Exception: Error Occurred During a Cryptographic Operation

SecureAuth IdP Version Affected: All

Description:  
When attempting to use transparent SSO, it does not work. Warning log shows

Exception: Error occurred during a cryptographic operation. - at System.Web.Security.Cryptography.HomogenizingCryptoServiceWrapper.HomogenizeErrors(Func`2 func, Byte[] input)
at System.Web.Security.FormsAuthentication.Decrypt(String encryptedTicket)
at MFA.Utilities.Encryption.GetTokenData(String cookiename, String mysecret, Int32 returntype)

Cause:  The two realms are using different targetframework in the httpruntime section of the Web.config meaning that machinekeys, although seemingly identical do not match.

Resolution:

1. Open the Admin Console
2. On the Realm in question, click on the System Info tab
3. Click "Click to edit Web Config file"
4. Search for targetFramework and make a note of the version
5. Check the other realm and make a note of the version
6. Match up the targetFramework versions on all participating realms. We typically recommend 4.5 as per the screenshot unless you have a specific reason to use something else.
7. Save the changes. 

Special Considerations:  

Note that another cause of this error can be found here:

https://support.secureauth.com/hc/en-us/articles/360035290132-Error-HomogenizingCryptoServiceWrapper-HomogenizeErrors

SecureAuth Knowledge Base Articles provide information based on specific use cases and may not apply to all appliances or configurations. Be advised that these instructions could cause harm to the environment if not followed correctly or if they do not apply to the current use case.
Customers are responsible for their own due diligence prior to utilizing this information and agree that SecureAuth is not liable for any issues caused by misconfiguration directly or indirectly related to SecureAuth products.