Electronic document authentication is becoming a major concern due to the huge data passing through computer networks, especially Internet. The asymmetric cryptography, the cryptography based on elliptic curves and more recently digital signature appear as credible alternatives to guarantee the authenticity, non forgery, non reuse, inalterability and irrevocability of electronic documents. In this paper, we evaluated the performance of document security systems by the digital signature. We perform tests that showed elliptic curve cryptography is more advantageous in terms of memory consumption and computing speed over RSA cryptosystem. The simulation result showed that elliptic curve cryptography is a preferred choice over RSA cryptosystem and allows its use in embedded systems equiped with very limited memory and computing power.