I was going to summarize but better just to post it all:
While the notion of using a blockchain as an immutable ballot box may seem promising, blockchain technology does little to solve the fundamental security issues of elections, and indeed, blockchains introduce additional security vulnerabilities. In particular, if malware on a voter’s device alters a vote before it ever reaches a blockchain, the immutability of the blockchainfails to provide the desired integrity, and the voter may never know of the alteration.
Blockchains are decentralized, but elections are inherently centralized. Although blockchains can be effective for decentralized applications, public elections are inherently centralized—requiring election administrators define the contents of ballots, identify the list of eligible voters, and establish the duration of voting. They are responsible for resolving balloting issues, managing vote tabulation, and announcing results. Secure voting requires that these operations be performed verifiably, not that they be performed in a decentralized manner.
While it is true that blockchains offer observability and immutability, in a centralized election scenario, observability and immutability may be achieved more simply by other means. Election officials need only, for example, post digitally signed versions of relevant election-related reports for public observation and download.
Ballots stored on a blockchain are electronic. While paper ballots are directly verifiable by voters, electronic ballots (i.e., ballots on a blockchain) can be more difficult to verify. Software is required to examine postings on blockchain. If such software is corrupted, then verifiability may be illusory. Software independence is not, therefore, achieved through posting ballots on a blockchain: as ballots are represented electronically, software independence may be more difficult to achieve.
The blockchain abstraction, once implemented, provides added points of attack for malicious actors. For example, blockchain “miners” or “stakeholders” (those who add items to the blockchain) have discretionary control over what items are added. Miners/stakeholders might collude to suppress votes from certain populations or regions. Furthermore, blockchain protocols generally yield results that are a consensus of the miners/stakeholders. This consensus may not represent the consensus of the voting public. Miners/stakeholders with sufficient power might also cause confusion and uncertainty about the state of a blockchain by raising doubts about whether a consensus has been reached.
Blockchains do not provide the anonymity often ascribed to them.33 In the particular context of elections, voters need to be authorized as eligible to vote and as not having cast more than one ballot in the particular election. Blockchains do not offer means for providing the necessary authorization.
Blockchains do not provide ballot secrecy. If a blockchain is used, then cast ballots must be encrypted or otherwise anonymized to prevent coercion andvote-selling. While E2E-V voting methods may provide the necessary cryptographic tools for this, ordinary blockchain methods do not.
It may be possible to employ blockchains within an election system by addressing the security issues associated with blockchains through the use of additional mechanisms (such as, for example, those provided by E2E-verifiability), but the credit for addressing such problems would lie with the additional mechanisms, not with the use of blockchains.
From the National Academy of Sciences
