Integrity Tests

To detect misconfigurations or non-malicious file manipulations, strongSwan supports integrity checking of the executables, libraries (libstrongswan, libcharon, etc.) and all loaded plugins. This prevents the IKE daemon from using old, incompatible and/or corrupted libraries and plugins.

Integrity testing can not detect malicious manipulations by an attacker. This is not the intention, and doing so would require a trusted computing environment.

The used checksums are not cryptographically secure and only have a length of 32 bits. This is good enough to detect non-malicious errors, FIPS 140-2 actually requires only 16 bit for error detection codes.

Building Checksums

To build strongSwan with integrity checking support, add


to your ./configure options. This will create checksums of executables like charon, the libraries and all plugins during the build/installation process. The checksum_builder in src/checksum will create a shared library containing all checksums.

Verifiying Checksums

To enable integrity checking, you additionally have to enable the

libstrongswan {
  integrity_test = yes

option in strongswan.conf. The following checks are performed:

library checksums

For the libraries, checksums are created both for on-disk integrity and in-memory code integrity. During library initialization both checksums are checked. Library initialization fails if at least one of the checksums does not match.

executable checksums

If integrity checking is enabled, the executables check their integrity by calculating the checksum of the file named argv[0] on disk. In-memory checks are currently not implemented.

plugin checksums

The plugin loader checks each plugin on-disk before loading the shared library. If the check was successful, the `plugin gets loaded. Before the plugin gets initialized, the in-memory checksum is verified.


Integrity testing has been tested on i386 platforms using ELF32 and on x86_64 platforms using ELF64 binaries.


Please be aware that utilities like strip or prelink change ELF executables and libraries and therefore cause the integrity test to fail miserably.