Re-generate a past private key

I know that every public key has a private key... I am wondering how to regenerate a private key that was generated by my Blockchain app (using a plain text passkey, which I am assuming was converted into the proper format by the app)

I have the wallet address where the bitcoins were sent, but cannot use the plain text private key I used in the application to spend the bitcoins...

The bitcoins have been sitting at this address since 2015, And I guess I was hoping if there is a way to convert the passphrase I used in the app into the proper private key to access the bitcoins at the address they were sent to...

I hope that this makes sense.... I can see them there, and not being able to access them is so frustrating! I lost the data in the application, I think due to a glitch. I was hoping since it is a mathematics thing to generate the private key that there must be a way to go backwards, using the public address and the plain text passkey I had used to find the proper format private key.

Steven

Posted 2017-08-01T05:08:08.083

Reputation: 1

I've updated the tag to blockchain.info, as I assume that's the service provider that you're referring to. – Murch – 2018-01-28T14:26:49.643

Answers

There's no way to go backwards from the public key to the private key, that would mean that anyone could steal your Bitcoin.

You might be able to do something with that passkey you have saved though. Is it a list of words? Do you remember what app you were using?

Edit: Looks like you actually have a passkey that was used to generate a private key and not a Mnemonic backup. Have you tried putting the private key into the 'wallet details' section of this website: https://www.bitaddress.org/ ?

Note that you can use the site offline and I recommend it.

PhilCassidy

Posted 2017-08-01T05:08:08.083

Reputation: 11

Thank you I will try it, I was using the Blockchain application on Android. When I bought some bitcoins I created a new address for them to be sent to and was prompted with a "Please type a passkey for this address" type thing, in which I typed just a short 11-16 character pass phrase which I was assuming would be used to generate a private key for that address... Now I only have the wallet address where they were sent and the passkey I set doesn't work to spend the coins, I assume it is the wrong format... I will try this and let you know, thank you! – Steven – 2017-08-01T05:43:35.260

Take a look at what's the steps to generate a private key here. If your passkey is the raw 256 bit sequences or any intermediate results, you may be able to generate the end private key by following those steps, assuming the app uses the same methods. That's the only way to you can generate a private key again. There is no way to go back from public key to private key. Hope this helps and you can get back your coins!

ycshao

Posted 2017-08-01T05:08:08.083

Reputation: 145

I'm not sure what raw 256 bit is... sorry! When I created the address for the bitcoins to be sent to I was prompted to enter a "passkey" which I assume was used to generate the proper private key, in which ever format that may be... If I knew I may be able to look up if there is a way to convert a simple 11-16 character passphrase into the actual import format needed to access the coins at this address... Sorry my understanding of Bitcoin is a bit limited so I am not sure what to look for to try and convert the passkey into the right format. Thank you for your help! – Steven – 2017-08-01T05:52:04.197

Hmm, you should ask someone who you can trust and have knowledge of page I posted to take a look at your passkey. Maybe you can contact the app owner to see what that passkey is. Maybe it's a form of retrieving actual private key for you. – ycshao – 2017-08-01T06:04:30.840