<p>For large numbers of coins, software wallets (online or desktop), no matter how well designed, are not safe. Online clients aren't safe because the ones that are encrypted your side (like blockchain) might somewhat be susceptible to man-in-the-middle attacks. As Lohoris mentioned, Blockchain uses js verification with Github, requiring both websites to be compromised - of which there is a slim chance. Standard desktop clients are inherently not safe either, not when you're storing thousands of $/£ in coins. Even with all the safeguards in place, the absolute safest storage method is to keep the keys offline.</p>

<p>You would be much better off generating a large number of keys using an offline computer and storing them on encrypted flash drives in safe locations. This is what the biggest known BTC hoarders (Winklevoss) do. </p>

<p>You can then add the addresses without the keys to Blockchain for easy monitoring and zero risk. </p>

CC BY-SA 3.0
2013-05-07T08:31:11.560Z
Totally a FUD. Online wallets aren't safer than standard clients, they only have _different_ security concerns.
o0'.
CC BY-SA 3.0
2013-05-07T08:59:47.513Z
I didn't recommend a standard client. I recommended generating keys that never touch the network - this IS safer. Every single bit of advice for large volumes of coins states that they are best kept offline where they cannot be accessed without the physical pen drive or bit of paper (depending on method). No FUD, just good practice.
George Pearce
CC BY-SA 3.0
2013-05-07T09:58:02.420Z
_"online wallets, no matter how well designed, are not safe"_ this is misleading, then. A reword could make this post much better.
o0'.
CC BY-SA 3.0
2013-05-07T10:01:12.503Z
I qualified my statement in a previous edit. They aren't safe because even the really good ones with browser side encryption (Blockchain.info et al) are subject to man-in-the-middle attacks. For someone storing a substantial value in Bitcoins (as per the question), this would present an unacceptable security risk. Edit: I see how it could be edited to say that any "wallet software" online or desktop, is unsafe. I will reword to this effect.
George Pearce
CC BY-SA 3.0
2013-05-07T10:09:01.083Z
Good edit. I've modified it just a bit since they aren't really always susceptible to MITM attacks, since blockchain.info for instance has a JS verifier against github, hence you'd need to crack both blockchain.info _and_ github to make the attack work.
o0'.
CC BY-SA 3.0
2013-05-07T10:11:15.903Z
I didn't know that. Thanks for your help with clarification :)
George Pearce
CC BY-SA 3.0
2013-05-07T13:31:46.507Z
Revised to include @Lohoris info on MITM attacks.
George Pearce
CC BY-SA 3.0
2013-05-07T08:16:21.710Z
2013-05-07T13:31:22.723Z
2013-05-07T13:31:22.723Z
George Pearce
<p>If I want to store a substantial number of Bitcoins, would there be any add security or safety to doing this in multiple blockchain.info hybrid ewallets, in stead of all in one?</p>

<blockchain.info><e-wallet><hybrid>
added security/safety to multiple blockchain.info wallets
Bastiaan Quast
# added security/safety to multiple blockchain.info wallets

(Asked by: username_0 on 2013-05-07)

If I want to store a substantial number of Bitcoins, would there be any add security or safety to doing this in multiple blockchain.info hybrid ewallets, in stead of all in one?

**Tags:** blockchain.info, e-wallet, hybrid


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## 1 answers

### Answer by username_1 on 2013-05-07. Score: 4 | Accepted answer

For large numbers of coins, software wallets (online or desktop), no matter how well designed, are not safe. Online clients aren't safe because the ones that are encrypted your side (like blockchain) might somewhat be susceptible to man-in-the-middle attacks. As Lohoris mentioned, Blockchain uses js verification with Github, requiring both websites to be compromised - of which there is a slim chance. Standard desktop clients are inherently not safe either, not when you're storing thousands of $/£ in coins. Even with all the safeguards in place, the absolute safest storage method is to keep the keys offline.

You would be much better off generating a large number of keys using an offline computer and storing them on encrypted flash drives in safe locations. This is what the biggest known BTC hoarders (Winklevoss) do.

You can then add the addresses without the keys to Blockchain for easy monitoring and zero risk.

> **Comments:**
> **username_2**: Totally a FUD. Online wallets aren't safer than standard clients, they only have _different_ security concerns.  
> **username_1**: I didn't recommend a standard client. I recommended generating keys that never touch the network - this IS safer. Every single bit of advice for large volumes of coins states that they are best kept offline where they cannot be accessed without the physical pen drive or bit of paper (depending on method). No FUD, just good practice.  
> **username_2**: _"online wallets, no matter how well designed, are not safe"_ this is misleading, then. A reword could make this post much better.  
> **username_1**: I qualified my statement in a previous edit. They aren't safe because even the really good ones with browser side encryption (Blockchain.info et al) are subject to man-in-the-middle attacks. For someone storing a substantial value in Bitcoins (as per the question), this would present an unacceptable security risk. Edit: I see how it could be edited to say that any "wallet software" online or desktop, is unsafe. I will reword to this effect.  
> **username_2**: Good edit. I've modified it just a bit since they aren't really always susceptible to MITM attacks, since blockchain.info for instance has a JS verifier against github, hence you'd need to crack both blockchain.info _and_ github to make the attack work.  
> **username_1**: I didn't know that. Thanks for your help with clarification :)  
> **username_1**: Revised to include @Lohoris info on MITM attacks.  

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