Is Mathematics or Computer Science more important for a career in cryptography I'm a Mathematics Major, and I currently enjoy the mathematical aspects of cryptography. I intend to pursue a career in cryptography research. 

https://www.csit.gov.sg/join-us/job-opportunities/job-detail/cryptologist 

However, although I'm comfortable with the mathematical aspects of it, I lack sufficient training in computer science and computer programming. Therefore, I'm trying to pick up programming and computer science skills at the moment. Are programming skills/computer science important for cryptography? (With respect to the job listed above)

And if so, which computer science topics are most relevant to cryptography? Are topics in data structures necessary for cryptography research? And lastly, how good do my programming skills need to be in order to pursue a career in cryptography? (Such as in the job listed above)
This question can be closed because the answers are opinion based. Nevertheless...

It depends. It does not look like they are going to design essentially new algorithms for encryption, signature, voting, etc. They have focus rather on applied aspects. In particular, they expect you to study and evaluate cryptographic algorithms and protocols of specific hardware and software. To be able to do that you definitely need skills in computer science.

Why are you asking about data structures particularly? It is a small topic compared to the others. Yes you should learn it, not because of this job, but because otherwise you will not be able to program.

To your questions: Yes, programming skills are important for this type of job.

Which topics are relevant? For this job following topics seem to be relevant:


Cryptography (of course)
Number theory
Programming
Software Architecture
Computer security
Networking