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Asymmetrical
encryption
DynDNS provider
SINAUT MD740-1
In asymmetrical encryption, data are encrypted with one key and
decrypted with a second key. Both keys are suitable for encryption
and decryption. One of the keys is kept secret by its owner (Private
Key), the other is issued to the public (Public Key), i.e. possible
communication partners.
A message encrypted with a Public Key can only be decrypted and
read by the recipient who has the corresponding Private Key. A
message encrypted with the Private Key can be decrypted by any
recipient who has the corresponding Public Key. Encryption with
the Private Key shows that the message actually originates from
the owner of the corresponding Public Key. We therefore speak of
a digital signature.
Asymmetrical encryption methods such as RSA are, however, slow
and vulnerable to certain attacks, which is why they are often
combined with a symmetrical method (# symmetrical encryption).
On the other hand, concepts are also possible which avoid the
complex administration of symmetrical keys.
Also Dynamic DNS provider. Each computer that is connected to
the Internet has an IP address (IP = Internet Protocol). An IP
address consists of 4 numbers, separated by dots, which can each
have up to three digits. If the computer is online using a telephone
line via modem, ISDN or ADSL, it is dynamically assigned an IP
address by the Internet service provider, i.e. the address changes
from one session to another. Even if the computer is online for 24
hours without interruptions (e.g. with a flat rate) the IP address is
changed from time to time.
If a local computer is to be accessible via the Internet it must have
an address which is known to the remote communication partner.
Only in this way can the communication partner establish a
connection to the local computer. However, if the address of the
local computer continually changes this is not possible, unless the
operator of the local computer has an account with a DynamicDNS
provider (DNS = Domain Name Server).
The operator can then determine a hostname with the provider at
which the computer is to be reached in the future, e.g.
www.xyz.abc.de. In addition, the DynamicDNS provider provides a
small program which has to be installed and executed in the
computer in question. In each Internet session of the local
computer this tool informs the DynamicDNS provider of the
computer's current IP address. The provider's Domain Name
Server registers the current Hostname / IP address allocation and
informs other Domain Name Servers on the Internet accordingly.
If a remote computer now wants to establish a connection to the
local computer which is registered with the DynamicDNS provider,
the remote computer uses the local computer's hostname as the
Glossary
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