with regard to security of the private key, do you know if there is any way to get the compressed WIF key from the source wallet rather than through a third party site like bitaddress?
He is talking about on
www.bitaddress.org - It shows you both "WIF" and "WIF Compressed" keys... You need to work out which BTC Address you have... and use the matching WIF key...
For example... goto
https://www.bitaddress.org, click the "Wallet Details" tab and enter "L1o37HSiJJ5W3M6fVHL9Wtucpesp96n26KZTtnkwau2NTLMF6fda" as the private key.
You'll get the following down the Left hand side of the Page:
Bitcoin Address - 1GeZT6WfC4iy5gqjzKCAT152vYZKKEP8HQ
Private Key WIF - 5JrQ8mWPVqjFjfzUJHPTrNGzxf2zohH6ESW76PbstBRnC4ZV4GS
and the following down the right hand side of the page:
Bitcoin Address Compressed - 1FaGfCTBfNGN9y58owBbsVJQJGbwzJArM1
Private Key WIF Compressed - L1o37HSiJJ5W3M6fVHL9Wtucpesp96n26KZTtnkwau2NTLMF6fda
So, if the address you want to sweep is 1GeZT6WfC4iy5gqjzKCAT152vYZKKEP8HQ, you need the "Private Key WIF" and to scan the Private Key QRcode on the left... but if the address you want to sweep is 1FaGfCTBfNGN9y58owBbsVJQJGbwzJArM1, you need the "Private Key WIF Compressed" and you need to scan the Private Key QRcode on the right.