Network Security
IPS can be classified into 4 different types
-Network-based intrusion prevention system (NIPS) -Host based intrusion prevention system (HIPS) -Wireless intrusion prevention systems (WIPS) -Network behavior analysis (NBA)
What is the extension of HTTP and which protocol it uses?
HTTPS Hypertext Transfer Protocol Secure is the extension of HTTP. It uses TCP/IP protocol.
IPsec helps keep data......
IPsec helps keep data over public networks secure. IPsec if often used to set up VPNs and it works by encrypting IP packets with authenticating the source where the packets come from.
SSL 2.0 Vulnerabilities
Short Key Length Weak MAC Construction Message integrity vulnerability Cipher suite rollback attack
What is/are the way/s to break substitution cipher? Which one is the best?
Some hackers might use applications and scripts to conduct a brute force attack. Brute force attacks are easy to conduct, they are accomplished by guessing logins and passwords to access a system.
Application Layer and its layers of security
-HTTP -FTP -SMTP -SSL or TLS -TCP -IP -Kerberos -UDP -S/MIME -PGP -SET
Network Layer and its layers of security
-HTTP -FTP -SMTP -TCP -IP/IPSec
TLS - Transport Layer Security - > HTTPS Connections Steps
1. Client Hello 2. Server Hello 3. Server Key Exchange 4. Client Key Exchange 5. Change Cipher Spec 6. Encrypted Handshake
OSI Model Layers
Application, Presentation, Session, Transport, Network, Data Link, Physical
Confidentiality
Enables communicating nodes to encrypt messages. Prevents eavesdropping by third parties.
Packet Switching must receive all or some of the packet before it can begin to transmit?
Packet switching must receive the entire packet before it can begin to transmit the first bit of the packet onto the outbound link. It needs to receive, store, and process the entire packet.
Whats the point of TLS?
Primary goal of the TLS protocol is to provide privacy and data integrity between two communicating applications.
SSL facts
SSL operates at the application layer of the OSI model. It encrypts HTTP traffic instead of directly encrypting IP packets. All web browsers already support SSL (whereas most devices are not automatically configured to support IPsec VPNs). Users can connect to SSL VPNs through their browser instead of through a dedicated VPN software application without much additional support from an IT team.
Transport Layer and its layers of security
-HTTP -FTP -SMTP -SSL or TLS -TCP -IP
What are the main objectives of IPS?
-Identification of malicious activity -Log information about said activity -Attempt to block/stop harmful activity -Report malevolent activity
Classic Encryption Techniques
1. Substitution Technique 2. Transposition Technique
Data Loss Prevention (DLP)
A procedure to filter outgoing traffic to prevent confidential information from leaving. Data loss prevention (DLP) is a cybersecurity solution that detects and prevents data breaches or unwanted leakage of sensitive data. Organizations use DLP to protect their data and comply with regulations. DLP can monitor, detect and block sensitive data while it is in use, in motion or at rest. DLP can also use encryption, antivirus software, AI and machine learning to enhance data security. Prioritize data classify the data Understand when data is at risk Monitor data in motion Communicate and develop controls Train employees and provide continuous guidance
How does access control work? Why is access control important?
Access control is the process of restricting access to resources or data only to authorized users or systems, while denying access to unauthorized entities. Access control works by using a combination of policies, procedures, and technologies to determine who can access resources, what resources they can access, and in what manner they can access them. Access control typically involves three main steps: Authentication: This is the process of verifying the identity of a user or system attempting to access a resource. Authentication can involve a variety of mechanisms, such as passwords, biometrics, smart cards, or other forms of identification. Authorization: Once a user or system has been authenticated, the next step is to determine what resources they are authorized to access. This involves checking the user's permissions and privileges to determine whether they are allowed to access the resource. Accountability: Access control also involves tracking and auditing access to resources, in order to monitor usage and detect potential security breaches or policy violations. Access control is important for several reasons: Security: Access control helps to protect sensitive data and resources from unauthorized access, theft, or damage. By limiting access to only authorized users, access control helps to reduce the risk of security breaches. Compliance: Many industries and organizations are subject to regulatory requirements that mandate access control measures to protect sensitive data. Compliance with these requirements is essential to avoid fines, legal liability, and damage to reputation. Productivity: Access control can also help to improve productivity by ensuring that users have access to the resources they need to do their jobs, while preventing unauthorized access or interference that could disrupt workflows.
Key management
Allows secure exchange of keys. Protection against certain types of security attacks, such as replay attacks.
Intrusion Prevention Systems (IPS) How do they work?
Also known as intrusion detection and prevention system (IDPS), are a network security application that monitors network and system activities for malicious or harmful activity.
What is cloud security?
Cloud security refers to the set of policies, procedures, and technologies designed to protect data, applications, and infrastructure that are hosted in cloud computing environments. Cloud computing has become an increasingly popular way for organizations to store and access data and applications, but it also presents unique security challenges that must be addressed to ensure the confidentiality, integrity, and availability of information. Cloud security includes a range of different components, such as access control, data protection, network security, identity and access management, and compliance. Some of the key considerations in cloud security include: Data protection: Cloud security involves protecting data from unauthorized access, theft, or loss. Encryption, access controls, and backup and recovery procedures are all important components of data protection in the cloud. Network security: Cloud security also includes securing the network infrastructure used to host and deliver cloud services. This can involve implementing firewalls, intrusion detection and prevention systems, and other network security measures. Identity and access management: Cloud security requires managing user identities and access to cloud resources. This includes authentication, authorization, and other access control mechanisms to ensure that only authorized users can access cloud services. Compliance: Cloud security must also comply with industry regulations and standards such as GDPR, HIPAA, and PCI-DSS. Compliance with these standards helps to ensure that data is protected and secure.
What is Cryptography?
Cryptography is the process of encrypting and decrypting data. Cryptosystems use a set of procedures known as cryptographic algorithms, or ciphers, to encrypt and decrypt messages to secure communications among computer systems, devices and applications. Cryptography is the art and science of achieving security by encoding message to make them non - readable. Cryptography is an effective way of protecting sensitive information as it is stored on media or transmitted through network communication paths.
What techniques cyber security involves? To implement the cyber security what factors are important?
Cybersecurity involves techniques such as access control, encryption, vulnerability management, incident response, and security awareness training to protect computer systems, networks and data from breaches, disruptions, damage, or anything that can compromise a network.To implement effective cybersecurity, factors such as risk assessment, policies and procedures, technology, personnel, and compliance are important.
Alice wants to use an affine cipher to encrypt her message before sending it to Bob. But Alice doesn't trust the security provided by the affine cipher so she encrypts the ciphertext of the affine cipher with another affine cipher. Is the resultant cipher more secure than the first cipher? How about hill cipher? Does encrypting the ciphertext from a hill cipher with another hill cipher make it more secure?
Encrypting the ciphertext of an affine cipher with another affine cipher does not necessarily make the message more secure, as the keyspace of the affine cipher is limited and an attacker can easily try all possible keys. Using a stronger cipher with a larger keyspace or multiple layers of encryption with different types of ciphers would be a better approach to increase security. Also, adding multiple layers of encryption can introduce new vulnerabilities making it less secure. Hill Cipher can make it more secure because it has a much larger keyspace compared to affine cipher.
Basic Cryptography Concepts
Encryption Scheme - functions to encrypt, and decrypt data -key generation algorithm Secret key vs public key -public key: publishing key does not reveal -secret key: more efficient, generally key = key^-1 Hash function, MAC -Map input to short hash; ideally, no collisions -MAC keyed hash used for message intergrity Signature Scheme Functions to sign data, verify signature
What is Encryption?
Encryption is the process of concealing information by mathematically altering data so that it appears random. In simpler terms, encryption is the use of a "secret code" that only authorized parties can interpret
What is encryption?
Encryption is the process of concealing information by mathematically altering data so that it appears random. In simpler terms, encryption is the use of a "secret code" that only authorized parties can interpret
TLS Consist of two protocols.....
Handshake protocol - Use a public key cryptography to establish a shared secret key between the client and the server Record protocol - Use the secret key established in the handshake protocol to protect communication between the client and the server.
How do IDS work?
IDS works with a copy of the traffic. It can detect an attack and send an alert (and take other actions), but it cannot prevent the attack because it does not operate on traffic inline in the forwarding path.
What is IPsec?
IPsec is a group of protocols that are used to set up encrypted connections between devices. It helps data sent over public networks secure. IPsec is often used to set up VPNs, and it works by encrypting IP packets, along with authenticating the source where the packets come from.
IPSec (Internet Protocol Security)
IPsec is a group of protocols that are used together to set up encrypted connections between devices. It helps keep data sent over public networks secure. IPsec is often used to set up VPNs, and it works by encrypting IP packets, along with authenticating the source where the packets come from.
What does IPsec do to packet?
IPsec protocol adds a header and trailer to packet. They can be found in the IP header of a packet and define how the data in the packet is handled, including its routing and delivery across a network. IPsec adds several components to the IP header, including security information and one or more cryptographic algorithms.
Why is it necessary for the numbers to be relative primes with 26 in affine cipher? What might be the consequences for the ciphertext if they are not relative primes?
In the affine cipher, it is necessary for the key 'a' (the multiplicative key) to be relatively prime with 26 (assuming a 26-letter alphabet) because the multiplicative key should have an inverse modulo 26 for decryption to work correctly. Two numbers are relatively prime if their greatest common divisor (GCD) is 1, meaning they do not share any common factors other than 1. The encryption function in an affine cipher is as follows: E(x) = (ax + b) mod 26 And the decryption function is: D(y) = a^(-1) (y - b) mod 26 Here, x is the plaintext letter, y is the ciphertext letter, a is the multiplicative key, b is the additive key, and a^(-1) is the modular multiplicative inverse of a modulo 26. If 'a' is not relatively prime to 26, then 'a' and 26 share a common factor greater than 1. In this case, 'a' will not have a modular inverse, which means that the decryption function cannot be correctly applied, making it impossible to recover the original plaintext from the ciphertext. Furthermore, if 'a' is not relatively prime to 26, the encryption function will not cover the entire alphabet, resulting in a loss of information and a less secure cipher. The ciphertext will have fewer possible characters, making it more vulnerable to frequency analysis attacks, as certain patterns and repetitions become more evident.
We know that passwords are never sent across the network, encryption keys are never directly exchanged, and you and application can mutually authenticate each other. Many organizations use it as the basis for a single sign-on. Which protocol do you think can do all those things?
Kerberos is a network authentication protocol designed to provide strong authentication for client-server applications by using secret-key cryptography. It was developed at the Massachusetts Institute of Technology (MIT) as part of the Athena Project. The name "Kerberos" comes from Greek mythology, where Kerberos (or Cerberus) is a three-headed dog guarding the gates of the underworld. Kerberos is built around the concept of "tickets," which are encrypted messages that prove the identity of a user or a service. The protocol has a centralized key distribution center (KDC), which consists of two main components: the Authentication Server (AS) and the Ticket Granting Server (TGS). Here's a simplified overview of how the Kerberos authentication process works: A user logs into a client machine and provides their username and password. The client sends a request to the Authentication Server (AS) for a Ticket Granting Ticket (TGT). The AS verifies the user's credentials, generates a session key, and issues a TGT encrypted with the TGS's secret key. The client receives the TGT and stores it locally. The TGT allows the user to request service tickets without re-authenticating. When the user wants to access a specific service, the client sends a request to the Ticket Granting Server (TGS) along with the TGT. The TGS decrypts the TGT, verifies its authenticity, and issues a service ticket encrypted with the service's secret key. The client receives the service ticket and sends it to the desired service. The service decrypts the service ticket, verifies its authenticity, and grants access to the user. Kerberos provides a secure and efficient authentication mechanism in a networked environment, reducing the need to transmit passwords over the network and protecting against common attacks such as eavesdropping and replay attacks.
Describe Malware attack, SQL injection attack, cross site scripting (XSS).
Malware Attack: Malware is malicious software that is designed to damage, disrupt, or steal information from computer systems. Malware attacks can take many forms, including viruses, trojans, ransomware, and spyware. Malware can be spread through infected email attachments, software downloads, or compromised websites. SQL Injection Attack: SQL injection is a type of attack that targets web applications that use SQL databases. In a SQL injection attack, an attacker inserts malicious SQL code into a web form or URL parameter, which is then executed by the application's database server. Cross-Site Scripting (XSS) Attack: Cross-site scripting (XSS) is a type of attack that targets web applications by injecting malicious scripts into web pages viewed by other users. In an XSS attack, an attacker injects code, such as JavaScript, into a web page that is then executed by other users' browsers. This allows the attacker to steal sensitive data or take control of the victim's browser.
Handshake Protocol
Negotiate version of the protocol and the set of cryptographic algorithms to be used Interoperability between different implementations of the protocol Authenticate client and server (optional) Use digital certificates to learn each other's public keys and verify each other's identity Use public keys to establish a shared secret
Name one key advantage of packet switching?
One key advantage of packet switching is its robustness and fault tolerance. In a packet-switched network, data is divided into smaller packets, which are then sent independently through the network. If a particular path or node fails, packets can be rerouted along alternative paths, ensuring that the communication remains uninterrupted. This dynamic routing capability makes packet-switched networks more resilient to failures and congestion than circuit-switched networks, where a dedicated communication path is established for the entire duration of a connection.
a) Describe how traffic engineering minimizes traffic delays on the network.
One of the ways network operators can tune a routing protocol configuration to affect how network traffic traverses the links in the network. We can use traffic shaping, Quality of Service (QoS), Load balancing, and routing optimization to reduce delays.
What is the open flow in SDN?
OpenFlow is a network communication protocol used between controllers and forwarders in an SDN.
What is a P2P network?
P2P, or Peer-to-Peer, is a decentralized process of communication and file sharing between computers on a network. In a P2P network, each computer, or peer, can act as both a client and a server, allowing data to be shared directly between them without the need for a centralized server or intermediary. In a P2P network, each peer has access to resources on other peers, and can also contribute its own resources to the network. This allows for more efficient use of resources, and can help improve network performance
How does IP routing work?
Packets can take different routes to the same place if necessary, just as a group of people driving to an agreed-upon destination can take different roads to get to the same location.
Origin authentication and data integrity
Provides assurance that a received packet was actually transmitted by the party identified as the source in the packet header. Confirms that the packet has not been altered or otherwise
Quick Summary of SSL/TLS
Public key encryption -key chosen secretly (handshake protocol) -key material sent encrypted with public key Symmetric encryption -Shared (secret) key encryption of data packets Signature-based authentication -Client can check signed server certificate -And vice-versa, in principal Hash for Integrity -Client, server check for hash of sequence of messages -MAC used in data packets (record protocol)
What layer does SSL and TLS operate on?
SSL (Secure Sockets Layer) and TLS (Transport Layer Security) are cryptographic protocols that provide secure communication over a network. They operate at the Transport Layer, which is the fourth layer of the OSI (Open Systems Interconnection) model. Specifically, SSL and TLS operate between the Application Layer (Layer 7) and the Transport Layer (Layer 4), establishing a secure connection between two endpoints by encrypting the data transmitted between them. This allows for the secure exchange of sensitive information, such as passwords, credit card numbers, and other personal data. The use of SSL and TLS is especially common in web applications, where they are used to secure communication between web servers and clients (e.g. web browsers). HTTPS, the secure version of HTTP, uses SSL/TLS to provide secure communication between a web server and a web browser.
How does SSL create a secure connection using a web browser?
SSL (Secure Sockets Layer) uses a combination of symmetric and asymmetric cryptography to establish a secure connection between a web server and a web browser. Here's how it works: The browser initiates a secure connection by sending a request to the web server, specifying that it wants to establish a secure connection using SSL/TLS. The server responds by sending its SSL/TLS certificate, which includes a public key that is used for encryption. The browser checks the certificate to make sure it is valid and issued by a trusted certificate authority (CA). If the certificate is invalid or not trusted, the browser will display a warning message. Once the certificate is verified, the browser generates a random symmetric key, which is used for encrypting data during the SSL/TLS session. The symmetric key is then encrypted with the server's public key and sent back to the server. The server decrypts the symmetric key using its private key, and the SSL/TLS session is established. All data transmitted between the browser and the server during the session is encrypted using the symmetric key. At the end of the session, the symmetric key is discarded, and the SSL/TLS connection is closed. In summary, SSL/TLS creates a secure connection by using asymmetric cryptography to exchange keys, and symmetric cryptography to encrypt data during the session. This ensures that data transmitted between the browser and the server is secure and protected from eavesdropping and tampering.
What are the two main detection methods of IPS?
Signature-based Detection and Statistical anomaly-based or Knowledge based detection Sig Detection This method of detection utilizes signatures of attack patterns that are preconfigured and predetermined. A signature-based intrusion prevention system monitors the network traffic for matches to these signatures. Once match is found the intrusion prevention system take the appropriate action. Stat Detection This method of detection determines normal network activity like what sort of bandwidth is generally used, what protocols are used, what ports and devices generally connect to each other. It alerts the administrator or user and prevents malicious contents when anomalous traffic is detected.
Steps for TLS
Step 1 - Client says hello to server -The client begins the communication and it lists the versions of SSL/TLS and cipher suites it is able to use. Step 2 - Server says hello client -The server will see the list of SSL/TLS versions and cipher suites and pick the newest version the server is able to use. Then the server sends a message to the client containing the SSL/TLS version and cipher suite it selected. Step 3 - Server Key Exchange -After the server and the client agree on the SSL/TLS version and cipher suites, the server sends two things. SSL/TLS certificate public key and signature The public key is included in the certificate. The client and the server use the public key to encrypt messages which can only be decrypted with the server's private key. The server never shares the private key....ever.
What is store and forward?
Store-and-forward is a networking technique used to transmit data between two or more network devices. In store-and-forward networking, the data is received by an intermediary device, such as a router, switch, or hub, which then stores the entire packet before forwarding it to its destination. This is in contrast to other networking techniques like cut-through switching, where the intermediary device begins forwarding the packet before the entire packet is received. In store-and-forward networking, the intermediary device examines the packet for errors before forwarding it. If the packet is error-free, the device forwards it to the next device in the path to its final destination. If the packet contains errors, the device discards it and requests that the packet be retransmitted. One of the advantages of store-and-forward networking is that it can help to prevent data loss and errors. Since the intermediary device stores the entire packet before forwarding it, it can examine the packet in its entirety and check for errors. If errors are detected, the device can request that the packet be retransmitted, which can help to ensure that the data is transmitted correctly. Overall, store-and-forward networking is a reliable technique for transmitting data over a network, and is commonly used in many different types of networks, including local area networks (LANs), wide area networks (WANs), and the Internet.
Describe each layer of the OSI model.
The OSI (Open Systems Interconnection) model is a conceptual framework that standardizes the functions of a telecommunication or computing system into seven distinct layers. Each layer performs specific tasks to facilitate communication between systems. Here is a brief description of each layer: Physical Layer (Layer 1): This layer is responsible for the physical connections between devices, such as cables, switches, and hubs. It deals with the transmission and reception of raw binary data (bits) over a communication medium. Data Link Layer (Layer 2): This layer establishes and maintains reliable data transfer between two devices on the same network. It is responsible for error detection, error correction, and flow control. Key protocols at this layer include Ethernet (for wired connections) and Wi-Fi (for wireless connections). Network Layer (Layer 3): This layer is responsible for routing data packets between different networks. It handles logical addressing (such as IP addressing) and selects the best path for data transmission using routing algorithms. The Internet Protocol (IP) is a key component of this layer. Transport Layer (Layer 4): This layer is responsible for providing end-to-end communication services, such as error detection, error recovery, and flow control. It establishes, maintains, and terminates connections between applications on different devices. Key protocols at this layer include the Transmission Control Protocol (TCP) and User Datagram Protocol (UDP). Session Layer (Layer 5): This layer manages and coordinates the communication sessions between applications. It establishes, maintains, and synchronizes the interaction between communicating devices, handling session setup, authentication, and data exchange. Presentation Layer (Layer 6): This layer is responsible for translating and converting data between the application layer and the lower layers. It deals with data representation, encryption, and compression to ensure that data is transmitted in a format that both the sender and receiver can understand. Application Layer (Layer 7): This is the topmost layer that interacts with the user and provides network services to applications. It is responsible for various application-level functions, such as file transfers, email services, and web browsing. Key protocols at this layer include the Hypertext Transfer Protocol (HTTP), File Transfer Protocol (FTP), and Simple Mail Transfer Protocol (SMTP).
Describe TCP handshake
The TCP (Transmission Control Protocol) handshake is a three-way process that occurs between two network devices (such as a client and a server) to establish a reliable connection before data transmission can begin. Steps involved in the TCP handshake: SYN: The client sends a SYN (synchronize) packet to the server, indicating that it wants to initiate a connection. The SYN packet contains a sequence number, which is a randomly chosen value used to keep track of the data being transmitted. SYN-ACK: The server responds with a SYN-ACK (synchronize-acknowledge) packet, indicating that it received the client's SYN packet and is willing to establish a connection. The SYN-ACK packet also contains a sequence number and an acknowledgment number, which is the sequence number from the client's SYN packet plus one. ACK: The client sends an ACK (acknowledge) packet to the server, confirming that it received the server's SYN-ACK packet. The ACK packet also contains an acknowledgment number, which is the sequence number from the server's SYN-ACK packet plus one. Once the three-way handshake is complete, the TCP connection is established, and data transmission can begin. During the transmission of data, each packet sent between the client and server will contain a sequence number and an acknowledgment number, which are used to ensure that data is transmitted reliably and in the correct order. The TCP handshake is a process that establishes a reliable connection between two network devices before data transmission can begin. It involves the exchange of SYN, SYN-ACK, and ACK packets, each containing sequence and acknowledgment numbers that are used to track and ensure reliable data transmission.
Why do HTTP, SMTP and POP3 run on top of TCP rather than UDP?
The applications associated with those protocols require that all application data be received in the correct order and without gaps. TCP provides this service whereas UDP does not
a) What is the basis for the IP? How do the packets travel through the network?
The basis for Internet Protocol is a set of rules for transmitting data packets over a network. IP is the primary protocol used on the Internet and provides a standardized method for routing packets between devices. When data is transmitted over a network, it's divided into smaller packets. Each packet has a header that contains the source and destination addresses along with other information. Packets are then transmitted from the source device to the destination device through a series of network routers. These network routers examine the packet headers to determine the best path for each packet to reach its destination. Routing table algorithms determine the best path for each packet based on a few factors. Once all the packets arrive at the destination they are reassembled into the original data stream and then processed by the receiving application.
a) What the best parameters to evaluate the performance of the network?
The best parameters to evaluate the performance is Delay, Loss, and Throughout. Delay is how long it takes for data to travel across the network from the source. Loss is how many packets or how much data fails to reach its destination. Throughput is how many packets the destination is receiving per unit of time.
IPsec protocol suite operates at.....
The network layer of the OSI model. It runs directly on top of IP (the internet protocol), which is responsible for routing data packets.
1.For a communication session between a pair of processes, which process is the client and which one is the server?
The process which initiates the communication is the client; the process that waits to be contacted is the server
What is network performance?
Throughput or bandwidth Delay or latency Packet Loss
a) What is traffic engineering and how it helps to prevent congestion and to improve network performance and efficiency?
Traffic engineering is a field of network engineering that targets optimizing the performance and efficiency of network traffic. It involves techniques such as traffic shaping, traffic prioritization, and traffic rerouting to prevent congestion, ensure smooth traffic flow, and minimize delays and packet loss. By utilizing these techniques, traffic engineers can help to improve network performance and efficiency and ensure that critical applications and services operate reliably.
What is a VPN (virtual private network)?
VPN is an encrypted connection between two or more computers. VPN connections take place over public networks., but the data exchanged over the VPN is still private because it is encrypted. VPNs make it possible to secure access and exchange confidential data over shared network infrastructure, such as the public internet. For instance, when employees are working remotely instead of in the office, they often use VPN's to access corporate files and applications. Many VPNs us the IPsec protocol suite to establish and run these encrypted connections. However not all VPNs use IPsec. Another protocol for VPNs is SSL/TLS which operates at a different layer in the OSI model than IPsec
How do you connect to an application over an insecure network? Explain authentication protocol? What is the benefit of this protocol?
When connecting to an application over an insecure network, use an authentication protocol to ensure secure access to the application. An authentication protocol is a set of rules that determines how a user can prove their identity to the application. This helps ensure that only authorized users can access the application. To further enhance security, use encryption to protect the data being transmitted between the user and the application.
Is it possible that two different plaintexts can give the same ciphertexts using Hill Cipher? Support your answer with an example.
Yes is it is possible if the matrix key is not invertible or has a determinant that is a factor of the alphabet size. Using the Key [3 2; 5 7] and the text1 = CAT and text2 = MOP. Both of these will cipher to YFGJU because the determinant key of the matrix is -1 and this is a factor of 26. The existence non-zero vector creates an issue when any two plaintexts differ by that vector. This will encrypt to the same ciphertext.
Affine Cipher formula
ax + b (mod M) Sure, let's consider an example using the affine cipher with a 26-letter alphabet (A=0, B=1, ..., Z=25). We will use the keys a=5 and b=8. Since the GCD(5, 26) = 1, 'a' is relatively prime to 26. Plaintext: HELLO First, convert the plaintext letters to their corresponding numerical values: H=7, E=4, L=11, L=11, O=14 Now, apply the encryption function for each letter using E(x) = (ax + b) mod 26:
End to end equation delay of one packet over two links
de2e = 2* L/R
Substitution ciphers are vulnerable to
frequency analysis attacks
TLS and SSL are located between
the application protocol layer and the TCP/IP layer, (Session Layer) where they can secure and send application data to the transport layer.