9.1 Public Key Cryptography Principles
3 min read•august 9, 2024
revolutionized . It uses two keys: a public one for and a private one for . This system eliminates the need for secure , making it safer than symmetric encryption.
This section covers the math behind public key crypto, , and its many applications. From to , public key cryptography is essential for modern online security and privacy.
Key Concepts
Fundamentals of Asymmetric Encryption
Top images from around the web for Fundamentals of Asymmetric Encryption
Security & Privacy ; Erik Wilde ; UC Berkeley School of Information View original
Is this image relevant?
Cryptography/A Basic Public Key Example - Wikibooks, open books for an open world View original
Is this image relevant?
Security Issues ; Erik Wilde ; UC Berkeley School of Information View original
Is this image relevant?
Security & Privacy ; Erik Wilde ; UC Berkeley School of Information View original
Is this image relevant?
Cryptography/A Basic Public Key Example - Wikibooks, open books for an open world View original
Is this image relevant?
1 of 3
Top images from around the web for Fundamentals of Asymmetric Encryption
Security & Privacy ; Erik Wilde ; UC Berkeley School of Information View original
Is this image relevant?
Cryptography/A Basic Public Key Example - Wikibooks, open books for an open world View original
Is this image relevant?
Security Issues ; Erik Wilde ; UC Berkeley School of Information View original
Is this image relevant?
Security & Privacy ; Erik Wilde ; UC Berkeley School of Information View original
Is this image relevant?
Cryptography/A Basic Public Key Example - Wikibooks, open books for an open world View original
Is this image relevant?
1 of 3
- uses two distinct keys for encryption and decryption
- Public key can be freely distributed and used by anyone to encrypt messages
- Private key remains secret and is used by the owner to decrypt messages
- consists of mathematically related public and private keys
- Provides stronger security compared to symmetric encryption, eliminating the need for secure key exchange
Mathematical Foundations
- forms the basis of asymmetric encryption algorithms
- Easy to compute in one direction but computationally infeasible to reverse
- Enables secure key generation and encryption processes
- extends one-way function concept
- Includes a secret "trapdoor" that allows easy computation of the inverse
- Enables efficient decryption for the private key holder while maintaining security
Key Management and Security
- Public key can be widely distributed without compromising security
- Often published in directories or shared through
- Private key must be kept strictly confidential
- Stored securely on the owner's device or in a hardware security module
- Key pair generation involves complex mathematical operations
- Ensures the mathematical relationship between public and private keys
- Utilizes prime numbers and modular arithmetic in many algorithms (RSA)
Applications
Secure Communication and Data Protection
- Digital signatures provide and
- Sender signs a message with their private key
- Recipients verify the signature using the sender's public key
- Ensures message hasn't been tampered with and confirms sender's identity
- Key exchange facilitates secure communication over insecure channels
- Allows parties to establish a shared secret key without prior communication
- key exchange protocol commonly used for this purpose
- achieved through public key encryption
- Sender encrypts message with recipient's public key
- Only the intended recipient can decrypt using their private key
Authentication and Trust Mechanisms
- prevents denial of message origin or content
- Combines digital signatures with secure timestamping
- Provides legal weight to electronic transactions and communications
- Authentication verifies the identity of communicating parties
- Can be achieved through
- Often combined with digital certificates for added trust
- establishes trust in public keys
- Utilizes to issue and manage digital certificates
- Enables secure web browsing (HTTPS) and email encryption (S/MIME)
Advanced Applications and Protocols
- uses public key cryptography for remote access
- Provides encrypted terminal connections and secure file transfers
- employs asymmetric encryption for email security
- Combines public key cryptography with symmetric encryption for efficiency
- relies on public key cryptography
- Secures cryptocurrency transactions and maintains user anonymity
- uses asymmetric encryption for initial handshake
- Establishes secure connections for various internet protocols (HTTPS, FTPS)
Key Terms to Review (25)
Asymmetric encryption: Asymmetric encryption is a cryptographic technique that uses a pair of keys—a public key for encryption and a private key for decryption. This method enhances security by allowing users to share their public keys openly while keeping their private keys secret, enabling secure communication and data integrity without needing to exchange secret keys in advance.
Authentication: Authentication is the process of verifying the identity of a user, device, or system before granting access to resources. This process is crucial in establishing trust in digital communications, ensuring that only authorized entities can interact with systems and data.
Blockchain technology: Blockchain technology is a decentralized digital ledger system that records transactions across multiple computers in a way that ensures the security and transparency of the data. It enables trustless transactions, meaning that participants do not need to know or trust each other to conduct business, as the integrity of the data is maintained through cryptographic techniques and consensus mechanisms.
Certificate Authorities: Certificate authorities (CAs) are trusted entities responsible for issuing digital certificates that authenticate the identity of individuals, organizations, or devices in a public key infrastructure (PKI). They play a crucial role in public key cryptography by verifying the legitimacy of the parties involved in secure communications, ensuring that the public keys exchanged are indeed associated with their rightful owners. This trust model is foundational for secure online transactions and communications.
Challenge-response protocols: Challenge-response protocols are security mechanisms used to authenticate users or devices by requiring them to provide a valid response to a challenge posed by the system. This process involves the system generating a random challenge, which the user must then respond to correctly, usually by performing a cryptographic operation using their secret key. These protocols enhance security by ensuring that only legitimate users can access sensitive information, particularly in scenarios where passwords alone may be insufficient.
Confidentiality: Confidentiality refers to the principle of ensuring that information is only accessible to those authorized to have access. It is a fundamental aspect of information security, aiming to protect sensitive data from unauthorized disclosure. This concept is closely tied to the measures and technologies used in cybersecurity to safeguard information, impacting how organizations design their security frameworks.
Decryption: Decryption is the process of converting encoded or encrypted data back into its original form, allowing authorized users to access the information. It plays a crucial role in ensuring data confidentiality and integrity by enabling secure communication. Understanding decryption is essential for recognizing how various encryption methods safeguard sensitive information across different contexts, including historical, classical, and modern cryptographic practices.
Diffie-Hellman: Diffie-Hellman is a cryptographic protocol that allows two parties to securely exchange cryptographic keys over a public channel. This method relies on the mathematical principles of modular exponentiation and discrete logarithms, enabling users to generate a shared secret that can be used for encrypted communication without needing to share the key directly. It’s foundational for establishing secure connections in various applications, emphasizing the importance of key management in secure communications.
Digital certificates: Digital certificates are electronic credentials used to prove the ownership of a public key, enabling secure communication over networks. They contain the public key, information about the entity that owns it, and are issued by a trusted authority known as a Certificate Authority (CA). By validating the identity of the certificate holder, digital certificates help establish trust in online transactions and secure communications.
Digital Signatures: Digital signatures are cryptographic tools that ensure the authenticity and integrity of digital messages or documents. They work by using a combination of hashing and asymmetric encryption to provide a unique identifier that verifies the sender's identity and confirms that the message has not been altered in transit. This process ties into key concepts such as maintaining confidentiality, integrity, and availability of information, while also playing a pivotal role in the evolution of cryptographic practices and the principles of public key cryptography.
Encryption: Encryption is the process of converting plaintext into ciphertext using an algorithm and a key, making the data unreadable to unauthorized users. It plays a crucial role in safeguarding sensitive information, ensuring confidentiality during data transmission, and providing mechanisms to maintain the integrity of data against unauthorized alterations.
Key Exchange: Key exchange is a method used in cryptography to securely share cryptographic keys between parties, ensuring that the keys can be used for encryption and decryption of messages. This process is critical for establishing secure communication channels, allowing users to authenticate each other and protect sensitive data from eavesdroppers. Various protocols exist for key exchange, with public key cryptography offering a robust framework for this essential task.
Key management: Key management refers to the process of handling cryptographic keys in a secure manner throughout their lifecycle, including their creation, storage, distribution, use, and destruction. Proper key management is crucial for ensuring the confidentiality, integrity, and authenticity of encrypted data, as it safeguards the keys that protect sensitive information from unauthorized access.
Key pair: A key pair consists of two cryptographic keys used in asymmetric encryption: a public key, which can be shared with anyone, and a private key, which must be kept secret. The relationship between these keys is fundamental to public key cryptography, enabling secure data transmission and authentication. The public key is used for encryption or verifying a digital signature, while the private key is used for decryption or creating a digital signature.
Message integrity: Message integrity refers to the assurance that a message has remained unchanged and unaltered during transmission, ensuring that the content received is exactly what was sent. It is crucial in preventing unauthorized modifications that can compromise the reliability of data and trust in communication systems. Techniques like cryptographic hash functions and digital signatures play a key role in providing message integrity, allowing parties to verify that the message they receive is authentic and intact.
Non-repudiation: Non-repudiation is a security principle that ensures that a party in a communication cannot deny the authenticity of their signature on a message or the sending of the message itself. This concept is crucial in establishing accountability and trust in digital communications, as it provides evidence that an action has taken place and can be verified. Non-repudiation is essential for legal and transactional contexts where it is necessary to prove that a specific individual engaged in a particular action.
One-way function: A one-way function is a mathematical function that is easy to compute in one direction but hard to reverse, meaning that it is practically infeasible to retrieve the original input from its output. This property makes one-way functions crucial in various cryptographic applications, especially for ensuring data integrity and secure communication through public key cryptography. They play a key role in creating digital signatures and hash functions, where authenticity and non-repudiation are required.
Pretty Good Privacy (PGP): Pretty Good Privacy (PGP) is an encryption program that provides cryptographic privacy and authentication for data communication, primarily used for securing emails and files. It utilizes a combination of symmetric-key cryptography and public-key cryptography, allowing users to encrypt their messages and ensure that only intended recipients can read them. PGP also facilitates digital signatures, ensuring both the integrity of the message and the identity of the sender.
Public Key Cryptography: Public key cryptography is a cryptographic system that uses pairs of keys: a public key, which can be shared openly, and a private key, which must be kept secret. This approach allows secure communication and digital signatures, enabling two parties to exchange information without needing to share a private key beforehand, thus facilitating secure transactions over insecure channels.
Public Key Infrastructure (PKI): Public Key Infrastructure (PKI) is a framework that enables secure communication through the use of public and private key pairs, ensuring the authenticity, integrity, and confidentiality of data exchanged over insecure networks. It provides a set of policies, hardware, software, and procedures to manage digital certificates and public-key encryption, which are crucial for secure transactions and communications. PKI underpins various security protocols and standards, facilitating trust and verification in digital environments.
Secure communication: Secure communication refers to the methods and protocols used to ensure that data exchanged between parties is protected from unauthorized access and tampering. This involves various techniques such as encryption, which transforms readable data into an unreadable format, making it secure from eavesdroppers. Secure communication is essential for maintaining confidentiality, integrity, and authenticity in the exchange of information across networks.
Secure Shell (SSH): Secure Shell (SSH) is a cryptographic network protocol that allows secure access to a computer over an unsecured network. It provides a secure channel for data transmission between a client and server by using encryption, ensuring the confidentiality and integrity of data. SSH is particularly important for remote administration and secure file transfers, leveraging public key cryptography principles to authenticate users and establish secure connections.
Secure web browsing: Secure web browsing refers to the practices and technologies that protect users while they navigate the internet, ensuring that their data and privacy are safeguarded from unauthorized access and cyber threats. This concept is essential as it encompasses various security measures such as encryption, secure connections, and user authentication that help create a safe online environment. Effective secure web browsing practices not only protect individual users but also contribute to the overall integrity of web communications.
Transport Layer Security (TLS): Transport Layer Security (TLS) is a cryptographic protocol designed to provide secure communication over a computer network. It ensures privacy, integrity, and authentication between communicating applications, primarily used for securing web traffic. TLS is crucial in protecting sensitive data during transmission, using both symmetric and asymmetric encryption techniques to establish a secure connection and prevent eavesdropping or tampering.
Trapdoor function: A trapdoor function is a type of mathematical function that is easy to compute in one direction but difficult to reverse without specific information, known as the 'trapdoor.' This concept is fundamental to public key cryptography, as it allows secure communications where one key can be used for encryption and another key can be used for decryption, ensuring that only the intended recipient can decode the message.