BLOCKCHAIN CRYPTOGRAPHY

Continuing on from my last article. Like was reiterated earlier on, data transmitted on a blockchain network is accessible and verifiable by all constituting users. However, these data sets (transactions and user contracts) are sent in an encrypted form. Only the sender and intended recipient(s) bear the necessary ‘keys’ to decrypt the data. Encryption of this sort on a blockchain network is implemented using the public key cryptography architecture (asymmetric cryptography)

Similar to conventional encryption protocols, data (transactions) transmitted via public key cryptography are encrypted from the sender and delivered throughput to the recipient.

To decipher the transmitted data recipients must possess the public key used to encrypt the sent data in the first place.

This is usually the public key of the recipient. Public key cryptography, however, adds an additional layer of cryptic security to the mix by incorporating a private key.

Private keys are unique to users (node) and are practically impossible to decipher with current computing capabilities. Essentially, they function as an ‘originality stamp’ indicating that a partition of transmitted data is emanating from a particular node on the blockchain network.

Which is why they should be kept a secret, if a third party got hold of a user’s private key, he/she would be able to sign and verify transactions originating from the user’s account. If the private key was ever lost, then the account is rendered useless since the user won’t be able to sign transactions from his/her account.

Consider this scenario

Say, User A of blockchain network X wants to send a block of encrypted data to user B. First, the information to be transferred is encrypted using a public key (sender or recipient). In addition to this encryption, a ‘digital signature’ fashioned out of the user A’s private key is also stamped on the data to be transmitted and the resulting block of information subsequently broadcast on blockchain X.

Because user B possesses the public key used to encrypt the data, he/she can decipher its content. And the unique digital signature parsed with the sent information confirms that user A indeed sent it.