Is the block hash a manipulable variable by a baker ? If not what about the value as a good source of randomness to use as a public verifiable random seed ?

2 Answers 2


blockhash can be manipulated by every single endorser. It should be avoided to be used as source of entropy.


Yes, the block hash can be manipulated by the baker since it depends on all operations included in the block. How is the hash code of blocks generated?

The block hash would not be a good source for randomness for projects where a successful attack was worth the effort.

You could use Acurast data providers. Join the telegram channel for more info: https://t.me/acurastnetwork

  • Hello, thank you for your input, but can you extend more your explanation please ? In my knowledge, the block have to be pre-baked. As such, the operations cannot be changed after the pre-commit. When the block will be endorsed, the endorsement and other data will be a part of the hash. So changing the operation after knowing the final hash result will end in a double bake process and that behavior will be slashed by the network.
    – Mieus
    Dec 6, 2022 at 9:18
  • This is a good thread your should look into: tezos.stackexchange.com/questions/1212/… Dec 6, 2022 at 11:18
  • This thread is old and the consensus changed recently on Tezos. My team does not agree with this analysis... What about my previous explanation ? It seems the only exploit is a restraint attack, but a slashing will be applied, of 10 xtz
    – Mieus
    Dec 7, 2022 at 15:19

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