(PowerShell) Walmart Partner API Authentication (Generate a Signature for a Request)

Demonstrates how to generate a signature for a Walmart Partner REST API call.

Chilkat .NET Downloads Chilkat .NET Assemblies

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.

$consumerId = "b68d2a72...."
$baseUrl = "https://marketplace.walmartapis.com/v2/feeds"
# This is your Base64 encoded private key
$privateEncodedStr = "MIICeAIBADANBgkqhkiG9w0BAQEFAA......"
$httpMethod = "GET"

# We need a timestamp in decimal string form representing the number of milliseconds since Jan 01 1970 UTC.
$dt = New-Object Chilkat.CkDateTime
# Set bLocal = $true for a timestamp in the local timezone.  Set bLocal = $false for a UTC timestamp.
$bLocal = $false
# This gets the timestamp in seconds, not milliseconds.
$timeStampVal = $dt.GetAsUnixTime($bLocal)

# Build the string to sign.
$sbStringToSign = New-Object Chilkat.StringBuilder
$sbStringToSign.Append($consumerId)
$sbStringToSign.Append("`n")
$sbStringToSign.Append($baseUrl)
$sbStringToSign.Append("`n")
$sbStringToSign.Append($httpMethod)
$sbStringToSign.Append("`n")
$sbStringToSign.AppendInt($timeStampVal)
# We add three zero's so that the timestamp value is in milliseconds.
# We don't care about accuracy down to less than a second.
# All the server cares about is that the request was signed at the current date/time
# within some reasonable margin of error (to account for systems having clocks
# that may be slightly different).
$sbStringToSign.Append("000`n")

$privKey = New-Object Chilkat.PrivateKey
# Load the private key into a private key object.
# Note: Technically the private key is not PEM because it lacks the header/footer strings
# used for PEM.  However, the LoadPem method will still accept it and load it correctly.
$success = $privKey.LoadPem($privateEncodedStr)
if ($success -ne $true) {
    $($privKey.LastErrorText)
    exit
}

$rsa = New-Object Chilkat.Rsa
$success = $rsa.ImportPrivateKeyObj($privKey)
if ($success -ne $true) {
    $($rsa.LastErrorText)
    exit
}

# We want a base64 signature string.
$rsa.EncodingMode = "base64"

$signatureString = $rsa.SignStringENC($sbStringToSign.GetAsString(),"SHA256")
if ($rsa.LastMethodSuccess -ne $true) {
    $($rsa.LastErrorText)
    exit
}

$("Signature String: " + $signatureString)