Latest posts of: The-coiner

just a weird thought but if you have ever spent anything from that address (1Fy8dvuHjiTL...) you can use the below link (complete the address in the link) it can show you the public key of your address. and if it was long (130 characters) instead of being short (66 characters) that means the private key that blockchain.info gave you (KyF21...) is a wrong one and it should start with 5 instead!
https://blockchain.info/q/pubkeyaddr/1Fy8dvuHjiTL.....

- read more about compressed and uncompressed here: https://bitcoin.stackexchange.com/questions/3059/what-is-a-compressed-bitcoin-key
- use this tool to count characters faster http://string-functions.com/length.aspx

Yes, i have spent from that address before. Actually, the key is a 130 characters as you said, and it goes as follows "04980461a19399593793b7394b26d4bf0af855b60406591ac8312....." Embarrassed

so it is as i suspected. a bug in blockchain.info!
you imported your private key a long time ago and that private key was an uncompressed private key (started with 5) and now blockchain.info has converted that into a compressed private key (starting with K). that is why the public key and the base58 (or bitcoin address you've got = 1Emhxm...) is different.

now all you need to do is to convert that compressed key to the uncompressed one.
to do that, the only trusted tool that i know is https://github.com/pointbiz/bitaddress.org
you can see the live version here: https://www.bitaddress.org
although you MUST take a copy of the project and run it offline for security reasons.

open it, then get rid of the address generation step (move your mouse around until it shows 100% complete.
then go to the wallet detail tab and paste in your private key (KyF21...) and click View details button.
scroll down and find the private key which is starting with 5 and copy that in electrum

edit: a picture help:

thanks alot