B2B Integration : A Practical Guide to Collaborative E-commerce

10.6.3. Public key encryption
Internet Security 295
To overcome the drawbacks of private key encryption, a new algorithm,
called public key encryption, was invented by Whitfield Diffie and
Martin Hellman in 1976.
Public key encryption or asymmetrical encryption uses two keys:
• One is called the private key, which is held by only one party; and
• The other is called the public key, which is available to the outside
world.
These keys complement each other like a mechanical lock and key.
The message is encrypted with the public key and can be unlocked or
decrypted only with the private key. Any company, like Company A,
wishing to communicate with Company B can encrypt the message with
Company B's public key and send it across (see Figure 10.3). Thus, the
two companies do not have to agree upon a key in advance. Since the
decryption can be done only with the private key, which is known only
to Company B, even if the message is intercepted, the interceptor will
not be able to comprehend the message. Thus, the message always
remains protected using public key encryption.
Public key encryption comes with its own share of drawbacks; speed
being the most critical. The keys used are much longer than symmetric
encryption, hence encryption overhead is much higher and performance
decreased.
Among the most popular algorithms available for public key
encryption is RSA, created by RSA Data Security, which uses key
lengths from 512 to 1024 bits.
Secret
Message
„ f
Encryption
«iith
Company A Public Key
of Gompany B
Decryption
with
Figure 10.3. — Public key encryption
Secret
Message
_ p
Private Key company B
of Company B