Enterprise Library Test Guide - Willy .Net

Using the Test Cases 245
This is the code that caused the problems.
public static ProtectedKey Read(string protectedKeyFileName, DataProtectionScope
dpapiProtectionScope)
{
using (FileStream stream = new FileStream(protectedKeyFileName, FileMode.
Open))
{
return Read(stream, dpapiProtectionScope);
}
}
Solution
To solve the first problem, the Read method was modified so that it read the symmetric
key only once from the file and then cached the key in a static collection. Subsequent
reads retrieved the file from the cache, which greatly reduced the performance
overhead.
To solve the second problem, the Read method was modified to use constructors that
included the FileShare.Read enumeration. This allowed multiple users to concurrently
read the file. The following is the code that solved both the performance problem
and the concurrency problem.
public static ProtectedKey Read(string protectedKeyFileName, DataProtectionScope
dpapiProtectionScope)
{
string completeFileName = Path.GetFullPath(protectedKeyFileName);
if (cache[completeFileName] != null)
return cache[completeFileName];
using (FileStream stream = new FileStream(protectedKeyFileName, FileMode.Open,
FileAccess.Read, FileShare.Read))
{
ProtectedKey protectedKey = Read(stream, dpapiProtectionScope);
cache[completeFileName] = protectedKey;
return protectedKey;
}
}
Verification
Running the test case again after applying the preceding code verified that the cost of
reading a key from a file was within acceptable limits. In addition, concurrent users
could now read the file.
Security Testing
The goals of security testing are the following:
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Identify the potential threats to the application blocks.
Identify the vulnerabilities of the application blocks.
Provide counter measures to these threats and vulnerabilities.