What is the key certificate?

The certificate is an electronic document that links signature verification data to a specific person, confirms the identity of that person and certified by an electronic digital signature Certification Center

4. What is a Certification Authority?
Certification Center - a specialized organization performing the following functions:
• registration of users;
• Production of signature key certificates;
• creation of electronic digital signature keys to guarantee the secrecy of the closed key EDS;
• Suspension and resumption of signature key certificates of action, as well as their cancellation;

• maintaining a register of signature key certificates, ensuring its relevance and the possibility of free circulation to it participants of information systems;
• verification of the uniqueness of a public key digital signature in the register of signature key certificates;
• certification of the signature key information about their action;
• implementation of the appeals of the user certificate authentication signature key signature in the electronic document in respect of signature key certificates issued to them.

6. How does the digital signature?
With the help of electronic signature information is encrypted and is accessible to anyone having access to it to the user. To determine the identity of the author of the document and the authenticity verification using the so-called "Hash function".

In the first stage of signing the document EDS built a special function (such as a checksum), a hash function that identifies the contents of the document. In the second stage the author of a document encrypts the content hash his personal private key. Thus they encrypted hash function is placed in the document and is stored and sent with it. The size of the hash function is negligible, so there is no appreciable increase in the size of the document.

When you receive a document signed by the electronic signature, the user can verify its authenticity. There it is. At the first stage the recipient of the document is building its own version of a hash of the signed document. In the second stage decrypted hash function, that contain the document. The third step is the comparison of the two hash functions. Their match is a guarantee of the authenticity of the document and its authorship.

What are the two keys are needed?

In the digital signature system used asymmetric encryption method, in which two different keys are used, none of which can be obtained from another. One key (open) is used to encrypt and the other (private) - to decrypt the information. The private key is in its holder, which ensures high secret key and the public key is distributed to all users of the system, so that they can carry out the authentication of the received documents and signatures. This key can not be used to decrypt the information so it makes no sense to limit its spread.

With the help of the public key of the recipient information, other users information system encrypts the information and no one but the recipient will not be able to decipher it, because to decrypt the private key is used, and it is available only from him.