Do I need an app and internet on my smartphone to enable a Lamassu ATM to detect and scan my QR code?

I want to send bitcoins to a friend through a Lamassu ATM. She has emailed me her request QR code and when I went to the Lamassu ATM point, after pressing on the start button and showing the QR code on my smartphone, nothing happens. I learned that the atm is supposed to scan the QR code and send bitcoins to the request QR code after putting in cash.
I am wondering, if I may need an app or internet on my smartphone to enable the Lamassu ATM to detect and scan the QR code on the phone screen.

same R value is used for two different addresses? finding z1 and z2 value and privatekey



input script 1


r = 6bcc247f1259262b4035bfa84f0397a69f69baa01659daaf94fe1164b650c86a

s1 = a044b38e8264a1c928ddd28b4657aa7109d1ea30e911208c7ce57abcb1451fe6

input script 2


s2 = 75e41da2596619e837af69cdf80933e519abd736210677970a6ac23a3709ee2e

Raw tx 1


calculating z1

replace the input with the corresponding output script


then do sha256(sha256(modified transaction))

z1 = 9ffb92bc05a398e3177b12fcdac5308d316b6bd6cc00365177711dc4e3f10e64

Raw tx 2


calculating z2

replace the input with the corresponding output script


then do sha256(sha256(modified transaction))

z2 = 539bcbcddc3fff95aa262d01b8a909504958b371b813cb71a457efebb41c398e

priv key calculation,it not given correct address and priv anything wrong

posting the r , s1 , s2 , z1 , z2 below

it given 18MRDftXYkGqzo9hvcdnUs7yaPXrD1DXsq address


trans 1 address = 19owWJcPbTEe1mVYer1ymnbduJDza9jpRH

trans 2 address = 1FRDgmxVrUUNiiB7GN3NNcJDEEXtFB22rm

what’s wrong

How to decrypt a MultiBit private key?

Looking for a way to decrypt a private key that was exported by Multibit WITHOUT using Multibit. I need to move they key elsewhere.

I need to go this route because I can’t get the key to import into Multibit properly (even though I have the password).


Is Quark as secure as SHA 256?

I’m trying to make certain I’m understanding the purpose behind the Quark algorithm.

There are lots of devices that need secure algorithms but have severe power and processing constraints such as RFIDs (the chips found in everything from clothes to cars) – hence Quark (and other algorithms) were developed. Quark seems to be secure and yet lightweight enough that CPUs are more that capable of hashing them without maxing out.

I’ve read lots of articles and posts that come up with reasons pro and con re Quark. What I’m wondering about is what makes Quark worthy as an algorithm for a currency? One advantage is that it uses multiple algorithms and the chance of multiple hash functions getting cracked at the same time approaches zero. But why would we really care if more or less electricity is being spent in creating a block? Of course I want my electric costs to be less – the same as anyone else. But more important than my electric costs is knowing that the currency is secure. I would also prefer that mining is distributed across the network (as opposed to ASICs) but again what counts first and foremost is that the system is secure.

That being the case how is an algorithm designed for RFID’s able to compete with SHA256?

I’m still struggling with these algorithms so I may be missing something very basic.

Multibit Private Key Restore

I backed up my private key and restored it into a new copy of Multibit (difference machine). The import was successful but the public key address has not been updated with my previous address.

I’ve done "Check Private Keys" which said it was successful as well as forced a resync with the blockchain. None of my old transactions are showing up.

Any thoughts? No doubt I’m doing something wrong.



Thanks for the response! I verified through that the private key I exported only matches the bitcoin address automatically generated when I created the new wallet.

But the old private key that I IMPORTED into this same wallet is nowhere to be found. Multibit says the import was a success. If this is true there should be TWO private keys in the export file; one for the auto-generated bitcoin address and one that matches the old imported private key.

I’d love to take the private key in my original export file and paste it into to see if it matches my public address but my export file is encrypted. So I have to import into Multibit, enter the password and then export it unencrypted to obtain the private key.

Does anyone know of a way to decrypt an encrypted private key file without using Multibit?

ELI5: What’s the difference between a child-key and a hardened child-key in BIP32

I’ve read BIP32, and I do understand it more or less.

Could someone please explain to me like I’m 5 years old what the difference between a child-key and a hardened child-key is?

I’m trying to add HD wallet generation to a service I’m building. I need to be completely informed about this before I dabble in it. Fret not, I’ll be using Bitcore, so I won’t be dabbling with the crypto directly.

Call function for block n on blockchain

I’ve been going through main.cpp in order to roughly find out which function calls the best block and I found out depending on situation there are several similar-sounding function names and code extracts that I suspect of calling the best block.
Here’s my list:

  • CBlockIndex *pindexBestKnownBlock
  • uint256 CCoinsView::GetBestBlock () const
  • CBlockIndex* pindexBestHeader
  • CBlockIndex* pindexBestForkTip
  • pindexBestInvalid
  • // move best block pointer to prevout block
  • chainActive.Tip()->GetBlockHash().ToString()

Now my question: Which one of the list items above can I use and modify in a way that calls a block that is n blocks deeper than the best block on the same blockchain?