Cryptography in Blockchain: Types & Applications [2024] | upGrad blog (2024)

Those who prefer staying technologically updated will know that blockchain is the new future. Along with that, cryptography is a key element to blockchain technology that provides the facility of secure communication. Cryptography is the best method of securing data from any unauthorized access which combined with Hashing helps make the Blockchain even more secure. In this article, you will get an in-depth understanding of what are the two main types of cryptography and how cryptography is applied in the blockchain.

Introduction to Blockchain

Blockchain is a peer-to-peer network; the word ‘blockchain’ is made up of two separate terms, ‘block’ and ‘chain’. A block being referred to a collection of data, alias data records, and chain being referred to a public database of these blocks, stored as a list.

These lists are linked using cryptography, making it the most essential and fundamental requirement for creating a blockchain. Blockchain is a growing list of records, and the blocks get appended to the list with time. Cryptography in blockchain can be a tricky concept, but we have tried to simplify it for your better understanding.

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Cryptography

Cryptography is a method of developing techniques and protocols to prevent a third party from accessing and gaining knowledge of the data from the private messages during a communication process. Cryptography is also made up of two ancient greek terms, Kryptos and Graphein, the former term meaning “hidden” and latter being “to write”. There are several terms related to cryptography, which are stated as follows:

Encryption: It is a process of plaintext (normal text) to a ciphertext (random sequence of bits).

Decryption: The inverse process of encryption, conversion of ciphertext to plaintext.

Cipher: The mathematical function, i.e. a cryptographic algorithm which is used to convert plaintext to ciphertext.

Key: A small amount of information that is required to induce the output of the cryptographic algorithm.

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Types of Cryptography

To understand cryptography in blockchain, one has to understand the types of cryptography. There are mainly three different ways in which we can perform cryptographic algorithms, namely, symmetric-key cryptography, asymmetric key cryptography, and hash functions. However, if your question is what are the two main types of cryptography then the answer will be symmetric-key and asymmetric-key cryptography.

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1. Symmetric-Key Cryptography– In this encryption method, we take a single key into application. This common key is used for both the encryption as well as the decryption process. Using a common single key creates a problem of securely transferring the key between the sender and the receiver. It is also called Secret-Key Cryptography.

This type of cryptography ensures that the key is known to both the sender and receiver. Symmetric-key cryptography schemes are of two types such as stream ciphers and block ciphers. In the case of stream ciphers, the keys repeatedly change as it works on a single bit at a time. On the other hand, as the name suggests, block ciphers encrypt one block of information at a time. However, in this case, the same plaintext block will continuously be encrypted to the same ciphertext.

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2. Asymmetric-Key Cryptography- This encryption method uses a pair of keys, an encryption key, and a decryption key, named public key and private key respectively. The key pair generated by this algorithm consists of a private key and a unique public key that is generated using the same algorithm. It is also called Public-Key Cryptography.

The use of asymmetric cryptography is where the environment is continuously expanding and the data is exchanged between different communication partners. The reason is its high scalability. In this type of cryptography, to perform key exchange, one party produces the secret key and encrypts it with the public key of the receiver. The receiver then can easily decrypt it using their private key. Once the connection is established, the rest of the communication will be completed by using the secret key as the encryption key.

However, unlike symmetric key, the problem with asymmetric rises when the public key has to be authenticated. The public key holds the risk of getting tampered with by any malicious third party. However, this problem can be solved by using Public-key infrastructure (PKI). In this method, another third party known as certificate authorities, check the ownership of the keys. Another method named “web of trust” can also be used to provide authenticity of key pairs.

On that note, the Rivest-Shamir-Adelman aka the RSA method is a public key cryptosystem that is used the most to implement asymmetric key authentication.

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3. Hash Functions- This type of encryption doesn’t make use of keys. It uses a cipher to generate a hash value of a fixed length from the plaintext. It is nearly impossible for the contents of plain text to be recovered from the ciphertext.

Therefore, the hash function is a unique identifier for any given piece of content. In this process, plaintext data of any size is converted into a unique ciphertext of a specific length. By looking at the definition of hash function it may appear very similar to encryption yet hashing and encryption are not the same. The very basic difference between the two is that, unlike encryption, hashing function does not require anything like decrypting the hash value. It basically works in a way that plaintext data is inserted and using a mathematical algorithm an unreadable output is generated.

The output is called hash digest, hash value or hash code, which is the unique identifier. Properties of a strong hash algorithm include determinism, preimage resistance, collision resistance, good speed and avalanche effect aka snowball effect.

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Use of Cryptography in Blockchain

As mentioned earlier that cryptography is a key element to blockchain technology, let’s look into the applications of cryptography in the blockchain. Blockchains make use of two types of cryptographic algorithms, asymmetric-key algorithms, and hash functions. Hash functions are used to provide the functionality of a single view of blockchain to every participant. Blockchains generally use the SHA-256 hashing algorithm as their hash function.

Cryptographic hash functions provide the following benefits to the blockchain:

• Avalanche effect – A slight change in the data can result in a significantly different output.
• Uniqueness – Every input has a unique output.
• Deterministic – Any input will always have the same output if passed through the hash function.
• Quickness – The output can be generated in a very small amount of time.
• Reverse engineering is not possible, i.e. we cannot generate the input by having the output and the hash function.

Hash functions have a major role in linking the blocks to one another and also to maintain the integrity of the data stored inside each block. Any alteration in the block data can lead to inconsistency and break the blockchain, making it invalid. This requirement is achieved by the property of the hash functions, called the ‘avalanche effect’.

According to this, if we make even a slight change in the input to the hash function, we will end up getting a totally unrelated output as compared to the original output. Let us take an example of an SHA-256 hash function, and compare their outputs,

Input: Blockchain at upGrad

Output: 04f0ecc95159533982d7571eada5f8d76592b6e97ead964467c603d31b9e7a9c

Input with a slight difference: Blockchain at upGrad

Output: 80b069904b6a8db46ed94e7091ff4e5fc72fae5422d46cc57d8f66db7abf4781

You can notice the huge difference in output after changing a single character at the input from lowercase to uppercase. This makes the data reliable and secure on the blockchain; any changes in the block data will lead to this difference in hash value and make the blockchain invalid, making it immutable.

Asymmetric-key cryptography is where the private key generally needs to be produced by a random number algorithm, and the public key is calculated by executing an irreversible algorithm. The asymmetric encryption algorithm has the advantage of having separate public and private keys, which can be transferred over unsecured channels.

Likely, it also has several disadvantages, some of them being low processing speed and unsatisfactory encryption strength. It is very much necessary to ensure the security of the asymmetric encryption algorithm during the transmission of data on the blockchain.

One of the major parts of asymmetric-key cryptography is digital signatures. Digital signatures provide integrity to the process; they are easily verifiable and cannot be corrupted. They also hold the quality of non-repudiation, making them similar to the signatures in the real-world. The digital signatures ensure that the blockchain is valid and the data is verified and correct.

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Hashing, public-private key pairs, and the digital signatures together constitute the foundation for the blockchain. These cryptographic features make it possible for blocks to get securely linked by other blocks, and also ensure the reliability and immutability of the data stored on the blockchain.

There are a huge number of applications of blockchain technology, and cryptography makes it possible. One of the major real-world applications of cryptography in the blockchain is cryptocurrencies. Let us look at its application in cryptocurrencies.

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Cryptocurrencies are one of the major applications of blockchains, and they use public-private key pairs to maintain the addresses of the users on the blockchain. For cryptography in blockchain, the public key is used as the address of the person. The public key is visible globally, i.e. it is visible to any participant of the participant. The private key is a secret value and is used to access that address data and authorize any of the actions for the ‘address’, which are generally transactions.

Digital signatures are widely used for cryptocurrencies. They are used to approve transactions by signing them securely (offline) and are also used for multi-signature contracts and digital wallets on the blockchain. To perform any action from these multi-signature contracts and digital wallets, the digital signatures from multiple (different) private keys are required before any action to be executed.

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Conclusion

Blockchain technology has been in the key focus areas of development for all the multinational companies and also a huge number of startups are emerging in this technology from the past few years. Blockchain is yet to witness its mainstream usage in society, yet there are numerous opportunities for professionals to explore and develop their careers in this field; one of which is cryptography in blockchain for sure. With time this field will be providing endless opportunities, and for this, you can start learning the blockchain technology and have the first-mover advantage with upGrad.

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Cryptography in the blockchain is the core of this technology, making it immutable and reliable. If you’re interested in this field and want to explore this technology, you can have a look at the various courses provided by upGrad.

• Advanced certificate program in blockchain technology: The course is provided by upGrad along with IIIT-B, focused on making individuals familiar with blockchain technology and blockchain development.
• Executive Certification in Blockchain from IIITB: It is a comprehensive 11-month program developed with IIIT-B, focusing on making individuals learn in-demand skills for blockchain development and their practical applications.

Individuals who plan to grow their career in blockchain can take up any of these courses and much more offered by upGrad to dive into blockchain technology to achieve the amazing blockchain career opportunities that are waiting for them in the future.