How to encrypt data using KMS key in AWS Powershell script

Question

I am trying to encrypt text using AWS KMS and create a powershell script. Therefore, I used New-KMSDataKeyKMS to encrypt my master key, which returns plaintextDataKeyand at the output ciphertextblob.

Now I use plaintextDataKeyto encrypt my plaintext with Invoke-KMSEncrypt, but I get an Invalid Operation error, as shown below:

Below is my script:

param([string]$zonesecret, [string]$KMSKey, [string]$Keyspec, [string]$region= 'us-east-1', [string]$AccessKey, [string]$SecretKey)

# splat
$splat = @{KeyId=$KMSKey; KeySpec=$Keyspec; Region=$region}
# generate a data key 
$datakey = New-KMSDataKey @splat

$plaintextDataKey = [Convert]::ToBase64String($datakey.Plaintext.ToArray())
$encryptedDataKey = [Convert]::ToBase64String($datakey.CiphertextBlob.ToArray())
Write-Host $plaintextDataKey
Write-Host $encryptedDataKey

#encrypt using aes-256; pass zonesecret and plaintextDataKey
# memory stream
[byte[]]$byteArray = [System.Text.Encoding]::UTF8.GetBytes($zonesecret)
$memoryStream = New-Object System.IO.MemoryStream($byteArray,0,$byteArray.Length)

$splat = @{Plaintext=$memoryStream; KeyId=$plaintextDataKey; Region=$region;}
if(![string]::IsNullOrEmpty($AccessKey)){$splat += @{AccessKey=$AccessKey;}}
if(![string]::IsNullOrEmpty($SecretKey)){$splat += @{SecretKey=$SecretKey;}}

# encrypt
**$encryptedMemoryStream = Invoke-KMSEncrypt @splat** # ERROR: 
Write-Host $encryptedMemoryStream

$base64encrypted = [System.Convert]::ToBase64String($encryptedMemoryStream.CiphertextBlob.ToArray())
Write-Host $base64encrypted

What can I do to fix everything? Am I doing something wrong here? There are no other cmdlets for data encryption: http://docs.aws.amazon.com/powershell/latest/reference/Index.html

Can anyone help here? How can I use the specified plaintext data key to encrypt my content?

Answer 1

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KMS , , KMS, , . , KMS , , . , KMS , , , AES.

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PS C:\Users\Administrator> $kmskey =  'abcdef01-2345-6789-0123-0123456789ab'
PS C:\Users\Administrator> ./encrypt.ps1 "This is a test" -KMSKey $kmskey | ConvertTo-Json > message.json
PS C:\Users\Administrator> type message.json
{
    "encryptedDataKey":      "AQEDAHix3RkObJxNv8rJGn2Oyy0bRR9GOvSOFTHR2OQ6SBt76wAAAH4wfAYJKoZIhvcNAQcGoG8wbQIBADBoBgkqhkiG9w0BBwEwHgYJYIZIAWUDBAEuMBEEDGui8Ycxf+XoJkAkuQIBEIA7R6eiM6PREoJdnaNA5gaeZfcSA3fC3UlRYGE6Epo96U+SqYPYzyXKOEyqB+1+3pCHz2zgZZlbcgzThrs=",
    "ciphertext":  "76492d1116743f0423413b16050a5345MgB8AGwANgBEAEwAaQB5AFQAOQByAGgAYgBPAGcAagBKAGIAQQBBAEwAQgBkAEEAPQA9AHwAMgAzADIAYgA0AGEAYgBlADgAMAA5AGQAZABkADEAOQBlADkAYgBjADgAZgA2ADgAMAA0ADgAZABhADQANQA5ADYAMABiAGIAYQAxADQANABiADAAOAA2ADYANgBlAGYANwAxADkANQA2ADEAMgBjAGEANQBjADAAYgBjAGMANAA=\r\n"
}
PS C:\Users\Administrator> ConvertFrom-JSON $(Get-Content .\message.json | Out-String) | .\decrypt.ps1 -KMSKey $kmskey

plaintext
---------
This is a test

PS C:\Users\Administrator> ./encrypt.ps1 "Super Secret Stuff" -KMSKey $kmskey | .\decrypt.ps1 -KMSKey $kmskey

plaintext
---------
Super Secret Stuff

:

encrypt.ps1

param(
    [Parameter(Mandatory=$True)]
    [string]$secret,

    [Parameter(Mandatory=$True)]
    [string]$KMSKey,

    [string]$Keyspec = 'AES_256',

    [string]$region = 'us-east-1'
)

# generate a data key
$datakey = New-KMSDataKey -KeyId $KMSKey -KeySpec $Keyspec -Region $region

[byte[]]$plaintextDataKey = $datakey.Plaintext.ToArray()
[byte[]]$encryptedDataKey = $datakey.CiphertextBlob.ToArray()

# Encrypt using AES using Powershell SecureString facilities
# Any AES encryption method would do, this is just the most convenient
# way to do this from Powershell.
#
# Note that trying to use the Invoke-KMSEncrypt method is not what you want
# to do when using Data Keys and envelope encryption.
$encrypted = ConvertTo-SecureString $secret -AsPlainText -Force `
    | ConvertFrom-SecureString -key $plaintextDataKey `
    | Out-String

# Thanks to http://stackoverflow.com/a/24778625/424301 
# for the tip on using psobject return values and
# ValueFromPipelineByPropertyName parameters (see decrypt.ps1)
return New-Object psobject -property @{ 
    "ciphertext" = $encrypted;
    "encryptedDataKey" = $([Convert]::ToBase64String($encryptedDataKey))
}

decrypt.ps1

[CmdletBinding()]
param(
    [Parameter(Mandatory=$true,
        Position=0,
        ValueFromPipelineByPropertyName=$true)]
    [string]$ciphertext,

    [Parameter(Mandatory=$true,
        Position=1,
        ValueFromPipelineByPropertyName=$true)]
    [string]$encryptedDataKey,

    [Parameter(Mandatory=$true,
        Position=2,
        ValueFromPipelineByPropertyName=$true)]
    [string]$KMSKey
)

[byte[]]$bytes = $([Convert]::FromBase64String($encryptedDataKey))
$stream = new-object System.IO.MemoryStream (,$bytes)

# decrypt the data key 
$response = Invoke-KMSDecrypt -CiphertextBlob $stream
if ($response.HttpStatusCode -eq 200) {
    $dataKey = $response.Plaintext.ToArray()
} else {
    throw "KMS data key decrypt failed: $(ConvertTo-Json $response)"
}
# Now AES decrypt the ciphertext and emit the plaintext
$secureString = ConvertTo-SecureString $ciphertext -key $dataKey
$plaintext =  [Runtime.InteropServices.Marshal]::PtrToStringAuto( `
    [Runtime.InteropServices.Marshal]::SecureStringToBSTR($secureString))
return  New-Object psobject -property @{
    "plaintext" = $plaintext
}