Description

With the work to enable OpenSSL providers support, a change was made to the System.Security.Cryptography.SafeEvpPKeyHandle.DuplicateHandle method, impacting the System.Security.Cryptography.ECDsaOpenSsl and System.Security.Cryptography.RSAOpenSsl constructors that have overloads with System.Security.Cryptography.SafeEvpPKeyHandle causing that external modifications of the passed-in handle will also affect handle stored in the instances of those classes.

Version

.NET 9 Preview 7

Previous behavior

• System.Security.Cryptography.SafeEvpPKeyHandle.DuplicateHandle created a new EVP_PKEY instance
• Modifications to the duplicated key (i.e. through direct calls to OpenSSL APIs) did not impact the original key
• SafeEvpPKeyHandle.DuplicateHandle is called by the constructors of ECDsaOpenSsl and RSAOpenSsl taking SafeEvpPKeyHandle

New behavior

DuplicateHandle increments the reference count of the existing EVP_PKEY and returns a handle to the same key, causing that external calls to OpenSSL APIs which modify EVP_PKEY will also affect instances of duplicated SafeEvpPKeyHandle which include ECDsaOpenSsl and RSAOpenSsl instances created from such handles.

Type of breaking change

• Binary incompatible: Existing binaries might encounter a breaking change in behavior, such as failure to load or execute, and if so, require recompilation.
• Source incompatible: When recompiled using the new SDK or component or to target the new runtime, existing source code might require source changes to compile successfully.
• Behavioral change: Existing binaries might behave differently at run time.

Reason for change

• enabling OpenSSL providers support
• a side effect of the DuplicateHandle simplification were also following performance improvements:
  • [Perf] Linux/x64: 8 Improvements on 7/20/2024 10:16:53 AM perf-autofiling-issues#38713
  • [Perf] Linux/x64: 10 Improvements on 7/20/2024 10:16:53 AM perf-autofiling-issues#38763
  • [Perf] Linux/arm64: 10 Improvements on 7/20/2024 10:16:53 AM perf-autofiling-issues#38910

Recommended action

Avoid modifications of EVP_PKEY passed in to .NET APIs. If modifications to EVP_PKEY can't be avoided user should create a copy of EVP_PKEY on their own (i.e. copy parameters into the new EVP_PKEY instance).

Feature area

Cryptography

Affected APIs

• System.Security.Cryptography.SafeEvpPKeyHandle.DuplicateHandle

DuplicateHandle is called by following public .NET APIs making them also affected:

• System.Security.Cryptography.ECDsaOpenSsl..ctor(System.Security.Cryptography.SafeEvpPKeyHandle)
• System.Security.Cryptography.RSAOpenSsl..ctor(System.Security.Cryptography.SafeEvpPKeyHandle)

Everything taking RSA or ECDsa instances originating from SafeEvpPKeyHandle will also be affected.

Associated WorkItem - 294097