Unable to generate authorization code via PKCE flow for SPA

This error "Invalid size of Code_Challenge parameter." usually occurs if the code_challenge is invalid. Make sure to generate a valid code_ challenge.

To generate code_challenge, you can make use of this tool like below:

I tried in my environment and got the code value successfully including the above the code challenge value: enter image description here

Make sure to include origin header like below:

After including all the required parameters, I was able to generate access token successfully via PKCE flow from Postman like below:

Another Solution:

Just strip your hash to 43 characters. Then your fine. For example:

$this->code_challenge = hash("sha256", random_bytes("96"));
$code_challenge = substr($this->code_challenge, 0, 43)

Another Solution:

You seem to be using S256 (SHA256) as the code challenge method (hashing algorithm to hash code verifier). So ensure that the length of the base 64 encoded code_challenge value is 43 characters. If there is a trailing '=', strip this off (this is the padding) before setting the code_challenge query string parameter value.

Another Solution:

This PS code works for me.

# Set the length of the code verifier
        $codeVerifierLength = 64
        # Set the code verifier and code challenge
        $codeVerifier = -join ((48..57) + (65..90) + (97..122) | Get-Random -Count $codeVerifierLength | ForEach-Object {[char]$_})
        $codeChallenge = [System.Convert]::ToBase64String([System.Security.Cryptography.SHA256]::Create().ComputeHash([System.Text.Encoding]::UTF8.GetBytes($codeVerifier)))
        $codeChallenge = $codeChallenge -replace "\+","-" -replace "/","_" -replace "=",""
        # Output the code verifier
        Write-Output "Code Verifier : $codeVerifier"
        # Output the code challenge
        Write-Output "Code Challenge: $codeChallenge"

# Set the request parameters
    $params = @{
        client_id = $clientId
        redirect_uri = $redirectUri
        response_type = "code"
        response_mode = "query"
        resource = $resource
        scope = $scope
        code_challenge = $codeChallenge
        code_challenge_method = "S256"
    }
    # Build the authorization URL
    $authUrl = $authEndpoint + "?" + $(($params.GetEnumerator() | ForEach-Object { "$($_.Name)=$($_.Value)" }) -join "&").tostring()

#azure-active-directory #codong #pkce

Pranav Codes

Unable to generate authorization code via PKCE flow for SPA