Knowledge Byte: Why You Should Care About Cryptography

Blockchain technology utilizes cryptography as a means of protecting the identities of users, ensuring transaction confidentiality, integrity, availability, and authentication. But is it really self-evident why it is such an important feature of blockchain?

Anyone using blockchain can have complete confidence that once something is recorded in a blockchain, it is done so legitimately and in a manner that preserves security.

• Cryptography is a mechanism where information is rendered and unintelligible to all except for the intended receiver.
• The sender enciphers a message into an unintelligible form, and the receiver deciphers it into intelligible form.
• The word “cryptology” is derived from the Greek kryptos (hidden) and logos (word).

A cryptographic key is the core part of cryptographic operations where it is a string of bits used by a cryptographic algorithm to transform plain text into ciphertext or vice versa.

There are three fundamental elements of cryptography:

• Public key: A public key converts messages into an unreadable format. A public key is used to encrypt the message intended for a specific receiver. The key is available via the public accessible directory.
• Private key: A private key is a secret key that is used to decrypt the message and the party that exchanges the message knows it. In the traditional method, a secret key is shared within communicators to enable encryption and decryption of the message, but if the key is lost, the system becomes void. To avoid this weakness, Public Key Infrastructure (PKI) came into force where a public key is used along with the private key.
• Key size and algorithms: There are RSA (Rivest, Shamir, and Adelman – The inventors of this technique), DSA (Digital Signature Algorithm), ECC (Elliptic Curve Cryptography) algorithms that are used to create a public and private key in public-key cryptography). The key size (bit-length) of public and private key pair decides how easily the key can be exploited with a brute force attack. The more computing power increases, the stronger keys to secure transmitting data it requires.

Features of Cryptography

The main reasons for using cryptography are:

Cryptography is one of the major features of blockchain. With the transaction being sent to an open network, it is important to ensure that the data is not tampered. Hence, cryptography ensures security in the system. Blockchain works on a distributed system concept and as a design, there is no central mechanism to ensure security parameters are enforced. But, it is the responsibility of every node to work in a secure fashion. Hence in blockchain, the cryptography method is used for the following reasons:

• Privacy/confidentiality: Ensuring that no block messages are read by anyone except the intended or authorized receiver.
• Authentication: The process of proving one’s identity. The authenticity of the receiver is assured and verifiable.
• Integrity: Assuring the receiver that the received message has not been altered in any way from the original message. Data cannot be forged or modified by an adversary intentionally or by unintended/accidental errors.
• Non-repudiation: A mechanism to prove that the sender really sent this message. After sending the message, the sender