Immutable and Irreversible
▸ A technology that allows you to encrypt a record of transaction
in a secure and tamper-proof manner.
▸ Entries are immutable and irreversible.
▸ Created by a distributed network of computers that participate
in the blockchain-mining process.
▸ Blockchain = a series of linked hashes with time stamps
▸ Security; Speed; Privacy; Decentralized architecture
▸ How does it work… ??
BLOCKCHAIN IS A LEDGER
BLOCKS IN BLOCKCHAINAmeer Rosic, “What Is Hashing? Under The Hood Of Blockchain,” Blockgeeks (blog), July 2017, https://
“The Great Chain of
Being Sure about
31, 2015, https://
THE HASH OF ALL THE HASHES OF THE TRANSACTIONS IN THE CURRENT BLOCK
Ameer Rosic, “What Is Hashing? Under The Hood Of Blockchain,” Blockgeeks (blog), July 2017, https://
Ameer Rosic, “What Is Hashing? Under The Hood Of Blockchain - Blockgeeks,”
Blockgeeks (blog), July 2017, https://blockgeeks.com/guides/what-is-hashing/.
1. A transaction is transformed into a hash.
2. The hash of a whole block is created.
3. A nonce (random string) is appended to the hash and hashed again.
4. The resulting hash is compared to the difﬁculty level required by a blockchain.
5. If it is less than the difﬁculty level, other nodes on the network checks and
conﬁrms the solution and updates their instances of the blockchain.
▸ If not, then the nonce is changed and the trial-and-error process repeats.
6. The hash of the header becomes the new block’s identifying string, and the
addition is propagated through the network.
7. That block is now part of the ledger.
8. The miners responsible for this are rewarded (if there is a reward associated
WHY DOES BLOCKCHAIN MATTER?
▸ Secure, immutable, and tamper-proof
▸ A promising new technology with the potential of great
BLOCKCHAIN IS A TRUST PROTOCOL
▸ A distributed public/private open/closed database where
records are kept tamper-proof by virtue of its technical
▸ Enables decentralized authority
(A 3rd-party intermediary authority is no longer required.)
▸ Immediate and low cost
▸ Provides privacy, transparency, and security
▸ Application in a wide range of areas
ISSUES WITH BLOCKCHAIN
▸ Lack of standard; Interoperability issues
▸ Huge energy consumption
▸ (Alternative: Proof of Stake instead of Proof of Work)
▸ Security - 51% attack
▸ Nevertheless, the DLT is expected to be widely adopted in
BLOCKCHAIN FOR LIBRARIES
▸ What are some of the opportunities and challenges that
blockchain may bring to libraries and beyond?
▸ What potential library services or program ideas do you
see in relation to blockchain?