user27289: Would you mind telling me what is the best introduced approach to secure the private key in the wallet and a transaction which is done using Bitcoin? I do not want to use a separate hardware, I am seeking for the best software based approach to protect the private key. 
Thanks in advance
Best Regards

user19459: Hm. Rather strange question you ask.
First of all: it depends mostly on the infrastructure you use for your bitcoin-client.
If your OperatingSystem is compromised, you probably can't guarantee security of your privateKey at all. 
The Bitcoinclient supports a very strong encryption of the wallet (and ofc the private Key) since like 2 years natively. 
I guess if you are paranoid and want extra security, use a VirtualMachine, install some hardened Linux-OS (DebianStable?), there make a TrueCrypt-Container with a hard password and install your Bitcoinclient there.
Ofcourse, as mentioned earlier, you can't be more secure than making an offline-wallet. Remebering your key instead of writing it down could also serve as the absolute security feature. - but i guess you don't want to go that far? :)
i saved my keys in a TrueCryp-container encrypted with sha512 and used a strong password - after this, backup copies of this container wherever you want, so you don't lose it. sha512 is not even crackable for the NSA.

27289: <p>Would you mind telling me what is the best introduced approach to secure the private key in the wallet and a transaction which is done using Bitcoin? I do not want to use a separate hardware, I am seeking for the best software based approach to protect the private key. </p>

<p>Thanks in advance</p>

<p>Best Regards</p>
 19459: <p>Hm. Rather strange question you ask.</p>

<p>First of all: it depends mostly on the infrastructure you use for your bitcoin-client.</p>

<p>If your OperatingSystem is compromised, you probably can't guarantee security of your privateKey at all. </p>

<p>The Bitcoinclient supports a very strong encryption of the wallet (and ofc the private Key) since like 2 years natively. </p>

<p>I guess if you are paranoid and want extra security, use a VirtualMachine, install some hardened Linux-OS (DebianStable?), there make a TrueCrypt-Container with a hard password and install your Bitcoinclient there.</p>

<p>Ofcourse, as mentioned earlier, you can't be more secure than making an offline-wallet. Remebering your key instead of writing it down could also serve as the absolute security feature. - but i guess you don't want to go that far? :)</p>

<p>i saved my keys in a TrueCryp-container encrypted with sha512 and used a strong password - after this, backup copies of this container wherever you want, so you don't lose it. sha512 is not even crackable for the NSA.</p>
