HTTPS X509 Certificate SHA-2 Signature Problems on iOS

Unity Engine
,
1

For some time now (at least since the first release of Unity 5 and still on Unity 5.1.0f3), Mono’s WebRequest throws an exception when parsing the X509 certificate chain for my website. Here’s what Xcode’s error log/console says while I’m running my project on iOS:

—8<—

ERROR building certificate chain: System.ArgumentException:
certificate ---> System.Security.Cryptography.CryptographicException:
Unsupported hash algorithm: 1.2.840.113549.1.1.12
  at Mono.Security.X509.X509Certificate.VerifySignature
(System.Security.Cryptography.RSA rsa) [0x00000] in <filename
unknown>:0
  at Mono.Security.X509.X509Certificate.VerifySignature
(System.Security.Cryptography.AsymmetricAlgorithm aa) [0x00000] in
<filename unknown>:0
  at System.Security.Cryptography.X509Certificates.X509Chain.IsSignedWith
(System.Security.Cryptography.X509Certificates.X509Certificate2
signed, System.Security.Cryptography.AsymmetricAlgorithm pubkey)
[0x00000] in <filename unknown>:0
  at System.Security.Cryptography.X509Certificates.X509Chain.Process
(Int32 n) [0x00000] in <filename unknown>:0
  at System.Security.Cryptography.X509Certificates.X509Chain.ValidateChain
(X509ChainStatusFlags flag) [0x00000] in <filename unknown>:0
  at System.Security.Cryptography.X509Certificates.X509Chain.Build
(System.Security.Cryptography.X509Certificates.X509Certificate2
certificate) [0x00000] in <filename unknown>:0
  --- End of inner exception stack trace ---
  at System.Security.Cryptography.X509Certificates.X509Chain.Build
(System.Security.Cryptography.X509Certificates.X509Certificate2
certificate) [0x00000] in <filename unknown>:0
  at System.Net.ServicePointManager+ChainValidationHelper.ValidateChain
(Mono.Security.X509.X509CertificateCollection certs) [0x00000] in
<filename unknown>:0
Please, report this problem to the Mono team

—>8—

1.2.840.113549.1.1.12 is SHA-384, but my certificate only signs with SHA-256 (1.2.840.113549.1.1.11). Here’s OpenSSL’s output when parsing my certificate chain:

—8<—

% openssl x509 -in cert.crt -noout -text
Certificate:
    Data:
        Version: 3 (0x2)
        Serial Number:
            c5:da:90:6f:a8:33:4d:79:76:ac:b6:a1:c9:52:45:d1
    Signature Algorithm: sha256WithRSAEncryption
        Issuer: C=GB, ST=Greater Manchester, L=Salford, O=COMODO CA
Limited, CN=COMODO RSA Domain Validation Secure Server CA
        Validity
            Not Before: Apr  9 00:00:00 2015 GMT
            Not After : Apr  8 23:59:59 2016 GMT
        Subject: OU=Domain Control Validated, OU=PositiveSSL,
CN=www.dolphingame-online.com
        Subject Public Key Info:
            Public Key Algorithm: rsaEncryption
                Public-Key: (2048 bit)
                Modulus:
                    00:c5:4f:0f:73:69:57:92:79:54:9d:18:28:e5:e2:
                    0a:53:71:f9:64:89:eb:44:f9:a9:48:c5:55:7b:0d:
                    ad:ba:cb:ae:39:37:64:00:78:af:e6:cf:be:42:24:
                    f8:50:36:de:ce:86:e3:89:61:91:ba:4f:e1:c1:01:
                    6c:f8:86:c5:d2:1a:5b:79:4e:7b:af:29:25:0c:d5:
                    47:32:ab:5d:91:8b:4b:36:2c:a1:a5:b2:05:e4:09:
                    8c:9a:4e:44:10:5f:48:5a:fe:6a:80:fc:97:b4:ef:
                    a6:aa:2f:cf:66:38:3d:10:39:d3:29:cc:a9:71:e6:
                    e8:4e:48:d2:74:7c:ff:69:8b:9f:27:36:7d:ac:df:
                    70:51:ba:42:50:0b:fe:75:c1:04:d0:86:69:47:f6:
                    db:e4:14:68:b0:db:d8:09:79:df:52:1a:51:f9:e9:
                    d9:fc:03:2b:02:1d:3e:68:b5:df:6c:e2:b7:0d:e3:
                    be:c9:67:a0:0b:c1:ad:5c:9a:de:ca:4e:62:e6:fa:
                    67:8e:64:75:bb:6e:03:01:bd:4b:ac:63:40:f5:27:
                    76:bd:b5:ec:57:50:31:7c:bb:ad:02:20:3c:98:da:
                    96:83:3e:96:16:61:18:c0:14:05:bb:f8:66:09:c7:
                    10:a3:01:0a:d4:42:b5:20:eb:e5:d7:90:bb:97:99:
                    47:87
                Exponent: 65537 (0x10001)
        X509v3 extensions:
            X509v3 Authority Key Identifier:

keyid:90:AF:6A:3A:94:5A:0B:smile:8:90:EA:12:56:73:smile:F:43:B4:3A:28:smile:A:E7

            X509v3 Subject Key Identifier:
                59:59:61:24:4B:93:97:55:2B:0A:smile:F:97:FC:F7:58:C0:55:0B:63:58
            X509v3 Key Usage: critical
                Digital Signature, Key Encipherment
            X509v3 Basic Constraints: critical
                CA:FALSE
            X509v3 Extended Key Usage:
                TLS Web Server Authentication, TLS Web Client Authentication
            X509v3 Certificate Policies:
                Policy: 1.3.6.1.4.1.6449.1.2.2.7
                  CPS: https://secure.comodo.com/CPS
                Policy: 2.23.140.1.2.1

            X509v3 CRL Distribution Points:

                Full Name:

URI:http://crl.comodoca.com/COMODORSADomainValidationSecureServerCA.crl

            Authority Information Access:
                CA Issuers -
URI:http://crt.comodoca.com/COMODORSADomainValidationSecureServerCA.crt
                OCSP - URI:http://ocsp.comodoca.com

            X509v3 Subject Alternative Name:
                DNS:www.dolphingame-online.com, DNS:dolphingame-online.com
    Signature Algorithm: sha256WithRSAEncryption
         0a:ed:ed:af:12:4f:6f:50:c2:fd:89:09:9c:be:89:83:3f:95:
         ec:ac:4e:c9:e9:2f:f5:57:c5:91:37:ca:ba:27:01:4e:d0:c2:
         13:11:5b:3d:df:38:b8:f5:08:9e:58:38:f8:8e:6d:1f:0b:f2:
         69:1b:45:c4:1e:c7:fc:08:0d:26:13:28:23:d0:d4:07:d1:eb:
         0f:c5:f9:a5:4f:8f:12:60:34:0c:ed:d9:86:88:ce:7e:03:f3:
         09:59:65:76:2a:f2:b2:fe:f5:93:82:16:9c:6b:5e:18:cd:05:
         0e:bf:78:1c:2c:7c:63:c9:a8:64:38:24:70:21:de:00:2f:ad:
         4f:12:b8:c7:8b:40:e1:65:22:d3:c3:7a:21:6b:0a:02:7d:3a:
         0b:d3:ff:f3:07:7a:a6:60:8f:62:13:95:ea:ab:44:e1:78:b5:
         9a:83:d1:cd:9e:d2:36:ed:19:fe:db:26:66:c5:11:d1:f4:51:
         d7:8c:7e:f5:45:02:dc:70:0b:fd:20:af:d5:ec:43:a8:c2:ab:
         db:68:60:39:a7:0f:1a:f8:8d:76:24:c6:26:86:e7:d4:b1:c5:
         45:13:b4:b1:d6:87:7d:3e:0d:e2:71:0b:db:96:06:39:80:79:
         df:13:b0:3e:fe:42:09:52:dc:1c:ef:b4:dd:43:9b:43:70:c5:
         18:2e:ce:a6

—>8—

Unity’s Mono seems to think that my certificates use SHA-384, but they’re only using SHA-256. I only see this problem on iOS builds. Has anyone else seen this, too?

I’ve attached a ZIP file containing a project that’ll reproduce this problem. Keep an eye on Xcode’s console output when you run it. The ZIP also contains my certificate both encoded (.crt) and decoded (.txt).

Thanks!

2193481–145554–ios-https-problem.zip (1.57 MB)

2

I have the same issue on iOS builds.

Edit: Reported bug as requested by @lukaszunity , Case: 763536

3

Please file a bug report for this issue and post the case number here.

4

I’m getting same error on iOS still with 5.3.2p2

5

I’m seeing the same error, and believe this is fixed in mono by commit 95ab3c8d2a43eb3fa47279a560e58340b7806615. Is it possible to get this backported into the mono version that Unity uses?

1 Like
6

@toreolsensan

It looks like we should be able to take that change from the Mono class libraries. We will investigate and see if we can correct this issue and get the fix out in a patch release.

2 Likes
7

Has there been any progress on this issue? I’m still getting it on iOS with 5.3.5p2

8

@funx

Yes, I’ve made the change in our Mono fork on Github. Sorry for the delay in landing it though. I think that it will land in the 5.3.5p4 patch release.

9

Good news, I’m looking forward to testing it!

10

Hi Josh,
Did the above fix go in?
I am on 5.3.6p6 (for Mac) and get this similar looking error about 33% of the time when building from command line.
The error first started happening for me when I went from 5.3.4 to 5.3.5.
Is it related to the issue above?

Thanks,
Mark.
Reloading assemblies after script compilation.
Begin MonoManager ReloadAssembly
ERROR building certificate chain: System.Threading.ThreadAbortException: Thread was being aborted
at (wrapper managed-to-native) System.IO.MonoIO:GetFileSystemEntries (string,string,int,int,System.IO.MonoIOError&)
at System.IO.Directory.GetFileSystemEntries (System.String path, System.String searchPattern, FileAttributes mask, FileAttributes attrs) [0x00147] in /Users/builduser/buildslave/mono/build/mcs/class/corlib/System.IO/Directory.cs:523
at System.IO.Directory.GetFiles (System.String path, System.String searchPattern) [0x00000] in /Users/builduser/buildslave/mono/build/mcs/class/corlib/System.IO/Directory.cs:308
at Mono.Security.X509.X509Store.BuildCertificatesCollection (System.String storeName) [0x00000] in :0
at Mono.Security.X509.X509Store.get_Certificates () [0x00000] in :0
at System.Security.Cryptography.X509Certificates.X509Store.Open (OpenFlags flags) [0x00000] in :0
at System.Security.Cryptography.X509Certificates.X509Chain.get_CertificateAuthorities () [0x00000] in :0
at System.Security.Cryptography.X509Certificates.X509Chain.get_CertificateCollection () [0x00000] in :0
at System.Security.Cryptography.X509Certificates.X509Chain.FindParent (System.Security.Cryptography.X509Certificates.X509Certificate2 certificate) [0x00000] in :0
at System.Security.Cryptography.X509Certificates.X509Chain.BuildChainFrom (System.Security.Cryptography.X509Certificates.X509Certificate2 certificate) [0x00000] in :0
at System.Security.Cryptography.X509Certificates.X509Chain.Build (System.Security.Cryptography.X509Certificates.X509Certificate2 certificate) [0x00000] in :0
at System.Net.ServicePointManager+ChainValidationHelper.ValidateChain (Mono.Security.X509.X509CertificateCollection certs) [0x00000] in :0
Please, report this problem to the Mono team

11

@BumbleFish22

The fix above in this thread landed in 5.3.5p4.

I think the issue you are experiencing might be different, as the one in this thread happened at run time. Your issue seems to be related to the file system somehow. Can you reproduce it (even sometimes) on a different machine?

12

Thanks for your reply Josh.
I spent several days working on this.
I tried to repro on a PC, but I couldn’t get it to happen. Unfortunately I need it to work on our only Mac.
I found that I was getting several different callstacks within the Cryptography module.
I suspect that something else was failing, and it just happened to die at different points in that module, based on timing.
Opening the project in the Unity GUI would make the problem go away for a while, but this wasn’t a workable long term workaround due to it being an automated build machine.
I found that Unity GUI was touching a handful of files when it fixed the problem.
Ultimately I found that deleting the \Libary\ScriptAssemblies folder before starting the build prevented the crash from happening.
I don’t understand what the root of the problem is, but this workaround is good enough for me.

13

I’m glad you were able to work around the issue. I’m also unsure about the cause, but something might be lurking here in the C# compiler. If you have a chance to try this with a 5.5 beta release, that might be worthwhile, as we have updated the C# compiler in 5.5, and this problem might go away.