SSL/TLS and PKI History
A PKI allows you to bind public keys (contained in SSL certificates) with a person in a way that allows you to trust the certificate. Public Key. Everything You Want to Know about the Cryptography behind SSL Encryption. Background. SSL (Secure Sockets Layer) is a standard security technology for establishing an encrypted link between a server and a PKI is also what binds keys with user identities by means of a Certificate Authority The DigiCert Difference. SSL (Secure Sockets Layer) certificates are an integral part of website security. When you visit a website with symbol on the browser bar. Compare SSL Prices .
Symmetric Key Cryptography or private key encryption Asymmetric Key Cryptography or public key encryption 1.
- How SSL TLS Protocol Utilizes Cryptography and PKI
- What is SSL, TLS and HTTPS?
Symmetric Key Cryptography It is also known as a single key or conventional algorithm. This encryption scheme is about using the same secret key for both enciphering and deciphering. Asymmetric Key Cryptography The public key cryptography uses two different mathematically related keys: As per PKI, the sender has a mathematically aligned Key Pair Public Key to Encrypt Private Key to Decrypt Thereby a message encrypted with a key by the sender can only be decrypted by the intended receiver with another key.
Public key infrastructure
PKI ensures confidentiality and authentication to confirm key ownership by using a digital certificate. Digital Certificates - Ensuring Whom To Trust A digitally signed certificate assures the public key and the identity of the client. The certification authority known as CA uniquely issues this certificate to specific domains and server.
They are authenticated by a Certificate Authority and valid for a definite Time period. Certificate Authority CA is a reliable third party, which is responsible for allotting, cancelling and distributing digital certificates. Verisign, Comodo, DigiCert, and GlobalSign are some of the examples of trusted third-party companies. Indeed, if CA2 signs a certificate for CA1, and CA1 signs a certificate for server S, then the end user who wants to validate that server S must trust CA2 for being honest, and competent, and also for somehow taking care not to issue a certificate to incompetent or dishonest CA.
CA1 does not say "server S is honest and trustworthy". If you iterate the process you end up with a handful of root CA called "trust anchors" in X. Whether the hundred or so of root CA that Microsoft found fit to include by default in Windows are that much trustworthy is an open question. The whole PKI structure holds due to the following characteristics: PKI depth is limited. A certificate chain from a root CA down to an SSL server certificate will include 3 or 4 certificates at most.
CA are very jealous of their power and won't issue certificates to just any wannabe intermediate CA.
Public key infrastructure - Wikipedia
Whether that "CA power" is delegated is specified in the certificate. When a CA issues a certificate to a sub-CA, with that specific mark, it does so only within a heavy context contracts, insurances, audits, and lots of dollars. Ultimately, trust is ensured through fear.
Offending CA are severely punished. Nobody really has interest in breaking the system, since there is no readily available substitute. Note that, down the chain, the server S is verified to really own a specific public key, but nobody says that the server is honest. When you connect to https: Moreover, all of this is association between the server name as it appears in the target URL and a public key.
This does not extend to the name intended by the user, as that name lives only in the user's brain. If the user wants to connect to www. The main use case for a PKI is distributing public keys for lots of entities. In the case of Web browsers and SSL, the browser user must be able to check that the server he tries to talk to is indeed the one he believes it to be; this must work for hundreds of millions of servers, some of which having come to existence after the browser was written and deployed.
Reducing that problem to knowing a hundred root CA keys makes it manageable, since one can indeed include a hundred public keys in a Web browser that's a million times easier than including a hundred million public keys in a Web browser. Client certificates are a SSL-specific feature. SSL additionally supports the other direction: The same mechanism can be used, with certificates.
How does SSL relate to the Public Key Infrastructure? - Software Engineering Stack Exchange
An important point to notice is that the server certificate and the client certificate live in different worlds. The server certificate is validated by the client. The client certificate is validated by the server. Both validations are independent of each other; they are performed by distinct entities, and may use distinct root CA.
The main reason why SSL servers have certificates is because clients cannot possibly know beforehand the public keys of all servers: On the other hand, when a server wants to authenticate a client, this is because that client is a registered user.