PKI – is the abbreviation for Public Key Infrastructure: a set of hardware, software, people, policies, and procedures needed to create, manage, distribute, use, store, and revoke digital certificates for a certain number of users. Many governments and organizations have built different types of PKI systems, but by infrastructure we must understand the baseline framework used in such cases in the financial transfer systems, server protection and private networks etc.

To be able to use at its maximum the advantages that internet gave us, some obstacles had to be passed. Some of the problems were: the development of trusted ways to identify reliably organizations and individuals, to achieve the necessary security in electronic data transfers and the related interception of unauthorized breaches, the assurance that a sent document is received and upon it, assurance of the non-deniability of acceptance, protection of sensitive information and denial of access to unauthorized persons of this data. For all of the above issues PKI served the most promising solution. An electronic signature based on PKI assures security and integrity, and an encryption system based on PKI assures on the other hand confidential operations dealing with sensitive data.

The technology that fulfills the security criteria of PKI systems implements asymmetric mathematics. PKI itself uses a pair of keys mathematically related to each other, (which are nothing but a string of bits), that encrypt and decrypt data. One of the keys is made public in order not to compromise the secrecy of the other, which is the secret one that is kept safely by the owner. PKI can be implemented as well on the symmetric key cryptography, in this case it uses the same key to encrypt and decrypt data, as well as other cryptographic protocols.

Public Key Infrastructure ensures a high level of security in the storing and transmission of information and data. PKI was introduced as the necessity of creating more secure systems for banking and transaction protocols, the secure storing of sensitive information in the continuous evolution and growing usage of electronic communications and e-commerce.