ConvertFrom-SecureString
SYNOPSIS
Converts a secure string to an encrypted standard string.
SYNTAX
Secure (Default)
ConvertFrom-SecureString [-SecureString] <SecureString> [[-SecureKey] <SecureString>] [<CommonParameters>]
AsPlainText
ConvertFrom-SecureString [-SecureString] <SecureString> [-AsPlainText] [<CommonParameters>]
Open
ConvertFrom-SecureString [-SecureString] <SecureString> [-Key <Byte[]>] [<CommonParameters>]
DESCRIPTION
The ConvertFrom-SecureString cmdlet converts a secure string ( System.Security.SecureString ) into an encrypted standard string ( System.String ). Unlike a secure string, an encrypted standard string can be saved in a file for later use. The encrypted standard string can be converted back to its secure string format by using the `ConvertTo-SecureString` cmdlet.
If an encryption key is specified by using the Key or SecureKey parameters, the Advanced Encryption Standard (AES) encryption algorithm is used. The specified key must have a length of 128, 192, or 256 bits because those are the key lengths supported by the AES encryption algorithm. If no key is specified, the Windows Data Protection API (DPAPI) is used to encrypt the standard string representation.
> [!NOTE] > Note that per DotNet (/dotnet/api/system.security.securestring?view=netcore-2.1#remarks), the > contents of a SecureString are not encrypted on non-Windows systems.
EXAMPLES
Example 1: Create a secure string
$SecureString = Read-Host -AsSecureString
This command creates a secure string from characters that you type at the command prompt. After entering the command, type the string you want to store as a secure string. An asterisk (`*`) is displayed to represent each character that you type.
Example 2: Convert a secure string to an encrypted standard string
$StandardString = ConvertFrom-SecureString $SecureString
This command converts the secure string in the `$SecureString` variable to an encrypted standard string. The resulting encrypted standard string is stored in the `$StandardString` variable.
Example 3: Convert a secure string to an encrypted standard string with a 192-bit key
$Key = (3,4,2,3,56,34,254,222,1,1,2,23,42,54,33,233,1,34,2,7,6,5,35,43)
$StandardString = ConvertFrom-SecureString $SecureString -Key $Key
These commands use the Advanced Encryption Standard (AES) algorithm to convert the secure string stored in the `$SecureString` variable to an encrypted standard string with a 192-bit key. The resulting encrypted standard string is stored in the `$StandardString` variable.
The first command stores a key in the `$Key` variable. The key is an array of 24 decimal numerals, each of which must be less than 256 to fit within a single unsigned byte.
Because each decimal numeral represents a single byte (8 bits), the key has 24 digits for a total of 192 bits (8 x 24). This is a valid key length for the AES algorithm.
The second command uses the key in the `$Key` variable to convert the secure string to an encrypted standard string.
Example 4: Convert a secure string directly to a plaintext string
$secureString = ConvertTo-SecureString -String 'Example' -AsPlainText
$secureString # 'System.Security.SecureString'
ConvertFrom-SecureString -SecureString $secureString -AsPlainText # 'Example'
PARAMETERS
-AsPlainText
When set, `ConvertFrom-SecureString` will convert secure strings to the decrypted plaintext string as output.
This parameter was added in PowerShell 7.0.
Type: System.Management.Automation.SwitchParameter
Parameter Sets: AsPlainText
Aliases:
Required: False
Position: Named
Default value: False
Accept pipeline input: False
Accept wildcard characters: False
-Key
Specifies the encryption key as a byte array.
Type: System.Byte[]
Parameter Sets: Open
Aliases:
Required: False
Position: Named
Default value: None
Accept pipeline input: False
Accept wildcard characters: False
-SecureKey
Specifies the encryption key as a secure string. The secure string value is converted to a byte array before being used as the key.
Type: System.Security.SecureString
Parameter Sets: Secure
Aliases:
Required: False
Position: 1
Default value: None
Accept pipeline input: False
Accept wildcard characters: False
-SecureString
Specifies the secure string to convert to an encrypted standard string.
Type: System.Security.SecureString
Parameter Sets: (All)
Aliases:
Required: True
Position: 0
Default value: None
Accept pipeline input: True (ByValue)
Accept wildcard characters: False
CommonParameters
This cmdlet supports the common parameters: -Debug, -ErrorAction, -ErrorVariable, -InformationAction, -InformationVariable, -OutVariable, -OutBuffer, -PipelineVariable, -Verbose, -WarningAction, and -WarningVariable. For more information, see about_CommonParameters.
INPUTS
System.Security.SecureString
You can pipe a SecureString object to ConvertFrom-SecureString.
OUTPUTS
System.String
ConvertFrom-SecureString returns a standard string object.
NOTES
- To create a secure string from characters that are typed at the command prompt, use the AsSecureString parameter of the `Read-Host` cmdlet. - When you use the Key or SecureKey parameters to specify a key, the key length must be correct. For example, a key of 128 bits can be specified as a byte array of 16 decimal numerals. Similarly, 192-bit and 256-bit keys correspond to byte arrays of 24 and 32 decimal numerals, respectively. - Some characters, such as emoticons, correspond to several code points in the string that contains them. Avoid using these characters because they may cause problems and misunderstandings when used in a password.