In case of your example you can't find the pubkey of the address 16jY7qLJnxb7CHZyqBP8qca9d51gAjyXQN. That's because it is a Pay 2 Public Key Hash address. What you tried to do I guess is a base58 decode of the address. The tool at http://gobittest.appspot.com/Address might be of help to you fur understanding purposes. Just fill in the address in the last field and you will get the values all the way to the RIPEMD-160 of the hash of the private key. But since RIPEMD and SHA are hashing algorithms that will only work in one direction there is no way you can calculate the public key.

In case of a P2PKH address the public key becomes known when the address is used for an outgoing transaction. In that case for the unlocking script the public key has to be supplied and it will be checked if it hashes to the correct value. But in your case the address doesn't have any outgoing transactions so the public key is not known to anyone but the person who also has the private key.

Another one question:
I open dos in JeanLuc github at kangaroo, and see a data about 64bit, as he wrote there:
"""
Exemple with a 64bit key:

Kangaroo.exe -d 10 -s -w save.work -wsplit -wi 10 ..\VC_CUDA8\in64.txt
"""

I look at info:

Kangaroo v1.6
Start:5B3F38AF935A3640D158E871CE6E9666DB862636383386EE0000000000000000
Stop :5B3F38AF935A3640D158E871CE6E9666DB862636383386EEFFFFFFFFFFFFFFFF

what??)) is it real range or another decoding i need to do or what is it?

Pollard Kangaroo algorithm needs as input a public key and an interval for private key.

So... you don't use kangaroo without pub key.

One can get a public key from spent transaction, or early P2PK transaction.

no pub key - no kangaroo

Jean_Luc,

Could be of interest to you:

https://github.com/bitcoin-core/secp256k1/pull/767


Not applicable to this thread. It's about fault attacks, where you cause a glitch in a cpu while signing to make it miscompute and leak a key. They demonstrate a particular form of this against several curves.

I don't think their countermeasure advice is all that great.  Sure, storing G as x/y is cheap and stops this particular approach (except in ecdh) so everyone should do that and effectively everything does, but if an attacker can cause skipped instructions there probably are a bunch of other ways to attack.  Better to verify after signing, like bitcoin core does.

Yes, I read the entire paper.


For  simplicity,  we  focus  on  the  attack against curves with j-invariant equal to 0 (i.e.,A= 0), but the attack also generalizes to the curves with non zero j-invariant. Indeed,  in  that  case,  the  faulty  curve  becomes  supersingular  according  to  Proposition  1,  and  hence  the  MOV  attack of  Proposition  2  applies


And they give attack costs about other curves. If an attacker can fault your computation, you're pretty screwed regardless of what curve you use unless countermeasures are implemented. I bet in a lot of implementations a well timed fault can cause them to just print the secret key.

Fault attacks remain completely irrelevant to this thread.

Sorry I cant add to the discourse but would really appreciate if you guys could help me out
1) Is the kangaroo algo essentially looking for the x,y coordinates on the curve that make up BTC key? All I could gather was that essentially 2 random points are selected and plotted and if an eventual collision occurs you have the key?

2) I tried to run the program with my 1080ti but couldnt make heads or tails of the settings (hence my previous question to try and understand what it all pertains to)...could you help me out with a config that would be adequate for that gpu?

Thanks

Running windows, but have a pc I can install Ubuntu on (have the USB ready

 
Thanks. So the idea is that the tame herd is a series of numbers that are  increasing in a constant way and the wild herd is variables that are "randomly" moving forward...when a collision occurs, how does that determine the public key?

Also, I did get the prog to run but this is what I get:

This output makes no sense to me as its unclear as to how well my GPU is performing. What is "dead" and why am I only using 12MB of expected RAM when I have 11GB?