In this paper we present an architecture development to be used in smart card. The architecture is dedicated for digital signature and it is based in the use of the open hard and soft sources. The development of the digital signature is based on the elliptic curve digital signature algorithm (ECDSA) and uses an open source cryptographic library named Miracl. The hardware development of the architecture is based on the use of the leon2 soft core processor. To make Leon suitable for smart card some changes are made in the open VHDL packages of the leon2 processor. We first in this paper present the simulation of the developed digital signature on an emulator environment of Leon named TSIM. Finally, we show the simulation of the enhanced architecture with the developed elliptic curve digital signature in Modelsim environment. In this paper we prove that nowadays open sources IP cores could be considered as solutions for soc application development.