The ARK Crew is looking for back-end/core developers who are not scared when they hear terms such as Byzantine Fault Tolerance, Finite-state machine, SHA-256, Elliptic-curve cryptography, Turing completeness, Merkle tree, Bloom filters, etc… In short, to have an understanding of cryptography and P2P networks.
To get basic understanding of the work have a look at this GitHub repository (main one) :
Cryptography: ECDSA, basic understanding of how to work with raw binary data
Networking: basic understanding of P2P networking and protocols
SysAdmin: basic console magic (servers, deploying, running)
Bonus (not requirement):
Development: GoLang, C, C++
Networking : higher level of P2P protocols knowledge, pen-testing