A Comprehensive Guide to IBM WebSphere Host Publisher Version 3.5

638 IBM WebSphere Host Publisher Version 3.5

Figure 20-7 Message digest secures data integrity

Message digest algorithms, such as MD5 and SHA-1, are used in public-key

cryptography to secure data integrity:

򐂰 SHA-1: The Secure Hash Algorithm has been adopted as the Federal

Information Processing Standard (FIPS). SHA-1 generates 160-bit

fingerprints. SHA is similar to MD5 but cryptographically stronger (harder to

break) and slower than MD5.

򐂰 MD5: The Message Digest algorithm (MD5) is a hash algorithm that

generates 128-bit fingerprints. It is slightly faster than SHA-1.

Both MD5 and SHA-1 can be applied to a single character as well as several

megabytes of data. The result is the same number of bits as defined above.

20.1.9 SSL tunneling

SSL tunneling refers to establishing a secure channel through the proxy. The

proxy only knows user authentication, source, and destination. The proxy has no

access to data exchanged between a client and a destination server. Digital

certificates are exchanged directly between a client and a destination server.

SSL tunneling is illustrated in Figure 20-8 on page 639.

Insecure network

Encrypt

input msg + digest

input

message

Message Digest

Algorithm

Message digest algorithm produces fixed length "digital

hash"

Same algorithm used to validate message received

sender's

private key

message

digest

sender's

public key

Decrypt

Compare

digests