In the "References" section of Bitcoin's whitepaper, Satoshi Nakamoto points to three papers that serve as inspiration for digital timestamping.

When you read those documents it is clear that timestamping is not just a stamp of time, but "the hashed value of [data + timestamp]".

That said, in Bitcoin, is the timestamp the hashed value of the block header vs. the just time in the blockheader?

Or, am I totally off base?

1 Answer 1


Update: There is some discussion about timestamps here- https://lists.linuxfoundation.org/pipermail/bitcoin-dev/2020-October/018251.html

When a Bitcoin block is produced there are essentially two times involved:

  1. The timestamp in the block header, put there by the miner
  2. The actual time the block was produced.

Bitcoin has two mechanisms to protect against miners manipulating the timestamp:

  1. Median Past Time (MPT) Rule – The timestamp must be further forwards than the median of the last eleven blocks. The median of eleven blocks implies six blocks could be re-organised and time would still not move backwards, which one can argue is reasonably consistent with the example, provided in Meni Rosenfeld’s 2012 paper, that six confirmations are necessary to decrease the probability of success below 0.1%, for an attacker with 10% of the network hashrate.
  1. Future Block Time Rule – The timestamp cannot be more than 2 hours in the future based on the MAX_FUTURE_BLOCK_TIME constant, relative to the median time from the node’s peers. The maximum allowed gap between the time provided by the nodes and the local system clock is 90 minutes, another safeguard. It should be noted that unlike the MPT rule above, this is not a full consensus rule. Blocks with a timestamp too far in the future are not invalid, they can become valid as time moves forwards.

Source: https://blog.bitmex.com/bitcoins-block-timestamp-protection-rules/

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