Public Key Infrastructures & Certificates – What They Are and Why They Matter

A PKI (Public Key Infrastructure) is often confused with a CA (Certificate Authority) but it is much more than that. A PKI includes all of the components required to enable the use of Certificates.

What is PKI?

Public Key Infrastructure (PKI) is a set of technologies, policies, and procedures that are used to create and manage Digital Certificates. PKI enables secure online communication by providing a system for securely exchanging and verifying Public Keys.

PKI is based on a system of Digital Certificates that provide authentication and encryption services. The Certificates are issued by a trusted third party, known as a Certificate Authority (CA), which is responsible for verifying the identity of the Certificate holder.

The PKI system involves a combination of Public and Private Keys. The Public Key is used for encryption, while the Private Key is used for decryption. When a user wants to send a secure message, they use the Public Key of the recipient to encrypt the message. The recipient can then use their Private Key to decrypt the message.

About Digital Certificates

What are Digital Certificates?

Digital Certificates are electronic documents that are used to verify the identity of a person, organization, or device in online communication. Digital Certificates serve as digital identities, providing proof of identity to enable secure communication and data exchange.

Digital Certificates are issued by a trusted third party, known as a Certificate Authority (CA). The CA verifies the identity of the certificate holder and issues a certificate that contains the certificate holder’s public key, along with other information, such as the certificate’s expiration date and the CA’s digital signature.

Digital Certificates are used to enable secure communication and data exchange in a variety of online applications, including e-commerce, online banking, and secure email communication.

How do Digital Certificates work?

Digital Certificates use a system of public key cryptography to secure online communication. Public key cryptography is a system in which a pair of keys is used to encrypt and decrypt data. The keys are mathematically related, but one key can be made public, while the other key is kept private.

The public key is used to encrypt data, while the private key is used to decrypt data. When a user wants to send a secure message, they use the public key of the recipient to encrypt the message. The recipient can then use their private key to decrypt the message.

Digital Certificates contain the public key of the certificate holder, along with other information, such as the certificate’s expiration date and the CA’s digital signature. The digital signature is used to verify the authenticity of the certificate.

When a user wants to communicate securely with another user, they first obtain the other user’s digital certificate from a trusted source, such as a Certificate Authority. The user can then use the recipient’s public key to encrypt the message, ensuring that only the recipient can read the message.

Why are Digital Certificates critical?

Digital Certificates are essential for secure online communication and data exchange. They provide a secure and reliable way to verify the identity of a person, organization, or device in online communication. Digital Certificates are used to enable secure communication and data exchange in a variety of online applications, including e-commerce, online banking, and secure email communication.

Digital Certificates also provide a way to protect against online threats, such as phishing and man-in-the middle attacks. By verifying the identity of the communicating parties, Digital Certificates help to ensure that confidential information is only shared between trusted parties.

Moreover, Digital Certificates provide a way to ensure the integrity of online transactions. The use of digital signatures in Digital Certificates helps to ensure that messages are not tampered with or altered during transmission.

How are Digital Certificates issued?

Digital Certificates are issued by a trusted third party, known as a Certificate Authority (CA). The CA verifies the identity of the certificate holder, and issues a certificate that contains the certificate holder’s public key, along with other information, such as the certificate’s expiration date and the CA’s digital signature.

To obtain a Digital Certificate, the certificate holder must first generate a key pair, consisting of a public key and a private key. The private key is kept secure by the certificate holder, while the public key is submitted to the CA for inclusion in the Digital Certificate.

The CA will then verify the identity of the certificate holder, usually by checking the holder’s identity documents or through other means, such as email or phone verification. Once the identity is verified, the CA will issue the Digital Certificate.

The Digital Certificate can then be installed on the certificate holder’s device, such as a web server or email client, enabling secure communication and data exchange.

How Digital Certificates Enable Secure eSignature?

In eSignature, digital certificates are used to sign and encrypt important documents, such as contracts, legal agreements, or other sensitive information. The use of digital certificates ensures that the signed document is authentic and cannot be tampered with.

When a document is signed with a digital certificate, the certificate provides a digital signature that is attached to the document. The digital signature is a mathematical representation of the document that verifies its authenticity and integrity. The digital certificate used for signing the document is issued by a trusted Certificate Authority (CA), which ensures that the identity of the signer has been verified.

To sign a document with a digital certificate, the signer uses a digital signature software that interfaces with the certificate. The software creates a digital signature by performing a hash function on the document and encrypting the hash with the signer’s private key. The encrypted hash, along with the signer’s digital certificate, is then attached to the document, providing a secure digital signature.

Once the document is signed, it can be transmitted securely over the internet or stored in a secure location. Anyone who receives the signed document can verify its authenticity and integrity by checking the attached digital signature with the signer’s digital certificate.

In summary, digital certificates play a critical role in eSignature by providing secure and authentic digital signatures that ensure the integrity of signed documents. The use of trusted digital certificates issued by reputable CAs enhances the security of eSignature and builds trust among signers and recipients.

About Public Keys / Private Keys and Asymmetric Encryption

Private and public keys are a fundamental component of asymmetric encryption, a type of encryption that uses different keys for encryption and decryption. Private keys are kept secret by the key owner and are used for decrypting messages that have been encrypted with the corresponding public key. Public keys are made widely available and are used by others to encrypt messages that can only be decrypted with the corresponding private key.

When two parties wish to establish secure communication, each generates a key pair consisting of a private key and a corresponding public key. The private key must be kept secret and is only known to the owner, while the public key is made available to others.

To encrypt a message, the sender uses the recipient’s public key to encrypt the message. The encrypted message can only be decrypted by the recipient using their corresponding private key. This means that even if someone intercepts the encrypted message, they will not be able to read its contents unless they have access to the recipient’s private key.

Likewise, if a sender wants to ensure that only a specific recipient can read the message, they can encrypt the message with the recipient’s public key, which only the recipient can decrypt with their corresponding private key.

In summary, private and public keys work together to establish secure communication by allowing messages to be encrypted and decrypted in a way that only the intended recipient can read them. The use of different keys for encryption and decryption ensures that the message is secure even if it is intercepted by an unauthorized party.

About Certificate Authority (CA)

What is a Certificate Authority?

A Certificate Authority (CA) is a trusted third-party organization that issues digital certificates to users, organizations, and servers. These certificates are used to verify the identity of the certificate holder and to secure online communications.
Digital certificates are electronic documents that contain a public key, an expiration date, and information about the owner of the certificate. They are issued by a CA after the CA verifies the identity of the certificate holder. Once a digital certificate is issued, it can be used to encrypt and authenticate online communications, providing a secure connection between two parties.

How Does a Certificate Authority Work?

When a user connects to a secure website or server, the server presents its digital certificate to the user’s browser. The browser then verifies the certificate with the issuing CA to ensure that it is authentic and has not been tampered with.
If the certificate is valid, the browser establishes a secure connection with the server, encrypting all data sent between the two parties. This process is known as the SSL/TLS handshake and is essential for securing online communications.

In conclusion, Public Key Infrastructure (PKI) and Digital Certificates are critical components of online security. PKI provides a framework for securely exchanging and verifying public keys, while Digital Certificates serve as digital identities that enable secure communication and data exchange.

Digital Certificates are issued by trusted third parties, known as Certificate Authorities, who verify the identity of the certificate holder and issue a certificate that contains the certificate holder’s public key, along with other information, such as the certificate’s expiration date and the CA’s digital signature.

The use of PKI and Digital Certificates is essential for secure online communication and data exchange, protecting against online threats such as phishing and man-in-the-middle attacks, and ensuring the integrity of online transactions.