Functions/New-JsonWebKey.ps1
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function New-JsonWebKey { <# .SYNOPSIS Generates a JSON Web Key from an x509 certificate. .DESCRIPTION Transforms an X509Certificate2 object into a JSON object known as a JSON Web Key (JWK). .PARAMETER Certificate The certificate that will be converted into a JSON Web Key. .PARAMETER KeyOperations The public key operation that this JWK will be used for. Verification is the default. .PARAMETER IncludeChain Tells the function to include the full certificate chain which includes not only the end-entity certificate, but also the issuing and root certificate in the x5c property (X.509 Certificate Chain). Not selecting this parameter will result in x5c property containing the end-entity certificate only. .PARAMETER AsJson Tells the function to return JSON as opposed to an object. .PARAMETER Compress Omits white space and indented formatting in the output JSON Web Key. .EXAMPLE $certThumbprint = "706428667193645C3B4704FC824BEDFCEBB4F038" $certPath = Join-Path -Path Cert:\LocalMachine\My -ChildPath $certThumbprint $verificationCert = Get-Item -Path $certPath $verificationCert | New-JsonWebKey -KeyOperations Verification Generates a JSON Web Key for purposes of signature verification from certificate with thumbprint 706428667193645C3B4704FC824BEDFCEBB4F038. .EXAMPLE $certificates = Get-ChildItem -Path Cert:\LocalMachine\My | Where Subject -Like "*jwt*" $jwks = @() foreach ($cert in $certificates) { $jwks+= $cert | New-JsonWebKey } $jwksSet = @{keys=$jwks} | ConvertTo-Json Obtains a collection of certificates from Cert:\LocalMachine\My where the subject contains the string "jwt", and for each one of them converts them to a JWK object, adds them to an array and serializes the result into a JWK set. .INPUTS System.Security.Cryptography.X509Certificates.X509Certificate2 A X509Certificate2 object is received by the Certificate parameter. .OUTPUTS System.Management.Automation.PSCustomObject or System.String .NOTES Unlike New-JsonWebKeySet, which only returns the JWK set serialized, New-JsonWebKey returns an object by default with the option to serialize via the AsJson parameter. .LINK https://tools.ietf.org/html/rfc7517 New-JsonWebToken New-JsonWebKeySet Get-ChildItem ConvertTo-Json https://docs.microsoft.com/en-us/powershell/module/microsoft.powershell.security/about/about_certificate_provider?view=powershell-7.1 #> [CmdletBinding()] [Alias('njwk', 'CreateJwk')] [OutputType([System.Management.Automation.PSCustomObject], [System.String])] Param ( [Parameter(Mandatory = $true, ValueFromPipeline = $true, Position = 0)] [System.Security.Cryptography.X509Certificates.X509Certificate2]$Certificate, [Parameter(Mandatory = $false, Position = 1)] [ValidateSet("Verification", "Encryption")] [System.String]$KeyOperations = "Verification", [Parameter(Mandatory = $false, Position = 2)][Switch]$IncludeChain, [Parameter(Mandatory = $false, Position = 3, ParameterSetName = "JSON")][Switch]$AsJson, [Parameter(Mandatory = $false, Position = 4, ParameterSetName = "JSON")][Switch]$Compress ) PROCESS { [PSCustomObject]$jwkObject = $null $encodedThumbprint = ConvertTo-Base64UrlEncodedString -Bytes ($Certificate.GetCertHash()) [string]$publicKeyUse = "" switch ($KeyOperations) { "Verification" { $publicKeyUse = "sig" } "Encryption" { $publicKeyUse = "enc" } default { $publicKeyUse = "sig" } } $X509CertificateChain = [List[String]]::new() if ($PSBoundParameters.ContainsKey("IncludeChain")) { [X509Chain]$certChain = [X509Chain]::new() $certChain.Build($Certificate) | Out-Null foreach ($chainElement in $certChain.ChainElements) { $rawData = $chainElement.Certificate.RawData $base64 = [Convert]::ToBase64String($rawData) $X509CertificateChain.Add($base64) } } else { $rawData = $Certificate.RawData $base64 = [Convert]::ToBase64String($rawData) $X509CertificateChain.Add($base64) } $key = $Certificate.PublicKey.Key if ($null -ne $key) { [RSAParameters]$parameters = $key.ExportParameters($false) [byte[]]$exp = $parameters.Exponent [byte[]]$mod = $parameters.Modulus [string]$encodedExponent = ConvertTo-Base64UrlEncodedString -Bytes $exp [string]$encodedModulus = ConvertTo-Base64UrlEncodedString -Bytes $mod } else { $noKeyExceptionMessage = "Unable to obtain public key from supplied certificate." $CryptographicException = [CryptographicException]::new($noKeyExceptionMessage) Write-Error -Exception $CryptographicException -Category SecurityError -ErrorAction Stop } $jwkObject = [PSCustomObject][ordered]@{kty = "RSA" use = $publicKeyUse e = $encodedExponent n = $encodedModulus kid = $encodedThumbprint x5t = $encodedThumbprint x5c = $X509CertificateChain } if ($PSCmdlet.ParameterSetName -eq "JSON") { [string]$jwkString = "" if ($PSBoundParameters.ContainsKey("Compress")) { $jwkString = $jwkObject | ConvertTo-Json -Compress } else { $jwkString = $jwkObject | ConvertTo-Json } return $jwkString } return $jwkObject } } |