Greenwood, 42, was stabbed more than 30 times in his own home on April 6.
According to Press Association, Judge Ian Pringle QC described the killing as a "savage stabbing" during a robbery that involved "significant planning and premeditation".
Pringle said: "It is clear that during the course of 2015 you drew up this list – probably to rob or burgle people – or perhaps kidnap people and hold them to ransom, so as to gain funds for yourself.”
A spreadsheet was found on the Danaher’s computer with the names of 14 "people of means" who he intended to steal from or kidnap.
He had visited Greenwood’s Oxford home to steal his valuable 108-year-old copy of the Kenneth Grahame classic novel which had been advertised online. The court had heard Greenwood had first met Danaher in late 2015 at an auction.
After killing Greenwood, Danaher then posed for a selfie with blood on his face as he left the murder scene with the book and other stolen items.
Three Week Trial
The jury took just three hours to convict him of murder after a three-week trial.
He also received a concurrent seven-year sentence for possession of an offensive weapon. The prosecution offered no evidence to a further charge of blackmail.
Greenwood's family issued a short statement saying they were "pleased justice has been done for Adrian through this conviction".
Detective Superintendent Kevin Brown, from Thames Valley Police, speaking outside court, said: "The conviction is not going to bring them comfort but I can say that they are satisfied that the person that has taken away their loved one has been punished severely."
Greenwood had been a dealer for the last 20 years, specialising in rare books but had wide ranging interests that included taxidermy and works by Banksy.
Although after 2011 he increasingly focused on writing historical books and biographies, he continued to attend auctions and fairs.
According to his website, Greenwood had started out in the trade by buying British Rail lost property and selling the items at car boot sales around London. He then moved on to antique furniture before starting to sell books online in 2000.