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Crypto++ 6.1

Crypto++ 6.1 was released on February 22, 2018. The 6.1 release was a minor, planned release. There were no CVE fixes.


The download is available from the Crypto++ website. The checksums for the download are below. Release signatures can be verified using GnuPG according to Release Signing.

Mirrors for the download are below. Note that GitHub checksums on the ZIP or TAR are different because the service creates the archive from sources.

Release Notes

The release notes for Crypto++ 6.1 follows.

Simon and Speck

Crypto++ changed its implementation for Simon and Speck from big-endian to little-endian. Formerly we followed the published test vectors from the paper, but they turned out to be incorrect. We later learned we should have followed the algorithmic description from the paper. The Crypto++ implementation now aligns with the Simon and Speck paper's algorithmic description and the Linux kernel.

The Simon and Speck changed was tracked via Issue 585.

Meltdown and Spectre

Meltdown and Spectre are security vulnerabilities announced in December 2017. The defects are present in modern CPU's due to speculative execution and allow attackers to recover secrets and other sensitve information. More reading is available at Meltdown and Spectre website.

Crypto++ 6.1 (and Crypto++ 6.0) did not ship with Meltdown and Spectre remediations in place. The first remediations appeared in GCC 7.3 at the end of January 2018. If you want to build Crypto++ with GCC remediations in place then you should add -mfunction-return=thunk and -mindirect-branch=thunk to your CXXFLAGS. Optionally, you can disable assembly language routines. The steps to engage the hardening are:

It is hard to say how effective CRYPTOPP_DISABLE_ASM is when containing Meltdown and Spectre. Crypto++ has a fair amount of assembly langauge routines, including hardware accelerated AES and SHA. Downgrading back to C++ means other side channel leakage could be present that were remediated with the hardware intructions.

Bug Fixes and Minor Issues

The bug fix and minor issue list for Crypto++ 6.1 follows. Many non-trivial issues are tracked for auditing and C&A purposes, but the list may not be complete. A number in parenthesis is the GitHub Issue number, if it was tracked. Sometimes a Git commit is referenced, but many trivial GitHub commits are omitted. Missing Issue numbers or lack of consecutiveness usually indicates feature requests and "won't fix/can't fix" type reports.

Notes for Distros


File Changes