Cryptography Flashcards
What is ECC?
Elliptic Curve Cryptography is a public-key cryptographic algorithm that uses elliptic curves to achieve security. ECC keys are smaller than RSA keys while still providing equivalent security. This makes ECC more efficient for devices with limited resources, such as mobile phones and embedded systems.
What is an ephemeral key?
An ephemeral key is a temporary cryptographic key that is generated for each session. Ephemeral keys are used in conjunction with long-term keys to provide perfect forward secrecy (PFS).
Define PFS.
Perfect Forward Secrecy is a security property of cryptographic protocols that ensures that even if the long-term key used to establish a secure session is compromised, all past and future communications encrypted under that session key remain secure. PFS is achieved by using a different, ephemeral key for each session.
What is CBC?
Cipher Block Chaining is a mode of operation for a block cipher that encrypts data in blocks. Each block of data is XORed with the previous ciphertext block before being encrypted by the block cipher. This chaining of blocks makes it more difficult for attackers to decrypt the data, even if they have knowledge of one of the blocks.
What is ECB?
Electronic Codebook is a mode of operation for a block cipher that encrypts each block of data independently. This means that the same plaintext block will always produce the same ciphertext block, regardless of the other blocks of data in the message. ECB is not as secure as CBC, but it is simpler to implement and can be faster in some cases.
Define GCM.
Galois/Counter Mode is a mode of operation for a block cipher that combines the benefits of CBC and CTR modes. It is as secure as CBC, but it is also more efficient. GCM is often used in protocols such as TLS and IPsec.
Define Symmetric Encryption and Asymmetric Encryption.
Symmetric encryption is an encryption method that uses the same key for both encryption and decryption. This means that the sender and receiver must agree on the key before they can communicate securely. Symmetric encryption is typically faster than asymmetric encryption, but it is also less secure. Asymmetric encryption is an encryption method that uses two different 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. Asymmetric encryption is more secure than symmetric encryption, but it is also slower.
What is AES?
Advanced Encryption Standard is a block cipher that uses a 128-bit, 192-bit, or 256-bit key. It is considered to be the most secure symmetric encryption algorithm available.
Define RSA.
RSA is a public-key cryptosystem that uses two 2048-bit keys. It is considered to be one of the most secure asymmetric encryption algorithms available.
Define steganography.
steganography is the practice of hiding a secret message within another message or medium. The purpose of steganography is to conceal the existence of the message, making it more difficult for unauthorized parties to detect and intercept it.
What is IPSEC?
Internet Protocol Security is a set of protocols that provide security for IP communications. IPsec can be used to protect data confidentiality, data integrity, and data origin authentication.
List the two different modes of IPSEC.
- Transport mode protects the data portion of an IP packet, but not the IP header. This means that the source and destination addresses of the packet are still visible. Transport mode is typically used for host-to-host communications, such as between two computers.
- Tunnel mode encapsulates the entire IP packet in another IP packet. This means that the source and destination addresses of the inner packet are hidden from the outside world. Tunnel mode is typically used for gateway-to-gateway communications, such as between two routers.
What is ESP?
Encapsulating Security Payload provides encryption and authentication for IP packets. ESP uses a symmetric-key encryption algorithm to encrypt the data portion of the packet. ESP can also be used to authenticate the packet using AH (Authentication header).
What is Authentication Header (AH)?
authentication header is an IPsec protocol that provides authentication and integrity for IP packets. AH uses a cryptographic hash function to create a message authentication code (MAC) for each packet. The MAC is then used to verify the authenticity and integrity of the packet.
What is CRC?
cyclic redundancy check is a checksum algorithm that is used to verify the integrity of data. CRCs are used in a variety of applications, including data storage, data transmission, and file verification.
