Signature not valid

What causes this issue?

The signature of your DSM system is not valid.
It seems that the DSM system setup is not complete. A signature is used
to sign the generated coding. This is to prevent any unauthorized or
malicious misusage of the DSM service deployment mechanism.

System Response

The service deployment ends with a syntax error and the service cannot
be used in the managed system.

How to fix this error?

To verify the signature, the public key of the DSM system has to be
imported into your managed systems. To accomplish this, proceed as
follows:
Log on to the DSM system.
Start Transaction STRUST.
Export the system certificate (System PSE).
Log on to the managed system.
Start Transaction STRUST.
Import the previously exported certificate.
Repeat the last three steps for all managed systemsin your system
landscape.

Procedure for System Administrators

The system issues an error message and will not allow you to continue with this transaction until the error is resolved.

Error message extract from SAP system. Copyright SAP SE.