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Here we explain some basic terms in connection with digital signature
With the help of the digital signature, a person can sign data and documents electronically. The handwritten signature is not available in digital form. Instead, the digital signature is a security method equivalent to the personal signature. Like a handwritten signature, the electronic signature is inseparably linked to the respective document. It can be viewed by any user but can only be changed by the signatory himself.
Encrypted hash values (checksums) are processed by means of cryptography. A possible change of the data can thus be detected immediately. This procedure guarantees the integrity of the data and makes the digital signature a secure procedure.
The algorithms used to calculate a hash ensure that small changes in the digital information lead to large changes in the hash. This also means that a recalculation is not possible in practice.
The most common algorithm for hash calculations is currently SHA256, which generates a hash with a fixed length of 256 bits.
The first key of such a pair is defined and designated as “private”. The second key is calculated from the first and is called “public”. Similar to hash values, it is not possible in practice to calculate back from the public to the private key.
The private key must be kept secret by the owner. Additional methods, such as procedures involving the entry of user name and password, can further strengthen the security of using this key.
In contrast, the public key is made known to the largest possible number of users. Access via the Internet makes the usability as simple and real-time as possible.
For this purpose, the digital information is encrypted with the freely accessible public key of the recipient. As is well known, decryption is not possible with the public key or with a key of another pair. Only the private key of the recipient can decrypt the digital information.
The disadvantage of this procedure is that the recipient cannot determine the identity of the sender.