(PureBasic) Azure Key Vault Sign with a Certificate's Private Key

See more Azure Key Vault Examples

Signs a hash using the private key of a certificate previously imported to an Azure Key Vault.

Note: This example requires Chilkat v9.5.0.96 or later.

For more information, see https://learn.microsoft.com/en-us/rest/api/keyvault/certificates/import-certificate/import-certificate?tabs=HTTP

Chilkat PureBasic Module Download Chilkat PureBasic Module

IncludeFile "CkJsonObject.pb"
IncludeFile "CkHttp.pb"
IncludeFile "CkStringBuilder.pb"
IncludeFile "CkHttpResponse.pb"
IncludeFile "CkCert.pb"
IncludeFile "CkRsa.pb"

Procedure ChilkatExample()

    ; This requires the Chilkat API to have been previously unlocked.
    ; See Global Unlock Sample for sample code.

    ; See Azure Key Vault Get Certificates for a more detailed explanation
    ; for how Chilkat is automatically getting the OAuth2 access token for your application.

    success.i

    ; Provide information needed for Chilkat to automatically get an OAuth2 access token as needed.
    json.i = CkJsonObject::ckCreate()
    If json.i = 0
        Debug "Failed to create object."
        ProcedureReturn
    EndIf

    CkJsonObject::ckUpdateString(json,"client_id","APP_ID")
    CkJsonObject::ckUpdateString(json,"client_secret","APP_PASSWORD")
    CkJsonObject::ckUpdateString(json,"resource","https://vault.azure.net")
    CkJsonObject::ckUpdateString(json,"token_endpoint","https://login.microsoftonline.com/TENANT_ID/oauth2/token")

    ; In this example, we'll sign the SHA256 hash of the string "This is a test"
    sb.i = CkStringBuilder::ckCreate()
    If sb.i = 0
        Debug "Failed to create object."
        ProcedureReturn
    EndIf

    signedString.s = "This is a test"
    CkStringBuilder::ckAppend(sb,signedString)
    hash_base64url.s = CkStringBuilder::ckGetHash(sb,"sha256","base64url","utf-8")

    ; We're going to send a POST to the following URL:
    ; POST {vaultBaseUrl}/keys/{key-or-cert-name}/{key-or-cert-version}/sign?api-version=7.4

    ; For example:

    ; POST https://VAULT_NAME.vault.azure.net/keys/CERT_NAME/CERT_VERSION/sign?api-version=7.4
    ; 
    ; {
    ;   "alg": "RS512",
    ;   "value": "RUE3Nzg4NTQ4QjQ5RjFFN0U2NzAyQzhDNEMwMkJDOTA1MTYyOTUzNjI5NDhBNzZDQTlFOTM1NDA2M0ZGMjk2Mg"
    ; }

    ; The alg can be one of the following
    ; ES256  ECDSA using P-256 and SHA-256
    ; ES256K ECDSA using P-256K and SHA-256
    ; ES384  ECDSA using P-384 and SHA-384
    ; ES512  ECDSA using P-521 and SHA-512
    ; PS256  RSASSA-PSS using SHA-256 and MGF1 with SHA-256
    ; PS384  RSASSA-PSS using SHA-384 and MGF1 with SHA-384
    ; PS512  RSASSA-PSS using SHA-512 and MGF1 with SHA-512
    ; RS256  RSASSA-PKCS1-v1_5 using SHA-256
    ; RS384  RSASSA-PKCS1-v1_5 using SHA-384
    ; RS512  RSASSA-PKCS1-v1_5 using SHA-512

    ; The sample POST above uses SHA512.  We'll instead sign a SHA256 hash..

    jsonBody.i = CkJsonObject::ckCreate()
    If jsonBody.i = 0
        Debug "Failed to create object."
        ProcedureReturn
    EndIf

    CkJsonObject::ckUpdateString(jsonBody,"alg","RS256")
    CkJsonObject::ckUpdateString(jsonBody,"value",hash_base64url)

    http.i = CkHttp::ckCreate()
    If http.i = 0
        Debug "Failed to create object."
        ProcedureReturn
    EndIf

    ; Instead of providing an actual access token, we give Chilkat the information that allows it to 
    ; automatically fetch the access token using the OAuth2 client credentials flow.
    CkHttp::setCkAuthToken(http, CkJsonObject::ckEmit(json))

    CkHttp::ckSetUrlVar(http,"certName","importCert01")
    CkHttp::ckSetUrlVar(http,"certVersion","7140c8755ed14839b5d86a9f7e7f0497")
    ; Note: Replace "VAULT_NAME" with the name of your Azure key vault.
    url.s = "https://VAULT_NAME.vault.azure.net/keys/{$certName}/{$certVersion}/sign?api-version=7.4"
    resp.i = CkHttp::ckPostJson3(http,url,"application/json",jsonBody)
    If CkHttp::ckLastMethodSuccess(http) = 0
        ; This means something failed before we got a response.
        Debug CkHttp::ckLastErrorText(http)
        CkJsonObject::ckDispose(json)
        CkStringBuilder::ckDispose(sb)
        CkJsonObject::ckDispose(jsonBody)
        CkHttp::ckDispose(http)
        ProcedureReturn
    EndIf

    statusCode.i = CkHttpResponse::ckStatusCode(resp)

    jsonResp.i = CkJsonObject::ckCreate()
    If jsonResp.i = 0
        Debug "Failed to create object."
        ProcedureReturn
    EndIf

    CkHttpResponse::ckGetBodyJson(resp,jsonResp)
    CkHttpResponse::ckDispose(resp)

    CkJsonObject::setCkEmitCompact(jsonResp, 0)
    Debug CkJsonObject::ckEmit(jsonResp)

    If statusCode <> 200
        Debug "Failed."
        CkJsonObject::ckDispose(json)
        CkStringBuilder::ckDispose(sb)
        CkJsonObject::ckDispose(jsonBody)
        CkHttp::ckDispose(http)
        CkJsonObject::ckDispose(jsonResp)
        ProcedureReturn
    EndIf

    ; A successful response body contains JSON like this:
    ; Note: Azure's documentation is not very clear, but base64url is the encoding, not "base64".
    ; {
    ;   "kid": "https://kvchilkat.vault.azure.net/keys/importCert01/7140c8755ed14839b5d86a9f7e7f0497",
    ;   "value": "JzWd2YF21gjtW ... Em37hKOQ"
    ; }

    ; Let's validate the signature using the cert's public key.
    ; This example will load the corresponding certificate from a local file and will verify the signature against the original data.
    ; 
    cert.i = CkCert::ckCreate()
    If cert.i = 0
        Debug "Failed to create object."
        ProcedureReturn
    EndIf

    success = CkCert::ckLoadFromFile(cert,"qa_data/certs/chilkat_code_signing_2024.cer")
    If success = 0
        Debug CkCert::ckLastErrorText(cert)
        CkJsonObject::ckDispose(json)
        CkStringBuilder::ckDispose(sb)
        CkJsonObject::ckDispose(jsonBody)
        CkHttp::ckDispose(http)
        CkJsonObject::ckDispose(jsonResp)
        CkCert::ckDispose(cert)
        ProcedureReturn
    EndIf

    rsa.i = CkRsa::ckCreate()
    If rsa.i = 0
        Debug "Failed to create object."
        ProcedureReturn
    EndIf

    ; Tell the RSA object to use the cert's public key.
    success = CkRsa::ckSetX509Cert(rsa,cert,0)
    If success = 0
        Debug CkRsa::ckLastErrorText(rsa)
        CkJsonObject::ckDispose(json)
        CkStringBuilder::ckDispose(sb)
        CkJsonObject::ckDispose(jsonBody)
        CkHttp::ckDispose(http)
        CkJsonObject::ckDispose(jsonResp)
        CkCert::ckDispose(cert)
        CkRsa::ckDispose(rsa)
        ProcedureReturn
    EndIf

    ; Verify the signature using the cert's public key against the original string.
    CkRsa::setCkEncodingMode(rsa, "base64url")
    valid.i = CkRsa::ckVerifyStringENC(rsa,signedString,"sha-256",CkJsonObject::ckStringOf(jsonResp,"value"))
    Debug "signature valid = " + Str(valid)


    CkJsonObject::ckDispose(json)
    CkStringBuilder::ckDispose(sb)
    CkJsonObject::ckDispose(jsonBody)
    CkHttp::ckDispose(http)
    CkJsonObject::ckDispose(jsonResp)
    CkCert::ckDispose(cert)
    CkRsa::ckDispose(rsa)


    ProcedureReturn
EndProcedure