Block timestamp

Each block contains a Unix time timestamp. In addition to serving as a source of variation for the block hash, they also make it more difficult for an adversary to manipulate the block chain.

A timestamp is accepted as valid if it is greater than the median timestamp of previous 11 blocks, and less than the network-adjusted time + 2 hours. “Network-adjusted time” is the median of the timestamps returned by all nodes connected to you. As a result, block timestamps are not exactly accurate, and they do not need to be. Block times are accurate only to within an hour or two.

Whenever a node connects to another node, it gets a UTC timestamp from it, and stores its offset from node-local UTC. The network-adjusted time is then the node-local UTC plus the median offset from all connected nodes. Network time is never adjusted more than 70 minutes from local system time, however.

Bitcoin uses an unsigned integer for the timestamp, so the year 2038 problem is delayed for another 68 years.

Attribution

This content is based on content sourced from https://en.bitcoin.it/wiki/Block_timestamp under Creative Commons Attribution 3.0. Although it may have been extensively revised and updated we acknowledge the original authors.

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Written by Ramon Quesada

Passionate about Blockchain & Bitcoin technology since 2013, Co- Founder of https://avalbit.org, Team Manager in the CoinTelegraph Spain franchise (2016-2017 years) Co. Organizer of the Blockchain Boot camp Valencia 2018, Co. Organizer of the mini Hackathon BitcoinSV Barcelona, in August 2019, current coordinator of the BSV Valencia Meetup. https://telegra.ph/Ramon-Quesada---Links-01-10

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