Compute AWS SES SMTP password using powershell (could be integrated in CloudFormation template)

generate-smtp-password-for-aws-ses.ps1

$key = "${SecretAccessKey}";
$region = "${AWS::Region}";

$date = "11111111";
$service = "ses";
$terminal = "aws4_request";
$message = "SendRawEmail";
$versionInBytes = 0x04;

function HmacSha256($text, $key2) {
    $hmacsha = New-Object System.Security.Cryptography.HMACSHA256
    $hmacsha.key = $key2;
    $hmacsha.ComputeHash([Text.Encoding]::UTF8.GetBytes($text));
}

$signature = [Text.Encoding]::UTF8.GetBytes("AWS4" + $key)
$signature = HmacSha256 "$date" $signature;
$signature = HmacSha256 "$region" $signature;
$signature = HmacSha256 "$service" $signature;
$signature = HmacSha256 "$terminal" $signature;
$signature = HmacSha256 "$message" $signature;
$signatureAndVersion = [System.Byte[]]::CreateInstance([System.Byte], $signature.Length + 1);
$signatureAndVersion[0] = $versionInBytes;
$signature.CopyTo($signatureAndVersion, 1);
$smtpPassword = [Convert]::ToBase64String($signatureAndVersion);

Write-Host $smtpPassword;