[Ethereum] way to manually import a private key into Mist

Paste the key into a text file, save it to disk and use the path to that file with geth account import. Here are some example Windows instructions that might help:

1. Open Notepad
2. Paste key into notepad without any extra characters or quotations
3. Save the file as nothing_special_delete_me.txt at C:\
4. Run the command, geth account import C:\nothing_special_delete_me.txt
5. After successful import, delete the file at C:\nothing_special_delete_me.txt

If you do not have geth installed already, do the following steps after step 3, and the continue to step 4:

• Open command prompt (cmd.exe).
• Inside the Command Prompt, type the following command to go to the folder containing your Geth.exe file: cd c:\Ethereum-Wallet-win64-0-7-3\resources\node\geth (insert your correct path there)

You can use MyEtherWallet or MyCrypto(fork of MyEtherWallet) offline only wallet "view wallet details" function to extract private key from wallet json file. Feel free to use its offline version on an air gapped computer to secure your private key.

Edit: MyCrypto only provides this function in the offline version of the wallet now for obvious security issues of getting a private key from an internet site on a connected computer. So you are warned that you should only do that on an air-gaped computer.