user15533: Using pycoin.
ku <ext_pri_key> -s 1/4/6/2/8/4/2/5.......

How many levels deep into the tree would I need to go (using only single digits) before it would be infeasible for an attacker to find it using a systematic search.
Twenty levels deep I thought would be adequate:
10**20 = 100000000000000000000

I know there are more effictive ways to obscure your address but I'm interested in this particular use case.
Thanks.

user23123: It's a bit strange to use single digits for the entire HD path since the BIP32 spec allows you to pick numbers up to 2^31 (non-hardened). BIP32 key derivation is largely using SHA512. Current ASICS for SHA256 can calculate about 10 trillion SHA256's per second, so about 160 quintillion hash operations in about 6 months. Assuming an ASIC can be built with roughly the same hashing power, you would need to go about 20 levels deep to force a machine like that to find your address in about 6 months. Of course, more machines mean faster cracking.
A far simpler solution would be to use the entire space of each level instead of just 10. 3 levels then would be plenty (~10^28)

15533: <p>Using pycoin.</p>

<pre><code>ku &lt;ext_pri_key&gt; -s 1/4/6/2/8/4/2/5.......
</code></pre>

<p>How many levels deep into the tree would I need to go (using only single digits) before it would be infeasible for an attacker to find it using a systematic search.</p>

<p>Twenty levels deep I thought would be adequate:</p>

<pre><code>10**20 = 100000000000000000000
</code></pre>

<p>I know there are more effictive ways to obscure your address but I'm interested in this particular use case.</p>

<p>Thanks.</p>
 23123: <p>It's a bit strange to use single digits for the entire HD path since the BIP32 spec allows you to pick numbers up to 2^31 (non-hardened). BIP32 key derivation is largely using SHA512. Current ASICS for SHA256 can calculate about 10 trillion SHA256's per second, so about 160 quintillion hash operations in about 6 months. Assuming an ASIC can be built with roughly the same hashing power, you would need to go about 20 levels deep to force a machine like that to find your address in about 6 months. Of course, more machines mean faster cracking.</p>

<p>A far simpler solution would be to use the entire space of each level instead of just 10. 3 levels then would be plenty (~10^28)</p>
