What is the Difference Between Public and Private Key Cryptography
Public Key Infrastructure (PKI) is a comprehensive framework that enhances the security of digital communications and transactions within organisations. PKI utilises encryption as a measure to protect sensitive data from unauthorised access and manipulation.
To ensure a secure IoT infrastructure, encryption is governed by the principles of cryptography. Cryptography utilises complex mathematical algorithms to transform readable data into encrypted data, ensuring confidentiality and integrity during transmission and storage.
The cryptography process involves public and private keys. But what is public and private key in cryptography?
In this guide, we explain how public and private keys work to safeguard your communications. Implementing Nexus Smart ID PKI can enhance your cybersecurity measures, offering advanced encryption and secure key management practices to protect your IoT devices and databases effectively.
What is a public key?
A public key is used in public key cryptography, also known as asymmetric cryptography. It is openly shared and used to encrypt messages or data that can only be decrypted by its corresponding private key. This ensures secure communication by allowing anyone to send encrypted messages that only the intended recipient can decrypt.
How does a public key work?
Here is a step-by-step breakdown of how a public key works:
- Key generation: A public and a private key are generated. The public key is shared openly, while the private key is kept confidential.
- Public key distribution: The public key is distributed to anyone who needs to send encrypted messages to the key owner. It can be shared via email, websites, or other public means.
- Encryption: When someone wants to send a secure message to the key owner, they use the recipient’s public key to encrypt the message. This process converts the original data or message (plaintext) into ciphertext, which appears as a random string of characters.
- Transmission: The encrypted message (ciphertext) is then to the recipient.
- Decryption: Upon receiving the encrypted message, the recipient uses their private key to decrypt it. The private key transforms the ciphertext back into the original plaintext, making the message readable only to the recipient.
Advantages of public key encryption
Public key encryption is a secure and reliable method for you to protect sensitive information and ensure that only intended recipients can access it. Here are some of its benefits:
Secure communication
Public key encryption ensures that your communications remain secure even over potentially insecure networks. By using your public key for encryption, others can send you confidential messages that only you can decrypt with your private key. This prevents access to the content of your communications, even if intercepted by hackers.
Confidentiality
With public key encryption, you can maintain the confidentiality of your sensitive data. When someone encrypts a message with your public key, only you can decrypt and read it with your private key. This ensures that your private information remains protected from unauthorised access.
Digital signatures
Public key encryption allows for the creation of digital signatures, which authenticate the identity of the sender. When you receive a digitally signed message, you can use the sender’s public key to verify that the message truly came from them. This adds an extra layer of security and trust to your digital communications.
Convenience
Public key encryption simplifies secure communication by eliminating the need to share private keys. You can freely distribute your public key without compromising security, making it easy for others to send you encrypted messages.
Limitations of public key encryption
While public key encryption is a popular method for secure communications, it does have a few limitations. One drawback is the slow speed of encryption and decryption compared to symmetric key encryption. This can be a concern when dealing with large volumes of data or requiring real-time communication, as it may impact performance and efficiency.
Another limitation is the complexity of key management. Public key encryption relies on a robust infrastructure to distribute and manage keys, which can be resource-intensive and complex to maintain. If your private key is compromised, all communications encrypted with the corresponding public key are at risk.
What is a private key?
A private key is used in symmetric cryptography, where the same key is used for both encryption and decryption. It is kept confidential and known only to the authorised parties involved in secure communication.
How does a private key work?
Here is how a private key functions step-by-step:
- Key generation: A single private key is generated, which is used for both encryption and decryption.
- Encryption: When you want to encrypt a message, you use the private key to convert the plaintext into ciphertext. This process ensures that only someone with the same private key can decrypt and read the message.
- Key distribution: The private key must be securely shared with the intended recipient. This step is crucial because if the key is intercepted or exposed, the encrypted messages can be compromised.
- Decryption: Upon receiving the encrypted message, the recipient uses the same private key to decrypt the ciphertext back into plaintext. This ensures that the original information is accessible only to those who possess the private key.
Effective key management is essential in symmetric encryption. Proper key management practices include using strong passwords or additional encryption to protect it from unauthorised access.
Advantages of private key encryption
The main advantages of private key encryption are efficient and simplified security. Using the same key for both encryption and decryption requires less computational power and time. This speed and simplicity make it ideal for encrypting large volumes of data quickly or real-time communication. Your business can maintain high security without sacrificing performance.
Limitations of private key encryption
The main problem with private key encryption lies in key exchange. Since the same key is used for both encryption and decryption, you will need to share this key with each intended recipient. Ensuring that the key remains confidential and uncompromised during distribution is crucial to maintaining the security of your encrypted communications.
Scalability is also an issue with private key encryption. As your business grows and the number of communication channels increases, managing and distributing private keys to multiple users can become resource-intensive. This complexity can lead to operational inefficiencies and potential security risks if proper key management practices are not followed.
Private key vs public key: How are they different?
Private keys and public keys are fundamental components of cryptographic systems, but they serve different purposes. In asymmetric cryptography, public keys are openly shared and used by anyone to encrypt messages. In symmetric cryptography, private keys are kept secret and used for both encrypting and decrypting data.
FAQs about public and private key cryptography
What is an example of a public key cryptosystem?
A widely used example of a public key cryptosystem is RSA (Rivest–Shamir–Adleman). RSA is an asymmetric encryption that utilises the mathematical properties of large prime numbers for secure encryption and decryption.
Can public and private key cryptography be used together?
Yes, hybrid systems often combine the strengths of both public and private key cryptography. For example, a message might be encrypted with a symmetric key, and this symmetric key itself is encrypted using the recipient’s public key for secure transmission.
Why is key management important in cryptography?
Effective key management is crucial to maintaining the security and integrity of cryptographic systems. It involves securely generating, distributing, storing, using, and revoking keys to prevent unauthorised access or decryption.
