Data losing original format - powershell

Question

I am relatively new to powershell and having a bit of a strange problem with a script. I have searched the forums and haven't been able to find anything that works.
The issue I am having is that when I covert output of commands to and from base64 for transport via a custom protocol we use in our environment it is losing its formatting. Commands are executed on the remote systems by passing the command string to IEX and store the output to a variable. I convert the output to base64 format using the following command
$Bytes = [System.Text.Encoding]::Unicode.GetBytes($str1)
$EncodedCmd = [Convert]::ToBase64String($Bytes)
At the other end when we recieve the output we convert back using the command
[System.Text.Encoding]::Unicode.GetString([System.Convert]::FromBase64String($EncodedCmd))
The problem I am having is that although the output is correct the formatting of the output has been lost. For example if I run the ipconfig command
Windows IP Configuration Ethernet adapter Local Area Connection 2: Media State . . . . . . . . . . . : Media disconnected Connection-specific DNS Suffix . : Ethernet
adapter Local Area Connection 3: Connection-specific DNS Suffix . : Link-local IPv6 Address . . . . . : fe80::3cd8:3c7f:c78b:a78f%14 IPv4 Address. . . . . . . . . . .
: 192.168.10.64 Subnet Mask . . . . . . . . . . . : 255.255.255.0 Default Gateway . . . . . . . . . : 192.168.10.100 Ethernet adapter Local Area Connection: Connection-sp
ecific DNS Suffix . : IPv4 Address. . . . . . . . . . . : 172.10.15.201 Subnet Mask . . . . . . . . . . . : 255.255.255.0 Default Gateway . . . . . . . . . : 172.10.15
1.200 Tunnel adapter isatap.{42EDCBE-8172-5478-AD67E-8A28273E95}: Media State . . . . . . . . . . . : Media disconnected Connection-specific DNS Suffix . : Tunnel ada
pter isatap.{42EDCBE-8172-5478-AD67E-8A28273E95}: Media State . . . . . . . . . . . : Media disconnected Connection-specific DNS Suffix . : Tunnel adapter isatap.{42EDCBE-8172-5478-AD67E-8A28273E95}: Media State . . . . . . . . . . . : Media disconnected Connection-specific DNS Suffix . : Tunnel adapter Teredo Tunneling Pseudo-Inter
face: Media State . . . . . . . . . . . : Media disconnected Connection-specific DNS Suffix . :
The formatting is all over the place and hard to read, I have played around with it a bit, but I can't find a really good way of returning the command output in the correct format. Appreciate any ideas on how I can fix the formatting

Answer 1

What happens here is that the $str1 variable is an array of strings. It doesn't contain newline characters but each line is on its own row.
When the variable is converted as Base64, all the rows in the array are catenated together. This can be seen easily enough:
$Bytes[43..60] | % { "$_ -> " + [char] $_}
0 ->
105 -> i
0 ->
111 -> o
0 ->
110 -> n
0 ->
32 ->
0 ->
32 ->
0 ->
32 ->
0 ->
69 -> E
0 ->
116 -> t
0 ->
104 -> h
Here the 0 are caused by double byte Unicode. Pay attention to 32 that is space character. So one sees that there is just space padding, no line terminators in the source string
Windows IP Configuration
Ethernet
As a solution, either add line feed characters or serialize the whole array as XML.
Adding line feed characters is done via joining the array elements with -join and using [Environment]::NewLine as the separator caracter. Like so,
$Bytes = [System.Text.Encoding]::Unicode.GetBytes( $($str1 -join [environment]::newline))
$Bytes[46..67] | % { "$_ -> " + [char] $_}
105 -> i
0 ->
111 -> o
0 ->
110 -> n
0 ->
13 ->
0 ->
10 ->
0 ->
13 ->
0 ->
10 ->
0 ->
13 ->
0 ->
10 ->
0 ->
69 -> E
0 ->
116 -> t
0 ->
Here, the 13 and 10 are CR and LF characters that Windows uses for line feed. After adding the line feed characters, the result string looks like the source. Be aware that thought it looks the same, it is not the same. Source is an array of strings, the outcome is single string containing line feeds.
If you must preserve the original, serialization is the way to go.