C191 - Trivia

What is a key that is used by a sender to encrypt a message using asymmetric encryption?

Public

What is a key that is used by a recipient to decrypt a message encrypted with asymmetric encryption?

Private

What is the benefit of asymmetric cryptography?

No need to exchange secret keys

What is the benefit of symmetric cryptography?

Uses the same secret key for both encryption and decryption.

In a Windows terminal, what does the * do in the Command Line Interface (CLI)

The asterisk is a wildcard character, which can be substituted for zero or more characters in a string

Which generation of computers used vacuum tubes and all programming was done by experts in machine language with no OS support or any other system software?

1st generation

Which generation of computers implemented transistors as smaller and faster switches and also implemented batch processing and multiprogramming using a batch OS?

2nd generation

Which generation of computers implemented integrated circuits that allowed the development of microchips, added an interactive multi-user OS and developed interrupts that allowed the OS to use time-sharing, keyboard and display terminal support?

3rd generation

Which generation of computers implemented very large scale integration (VLSI) that allowed the placement of a complete microprocessor on a single chip, leading to the development of personal computers using desktop and laptop OSs? It also marked the beginning of user-friendly GUI

4th generation

Which generation of computers enabled networking hardware that allowed the harnessing of the power of multiple computers? These networks gave rise to the internet. It led to parallel and distributed computing.

5th generation

The invention of transistors marks the transition to the _____ generation of computer systems.

2nd generation

The invention of integrated circuits marks the transition to the _____ generation of computer systems.

3rd generation

The invention of microprocessors marks the transition to the _____ generation of computer systems.

4th generation

The invention of vacuum tubes marks the transition to the _____ generation of computer systems.

1st generation

The implementation of networking hardware marks the transition to the _____ generation of computer systems.

5th generation

A company requires a computing environment that supports high-volume data processing and the management of a large amount of storage.

Which general purpose computing environment should the company use?

Mainframe

An advanced aircraft is likely to have a _____ on board to help control the aircraft

Real-time computer

Computing system (usually embedded). Chosen for its reliability in life-critical applications.

Real-time computer

Computing system: A system of multiple CPUs and memories interconnected by a fast network into a single parallel computer.

Multiprocessor

Computing system: A network of independent computers interconnected via a communication network.

Distributed

Computing system: A large computer that responds to requests from individual clients.

Server

A company needs a computing system that minimizes power consumption for controlling the temperature in their warehouse.

Which computing environment should the company use?

Sensor network

Which type of CPU instruction sets are supported by the CPU user mode?

Only non-privileged

Which type of CPU instruction sets are supported by the CPU Kernel mode?

Both privileged and non-privileged

Select the correct statement regarding this table:

a. A process p in domain D1 can execute object O1

b. A process p in domain D3 is the owner of both object O6 and O5

c. A process p in domain D2 can destroy object O2

d. A process p in domain D3 can destroy both objects O6 and O4

+----+------+-------+------+-------+------+-------+

| | O1 | O2 | O3 | O4 | O5 | O6 |

+----+------+-------+------+-------+------+-------+

| D1 | r | | | | rwx | |

+----+------+-------+------+-------+------+-------+

| D2 | rwx | | rwx | r | r | |

+----+------+-------+------+-------+------+-------+

| D3 | | rwxo| rwx | rwxo | rwx | rwxo |

+----+------+-------+------+-------+------+-------+

Answer d.

The presence of the letter o in cells (D3,O4) and (D3,06) means ownership. Only the owner process can destroy an object.

Optional tip:

To make this easier think of D as an user and O as a file. Focus only on finding a specific cell (A process p in domain D1 can execute object O1 === Find (D1,O1). Can an user D1 execute the file O1? even simpler: Is there an x in this cell (D1, O1)?

Additional note: Asterisks mean that the permission with the asterisk can be copied to another process.

So, (D1,O1) can add read permissions to other processes like D2 and D3 (although D2 already has that permission)

Select the correct statement regarding this table:

a. A process p in domain D1 can add x to (D1,O1)

b. A process p in domain D1 can add x to (D1,06)

c. A process p in domain D3 can destroy both objects O6 and O4

d. A process p in domain D2 has r permissions for O2 through O6

+----+------+-------+------+-------+------+-------+

| | O1 | O2 | O3 | O4 | O5 | O6 |

+----+------+-------+------+-------+------+-------+

| D1 | r | | | | rwx | |

+----+------+-------+------+-------+------+-------+

| D2 | rwx | | rwx | r | r | |

+----+------+-------+------+-------+------+-------+

| D3 | | rwxo| rwx | rwxo | rwx | rwxo |

+----+------+-------+------+-------+------+-------+

Answer d.

Files 2,3,4,5,6 have read permissions for user 3

Optional tip:

To make this easier think of D as an user and O as a file.

Translate:

a. User 1 can give execution permissions to file 1 in user's 1 profile.

b. User 1 can give execution permissions to file 6 in user's 1 profile

c. User 3 can delete files 6 and 4

d. User 2 can read files 2,3,4,5,6

Note that only the owner can give and remove permissions and destroy objects.

UNLESS there is an asterisk. In that case that process can give the permission with an asterisk to another process.

Decide whether the following statements are true or false

A process in D2 can read object O1

A process in D2 can read object O3

(D3,O2) can copy write permissions to (D2,02)

A process in D3 can read object O1

+----+------+-------+------+-------+------+-------+

| | O1 | O2 | O3 | O4 | O5 | O6 |

+----+------+-------+------+-------+------+-------+

| D1 | r | | | | rwx | |

+----+------+-------+------+-------+------+-------+

| D2 | rwx | | rwx | r | r | |

+----+------+-------+------+-------+------+-------+

| D3 | | rwx | rwx | rwxo | rwx | rwxo |

+----+------+-------+------+-------+------+-------+

True - There is an r in (D2,O1)

True - There is an r in (D2, O3)

True - There is an asterisk in next to the w in (D3,O2), which means it can copy the w to any process for the same object

False - There is no r in (D3,O1)

What is a symmetric key algorithm?

DES

What provides asymmetric cryptography?

RSA

What random value makes a brute force attack computationally difficult when attempting to get crack a password file?

Salt

What is the most accurate biometric authentication method between the following?

Signature recognition

Voice analysis

Face recognition

Fingerprint analysis

Fingerprint analysis

For the following biometric authentication methods, keep the most accurate ones:

Signature recognition

Voice analysis

Face recognition

Fingerprint analysis

Hand Geometry

Retina Scan

Iris Scan

Fingerprint

Retina

Iris

For the following biometric authentication methods, keep the most expensive ones:

Signature recognition

Voice analysis

Face recognition

Fingerprint analysis

Hand Geometry

Retina Scan

Iris Scan

Iris

Retina

For the following biometric authentication methods, keep the most convenient ones:

Signature recognition

Voice analysis

Face recognition

Fingerprint analysis

Hand Geometry

Retina Scan

Iris Scan

Signature

Voice

Face

Hand

For one point, describe in excruciating detail, the process of a digital signature

To generate a digital signature for a document P, the sender first generates a digest d of P using a one-way hash function. The sender encrypts the digest using the private key KSpri. The result is the digital signature, which is sent to the receiver along with the unencrypted document P. The receiver decrypts the signature using the sender's public key KSpub, which yields the original digest d. The receiver also produces a new digest from the unencrypted message P. If the two digests match, then an undeniable link between the sender and the document has been established.

Positioning Time

On an HDD, the time it takes the read-write head to position over the desired track.

Rotational Latency or Rotational Delay

On an HDD, the time it takes the read-write head, once over the desired cylinder, to access the desired track.

Wear Leveling

In nonvolatile memory, the effort to select all NAND cells over time as write targets to avoid premature media failure due to wearing out a subset of cells.

Seek time

On an HDD, the time it takes the read-write head to position over the desired cylinder.

Head crash

On an HDD, a mechanical problem involving the read-write head touching a platter.

Magnetic Tape

A magnetic media storage device consisting of magnetic tape spooled on reels and passing over a read-write head. Used mostly for backups.

Device controller or device adapter

It is an electronic circuit capable of operating a specific I/O device using binary signals

Not to be confused with device driver

Device Driver

It is a device-specific program that implements I/O operations, requested by user applications or the OS, by interacting with the device controller

Monitor

It is a high-level synchronization primitive implemented using P and V operations. Following the principles of abstract data types, a monitor encapsulates data along with functions through which the data may be accessed and manipulated.

Present Bit

It is present in each page table entry and it indicates whether the corresponding page is currently resident in memory. If a page is resident, then the entry points to the frame that holds the page.

modify bit (dirty bit)

Bit which indicate whether or not a page in memory has been written to since it was loaded.

Swapping

To move between main memory and a backing store. A process may be swapped out to free main memory temporarily and then swapped back in to continue execution.

Bootstrap loader

This image in turn knows enough about the file-system structure to be able to find and load the kernel and start it executing.

Bootstrap

The set of steps taken at computer power-on to bring the system to full operation.

Boot Disk

A disk that has a boot partition and a kernel to load to boot the system. A device that has a boot partition and can store an operating system for booting the computer.

Boot partition

A storage device partition containing an executable operating system.

System services or system utilities

Provide a convenient environment for program development and execution

Static linking

System libraries and program code combined by the loader into the binary program image

Dynamic linking

The loading of a process routine when it is called rather than when the process is started.

Storage Attachment (ways to access)

Host-attached storage, network-attached storage, and cloud storage.

Host attached Storage

It is storage accessed through local I/O ports. These ports use several technologies, the most common being SATA, as mentioned earlier. A typical system has one or a few SATA ports.

Network-attached storage (NAS)

Storage accessed from a computer over a network.

Cloud Storage

Storage accessed from a computer over a network to a distant, shared resource data center.

Extended File System

The most common class of Linux file systems, with ext3 and ext4 being the most commonly used file system types.

UNIX file system (UFS)

An early UNIX file systems; uses inodes for FCB.

inode

In many file systems, a per-file data structure holding most of the metadata of the file. The FCB in most UNIX file systems.

DMA (Direct Memory Access)

Component that allows devices to access main memory directly, without the involvement of the CPU

What transfers data between a device controller and main memory?

DMA

With DMA the busy flag...

It is needed only before starting a new I/O operation

Long term scheduling

decides when a process should enter the ready state and start competing for the CPU.

Non-preemptive

Allows a running process to continue until the process terminates or blocks on a resource.

Preemptive

May stop the currently running process and choose another process to run.

- A new process enters the ready list.

- A previously blocked or suspended process re-enters the RL.

- The OS periodically interrupts the currently running process to give other processes a chance to run.

Short term scheduling

decides which of the ready processes should run next on the CPU.

User threads advantages

Because they do not require any cooperation from the kernel, they are much faster to manage (create, destroy, and schedule) and thus many more can be created

Applications using them are portable between different OSs without modifications.