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I do understand Tangle has a graph based data structure i.e. forming a direct acyclic graph. It is not a merkle tree like a typical blockchain. But I could not figure out this relation makes it quantum proof or not. Is no-mining, and peer verification enough to make a distributed ledger quantum proof?

Daniel F
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Mayukh Mukhopadhyay
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  • It's got something to with the Winternitz signing algorithm. There's a whitepaper on it. But, I don't understand whether it is as good as a the Lamport signing algorithm or not. Lamport is quantum resistant. – Christian Findlay Jan 03 '18 at 02:27

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I asked a very similar thing here https://bitcoin.stackexchange.com/questions/55202/iota-quantum-resistance

The way the ledger is organized: linked-list (as in blockchain) or DAG (Tangle) has no impact for sure. There is still some sort of PoW (when you submit a new transaction) but that is also irrelevant.

Basically with a quantum computer cryptographic one-way hash functions (like SHA-2, SHA-3, BLAKE2) are still ok with a few caveats, the same goes for block ciphers (like AES). Traditional public key cryptography (RSA, DSA, Diffie-Hellman and the eliptic versions) are however NOT secure anymore. So you can't have signatures (which is a quite necessary thing for cryptocurrencies). There are some complicated workaround constructions but the simplest is one based on hash functions (Lamport OTS). More references are in my question. Note that I still don't know how exactly IOTA does this. Basically I got stuck at reading about their Curl hash function.

fiction
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  • for what it's worth, Curl is out (at least temporarily) and has been replaced by Keccak (SHA-3). https://blog.iota.org/upgrades-updates-d12145e381eb – R.J. Nov 15 '17 at 03:45