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Cryptography and Hashing Overview : Coursera Quiz Answers 2023

 Week 1 Quiz Answers

Question 1

In the context of information security in software systems, the term identification refers to:

1 point
Question 2

The term authorization refers to:

1 point
Question 3

The term authentication refers to:

1 point
Question 4

Ideally, a ledger has both public and private functions. Which one of the following actions is the private function?

1 point
Question 5

Both a ledger and a sales receipt can help document ownership. What can the ledger DO that the sales receipt CANNOT?

1 point
Question 6

What can be done with a ledger in order to eliminate (or at least significantly minimize) the risk of losing the information it contains?

1 point
Question 7

Which one of the following situations is a specific example of the kind of double spending that the blockchain can be used to prevent?

1 point
Question 8

One of the functional requirements for the blockchain is the ability to distribute ledgers to nodes in an untrustworthy environment. How can it do this?

1 point
Question 9

Which one of the following statements is correct about how the blockchain handles transaction data?

1 point
Question 10

ABC Online Bookseller, which accepts bitcoin cash for payment, is limited in its capacity to ship books due to its small warehouses and small fleet of delivery trucks. So, they limit customers to purchasing only five books per day. Which aspect of transaction integrity does this limit represent?

1 point

Week 2 Quiz Answers

The submitted essay is cohesive, unified piece of writing

The blockchain revolution has recently come to the education sector providing legitimate credentials that show ownership and use of academic records. In other words, records need not be transferred using third parties.

In simple terms, a blockchain is a digital ledger that is open to the public, and yet secure from unauthorized modifications. Technically, a blockchain is a distributed database made of immutable and incorruptible chunks of data known as blocks. Any edit or modification of data has to be verified and approved by all of the parties mutually. This makes the data trustable. Also, when information is edited in a blockchain, it does not change anything in the older blocks. Each modification of information after the verification and approval create a new block attached to the older one with a timestamp of the modification. This creates a virtual chain of blocks containing all the information with time and date.

Education has traditionally been relatively centralized — with a single university or institution in charge of nearly all the data. It's also featured long lectures and certifications, all designed and approved by this single institution. With the internet taking over, more options — such as online courses, distance learning, seminars, webinars, conferences, tutorials, and more, came in to democratize the sector. Despite all of this, there remained a dependence on this authority for the basics — such as your certificate, degrees, or even minor changes to other details.

Blockchains allow us to store multiple copies of data, and each change that is to be updated to the chain goes through complex verification processes approved by all the miners on the blockchain. What this ensures is that the data on the blockchain is legitimate, and not owned by any singular entity.

Blockchain is the solution. Volunteers can be students, teachers, lecturers, trainers, universities, institutions, and even employers. All parameters pertaining to a student — his identity and achievements, and more could be securely recorded and stored. Students will remain the owners of their learning history, and be able to select who this information should be shared with. This pretty much covers the textbook definition of ownership and is an unprecedented idea in the education sector, made possible only because of the blockchain. Employers could track records, learnings, skills, achievements, etc. but cannot access the information they are not meant to, such as the student's university bills, payment history, driving license, or anything that is strictly personal.

All of this of course, has a long way to go before it becomes the norm. Some complex questions remain needed to be answered — access rights will need to be well-calibrated and defined. Most importantly, the security of the system will have to be tamper-proof. Blockchains can potentially blend learning and earning in near future and make education a trustworthy mediator-free system altogether, bringing us a whole new look at an age-old industry.

Answer these question in your final essay:

  1. What item changes ownership in an educational context?

  2. What data would need to be included in each transaction block?

  3. Will educational institutions need to be involved in validating degrees and transcripts? How does the validation process work in a distributed, blockchain environment?

  4. If you’re applying for a job and your prospective employers wants to see evidence of your education, how might this work?


The blockchain revolution has recently come to the education sector providing legitimate credentials that show ownership and use of academic records. In other words, records need not be transferred using third parties.

In simple terms, a blockchain is a digital ledger that is open to the public, and yet secure from unauthorized modifications. Technically, a blockchain is a distributed database which is made of immutable and incorruptible chunks of data known as blocks. Any edit or modification of data has to be verified and approved by all of the parties mutually. This makes the data trustable. Also, when information is edited in a blockchain, it does not change anything in the older blocks. Each modification of information after the verification and approval creates a new block attached to the older one with a timestamp of the modification. This creates a virtual chain of blocks containing all the information with time and date.

Education has traditionally been fairly centralised — with a single university or institution in charge of nearly all the data. It's also featured long lectures and certifications, all designed and approved by this single institution. With the internet taking over, more options — such as online courses, distance learning, seminars, webinars, conferences, tutorials and more, came in to democratise the sector. Despite all of this, there remained a dependence on this single authority for the very basics — such as your certificate, degrees, or even minor changes to other details.

Blockchains allow us to store multiple copies of data, and each change that is to be updated to the chain goes through complex verification processes approved by all the miners on the blockchain. What this ensures is that the data on the blockchain is legitimate, and not owned by any singular entity.

Blockchain is the solution. Volunteers can be students, teachers, lecturers, trainers, universities, institutions and even employers. All parameters pertaining to a student — his identity and achievements, and more could be securely recorded and stored. Students will remain the owners of their learning history, and be able to select who this information should be shared with. This pretty much covers the textbook definition of ownership and is an unprecedented idea in the education sector, made possible only because of the blockchain.

Employers could track records, learnings, skills, achievements etc. but cannot access the information they are not meant to, such as the student's university bills, payment history, driving license or anything that is strictly personal.

All of this is, of course, has a long way to go before it becomes the norm. Some complex questions remain needed to be answered — access rights will need to be well-calibrated and defined. Most importantly, the security of the system will have to be tamper proof. Blockchains can potentially blend learning and earning in the near future and make education a trustworthy mediator free system, bringing us a whole new look at an age-old industry.


Week 3 Quiz Answers

Question 1

Using the short format hash value generator at http://www.blockchain-basics.com/Hashing.html, determine the hash value of this phrase (all lowercase with just one space between the words): hashing is very important

1 point
Question 2

Using the short format hash value generator at http://www.blockchain-basics.com/Hashing.html, perform a two-step repeated hashing of these two words (all lowercase with just one space between them): continuing education

1 point
Question 3

A hash function is said to be collision resistant when:

1 point
Question 4

Suppose you forgot your password for your favorite online shopping vendor. Upon clicking “forgot password” and answering several security questions (pet’s name, street where you grew up, etc.), they promptly email your password to you. Based on this, which one of the following statements is most likely true?

1 point
Question 5

Cconsider the Merkle tree diagram below, which represents a set of linked transaction data:

Suppose a hacker makes some changes to the data for Transaction 2. Which hash reference is no longer valid?

1 point
Question 6

Consider this hash puzzle: The data string is Irvine (capital “I” and everything else lower case) and we want to apply a nonce that results in a hash with a difficulty of 2. In which of the ranges below is the nonce? (Use the hash puzzle website at http://www.blockchain-basics.com/HashPuzzle.html.)

1 point
Question 7

The use of a key to both encrypt and decrypt data is called:

1 point
Question 8

How can asymmetric cryptography be used as a form of digital signature when John wants to send a message to Jill and Jill wants to be sure it was really John who sent it?

1 point
Question 9

Asynchronous cryptography is used in the blockchain to:

1 point
Question 10

A sender who encrypts his/her message using the recipient's public key:

1 point

Week 4 Quiz Answers

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