Home

Cryptography

What is cryptography and why is it important?

Cryptography is the science of encoding and decoding information to protect it from unauthorized access. It's important for maintaining the confidentiality of data, ensuring its integrity, and verifying the identity of communication participants. It has significant applications in our daily life including secure online transactions, password protection, and secure email communications.

What are some real-world applications of cryptography?

Cryptography is used in online banking and shopping to secure financial transactions, in password protection to authenticate users, in VPNs for secure remote access to networks, and even in cryptocurrencies like Bitcoin to validate transactions.


What are the key principles of cryptography?

The key principles of cryptography are confidentiality, integrity, availability, and authenticity. Confidentiality ensures that information is not disclosed to unauthorized individuals, integrity makes sure that the information isn't altered during transit, availability makes data always accessible to authorized users, and authenticity confirms the identity of users or data sources.

Can you explain how cryptography upholds these principles?

Cryptography upholds these principles using various techniques and protocols. It applies encryption algorithms to keep data confidential, uses hashing functions to check data integrity, leverages key management to ensure data availability, and employs digital signatures to authenticate identities.


What is encryption and how does it work?

Encryption is a procedure that transforms readable data, or plaintext, into unreadable data, or ciphertext, using a specific encryption algorithm and a key. It's the primary method to ensure data confidentiality in cryptography. The same key (symmetric encryption), or a different key (asymmetric encryption), is then needed to convert the ciphertext back to plaintext.

What's the difference between symmetric and asymmetric encryption?

Symmetric encryption uses the same key for both encryption and decryption - it's faster but key distribution can be a concern. Asymmetric encryption uses different keys (public and private) - it's more secure but computationally heavier.


Can you explain what a cryptographic hash function is?

A cryptographic hash function is a method that takes an input and returns a fixed-size string of bytes. It is designed to be a one-way function, meaning that once data has been transformed to a hash, it's computationally infeasible to revert it back to its original form. Hash functions are widely used to check data integrity.

How does a hash function ensure data integrity?

Hash functions ensure data integrity by generating a unique hash value for each unique data input. If a single character of the data is changed, the resulting hash varies dramatically. By comparing hash values, one can easily identify if data has been tampered with during transit.


What is a digital signature and what function does it serve?

A digital signature is a cryptographic tool that allows an individual to authenticate the source of data and guarantee its integrity. It's created by applying a private key to a hash of the message or document being signed. If the signature matches the document when checked with the public key, it proves the authenticity and integrity of the data.

Is a digital signature the same as an electronic signature?

No, a digital signature is not the same thing as an electronic signature. An electronic signature can simply be a scanned image of a person's ink signature, whereas a digital signature uses cryptography to secure data, authenticate the signer, and prevent the data from being altered.


What is public key cryptography and how does it work?

Public key cryptography, also known as asymmetric cryptography, uses a pair of mathematically linked keys: one private and one public. The private key is kept secret, and the public key is distributed freely. A message encrypted with the public key can only be decrypted with the private key, ensuring secure communication.

How is public key cryptography used in secure email communications?

In secure email communications, public key cryptography is used to encrypt the content of the email. The sender uses the receiver's public key for encryption, and only the receiver's private key can decrypt it. This ensures the confidentiality and integrity of the email contents.


What is a cipher and how is it used in cryptography?

A cipher is an algorithm that performs encryption or decryption. In cryptography, plaintext (readable data) is encrypted into ciphertext (unreadable data) using a cipher and a key. The cipher defines the steps and computations to transform plaintext into ciphertext and vice versa.

What are examples of some common ciphers used in cryptography?

Some common ciphers used in modern cryptography include the Advanced Encryption Standard (AES), the RSA algorithm, and the Diffie-Hellman key exchange algorithm. Each of these has different use cases and security levels and is designed to handle specific cryptographic tasks.


What is an encryption key and why is it relevant in cryptography?

An encryption key is a piece of information used in encryption and decryption processes to transform plaintext into ciphertext and vice versa. It serves as the 'secret' that allows data to be locked and unlocked, and is integral to maintaining the security and confidentiality of information in cryptography.

What are some measures for safeguarding encryption keys?

Safeguarding encryption keys involves practices such as regular key rotation, storing keys securely in a key vault, not transmitting keys openly, and using key derivation functions. In case of public-key cryptography, private keys must be kept very confidential since their exposure can compromise all the data encrypted with the corresponding public key.


How does secure communication occur over the internet using cryptography?

Secure communication over the internet using cryptography is often facilitated through protocols like SSL/TLS. When a secure connection is established, the website's public key is used to encrypt data sent from the user, which can only be decrypted by the website with its private key. This ensures the confidentiality and integrity of the data transmitted.

How does a website prove it owns the private key in an SSL/TLS exchange without revealing it?

In an SSL/TLS exchange, the website doesn't directly reveal its private key. Instead, it provides a digital certificate, verified by a trusted Certificate Authority (CA), which contains the website's public key and the CA's digital signature. The website can then provide proof it owns the private key by performing operations that only the matching private key could do.


What is the role of a Cryptographic algorithm?

A cryptographic algorithm (or cipher) plays a critical role in the process of encryption and decryption. It’s the method by which plain text (readable data) is transformed into cipher text (unreadable data), and vice versa, using an encryption key. Cryptographic algorithms uphold confidentiality, integrity, and authenticity of data in cryptography.

What are some widely used cryptographic algorithms?

Some widely used cryptographic algorithms include the Advanced Encryption Standard (AES), RSA (Rivest-Shamir-Adleman) for public-key cryptography, and SHA (Secure Hash Algorithm) for creating hashes. Each offers different levels of security and is suited for different situations.