B2B Integration : A Practical Guide to Collaborative E-commerce

300 B2B Integration — A Practical Guide to Collaborative E-commerce
10.6.6. Digital certificates and role of Certificate
Authorities (CAs)
All of the above mechanisms of security relied on using public keys
and private keys for both the sender and the receiver. The question
arises — where do these keys come from? How does the outside world
get hold of the public key of a particular party?
The answer lies in digital certificates, issued by organizations called
Certificate Authorities (CAs). Certificates can be used to replace passwords
and login ID's wherever access is to be restricted to certain
users, such as registered customers. In several applications, certificates
may replace 'cookies', which have proven unpopular with many Web
users.
Any company/individual wishing to communicate securely over the
Internet can apply to a CA for a digital certificate. It has to send
its identification information and public key to the CA. The CA will
verify the authenticity of information and then issue a certificate with
the given information and public key. To seal the certificate, the CA
encrypts it with its private key and sends it to the applicant (see
Figure 10.9).
In this approach, when Company A wants to communicate with
Company B, it will ask Company B for its certificate. On receiving this
certificate, Company A will decrypt the same using the CA's public key.
It will then read the identifying information on the certificate. If satisfied,
it will use the public key present on the certificate to send across the
information to Company B.
This methodology is not only secure, but requires the sender to
know only the CA's public key, rather than remember the public key of
every party it wishes to communicate with.
The most widely recognized standard public key certificate format is
defined in the ITU X.509 standard.
Serial
Number
Signature
N umber
CA Info
CA
Number
Owner Info
Owner's
N umber
Owner's
Public Key
N umber
Validity
Period
Figure 10.9. — Simple public key certificate
CA
Digital
Signature