how secure is double encryption of blockchain?

[cp1]

Just use offline storage / signing.

[redwhitenblue]

You have two possible vulnerabilities:

1) your wallet is set to backup to a dropbox/email that can be hacked and your wallet is backed up prior to setting your very long password. You should note that your email account can potentially have it's password reset with "security/secret" questions that the answers to are possibly public.

This attack would happen as follows:
a) you create a wallet with a weak password (password = pw123 - can crack instantly)
b) you set your wallet to backup to a dropbox that can easily be hacked
c) you create a BTC address (BTC-1)
d) the private key to BTC address (BTC-1) is backed up to the above dropbox account
e) you change your wallet password to a 30 character password (password = pw30chr - cant crack)
f) you change your wallet sending password to a 40 character password (password = pw40chr - can't crack)
g) you create a 2nd BTC address (BTC-2)
h) the private key to BTC addresses (BTC-1) and (BTC-2) are backed up to a dropbox that can easily be hacked (your wallet password and sending password are still in tact).
i) you send 50% BTC to (BTC-1) and 50% of your BTC to (BTC-2)
j) attacker hacks your dropbox account and downloads both wallet backups
k) attacker easily cracks the password from backup from step "d"
l) attacker steals BTC from address (BTC-1)

This attack can be prevented by archiving and then deleting any addresses that are associated with a wallet prior to setting strong passwords, resulting in any backups of your wallet only containing addresses with strong passwords that cannot be cracked and any backups that have passwords that can be cracked only have addresses with no unspent BTc

2) the 2nd attack would simply be for an attacked to install a keylogger to your computer and simply wait for you to log into your wallet and send a small amount of BTC. Attacker now how both your primary password and sending password.

[bitcoinforhelp]

nothing is 100% safe, weakest point is often human
so its not more safe than any other webservice

[Bit_Happy]

Threads like this should be stickied, so more people learn about security..
Someday I will need the info in this thread. The best thing about not having many BTC is not having to be excessively concerned with triple layers of security.

[jc01480]

I'll hold it for 30 days free.  After that other arrangements can be made to help you secure them.  A moving target is hard to hit.

[ShakyhandsBTCer]

I'll hold it for 30 days free.  After that other arrangements can be made to help you secure them.  A moving target is hard to hit.

I am not sure if you are serious or not but this would be extremely risky for the OP.