Paper 2006/086

Analysis of the Linux Random Number Generator

Zvi Gutterman, Benny Pinkas, and Tzachy Reinman


Linux is the most popular open source project. The Linux random number generator is part of the kernel of all Linux distributions and is based on generating randomness from entropy of operating system events. The output of this generator is used for almost every security protocol, including TLS/SSL key generation, choosing TCP sequence numbers, and file system and email encryption. Although the generator is part of an open source project, its source code (about $2500$ lines of code) is poorly documented, and patched with hundreds of code patches. We used dynamic and static reverse engineering to learn the operation of this generator. This paper presents a description of the underlying algorithms and exposes several security vulnerabilities. In particular, we show an attack on the forward security of the generator which enables an adversary who exposes the state of the generator to compute previous states and outputs. In addition we present a few cryptographic flaws in the design of the generator, as well as measurements of the actual entropy collected by it, and a critical analysis of the use of the generator in Linux distributions on disk-less devices.

Available format(s)
Publication info
Published elsewhere. Unknown where it was published
Contact author(s)
zvi @ gutterman net
2006-03-07: received
Short URL
Creative Commons Attribution


      author = {Zvi Gutterman and Benny Pinkas and Tzachy Reinman},
      title = {Analysis of the Linux Random Number Generator},
      howpublished = {Cryptology ePrint Archive, Paper 2006/086},
      year = {2006},
      note = {\url{}},
      url = {}
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