(PowerShell) Ibanity HTTP Signature for XS2A, Isabel Connect, Ponto Connect

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Demonstrates how to add a Signature header for Ibanity HTTP requests.

For more information, see https://documentation.ibanity.com/http-signature

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Add-Type -Path "C:\chilkat\ChilkatDotNet47-9.5.0-x64\ChilkatDotNet47.dll"

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

# In order to sign your HTTP requests, you have to add 2 headers to the HTTP request: Digest: the digest of the request payload and Signature: the actual signature of the request. 

# POST /xs2a/customer-access-tokens HTTP/1.1
# Host: api.ibanity.com
# Content-Type: application/json
# Digest: SHA-512=z4PhNX7vuL3xVChQ1m2AB9Yg5AULVxXcg/SpIdNs6c5H0NE8XYXysP+DGNKHfuwvY7kxvUdBeoGlODJ6+SfaPg==
# Ibanity-Idempotency-Key: 61f02718-eeee-46e1-b5eb-e8fd6e799c2d
# Signature: keyId="62f02718-eeee-46e1-b5eb-e8fd6e799c2e",created=1599659223,algorithm="hs2019",headers="(request-target) host digest (created) ibanity-idempotency-key",signature="SjWJWbWN7i0...zsbM="
# 
# {"data":{"type":"customerAccessToken", "attributes":{"applicationCustomerReference":"15874569"}}}

# The payload (body) of the above HTTP request is the JSON.
# Build the JSON above.
# Use this online tool to generate code from sample JSON: 
# Generate Code to Create JSON
$json = New-Object Chilkat.JsonObject
$json.UpdateString("data.type","customerAccessToken")
$json.UpdateString("data.attributes.applicationCustomerReference","15874569")

$payload = $json.Emit()
$("payload = " + $payload)

# Step 1: Build the (created) virtual header

$dtNow = New-Object Chilkat.CkDateTime
$dtNow.SetFromCurrentSystemTime()
$created = $dtNow.GetAsUnixTimeStr($false)
$("created = " + $created)

# Step 2: Build the Digest header
$crypt = New-Object Chilkat.Crypt2
$crypt.HashAlgorithm = "sha512"
$crypt.EncodingMode = "base64"
$crypt.Charset = "utf-8"

$sbDigestHdrValue = New-Object Chilkat.StringBuilder
$sbDigestHdrValue.Append("SHA-512=")
$sbDigestHdrValue.Append($crypt.HashStringENC($json.Emit()))

$($sbDigestHdrValue.GetAsString())

# Step 3: Build the (request target) virtual header

# In order to build the signature you will need a virtual header named (request-target) (the parentheses are important). 
# The (request-target) is the string concatenation of the HTTP method (in lowercase) with the path and query parameters.
$request_target = "post /xs2a/customer-access-tokens"

# Step 4: Build the signing string

# The signing string is the concatenation of the signed header names (in lowercase) and values separated by a LF.

# You must always sign the following headers: (request-target), host, (created), digest. 
# If used, you must also sign the authorization header and any ibanity-* headers, such as ibanity-idempotency-key. 

$sbSigningString = New-Object Chilkat.StringBuilder
$sbSigningString.Append("(request-target): ")
$sbSigningString.AppendLine($request_target,$false)
$sbSigningString.Append("host: ")
$sbSigningString.AppendLine("api.ibanity.com",$false)
$sbSigningString.Append("digest: ")
$sbSigningString.AppendLine($sbDigestHdrValue.GetAsString(),$false)
$sbSigningString.Append("(created): ")
$sbSigningString.AppendLine($created,$false)
$sbSigningString.Append("ibanity-idempotency-key: ")
$idempotencyKey = $crypt.GenerateUuid()
$sbSigningString.Append($idempotencyKey)

# Step 5: Build the signed headers list

# To allow Ibanity to check the signed headers, you must provide a list of the header names. They should be lowercase and in the same order used to create the signing string. 
$signed_headers_list = "(request-target) host digest (created) ibanity-idempotency-key"

# Step 6: Build the Signature header

# This is where the real signing happens. The signature header is a combination of several sub-headers -
# 
#     keyId: the identifier for the application's signature certificate, obtained from the Developer Portal
#     algorithm: the digital signature algorithm used to generate the signature (must be hs2019)
#     headers: The list of HTTP headers created in step 5
#     signature: the Base64-encoded digital signature of the signing string created in step 4.

$privKey = New-Object Chilkat.PrivateKey
$success = $privKey.LoadEncryptedPemFile("my_ibanity_signature_private_key.pem","pem_password")
if ($success -eq $false) {
    $($privKey.LastErrorText)
    exit
}

$rsa = New-Object Chilkat.Rsa
$rsa.PssSaltLen = 32
$rsa.EncodingMode = "base64"
# Use the RSASSA-PSS signature algorithm
$rsa.OaepPadding = $true

$success = $rsa.ImportPrivateKeyObj($privKey)
if ($success -eq $false) {
    $($rsa.LastErrorText)
    exit
}

# Sign the signing string.
$sigBase64 = $rsa.SignStringENC($sbSigningString.GetAsString(),"sha-256")
if ($rsa.LastMethodSuccess -eq $false) {
    $($rsa.LastErrorText)
    exit
}

# Build the signature header value.
$sbSigHeaderValue = New-Object Chilkat.StringBuilder
$sbSigHeaderValue.Append("keyId=`"")
# Use your identifier for the application's signature certificate, obtained from the Developer Portal
$sbSigHeaderValue.Append("62f02718-eeee-46e1-b5eb-e8fd6e799c2e")
$sbSigHeaderValue.Append("`",created=")
$sbSigHeaderValue.Append($created)
$sbSigHeaderValue.Append(",algorithm=`"hs2019`",headers=`"")
$sbSigHeaderValue.Append($signed_headers_list)
$sbSigHeaderValue.Append("`",signature=`"")
$sbSigHeaderValue.Append($sigBase64)
$sbSigHeaderValue.Append("`"")

$($sbSigHeaderValue.GetAsString())