Safe handle has been closed

Unexpected behavior when disposing RSACryptoServiceProvider.

When you create a token using the following the instructions in RSACryptoServiceProvider https://docs.microsoft.com/en-us/dotnet/api/system.security.cryptography.rsacryptoserviceprovider?view=net-5.0, the token creation fails every other time.

So, the first call succeeds but the call immediately after that fails with exception:

System.ObjectDisposedException: Safe handle has been closed. Object name: 'SafeHandle'. at System.Runtime.InteropServices.SafeHandle.DangerousAddRef(Boolean& success) at System.StubHelpers.StubHelpers.SafeHandleAddRef(SafeHandle pHandle, Boolean& success) at Interop.Advapi32.CryptCreateHash(SafeProvHandle hProv, Int32 Algid, SafeKeyHandle hKey, CryptCreateHashFlags dwFlags, SafeHashHandle& phHash) at Internal.NativeCrypto.CapiHelper.CreateHashHandle(SafeProvHandle hProv, Byte[] hash, Int32 calgHash) at Internal.NativeCrypto.CapiHelper.SignValue(SafeProvHandle hProv, SafeKeyHandle hKey, Int32 keyNumber, Int32 calgKey, Int32 calgHash, Byte[] hash) at System.Security.Cryptography.RSACryptoServiceProvider.SignHash(Byte[] rgbHash, Int32 calgHash) at System.Security.Cryptography.RSACryptoServiceProvider.SignHash(Byte[] hash, HashAlgorithmName hashAlgorithm, RSASignaturePadding padding) at Microsoft.IdentityModel.Tokens.AsymmetricAdapter.SignWithRsa(Byte[] bytes) at Microsoft.IdentityModel.Tokens.AsymmetricAdapter.Sign(Byte[] bytes) at Microsoft.IdentityModel.Tokens.AsymmetricSignatureProvider.Sign(Byte[] input) at Microsoft.IdentityModel.JsonWebTokens.JwtTokenUtilities.CreateEncodedSignature(String input, SigningCredentials signingCredentials) at System.IdentityModel.Tokens.Jwt.JwtSecurityTokenHandler.CreateJwtSecurityTokenPrivate(String issuer, String audience, ClaimsIdentity subject, Nullable1 notBefore, Nullable1 expires, Nullable1 issuedAt, SigningCredentials signingCredentials, EncryptingCredentials encryptingCredentials, IDictionary2 claimCollection, String tokenType) at System.IdentityModel.Tokens.Jwt.JwtSecurityTokenHandler.CreateJwtSecurityToken(SecurityTokenDescriptor tokenDescriptor) + the codeline pointing to tokenHandler.CreateJwtSecurityToken

See the mini-project in here: https://github.com/Ozzian/InterestingBehaviour/blob/19df369549a21907880c2f8d4cb77b6cb37db45e/InterestingBehaviour/JWT.cs#L20

Is the intent not to dispose the RSACryptoServiceProvider during your service lifetime? What is up with this?

[brentschmaltz]

@Ozzian we will investigate this. Since the RsaSecurityKey ctor is passed a RSA instance, we should not be disposing that instance. Internally we cache an AsymmetricSignatureProvider associated with the RSA instance, that provider reuses the RSA instance after it was disposed.

[Tobias841]

@Tobias841 what is stopping you from upgrading to 6.x?

andybakerbrfc is correct. All the information is there in the original post I think by Ozzian: “The token creation fails every other time”. This is stopping us to upgrade to v 6.x. You seem to have a state dependency in the dispose method in between calls that causes the bug judging from the call stack and error message. But I’m on vacation now so I might remember this wrong…

I also added a link to a test project with minimal code that reveals the problem. I would suggest downloading that code. It should make it simple for you guys to find the problem I think using that test code. We can’t upgrade to v 6.x until this has been fixed.