{"p":"can-20","op":"mint","tick":"can","amt":"1000","rows":[{"df":"qa","content":[{"q":"How can the fairness and security of program execution be ensured in a blockchain?","a":"Data immutability: Blockchain uses encryption algorithms to ensure that once data is recorded in a block, it is difficult  to tamper with. Each block contains the hash value of the previous block, forming a chain of blocks. Modifying a single block would require re-calculating the hash values of all subsequent blocks, which is computationally expensive and practically impossible."}]}],"pr":"1e8f3f98898567afdf75357b44f0adcd0c342f77ac9cb84e597416e257ca7523"}