I could offer you the following architectures:
1. Centralized - that means that your MyOwnNewDigitalCoins are stored on a central server
2. Decentralized - that means that we would be using a true P2P Distributed Hash Table to store the Coin data. Your coin data is stored in trusted computers or "everywhere".
As for the hash functions, the SHA family is a popular candidate. Bitcoin uses SHA-256. So SHA-512 or SHA-3 could be interesting.
Communication and security would be handled through public key cryptography.
We would be providing you with source code and installation documentation and support.
Also, note that I am new to Freelancer.com and although I do have 13 years or so in industry and a few years in corporate research, since I am new, you won't see any reviews or past contracts in my profile.
We can develop in any of the following core technologies:
Programming Languages: C/C++C, Java SE/J2EE, Perl/Dos/Bash Scripting, Fortran, ABAP, SQL, HTML
Development Environments: Visual Studio 2010, Eclipse, Netbeans, Matlab, Mathematica, SAP, GCC
Other Software Experience: Intel/AMD64, Tesla GPGPU, VHDL (Xilinx Virtex/Wildstar VME), Microsoft HPC Cluster Server, HyperV, SAP, Microsoft Office, LaTeX, Oracle, MySQL, Apache/Tomcat WebServers
Other CS Experience: theoretical computer science, neural networks & machine learning, image processing, cryptography
Operating Systems: Windows NT, Windows XP, Windows Vista, Windows 7, Windows 8, Mac OS X, Linux