Breaking Mimblewimble’s Privacy Model

Several researchers have previously hypothesized possible privacy weaknesses in Mimblewimble’s protocol. Today, Ivan Bogatyy, founding partner of Dragonfly Capital, released research demonstrating a precise way to perform an attack on the protocol’s privacy. The vulnerability allows an attacker to overcome Mimblewimble’s techniques used to combat transaction linkability. In live testing on Grin ($GRIN) using only $60/week of AWS spend, Bogatyy was able to unmask the flow of transactions in real time with a 96% success rate. Bogatyy believes the vulnerability is inherent to Mimblewimble, concluding that Mimblewimble’s privacy is fundamentally flawed.

Why it matters:

• This is a known vulnerability of the Mimblewimble protocol. Developers designed Dandelion and full-block cut-through aggregation to prevent linkability, but both rely on a large participant base (more users makes linking transactions or becoming a supernode more impractical), which is lacking in the early days of Mimblewimble projects.
• While transaction linkability may be compromised by this vulnerability, transaction amounts are still hidden. Privacy is just one feature Mimblewimble promises, with the other being scalability.