Introduction to SSL Certificates

Netscape was one of the first to use the SSL protocol to design an encrypted path for the transfer of classified information between the client and the server.

Since the adoption of SSL in 1994, SSL has gone through version changes that have made it capable of taking advantage of encryption schemes, such as the AES (Advanced Encryption Standard). SSL version 3.0 is the standard security offered by most web servers.

Private Keys

Once the information passing through a Secure Socket Layer has been encrypted, it needs to be decrypted so that the intended recipient of the information is able to use it. This works because the organization or individual receiving the encrypted information has two SSL keys: private and public. The public key is issued for encryption of information. This key is for everyone. The information that is encrypted using the public key can be only decrypted using a private key. This private key is a secret guarded well by the organization signing the SSL certificate.

Certificate Signing Requests (CSR)

The CSR is generated by one user or individual towards a certifying authority that provides a digital identity or valid signature to the individual. The process of CSR generation is preceded by the creation of a public and private key, and the digital signing of the document concerned using the private key that identifies the provider of a document. There are two common formats for CSRs:

• PKCS#10 specification
• Signed Public Key and Challenge (Spkac) format

Certificates (CRT)

Certificates can be used to validate the identity of the server and the client to ensure that exchange of sensitive information takes place between the intended parties and a third party is unable to impersonate either the client or the server to obtain or distribute the information. SSL certificates are available in many interchangeable formats. Windows servers use .pfx files, whereas Apache servers use PEM (.crt,.cer) files. Certificate Authorities mostly use PEM certificates with extensions such as .pem, .cer, .key and .crt. PEM certificates are Base64 encoded ASCII files.