Basic concepts
1. Public Key: Think of this as a padlock that anyone can see and use. It’s used for locking or encrypting information. You can freely share your public key with others.
2. Private Key: Imagine this as the unique key to unlock the padlock (public key). It’s a secret key that only you should have access to. It’s used to unlock or decrypt information that was locked with your public key.
3. Certificate Authority (CA): Picture the CA as a trustworthy authority, like a notary or a security guard, that confirms your identity online. They issue a digital certificate that says, “This public key belongs to this person or organization.” This certificate vouches for your identity.
4. Certificate Chain: Think of this as a chain of trust. When you visit a secure website (HTTPS), your browser wants to make sure it can trust the website’s certificate. So, it checks if the certificate was issued by a trusted CA. If not, it looks for a certificate that vouches for the CA’s identity, and so on, creating a chain of trust until it finds a certificate it knows and trusts.
Certificates and keys work together to keep information safe and prove who you are online.
Certificate Types and Purposes
Certificates are digital documents used for security and authentication on the internet. Each type of certificate serves a specific purpose and has a different file format. Here’s a simple explanation of the differences and purposes of common certificate file types:
.cer (or .crt)(Certificate): This is a commonly used file format for single public key certificates. These certificates are often used to secure websites (HTTPS). They contain only the public key and some information about the certificate holder. You can share these with others to prove your identity or secure your website.
.pfx (or .p12)(Personal Information Exchange)(PKCS #12): This file format is used for storing both the public key and the private key. It’s typically used for securing email communications or authenticating to a server. Think of it as a digital keychain that allows you to both encrypt and decrypt information. It’s protected by a password.
.p7b(PKCS #7 Binary): This format is used to bundle multiple certificates together, often in a Certificate Chain. Certificate chains are used in more complex security setups, like securing a web server with an SSL certificate issued by a trusted Certificate Authority (CA).
PKCS stands for “Public Key Cryptography Standards.” It is a set of standards and protocols for securing digital communication and data storage using public-key cryptography. The numbers like #12 and #7 refer to specific PKCS standards within this set. Here’s what they mean:
1. PKCS #12: This standard, often referred to as PFX (Personal Information Exchange), defines a file format for storing and transporting a user’s private keys, public keys, and certificates securely. It’s commonly used for securely storing both the public and private keys in a single file, typically protected by a password.
2. PKCS #7: This standard specifies a format for Cryptographic Message Syntax (CMS). In the context of certificates, PKCS #7 is used for creating digitally signed messages and certificates. It’s often used in certificate chains and other cryptographic operations to ensure the integrity and authenticity of data.
So, the numbers indicate specific standards within the PKCS series, each serving a particular purpose in the realm of public-key cryptography and certificate management.
The choice of which certificate format to use depends on your specific security needs and the applications or systems you’re working with.