Lianja Requires Chilkat v11.0.0+
Azure Key Vault Sign with a Certificate's Private Key

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

Lianja
llSuccess = .F.

//  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.

//  Provide information needed for Chilkat to automatically get an OAuth2 access token as needed.
loJson = createobject("CkJsonObject")
loJson.UpdateString("client_id","APP_ID")
loJson.UpdateString("client_secret","APP_PASSWORD")
loJson.UpdateString("resource","https://vault.azure.net")
loJson.UpdateString("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"
loSb = createobject("CkStringBuilder")
lcSignedString = "This is a test"
loSb.Append(lcSignedString)
lcHash_base64url = loSb.GetHash("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..

loJsonBody = createobject("CkJsonObject")
loJsonBody.UpdateString("alg","RS256")
loJsonBody.UpdateString("value",lcHash_base64url)

loHttp = createobject("CkHttp")

//  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.
loHttp.AuthToken = loJson.Emit()

loHttp.SetUrlVar("certName","importCert01")
loHttp.SetUrlVar("certVersion","7140c8755ed14839b5d86a9f7e7f0497")
//  Note: Replace "VAULT_NAME" with the name of your Azure key vault.
lcUrl = "https://VAULT_NAME.vault.azure.net/keys/{$certName}/{$certVersion}/sign?api-version=7.4"
loResp = createobject("CkHttpResponse")
llSuccess = loHttp.HttpJson("POST",lcUrl,loJsonBody,"application/json",loResp)
if (llSuccess = .F.) then
    ? loHttp.LastErrorText
    release loJson
    release loSb
    release loJsonBody
    release loHttp
    release loResp
    return
endif

lnStatusCode = loResp.StatusCode

loJsonResp = createobject("CkJsonObject")
loResp.GetBodyJson(loJsonResp)

loJsonResp.EmitCompact = .F.
? loJsonResp.Emit()

if (lnStatusCode <> 200) then
    ? "Failed."
    release loJson
    release loSb
    release loJsonBody
    release loHttp
    release loResp
    release loJsonResp
    return
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.
//  
loCert = createobject("CkCert")
llSuccess = loCert.LoadFromFile("qa_data/certs/chilkat_code_signing_2024.cer")
if (llSuccess = .F.) then
    ? loCert.LastErrorText
    release loJson
    release loSb
    release loJsonBody
    release loHttp
    release loResp
    release loJsonResp
    release loCert
    return
endif

loRsa = createobject("CkRsa")
//  Tell the RSA object to use the cert's public key.
llSuccess = loRsa.SetX509Cert(loCert,.F.)
if (llSuccess = .F.) then
    ? loRsa.LastErrorText
    release loJson
    release loSb
    release loJsonBody
    release loHttp
    release loResp
    release loJsonResp
    release loCert
    release loRsa
    return
endif

//  Verify the signature using the cert's public key against the original string.
loRsa.EncodingMode = "base64url"
llValid = loRsa.VerifyStringENC(lcSignedString,"sha-256",loJsonResp.StringOf("value"))
? "signature valid = " + str(llValid)


release loJson
release loSb
release loJsonBody
release loHttp
release loResp
release loJsonResp
release loCert
release loRsa