Setting the User Default CSP

One user default CSP can be specified for each CSP type. The user default CSP is used when an application calls CryptAcquireContext with only a CSP type specified. Unless there are important reasons for setting up a custom CSP as the user default CSP, the normal default CSP should not be changed.

If the user default CSP must be changed, user defaults are stored in the registry's HKEY_CURRENT_USER window and can only be set if the actual end user is currently logged on to the computer. In any case, the end user should be consulted or informed whenever the user default CSP is changed. The user default CSP is set using the CryptSetProvider function, which internally sets the following registry entry:

HKEY_CURRENT_USER
Software
Microsoft
Cryptography
Provider Type<CSP type>
>Name:REG_SZ:<CSP name>

The <CSP type> entry is in decimal format and exactly 3 digits in length. For example, if the CSP is of type 25, the key name is Type 025.

The <CSP name> entry must be set to the textual name of the CSP. This must exactly match the <CSP name> registry key discussed in Registering the CSP.