Unprotect-CmsMessage

Unprotect-CmsMessage
    [-EventLogRecord] <EventLogRecord>
    [[-To] <CmsMessageRecipient[]>]
    [-IncludeContext]
    [<CommonParameters>]

Unprotect-CmsMessage
    [-Content] <string>
    [[-To] <CmsMessageRecipient[]>]
    [-IncludeContext]
    [<CommonParameters>]

Unprotect-CmsMessage
    [-Path] <string>
    [[-To] <CmsMessageRecipient[]>]
    [-IncludeContext]
    [<CommonParameters>]

Unprotect-CmsMessage
    [-LiteralPath] <string>
    [[-To] <CmsMessageRecipient[]>]
    [-IncludeContext]
    [<CommonParameters>]

The Unprotect-CmsMessage cmdlet decrypts content that has been encrypted using the Cryptographic Message Syntax (CMS) format.

The CMS cmdlets support encryption and decryption of content using the IETF standard format for cryptographically protecting messages, as documented by RFC5652.

The CMS encryption standard uses public key cryptography, where the keys used to encrypt content (the public key) and the keys used to decrypt content (the private key) are separate. Your public key can be shared widely, and isn't sensitive data. If any content is encrypted with this public key, only your private key can decrypt it. For more information, see Public-key cryptography.

Unprotect-CmsMessage decrypts content that has been encrypted in CMS format. You can run this cmdlet to decrypt content that you have encrypted by running the Protect-CmsMessage cmdlet. You can specify content that you want to decrypt as a string, by the encryption event log record ID number, or by path to the encrypted content. The Unprotect-CmsMessage cmdlet returns the decrypted content.

Support for Linux and macOS was added in PowerShell 7.1.

In the following example, you decrypt content that's located at the literal path C:\Users\Test\Documents\PowerShell. For the value of the required To parameter, this example uses the thumbprint of the certificate that was used to perform the encryption. The decrypted message, "Try the new Break All command," is the result.

$parameters = @{
  LiteralPath = "C:\Users\Test\Documents\PowerShell\Future_Plans.txt"
  To = '0f 8j b1 ab e0 ce 35 1d 67 d2 f2 6f a2 d2 00 cl 22 z9 m9 85'
}
Unprotect-CmsMessage -LiteralPath @parameters

Try the new Break All command

The following example gets an encrypted event from the PowerShell event log and decrypts it using Unprotect-CmsMessage.

$event = Get-WinEvent Microsoft-Windows-PowerShell/Operational -MaxEvents 1 |
    Where-Object Id -EQ 4104
Unprotect-CmsMessage -EventLogRecord $event

The following example gets all encrypted events from the PowerShell event log and decrypts them using Unprotect-CmsMessage.

Get-WinEvent Microsoft-Windows-PowerShell/Operational |
    Where-Object Id -EQ 4104 |
    Unprotect-CmsMessage

This cmdlet supports the common parameters: -Debug, -ErrorAction, -ErrorVariable, -InformationAction, -InformationVariable, -OutBuffer, -OutVariable, -PipelineVariable, -ProgressAction, -Verbose, -WarningAction, and -WarningVariable. For more information, see about_CommonParameters.

You can pipe an object containing encrypted content to this cmdlet.

This cmdlet returns the unencrypted message.