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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. 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