Common Data Security Architecture (CDSA) White Paper

Chapter 1 67
Common Data Security Architecture (CDSA) White Paper
Validating the CSP Credentials
Integrity Check prior to Loading
The integrity check performed on the CSP prior to loading ensures that the add-in shared
library has not been tampered with before it is loaded. The CSSM performs this check before
loading any CSP add-in module.
1. First, the signature on the signed .SF file is validated. To accomplish this, the CSSM uses
the certificate chain of X.509 certificates embedded in the credential file.
2. If the chain can be validated, the public key of the validated signer’s certificate is used to
verify the signature of the .SF file, as shown in Figure 1-9 on page 67.
Figure 1-9 Verifying the signature on the .SF file
3. After the signature of the .SF file is validated, a SHA-1 hash of the section in the .MF file
referring to the shared library to be loaded is calculated and compared with the hash in
the .SF file. This is shown in Figure 1-10.
.DSA file,
containing
signer's DSA
signature
.SF file,
containing hash
of data in .MF file
Signer's
public key
DSA
Verify
Did the
Signature
verify?
.SF file was created
by unknown entity.
STOP!
.SF file was
created by Signer
No
Yes