—Should quantum computing become viable, current public-key cryptographic schemes will no longer be valid. Since cryptosystems take many years to mature, research on post-quantum cryptography is now more important than ever. Herein, lattice-based cryptography is focused on, as an alternative post-quantum cryptosystem, to improve its efficiency. We put together several theoretical developments so as to produce an efficient implementation that solves the Closest Vector Problem (CVP) on Goldreich-Goldwasser-Halevi (GGH)-like cryptosystems based on the Residue Number System (RNS). We were able to produce speed-ups of up to 5.9 and 11.2 on the GTX 780 Ti and i7 4770K devices, respectively, when compared to a single-core optimized implementation. Finally, we show that the proposed implementation is a competitive alternative to the Rivest-Shamir-Adleman (RSA).