diff --git a/_posts/Lecture Notes/Internet Security/2023-09-10-security-intro.md b/_posts/Lecture Notes/Internet Security/2023-09-10-security-intro.md index 8e10fdd..c256e8e 100644 --- a/_posts/Lecture Notes/Internet Security/2023-09-10-security-intro.md +++ b/_posts/Lecture Notes/Internet Security/2023-09-10-security-intro.md @@ -36,7 +36,7 @@ attachment: In this course, we are mainly interested in system/network security! There are two categories in **IT Security**, (though the boundary is blurry) -- **Computer** (system) **security** uses automated tools and mechanisms to protect **data in a computer**, against hackers, malware, etc. +- **Computer** (system) **security** uses automated tools and mechanisms to protect the **data in a computer**, against hackers, malware, etc. - **Internet** (network) **security** prevents, detects, and corrects security violations that involve the **transmission of information** in a network. In internet security, we assume that: @@ -52,7 +52,7 @@ In internet security, we assume that: - inserting, modifying, deleting, replaying messages - poisoning data - impersonate and pretend to be someone else -- Conventionally, we use the terms: +- Conventionally, we use the following names: - Alice and Bob for the two parties participating in the communication. - Eve (or Mallory, Oscar) for the adversary. @@ -94,9 +94,9 @@ This is only an overview, so the attacks are introduced briefly. There are two types of attacks in security attacks - **Active attacks**: modify the content of messages - Ex. (D)DoS, MITM, poisoning, smurf attack, system attacks. - - *Prevention* is important since the active attacks are a danger to *data integrity* and *availability*. + - *Prevention* is important since the active attacks concern *data integrity* and *availability*. - **Passive attacks**: does not modify information, but observes the content or copies it. - - Ex. eavesdropping, port scanning (idle scan secretly scanns). + - Ex. eavesdropping, port scanning (idle scan secretly scans). - *Detection* is important since passive attacks are a danger to *confidentiality*. ## Security Services and Mechanisms @@ -112,7 +112,7 @@ What kind of security services do we want? The basic network security services m Additionally, we also need: - **Authentication**: a way to authenticate users (ID, passwords) - **Non-repudiation**: ensure that no party can deny that it sent or received a message or approved some information - - Assurance that someone cannot deny the validity of something + - Assurance that someone cannot deny the validity of message or information ### Attacks Against CIA Triad @@ -142,10 +142,10 @@ There are many ways of achieving security. - It may be desirable to not leak *any* information, so one might add padding to the traffic, so the traffic is indistinguishable by the adversary (prevents side-channel attacks) - **Digital signatures**: provides authenticity of digital messages or documents - **Trusted Third Party** (TTP): a safe third-party that we can trust - - If we have a TTP, a lot of problems go away. We can always ask the TTP for the truth - - But TTP can become a *single point of failure* (SPOF), and security architectures may become too dependent on the TTP + - If we have a TTP, a lot of problems go away. We can always ask the TTP for the truth. + - But TTP can become a *single point of failure* (SPOF), and security architectures may become too dependent on the TTP. - **Append-only server**: keeps track of all modifications, good for auditing - - Blockchain is a kind of append-only data structure + - Blockchain is a kind of append-only data structure. ## Cryptography @@ -155,7 +155,7 @@ There are many ways of achieving security. ### Basics of a Cryptosystem -![is-01-cryptosystem.png](../../../assets/img/posts/Lecture%20Notes/Internet%20Security/is-01-cryptosystem.png) +![is-01-cryptosystem.png](../../../assets/img/posts/Lecture%20Notes/Internet%20Security/is-01-cryptosystem.png#) - A **message** in *plaintext* is given to an **encryption algorithm**. - The encryption algorithm uses an **encryption key** to create a *ciphertext*. @@ -168,7 +168,7 @@ There are many ways of achieving security. There are two criteria for classifying cryptosystems. - How are the keys used? - - **Symmetric** cryptography uses a single key for both encryption and decryption + - **Symmetric** cryptography uses a single key for both encryption and decryption. - **Public key** cryptography uses different keys for encryption and decryption, respectively. - How are plaintexts processed? - **Block cipher** @@ -232,7 +232,7 @@ In a smartphone, assets (things of value) would be For example, |Attacker|Abilities|Goals| -|-|-|-| +|:-:|-|-| |Thief|Steal the phone|Take the device| |FBI|Lot of things...|Obtain evidence from the device| |Eavesdropper|Observe network traffic|Steal information|