IS claims the explosive was smuggled aboard the flight for St Petersburg by exploiting a security weakness at Sharm al-Sheikh airport.
The group claims it initially planned to bring down a plane belonging to a country participating in the US-led coalition bombing it in Syria and Iraq, but changed its mind after Russia began its airstrikes in Syria.
Dabiq - a propaganda magazine for Islamic State - has published a photo of what it describes as an improvised bomb that later brought down the Russian airliner in Egypt.
The picture shows a yellow can of soft drink marketed in Egypt, and what appears to be other bomb components made of plastic and metal.
Former bomb disposal expert Chris Hunter has told Al-Jazeera the components look viable.
"The picture itself on the right hand side of the image, you can see what we call the timing of the power units. This is a sort of brains of the bomb and that's what effectively contains the safe-to-arm switches, the times for example and the power source itself. And then in the centre of the photograph is the detonator which is used to trigger the high explosive and in the can itself, is the high explosive presumably."
He says it's worrying how the components were smuggled on board.
"They should all have been detectable through a normal x-ray metal detector, that sort of thing. So it suggests that it's possibly, if it's been smuggled on board as passenger carry-on luggage, that the checks were definitely lax. But if it's gone into the hold itself, because it's a comparatively small amount of explosive, unless it was placed in intimate contact with the shell it potentially wouldn't actually work so it means somebody would have had to physically been involved in the chain, an inside job and place it in exactly the optimum position."
The militant group also published a picture of what it said were passports belonging to people who died in the plane crash.
The authenticity of the photos published in the magazine has not been verified.
Earlier, the Russian Defence Ministry released a video showing what it says are long-range bombers carrying out a massive airstrike on Islamic State targets in Syria.
It says the operation was carried out on Tuesday.
The ministry also said crews from long-range Russian Air Force bombers carried out the strikes using air-based cruise missiles.
Meanwhile, China has voiced its support for Russia's actions.
Chinese Foreign Ministry spokesman Hong Lei says his country firmly supports Russia's anti-terrorist efforts and actions to safeguard its national security.
"Terrorism is the common enemy of humankind. China has always opposed all forms of terrorism. As Russia's comprehensive strategic partner, China supports Russia to safeguard its national security and stability and relevant anti-terrorism measures."
He adds that China is ready to work with the international community to jointly fight against the terrorism threat.
"China is willing to work with Russia, as well as the international community to increase cooperation in security, face together threats and challenges from terrorism and safeguard world peace and stability."
Suspicions that a bomb caused the crash have led to flight cancellations to and from Egypt, and dealt a major blow to its vital tourism industry.
The United Kingdom banned flights to Sharm el-Sheikh on November the 4th.
Russia banned all flights to Egypt a day later, and last Friday it banned Egypt's national carrier from flying to Russia.
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