Trust in Bitcoin builds by solving one 'puzzle' at a time

What makes Bitcoin transactions secure and trustworthy? Computer security and cryptography expert Zulfikar Ramzan explains in this video from Khan Academy.

AccessTimeIconMay 31, 2013 at 2:03 a.m. UTC
Updated Sep 10, 2021 at 10:47 a.m. UTC

What makes Bitcoin transactions secure and trustworthy? Computer security and cryptography expert Zulfikar Ramzan explains the workings of the transaction blockchain in this video, one of a series that are featured on the online learning site Khan Academy.

Understanding the transaction blockchain, Ramzan says, helps to illustrate "how somebody might try to game or defraud the system and why that's not only mathematically hard to do but why there's actually an incentive -- actually an economic incentive in the Bitcoin system -- for different people to behave honestly."

That incentive comes through the process of mining, which involves solving a so-called "proof-of-work" puzzle. Whoever solves the puzzle first "mines" a new batch of bitcoins. While a single miner trying to solve a proof-of-work puzzle could spend a year or two looking for the answer, the network of miners is so large that someone, somewhere finds a solution, on average, every 10 minutes. Over time, the chain of puzzles and solutions becomes so long -- and so many people have contributed their work and computing power to it -- that it becomes increasingly unlikely to be tampered with.

"The more work that went into the overall chain, the more trust they'll have in that transaction," Ramzan notes. "There are no known shortcuts for solving these puzzles ... To succeed in a proof-of-work is kind of like winning the lottery."

Watch the whole video here:


Please note that our privacy policy, terms of use, cookies, and do not sell my personal information has been updated.

The leader in news and information on cryptocurrency, digital assets and the future of money, CoinDesk is a media outlet that strives for the highest journalistic standards and abides by a strict set of editorial policies. CoinDesk is an independent operating subsidiary of Digital Currency Group, which invests in cryptocurrencies and blockchain startups. As part of their compensation, certain CoinDesk employees, including editorial employees, may receive exposure to DCG equity in the form of stock appreciation rights, which vest over a multi-year period. CoinDesk journalists are not allowed to purchase stock outright in DCG.

Learn more about Consensus 2024, CoinDesk’s longest-running and most influential event that brings together all sides of crypto, blockchain and Web3. Head to to register and buy your pass now.