certificates. For instance, TLS/SSL server and client certificates, email certificates, code signing certificates, and qualified certificates are all end-entity certificates. Subject Alternative Name (SAN) certificates are an extension to X.509 that allows various values to be associated with a security certificate using a subjectAltName field. These values are called Subject Alternative Names (SANs). Names include: RFC   2818 (May 2000) specifies Subject Alternative Names as

2511-417: Is called a Wildcard certificate. Through the use of * , a single certificate may be used for multiple sub-domains . It is commonly used for transport layer security in computer networking . For example, a single wildcard certificate for https://*.example.com will secure all these subdomains on the https://*.example.com domain: Instead of getting separate certificates for subdomains, you can use

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2592-520: Is defined by X.509 . Because X.509 is very general, the format is further constrained by profiles defined for certain use cases, such as Public Key Infrastructure (X.509) as defined in RFC   5280 . The Transport Layer Security (TLS) protocol – as well as its outdated predecessor, the Secure Sockets Layer (SSL) protocol – ensures that the communication between a client computer and

2673-804: Is delegated certain tasks on behalf of a CA)." While Microsoft may have referred to a subordinate CA as an RA, this is incorrect according to the X.509 PKI standards. RAs do not have the signing authority of a CA and only manage the vetting and provisioning of certificates. So in the Microsoft PKI case, the RA functionality is provided either by the Microsoft Certificate Services web site or through Active Directory Certificate Services which enforces Microsoft Enterprise CA, and certificate policy through certificate templates and manages certificate enrollment (manual or auto-enrollment). In

2754-407: Is equivalent to interacting with the entity in contact with the email address listed in the public registrar under "example.com", even though that email address may not be displayed anywhere on the web site. No other surety of any kind is implied. Further, the relationship between the purchaser of the certificate, the operator of the web site, and the generator of the web site content may be tenuous and

2835-434: Is indicated with a set of trust bits in a root certificate storage system. A certificate may be revoked before it expires, which signals that it is no longer valid. Without revocation, an attacker would be able to exploit such a compromised or misissued certificate until expiry. Hence, revocation is an important part of a public key infrastructure . Revocation is performed by the issuing certificate authority , which produces

2916-590: Is located in the Subject field. The X509v3 Subject Alternative Name field contains a list of domain names covered by the certificate. The X509v3 Extended Key Usage and X509v3 Key Usage fields show all appropriate uses. In the European Union, (advanced) electronic signatures on legal documents are commonly performed using digital signatures with accompanying identity certificates. However, only qualified electronic signatures (which require using

2997-453: Is no Authority Key identifier, then Issuer string should match with Subject string ( RFC   5280 ). For instance, the PKIs supporting HTTPS for secure web browsing and electronic signature schemes depend on a set of root certificates. A certificate authority can issue multiple certificates in the form of a tree structure . A root certificate is the top-most certificate of the tree,

3078-472: Is not guaranteed. At best, the certificate guarantees uniqueness of the web site, provided that the web site itself has not been compromised (hacked) or the certificate issuing process subverted. Public-key infrastructure A public key infrastructure ( PKI ) is a set of roles, policies, hardware, software and procedures needed to create, manage, distribute, use, store and revoke digital certificates and manage public-key encryption . The purpose of

3159-467: Is not of utmost importance to prevent the integrity being compromised (tamper proof), however, it is of utmost importance that if integrity is compromised there is clear evidence of it having done so (tamper evident). Authenticity: Assurance that every entity has certainty of what it is connecting to, or can evidence its legitimacy when connecting to a protected service. The former is termed server-side authentication - typically used when authenticating to

3240-584: Is part of the open source Firefox web browser, so it is broadly used outside Firefox. For instance, while there is no common Linux Root Program, many Linux distributions, like Debian, include a package that periodically copies the contents of the Firefox trust list, which is then used by applications. Root programs generally provide a set of valid purposes with the certificates they include. For instance, some CAs may be considered trusted for issuing TLS server certificates, but not for code signing certificates. This

3321-571: Is particularly important in HTTPS, where a web site operator generally wants to get a certificate that is trusted by nearly all potential visitors to their web site. The policies and processes a provider uses to decide which certificate authorities their software should trust are called root programs. The most influential root programs are: Browsers other than Firefox generally use the operating system's facilities to decide which certificate authorities are trusted. So, for instance, Chrome on Windows trusts

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3402-504: Is referred to as decentralized PKI (DPKI). Developments in PKI occurred in the early 1970s at the British intelligence agency GCHQ , where James Ellis , Clifford Cocks and others made important discoveries related to encryption algorithms and key distribution. Because developments at GCHQ are highly classified, the results of this work were kept secret and not publicly acknowledged until

3483-480: Is responsible for one or more of the following functions: the identification and authentication of certificate applicants, the approval or rejection of certificate applications, initiating certificate revocations or suspensions under certain circumstances, processing subscriber requests to revoke or suspend their certificates, and approving or rejecting requests by subscribers to renew or re-key their certificates. RAs, however, do not sign or issue certificates (i.e., an RA

3564-670: Is supported in accordance with RFC   2818 . It is not possible to get a wildcard for an Extended Validation Certificate . A workaround could be to add every virtual host name in the Subject Alternative Name (SAN) extension, the major problem being that the certificate needs to be reissued whenever a new virtual server is added. (See Transport Layer Security § Support for name-based virtual servers for more information.) Wildcards can be added as domains in multi-domain certificates or Unified Communications Certificates (UCC). In addition, wildcards themselves can have subjectAltName extensions, including other wildcards. For example,

3645-405: Is typical for standard libraries in programming languages to not support "partial-wildcard" certificates. For example, any "partial-wildcard" certificate will not work with the latest versions of both Python and Go. Thus, Do not allow a label that consists entirely of just a wildcard unless it is the left-most label A cert with multiple wildcards in a name is not allowed. A cert with * plus

3726-549: Is unavailable (either due to accident or an attack), clients must decide whether to fail-hard and treat a certificate as if it is revoked (and so degrade availability ) or to fail-soft and treat it as unrevoked (and allow attackers to sidestep revocation). Due to the cost of revocation checks and the availability impact from potentially-unreliable remote services, Web browsers limit the revocation checks they will perform, and will fail-soft where they do. Certificate revocation lists are too bandwidth-costly for routine use, and

3807-420: Is willing to guarantee certificates, as a trusted introducer. If the "web of trust" is completely trusted then, because of the nature of a web of trust, trusting one certificate is granting trust to all the certificates in that web. A PKI is only as valuable as the standards and practices that control the issuance of certificates and including PGP or a personally instituted web of trust could significantly degrade

3888-527: The Common Access Cards program. PKIs of one type or another, and from any of several vendors, have many uses, including providing public keys and bindings to user identities which are used for: Some argue that purchasing certificates for securing websites by SSL/TLS and securing software by code signing is a costly venture for small businesses. However, the emergence of free alternatives, such as Let's Encrypt , has changed this. HTTP/2 ,

3969-695: The Dutch certificate authority DigiNotar suffered a security breach. This led to the issuing of various fraudulent certificates, which was among others abused to target Iranian Gmail users. The trust in DigiNotar certificates was retracted and the operational management of the company was taken over by the Dutch government . In 2009, an employee of the China Internet Network Information Center (CNNIC) applied to Mozilla to add CNNIC to Mozilla's root certificate list and

4050-502: The Online Certificate Status Protocol presents connection latency and privacy issues. Other schemes have been proposed but have not yet been successfully deployed to enable fail-hard checking. In this model of trust relationships, a CA is a trusted third party – trusted both by the subject (owner) of the certificate and by the party relying upon the certificate. According to NetCraft report from 2015,

4131-440: The Online Certificate Status Protocol presents connection latency and privacy issues. Other schemes have been proposed but have not yet been successfully deployed to enable fail-hard checking. The most common use of certificates is for HTTPS -based web sites. A web browser validates that an HTTPS web server is authentic, so that the user can feel secure that his/her interaction with the web site has no eavesdroppers and that

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4212-619: The SSL protocol (' https ' in Web URLs ); it included key establishment, server authentication (prior to v3, one-way only), and so on. A PKI structure was thus created for Web users/sites wishing secure communications. Vendors and entrepreneurs saw the possibility of a large market, started companies (or new projects at existing companies), and began to agitate for legal recognition and protection from liability. An American Bar Association technology project published an extensive analysis of some of

4293-488: The public key bound to a given user. This is done using the CA's own private key, so that trust in the user key relies on one's trust in the validity of the CA's key. When the CA is a third party separate from the user and the system, then it is called the Registration Authority (RA), which may or may not be separate from the CA. The key-to-user binding is established, depending on the level of assurance

4374-406: The basis of information about that entity. A third-party validation authority (VA) can provide this entity information on behalf of the CA. The X.509 standard defines the most commonly used format for public key certificates . PKI provides "trust services" - in plain terms trusting the actions or outputs of entities, be they people or computers. Trust service objectives respect one or more of

4455-447: The binding has, by software or under human supervision. The term trusted third party (TTP) may also be used for certificate authority (CA). Moreover, PKI is itself often used as a synonym for a CA implementation. A certificate may be revoked before it expires, which signals that it is no longer valid. Without revocation, an attacker would be able to exploit such a compromised or mis-issued certificate until expiry. Hence, revocation

4536-406: The case of Microsoft Standalone CAs, the function of RA does not exist since all of the procedures controlling the CA are based on the administration and access procedure associated with the system hosting the CA and the CA itself rather than Active Directory. Most non-Microsoft commercial PKI solutions offer a stand-alone RA component. An entity must be uniquely identifiable within each CA domain on

4617-636: The certificate authorities included in the Microsoft Root Program, while on macOS or iOS, Chrome trusts the certificate authorities in the Apple Root Program. Edge and Safari use their respective operating system trust stores as well, but each is only available on a single OS. Firefox uses the Mozilla Root Program trust store on all platforms. The Mozilla Root Program is operated publicly, and its certificate list

4698-555: The complexities of X.509 and PGP 's web of trust. SPKI does not associate users with persons, since the key is what is trusted, rather than the person. SPKI does not use any notion of trust, as the verifier is also the issuer. This is called an "authorization loop" in SPKI terminology, where authorization is integral to its design. This type of PKI is specially useful for making integrations of PKI that do not rely on third parties for certificate authorization, certificate information, etc.;

4779-472: The electronic certificate issued by CNNIC. on April 4, following Google, Mozilla also announced that it no longer recognized the electronic certificate issued by CNNIC. In 2016, WoSign , China 's largest CA certificate issuer owned by Qihoo 360 and its Israeli subsidiary StartCom , were denied recognition of their certificates by Google . Microsoft removed the relevant certificates in 2017. WoSign and StartCom issued hundreds of certificates with

4860-407: The first few years of the 21st century, the underlying cryptographic engineering was clearly not easy to deploy correctly. Operating procedures (manual or automatic) were not easy to correctly design (nor even if so designed, to execute perfectly, which the engineering required). The standards that existed were insufficient. PKI vendors have found a market, but it is not quite the market envisioned in

4941-404: The following capabilities: Confidentiality, Integrity and Authenticity (CIA). Confidentiality: Assurance that no entity can maliciously or unwittingly view a payload in clear text. Data is encrypted to make it secret, such that even if it was read, it appears as gibberish. Perhaps the most common use of PKI for confidentiality purposes is in the context of Transport Layer Security ( TLS ). TLS

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5022-656: The foreseeable legal aspects of PKI operations (see ABA digital signature guidelines ), and shortly thereafter, several U.S. states ( Utah being the first in 1995) and other jurisdictions throughout the world began to enact laws and adopt regulations. Consumer groups raised questions about privacy , access, and liability considerations, which were more taken into consideration in some jurisdictions than in others. The enacted laws and regulations differed, there were technical and operational problems in converting PKI schemes into successful commercial operation, and progress has been much slower than pioneers had imagined it would be. By

5103-418: The industry standard for monitoring active Transport Layer Security (TLS) certificates, states that "Although the global [TLS] ecosystem is competitive, it is dominated by a handful of major CAs — three certificate authorities ( Symantec , Sectigo , GoDaddy ) account for three-quarters of all issued [TLS] certificates on public-facing web servers. The top spot has been held by Symantec (or VeriSign before it

5184-449: The information, and potentially signs an end-entity certificate based on that information. To perform this role effectively, a CA needs to have one or more broadly trusted root certificates or intermediate certificates and the corresponding private keys. CAs may achieve this broad trust by having their root certificates included in popular software, or by obtaining a cross-signature from another CA delegating trust. Other CAs are trusted within

5265-412: The larger certificate authorities in the market include IdenTrust , DigiCert , and Sectigo . Some major software contain a list of certificate authorities that are trusted by default. This makes it easier for end-users to validate certificates, and easier for people or organizations that request certificates to know which certificate authorities can issue a certificate that will be broadly trusted. This

5346-511: The latest version of HTTP protocol, allows unsecured connections in theory; in practice, major browser companies have made it clear that they would support this protocol only over a PKI secured TLS connection. Web browser implementation of HTTP/2 including Chrome , Firefox , Opera , and Edge supports HTTP/2 only over TLS by using the ALPN extension of the TLS protocol. This would mean that, to get

5427-511: The mid-1990s, and it has grown both more slowly and in somewhat different ways than were anticipated. PKIs have not solved some of the problems they were expected to, and several major vendors have gone out of business or been acquired by others. PKI has had the most success in government implementations; the largest PKI implementation to date is the Defense Information Systems Agency (DISA) PKI infrastructure for

5508-474: The mid-1990s. The public disclosure of both secure key exchange and asymmetric key algorithms in 1976 by Diffie , Hellman , Rivest , Shamir , and Adleman changed secure communications entirely. With the further development of high-speed digital electronic communications (the Internet and its predecessors), a need became evident for ways in which users could securely communicate with each other, and as

5589-422: The other one digitally signed email and opt to import the sender's certificate. Some publicly trusted certificate authorities provide email certificates, but more commonly S/MIME is used when communicating within a given organization, and that organization runs its own CA, which is trusted by participants in that email system. A self-signed certificate is a certificate with a subject that matches its issuer, and

5670-657: The preferred method of adding DNS names to certificates, deprecating the previous method of putting DNS names in the commonName field. Google Chrome version 58 (March 2017) removed support for checking the commonName field at all, instead only looking at the SANs. As shown in the picture of Wikimedia's section on the right, the SAN field can contain wildcards. Not all vendors support or endorse mixing wildcards into SAN certificates. A public key certificate which uses an asterisk * (the wildcard ) in its domain name fragment

5751-411: The private key which is used to "sign" other certificates. All certificates signed by the root certificate, with the "CA" field set to true, inherit the trustworthiness of the root certificate—a signature by a root certificate is somewhat analogous to "notarizing" identity in the physical world. Such a certificate is called an intermediate certificate or subordinate CA certificate. Certificates further down

5832-486: The problem of public authentication of public key information is the web-of-trust scheme, which uses self-signed certificates and third-party attestations of those certificates. The singular term "web of trust" does not imply the existence of a single web of trust, or common point of trust, but rather one of any number of potentially disjoint "webs of trust". Examples of implementations of this approach are PGP (Pretty Good Privacy) and GnuPG (an implementation of OpenPGP ,

5913-400: The risk of a key compromise. When a key is known to be compromised, it could be fixed by revoking the certificate, but such a compromise is not easily detectable and can be a huge security breach. Browsers have to issue a security patch to revoke intermediary certificates issued by a compromised root certificate authority. Root certificate In cryptography and computer security ,

5994-422: The speed benefits of HTTP/2, website owners would be forced to purchase SSL/TLS certificates controlled by corporations. Currently the majority of web browsers are shipped with pre-installed intermediate certificates issued and signed by a certificate authority, by public keys certified by so-called root certificates . This means browsers need to carry a large number of different certificate providers, increasing

6075-458: The standardized specification of PGP). Because PGP and implementations allow the use of e-mail digital signatures for self-publication of public key information, it is relatively easy to implement one's own web of trust. One of the benefits of the web of trust, such as in PGP , is that it can interoperate with a PKI CA fully trusted by all parties in a domain (such as an internal CA in a company) that

6156-654: The tree also depend on the trustworthiness of the intermediates. The root certificate is usually made trustworthy by some mechanism other than a certificate, such as by secure physical distribution. For example, some of the best-known root certificates are distributed in operating systems by their manufacturers. Microsoft distributes root certificates belonging to members of the Microsoft Root Certificate Program to Windows desktops and Windows Phone 8 . Apple distributes root certificates belonging to members of its own root program . In 2011,

6237-449: The trustworthiness of that enterprise's or domain's implementation of PKI. The web of trust concept was first put forth by PGP creator Phil Zimmermann in 1992 in the manual for PGP version 2.0: As time goes on, you will accumulate keys from other people that you may want to designate as trusted introducers. Everyone else will each choose their own trusted introducers. And everyone will gradually accumulate and distribute with their key

6318-404: The web site is who it claims to be. This security is important for electronic commerce . In practice, a web site operator obtains a certificate by applying to a certificate authority with a certificate signing request . The certificate request is an electronic document that contains the web site name, company information and the public key. The certificate provider signs the request, thus producing

6399-537: The wildcard certificate *.wikipedia.org has *.m.wikimedia.org as a Subject Alternative Name. Thus it secures www.wikipedia.org as well as the completely different website name meta.m.wikimedia.org . RFC   6125 argues against wildcard certificates on security grounds, in particular "partial wildcards". The wildcard applies only to one level of the domain name. *.example.com matches sub1.example.com but not example.com and not sub2.sub1.domain.com The wildcard may appear anywhere inside

6480-424: Was approved. Later, Microsoft also added CNNIC to the root certificate list of Windows . In 2015, many users chose not to trust the digital certificates issued by CNNIC because an intermediate CA issued by CNNIC was found to have issued fake certificates for Google domain names and raised concerns about CNNIC's abuse of certificate issuing power. On April 2, 2015, Google announced that it no longer recognized

6561-536: Was purchased by Symantec) ever since [our] survey began, with it currently accounting for just under a third of all certificates. To illustrate the effect of differing methodologies, amongst the million busiest sites Symantec issued 44% of the valid, trusted certificates in use — significantly more than its overall market share." Following major issues in how certificate issuing were managed, all major players gradually distrusted Symantec issued certificates, starting in 2017 and completed in 2021. This approach involves

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