Use encrypted password for Plink/PuTTY

Question

I would like to encrypt a password in PowerShell and use it with plink and putty.

Yes, I know that it expects only cleartext password (Password encryption using SecureString for plink.exe command).

No, I will not use generated keys because we don't support it.

My questions:

1. Any suggestions how can I use encrypted password for -pw flag in putty or plink
2. Can I generate specific string as key? I mean taking current cleartext password and convert it to a key, then using it as -i instead of -pw

My securePass.ps1 code:

$password = read-host -prompt "Enter your Password" 
write-host "$password is password" 
$secure = ConvertTo-SecureString $password -force -asPlainText 
$bytes = ConvertFrom-SecureString $secure 
$bytes | out-file C:\encrypted_password1.txt

In main:

$securePass = Get-Content C:\encrypted_password1.txt
$pass = $securePass | ConvertTo-SecureString
plink -batch -ssh $defUser@$srv -pw $pass
putty -ssh $defUser@$srv -pw $pass

Answer 1

As you know, you cannot use encrypted password (SecureString) for PuTTY/Plink.

All you can do is to decrypt the secure string and pass the decrypted plain text password to the PuTTY/Plink.

For for decryption, see PowerShell - Decode System.Security.SecureString to readable password:

$securePass = Get-Content C:\encrypted_password1.txt
$pass = $securePass | ConvertTo-SecureString

$Ptr = [System.Runtime.InteropServices.Marshal]::SecureStringToCoTaskMemUnicode($pass)
$decrypted = [System.Runtime.InteropServices.Marshal]::PtrToStringUni($Ptr)
[System.Runtime.InteropServices.Marshal]::ZeroFreeCoTaskMemUnicode($Ptr)
plink -batch -ssh $defUser@$srv -pw $decrypted 

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PuTTY 0.77 Plink newly supports -pwfile switch that allows more safe way to pass the password via a local text file (while still plain-text).

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Your question 2) does not make any sense. You wrote that you cannot use keys. So you cannot use -i switch. Let alone use some "generated password" with it.