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AFLplusplus/llvm_mode/README.ngram.md
2020-03-20 17:56:24 +01:00

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# AFL N-Gram Branch Coverage
## Source
This is an LLVM-based implementation of the n-gram branch coverage proposed in
the paper ["Be Sensitive and Collaborative: Analzying Impact of Coverage Metrics
in Greybox Fuzzing"](https://www.usenix.org/system/files/raid2019-wang-jinghan.pdf),
by Jinghan Wang, et. al.
Note that the original implementation (available
[here](https://github.com/bitsecurerlab/afl-sensitive))
is built on top of AFL's QEMU mode.
This is essentially a port that uses LLVM vectorized instructions to achieve
the same results when compiling source code.
## Usage
The size of `n` (i.e., the number of branches to remember) is an option
that is specified in the `AFL_LLVM_NGRAM_SIZE` environment variable.
Good values are 2, 4 or 8.