"Access Token missing or malformed" when doing "addKey" to add Application Certificate

Question

I am trying to add a new certificate to an App Registration via Graph API. The steps detailed in this article basically. I created a token along the lines of what is mentioned in this article . I wanted to use PowerShell Core so I did the following:

   $signingCert = New-Object System.Security.Cryptography.X509Certificates.X509Certificate2(${certPath}${certName}", "$certPassword")  
   $signingCreds = New-Object Microsoft.IdentityModel.Tokens.X509SigningCredentials($signingCert)  
     
   $claimsDict = New-Object System.Collections.Generic.Dictionary"[String,Object]"  
   $claimsDict."aud" = "00000002-0000-0000-c000-000000000000"  
   # This is the Id of the App Registration using which I am making the Graph API call. This is not the App Id (though I tried with that too) but the Graph Id (what I get from Get-MgApplication)  
   $claimsDict."iss" = "9db7dfa6-4f4c-430b-a573-d64d5dc172fd"  
     
   $securityToken = New-Object Microsoft.IdentityModel.Tokens.SecurityTokenDescriptor  
   $securityToken.claims = $claimsDict  
   $securityToken.NotBefore = [datetime]::now  
   $securityToken.Expires = [datetime]::now.AddMinutes(10)  
   $securityToken.SigningCredentials = $signingCreds  
     
   $handler = New-Object Microsoft.IdentityModel.JsonWebTokens.JsonWebTokenHandler  
   $token = $handler.CreateToken($securityToken)

Next I put this token as the proof in a POST request:

   $certData = New-Object System.Security.Cryptography.X509Certificates.X509Certificate2(${certPath}${newCertName}")  
   $bodyParameter = @{  
       "keyCredential" = @{   
           "type" = "AsymmetricX509Cert";  
           "usage" ="Verify";   
           "key" = [System.Convert]::ToBase64String($certData.RawData)   
       };  
       "passwordCredential" = $null;  
       "proof" = $token  
   }  
   (ConvertTo-Json $bodyParameter)

The result is some JSON along these lines:

   {  
     "proof": "eyJhbGciOiJSUzI1NiIsImtpZCI6IjZFOEU3ODRGQ0ZGREQyQzY5RTI3RDQ2OEM4QjgxNEU3QzRFRDgwOEIiLCJ0eXAiOiJKV1QiLCJ4NXQiOiJibzU0VDhfOTBzYWVKOVJveUxnVTU4VHRnSXMifQ.eyJhdWQiOiIwMDAwMDAwMi0wMDAwLTAwMDAtYzAwMC0wMDAwMDAwMDAwMDAiLCJpc3MiOiI5ZGI3ZGZhNi00ZjRjLTQzMGItYTU3My1kNjRkNWRjMTcyZmQiLCJleHAiOjE2MzM5ODIwMjEsIm5iZiI6MTYzMzk4MTQyMSwiaWF0IjoxNjMzOTgxNDIyfQ.a__8to9Mav7r5to85O8PMHzUaz5el_VhsJQ6ahqHqdJRQ2TlcPDuNVEcUc1qHyq7pNaQid0LdnbR8s4Bt5ulZJBGRjXmf64cgPQFOGJFl2TQAneZlhoB_6zVQBwGPCnLL4EZHybT6GwTFhVYKvAiCK3HVdQUgTkVUEsGNKLjUtBzYNGgqxFWoOwKt-uZM7yCALYt2BHH2G8P0KroZEYmUZEU1KcSh1UqyEPg--Pr6qu4CwxFwurtNhmysiYMM3e7vdpIFPaJOT52hKeeppP-lAFsTkeoWQSD0G5Cvwl-HPU2A7uWHgQaZzer2htt5Xeys3woHhcNSHJgHRmceud7fSRMRbctexywlXzeclCOQjWOBYXAWAkIH3gzXbBZ6TomfgR6-EIenXwaxtADHnoflvQKsnclXQLF8BQ69Lw6UaxPBLG6EC1KMC4b_BLaR5E6P5FYf7E4WoljqwtiqD-3DwzQ_0PXBABFqHYV9JtW7cq1skA3pyc9XbUm1PHTh5Z0p7VC2lXRJ00MLuZiDAQxOPjV7RH-VucQZJcvZ06Wbz62hKDEbmKLWfq0BqCgjPPQQfQWsrEeN_eJ4INqrAWh_LWJ-utaiB9hNFq4qe-AvaPulKoIBYRkIb8j_dclR6DWRbvklNOgQ2rg6G56Mk96i_PJZq2afeJW-ocj67o72hk",  
     "passwordCredential": null,  
     "keyCredential": {  
       "key": "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",  
       "type": "AsymmetricX509Cert",  
       "usage": "Verify"  
     }  
   }

As far as I can see this looks correct and similar to the example in the Microsoft doc. If I put the proof token in a JWT decoder like https://jwt.ms I see that it is correct:

   {  
     "alg": "RS256",  
     "kid": "6E8E784FCFFDD2C69E27D468C8B814E7C4ED808B",  
     "typ": "JWT",  
     "x5t": "bo54T8_90saeJ9RoyLgU58TtgIs"  
   }.{  
     "aud": "00000002-0000-0000-c000-000000000000",  
     "iss": "9db7dfa6-4f4c-430b-a573-d64d5dc172fd",  
     "exp": 1633982021,  
     "nbf": 1633981421,  
     "iat": 1633981422  
   }.[Signature]

That certificate thumbprint matches the one that's already in the App Registration (which is the certificate I used to sign the token as per the docs).

However if I make a request with the above $bodyParamter JSON I get the following error:

   {  
       "error": {  
           "code": "Authentication_MissingOrMalformed",  
           "message": "Access Token missing or malformed.",  
           "innerError": {  
               "date": "2021-10-11T19:44:46",  
               "request-id": "1177fc83-1342-4a3d-82f8-172b452f8471",  
               "client-request-id": "1177fc83-1342-4a3d-82f8-172b452f8471"  
           }  
       }  
   }

This happens if I use a tool like Postman or Invoke-MgGraphRequest -Method POST -Uri "https://graph.microsoft.com/v1.0/applications/$appId/addKey" -Body (ConvertTo-Json $bodyParameter) or Add-MgApplicationKey -ApplicationId $appId -BodyParameter $bodyParameter... Any suggestions on what I could be doing wrong here?

Thanks.

Answer

Working solution using Microsoft.Graph.Authentication Module only.
Tested under powershell 7.4.1 and Windows PowerShell 5.1.22621.2506

For me the error was that I did not remove the padding in both jwt headers, I also don't see anything inherently wrong with your version, but it might be that your datetimes are not in UTC. not that you are likely to read this two and a half years later.

# Replace for your Environment
Connect-MgGraph -TenantId $graphConfig.tenantID -ClientId $graphConfig.unprivClientID -CertificateThumbprint $graphConfig.thumb

# Application / Client ID of the App you are rotating the Certificate on
$clientID = $graphConfig.unprivClientID

# Load Certificate from Windows Store
$cert = Get-Item "Cert:\CurrentUser\My\$($graphConfig.thumb)" -ErrorAction Stop
# Alternative from a Certificate file, drop in Replacement
# $cert = Get-PfxCertificate "[pathToCer]"

# Get base64 hash of certificate in Web Encoding
$CertificateBase64Hash = [System.Convert]::ToBase64String($cert.GetCertHash()) -replace '\+', '-' -replace '/', '_' -replace '='


# Very far removed, but still based on https://adamtheautomator.com/powershell-graph-api/

$StartDate = (Get-Date "1970-01-01T00:00:00Z").ToUniversalTime()
$now = (Get-Date).ToUniversalTime()
# Create JWT timestamp for expiration
$JWTExpirationTimeSpan = ( New-TimeSpan -Start $StartDate -End $now.AddMinutes(2) ).TotalSeconds
$JWTExpiration = [math]::Round($JWTExpirationTimeSpan, 0)
    
# Create JWT validity start timestamp
$NotBeforeExpirationTimeSpan = ( New-TimeSpan -Start $StartDate -End $now ).TotalSeconds
$NotBefore = [math]::Round($NotBeforeExpirationTimeSpan, 0)
 
# Create JWT header
$JWTHeader = @{
    alg = "RS256"
    typ = "JWT"
    x5t = $CertificateBase64Hash 
}

# Create JWT payload
$JWTPayLoad = @{
    aud = "00000002-0000-0000-c000-000000000000"
    exp = $JWTExpiration
    iss = $clientID
    jti = [guid]::NewGuid()
    nbf = $NotBefore
    sub = $clientID
}
    

# Check if there are Equals in the JWT to replace, since that is referenced in one of the articles (add)
# Convert header and payload to base64
$JWTHeaderToByte = [System.Text.Encoding]::UTF8.GetBytes(($JWTHeader | ConvertTo-Json))
$EncodedHeader = [System.Convert]::ToBase64String($JWTHeaderToByte) -replace '='
    
$JWTPayLoadToByte = [System.Text.Encoding]::UTF8.GetBytes(($JWTPayload | ConvertTo-Json))
$EncodedPayload = [System.Convert]::ToBase64String($JWTPayLoadToByte) -replace '='
    
$JWT = $EncodedHeader + "." + $EncodedPayload
    
# Define RSA signature and hashing algorithm
$RSAPadding = [Security.Cryptography.RSASignaturePadding]::Pkcs1
$HashAlgorithm = [Security.Cryptography.HashAlgorithmName]::SHA256
    
# Sign the JWT
$rsaCert = [System.Security.Cryptography.X509Certificates.RSACertificateExtensions]::GetRSAPrivateKey($cert)
$Signature = [Convert]::ToBase64String(
    $rsaCert.SignData([System.Text.Encoding]::UTF8.GetBytes($JWT), $HashAlgorithm, $RSAPadding)
) -replace '\+', '-' -replace '/', '_' -replace '='
    
# Add Signature to JWT
$JWT = $JWT + "." + $Signature

# Load the new Certificate, again use Get-PfxCertificate as a drop in Replacement
$newCert = Get-Item "Cert:\CurrentUser\My\$($graphConfig.newThumb)" -ErrorAction Stop

$params = @{
	keyCredential = @{
		type = "AsymmetricX509Cert"
		usage = "Verify"
		key = [convert]::ToBase64String($newCert.GetRawCertData())
	}
	passwordCredential = $null
	proof = $JWT
}

Invoke-MgGraphRequest POST "/v1.0/applications(appId='$clientID')/addKey" -Body $params

Answer

I noticed that you are using the old AAD graph, 00000002-0000-0000-c000-000000000000 is AAD Graph API, if you use it as an audience, then you will get AAD Graph token.

As far as I know, AAD graph tokens cannot call MS graph, so you need to change aud to: $claimsDict."aud" = "00000003-0000-0000-c000-000000000000" or $claimsDict."aud" = "https://graph.microsoft.com" to obtain the MS graph token.

In addition, according to my experience, iss should be your tenant id.

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