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Emerging scientific technologies help defend human rights

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Science  31 Aug 2018:
Vol. 361, Issue 6405, pp. 859-860
DOI: 10.1126/science.361.6405.859

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  • A blockchain is fragile against the database approach

    Anne Q. Hoy wrote an article entitled "Emerging scientific technologies help defend human rights" (1). The article mentioned the emerging scientific technologies including blockchain (1). At least more than $1.3 billion has been globally invested to blockchain-based systems in 2018 (2). A blockchain is resistant to modification of the data where each block uses a cryptographic hash. SHA-256 is a hashing function used in the blockchain. SHA-256 cannot be reversed because it's a one-way function. US military states that SHA-256 is appropriate for protecting classified information (3). Researchers are building blockchain-based systems to encourage patients to securely share information (4). Many scientists are excited about blockchain for healthcare (5,6,7).

    Although sha-256 is irreversible, it is possible to reverse. This sha-256 algorithm takes as input a 2^64 maximum length message, and outputs a 256 bits hash. Instead of cracking the algorithm, the relationship between a message and a hash can be stored in a database. The single keyword reversibility is demonstrated by the following three steps:
    1. The following simple Python program generates a hash for a message composed of a single keyword “sciencemag”. Note that you must install hashlib library in Python.

    import hashlib
    ho=hashlib.sha256(b'sciencemag')
    print(ho.hexdigest())

    generated hash:
    3f0197a909ecaba9e0107455e69219e2ae7f98bdcc4fb950c0543a42aa2...

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    Competing Interests: None declared.

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