GlobalEnableSha256XmlSignatures causes conflict with signatures in IdSvr3 #303

tonyeung opened this Issue Sep 15, 2015 · 9 comments


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Algs can get added to the cryptoconfig, but is there any way to get rid of them? or perhaps only have them work conditionally?

The problem is that the System.IdentityModel.Tokens.JwtSecurityTokenHandler.WriteToken(SecurityToken token) can no longer sign tokens if the global enable sha256 xml sigs is enabled.

Also, the hash algorithm on my cert is System.Security.Cryptography.SHA256Managed, but it changes to System.Security.Cryptography.SHA256Cng after RSAPKCS1SHA256SignatureDescription is added but either way the formatter is still System.Security.Cryptography.RSAPKCS1SignatureFormatter

    static internal readonly string RsaSha256Namespace = "";

    /// <summary>
    /// Make Sha256 signature algorithm available in this process (not just Kentor.AuthServices)
    /// </summary>
    [System.Diagnostics.CodeAnalysis.SuppressMessage( "Microsoft.Naming", "CA1704:IdentifiersShouldBeSpelledCorrectly", MessageId = "Sha" )]
    public static void GlobalEnableSha256XmlSignatures()
        CryptoConfig.AddAlgorithm(typeof(RSAPKCS1SHA256SignatureDescription), RsaSha256Namespace);

In IdSvr3,

This line in particular will blow up when

        var handler = new JwtSecurityTokenHandler();
        return handler.WriteToken(jwt);

As you can see from this stack trace, something screwy happens when somewhere around CreateSignature()

2015-09-15 15:08:57,789 [6] DEBUG IdentityServer3.Core.Services.Default.DefaultTokenService [(null)] - Creating JWT identity token
2015-09-15 15:08:57,867 [6] DEBUG WebApi Diagnostics [(null)] - Operation=ReflectedHttpActionDescriptor.ExecuteAsync, Exception=System.Security.Cryptography.CryptographicException: Invalid algorithm specified.

   at System.Security.Cryptography.CryptographicException.ThrowCryptographicException(Int32 hr)
   at System.Security.Cryptography.Utils.SignValue(SafeKeyHandle hKey, Int32 keyNumber, Int32 calgKey, Int32 calgHash, Byte[] hash, Int32 cbHash, ObjectHandleOnStack retSignature)
   at System.Security.Cryptography.Utils.SignValue(SafeKeyHandle hKey, Int32 keyNumber, Int32 calgKey, Int32 calgHash, Byte[] hash)
   at System.Security.Cryptography.RSACryptoServiceProvider.SignHash(Byte[] rgbHash, Int32 calgHash)
   at System.Security.Cryptography.RSAPKCS1SignatureFormatter.CreateSignature(Byte[] rgbHash)
   at System.IdentityModel.Tokens.AsymmetricSignatureProvider.Sign(Byte[] input)
   at System.IdentityModel.Tokens.JwtSecurityTokenHandler.CreateSignature(String inputString, SecurityKey key, String algorithm, SignatureProvider signatureProvider)
   at System.IdentityModel.Tokens.JwtSecurityTokenHandler.WriteToken(SecurityToken token)

This ticket on the IdSvr3 side has more details on how I came to this conclusion: IdentityServer/IdentityServer3#1903

@tonyeung tonyeung referenced this issue in IdentityServer/IdentityServer3 Sep 15, 2015

Invalid algorithm specified #1903


Okay, I feel like an idiot now.. but in case anyone else runs into this problem...

I had added the GlobalEnableSha256XmlSignatures because my app would blow up every time i connected to the dev IdP, and it turns out I needed to enable the option. HOWEVER. the production server has no such issues, so enabling it only caused me two days of grief.

If you're getting this error and you have GlobalEnableSha256XmlSignatures turned on, just rip that line of code out and everything will be hunky dory.

@tonyeung tonyeung closed this Sep 15, 2015

okay, so never mind.. i was able to get it to work because the signon cookie was still there. A new session blew up in my face when trying to verify the xml sig. I think I found a work around while troubleshooting this that can go on the kentor side.

@tonyeung tonyeung reopened this Sep 15, 2015

I don't know why the cert doesn't work, but after I created a new cert and specified Microsoft Enhanced RSA and AES Cryptographic Provider as the CSP, it worked. If anyone else has this problem, please note that on the cert request either from the MMC or IIS will not let you chose the CSP (the option should be there but it will be hidden AND disabled). You will need to generate the request via certreq.exe. Its a PITA but that's the only work around that I know of right now.

@tonyeung tonyeung closed this Sep 17, 2015

Tony, What work around did you use when verifying the XML signature to allow the Create JWT to work in tandem? Cheers.


Is it possible to use the System.IdentityModel.Tokens.Jwt.CreateToken overload which accepts a SignatureProvider to workaround this? Or this is different to the CryptographyProvider?


@peterswallow AuthServices never calls Jwt.CreateToken, that's part of IdSrv3.

Our problem is that the signature algorithm is not part of a per-call or per-instance config. It's read from a process-global registry in,796.

Unfortunately I don't see a way working around this in AuthServices, I see it as a bug in IdSrv3 or System.IdentityModel.

@AndersAbel AndersAbel added this to the Not in Release milestone Feb 8, 2016
@AndersAbel AndersAbel reopened this Jun 15, 2016
@AndersAbel AndersAbel removed this from the Not in Release milestone Jun 15, 2016
@AndersAbel AndersAbel added the bug label Jun 15, 2016
@AndersAbel AndersAbel added a commit that closed this issue Jun 15, 2016
@AndersAbel AndersAbel Add own SignatureDescriptor for SHA256
- Magically change CryptoServiceProvider to one that supports SHA256.
- Fixes #303

Been working on this today and found out that this can actually be fixed in AuthServices. X509AsymmetricSecurityKey contains some black magic to ensure that a crypto service provider supporting SHA256 is used. That magic is bypassed if a SHA256 algorithm is registered on an application level.

@AndersAbel AndersAbel referenced this issue in AzureAD/azure-activedirectory-identitymodel-extensions-for-dotnet Jun 15, 2016

"invalid algorithm specified" after adding RSAPKCS1SHA256SignatureDescription to cryptoconfig #246

@AndersAbel AndersAbel added this to the v0.19.0 milestone Jun 21, 2016
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