Unless Lutpin is using some provably fair method that will be posted, although she is a third party, it isn't provably fair.
Lutpin knows what she does and this isn't the first time Lutpin does it.
Trust me, when it comes to being provably fair, I take matters seriously and I know how to ensure it.
If you want to use the blockchain, you can consider using
the script that was used for another raffle by someone else to generate a random number using the hash of a certain block. Obviously some changes will need to be made, like numbering entries and changing the script to generate a number in the range of the participant number.
I'd rather do straightup numbering of the participants to ending characters of block hashes.
IIRC that chasing casascius raffle was kind of a mess, I'd rather do it easy for everyone to understand and verify.
You can announce the block ID after or before the raffle closes, but make sure to pick a block that hasn't been generated at the time of posting. Also, for numbering, you can consider making people post their usernames in a thread here and using the post numbers as the number.
I've been involved in enough raffles over at the collectibles section (maily as participant) and even helped out in some (those last few organised by mj).
Point is, I know my way around, no worries.