SSL and STS differences

Answer

The differences between STS and SSL are described in the Connect:Direct Secure+ Option for UNIX Implementation Guide. This guide can be downloaded from this Web site:
ftp://public.dhe.ibm.com/software/commerce/doc/mft/cdunix/38/secureplusimplementationguide_38.pdf

The Guide describes each method in depth.

Download and read the Implementation Guide for full details.

Here is a brief description of each:

The STS or Station-to-Station Protocol is a three-pass variation of the basic Diffie-Hellman protocol. It enables you to establish a shared secret key between two nodes with mutual entity authentication. Nodes are authenticated using digital signatures that sign and verify messages.

SSL or Secure Sockets Layer Protocol uses certificates to exchange a session key between the node that initiates the data transfer (the primary node or pnode) and the node that received the data (the secondary or snode). A certificate is an electronic document that associates a public key with an individual or other entity. It enables you to verify the claim that a given public key belongs to a given entity. A certificate authority (CA) validates an applicant's identity, creates a certificate, and then signs the certificate, thus vouching for an entity's identity. SSL provides three levels of security.