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Comment by bmoresbest55 | Hacker News Reader

What kind of security concern would there be with using JS to implement your wallet? Or building the wallet yourself as opposed to a solution with updates and whatnot?

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Looking at the two popular web wallets as an example. Blockchain.info and Coinbase. Blockchain.info is a client-side wallet implemented in JS Keys are encrypted client-side and encrypted keys stored in the server. There are good good benefits there because if blockchain.info is hacked, your keys are still with you and not compromised (Different story if the server starts serving malicious JS though)

The server-side wallet approach means that if their hot wallets gets hacked, all the funds will be gone.

A lot of casinos and exchanges are using blockchain.info as a hot wallet instead of rolling their own multi sig hot wallet. Crazy risk

Generally server-side wallets don't keep all user funds online. Most are stored offline in cold storage, which requires multiple signatures to access.

They still have to keep at least the amount the richest user owns online in case that user decides to withdraw all their coins.

This introduction appears to be geared toward experimentation rather than production use. However, using JS server-side with node would be solely dependent on the implementation (the same as using any other language). Client-side (in-browser) adds all the usual client-side JavaScript crypto caveats¹.

¹ http://www.matasano.com/articles/javascript-cryptography/

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