A public key certificate, also known as a digital certificate, is a digital document used in cryptography to verify the ownership of a public key. It contains information about the key, information about the identity of its owner (called the subject), and the digital signature of an entity that has verified the certificate’s contents (called the issuer). There are various types of certificates, including root, intermediate, end-entity, and wildcard certificates, each serving different functions within the certificate hierarchy. Certificate Authorities (CAs) such as IdenTrust, DigiCert, and Sectigo, issue these certificates and also manage their revocation. Certificates are crucial in sítio Web[1] security[2], ensuring secure connections over SSL/TLS protocols, and offer different validation levels. They follow certain standards and are recommended for secure website usage. Understanding public key certificates is integral to appreciating web security and encryption.
In cryptography, a public key certificate, also known as a digital certificate ou identity certificate, is an electronic document used to prove the validity of a public key. The certificate includes the public key and information about it, information about the identity of its owner (called the subject), and the digital signature of an entity that has verified the certificate's contents (called the issuer). If the device examining the certificate trusts the issuer and finds the signature to be a valid signature of that issuer, then it can use the included public key to communicate securely with the certificate's subject. In email encryption, code signinge e-signature systems, a certificate's subject is typically a person or organization. However, in Transport Layer Security (TLS) a certificate's subject is typically a computer or other device, though TLS certificates may identify organizations or individuals in addition to their core role in identifying devices. TLS, sometimes called by its older name Secure Sockets Layer (SSL), is notable for being a part of HTTPS, a protocol for securely browsing the web.
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 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 inRFC 5280.
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