Public-Key Infrastructure (PKI) is a set of policies, procedures, software, and hardware that enables secure electronic transactions over the internet. PKI uses public-key cryptography to provide confidentiality, integrity, and authentication for electronic communications.
Public-key cryptography uses two mathematically related keys: a public key and a private key. The public key is used to encrypt data, and the private key is used to decrypt data. The public key can be shared with anyone, but the private key must be kept secret.
PKI uses digital certificates to bind a public key to a specific identity. A digital certificate is an electronic document that contains a public key, the identity of the public key holder, and the signature of a trusted third party, known as a certificate authority (CA).
To use PKI, a user must first obtain a digital certificate from a CA. The user can then use their digital certificate to encrypt messages and sign electronic documents. The recipient of the message or document can then use the user’s public key to verify the signature and decrypt the message.
PKI is used in a variety of applications, including:
- Secure email communications (S/MIME)
- Secure web browsing (HTTPS)
- Secure file transfer (SFTP)
- Digital signatures
- Code signing
- Electronic commerce
MCQs and Answers
- What is the purpose of a public key in PKI?
(A) To encrypt data. (B) To decrypt data. (C) To sign data. (D) All of the above.
Answer: (A) To encrypt data.
- What is the purpose of a private key in PKI?
(A) To encrypt data. (B) To decrypt data. (C) To sign data. (D) All of the above.
Answer: (B) To decrypt data.
- What is a digital certificate?
(A) An electronic document that contains a public key, the identity of the public key holder, and the signature of a certificate authority. (B) A mathematical algorithm used to encrypt and decrypt data. (C) A set of policies and procedures for managing public and private keys. (D) A software application used to generate and manage digital signatures.
Answer: (A) An electronic document that contains a public key, the identity of the public key holder, and the signature of a certificate authority.
- What is a certificate authority?
(A) A trusted third party that verifies the identities of public key holders and issues digital certificates. (B) A software application used to generate and manage digital signatures. (C) A mathematical algorithm used to encrypt and decrypt data. (D) A set of policies and procedures for managing public and private keys.
Answer: (A) A trusted third party that verifies the identities of public key holders and issues digital certificates.
- Which of the following is an example of a PKI application?
(A) Secure email communications (S/MIME) (B) Secure web browsing (HTTPS) (C) Secure file transfer (SFTP) (D) All of the above
Answer: (D) All of the above
Conclusion
PKI is an important security technology that can be used to protect electronic communications and transactions. By understanding the basics of PKI, you can help to protect your data and your privacy.