Creating correct SHA256 hash in Powershell - powershell

Question

Good evening everybody. I have a problem with sha256 Hash.
I have this example string from the amazon pages:
GET
/
Action=ListUsers&Version=2010-05-08
content-type:application/x-www-form-urlencoded; charset=utf-8
host:iam.amazonaws.com
x-amz-date:20150830T123600Z
content-type;host;x-amz-date
e3b0c44298fc1c149afbf4c8996fb92427ae41e4649b934ca495991b7852b855
Amazon shows the hash result of this example string
as the following:
**f536975d06c0309214f805bb90ccff089219ecd68b2577efef23edd43b7e1a59**
The description is: this one: The hashed canonical request must be represented as a string of lowercase hexadecimal characters. The following example shows the result of using SHA-256 to hash the example canonical request.
Example Hashed canonical request
No matter what i do, i receive this hash:
B51325A14138B31939381CB391819CE8A5F09DEEA778721C4360F0DAC1FAB79C
Here are 3 example codes:
function hash($request) {
$sha256 = new-object -TypeName System.Security.Cryptography.SHA256Managed
$utf8 = new-object -TypeName System.Text.UTF8Encoding
$hash = [System.BitConverter]::ToString($sha256.ComputeHash($utf8.GetBytes($request)))
return $hash.replace('-','').toLower()
}
function hash2($request){
$mystream = [IO.MemoryStream]::new([byte[]][char[]]$request)
$hash = Get-FileHash -InputStream $mystream -Algorithm SHA256
$hash = $hash.Hash
return $hash.toLower()
}
function hash3($request)
{
$hasher = [System.Security.Cryptography.HashAlgorithm]::Create('sha256')
$hash = $hasher.ComputeHash([System.Text.Encoding]::UTF8.GetBytes($request))
$hashString = [System.BitConverter]::ToString($hash)
$hash = $hashString.Replace('-', '')
return $hash.toLower()
}
$string = "GET
/
Action=ListUsers&Version=2010-05-08
content-type:application/x-www-form-urlencoded; charset=utf-8
host:iam.amazonaws.com
x-amz-date:20150830T123600Z
content-type;host;x-amz-date
e3b0c44298fc1c149afbf4c8996fb92427ae41e4649b934ca495991b7852b855"
hash $string
hash2 $string
hash3 $string
The only online calculator i found which calculates the same hash as amazon was this one: https://xorbin.com/tools/sha256-hash-calculator
Here is the original conent from amazon: https://docs.aws.amazon.com/general/latest/gr/sigv4-create-canonical-request.html
Can anyone help, please?
Best regards
Patrick

Answer 1

At first I couldn't reproduce this behavior by copy-pasting your code. Then I pasted it into an editor configured to save all linebreaks as CRLF - at which point I also got B51325A14138B31939381CB391819CE8A5F09DEEA778721C4360F0DAC1FAB79C.
So the likely explanation is that you wrote your script in an editor that saves all files with Windows-style line breaks.
You can work around this by replacing all Windows style linebreaks in the resulting string value with a single newline character at runtime:
hash $string.Replace("`r`n", "`n")

Answer 2

To complement Mathias R. Jessen's helpful answer:
It is the newline format (Windows CRLF vs. Unix LF) of the enclosing script file (.ps1) that determines the newline format of multiline string literals contained in the script (including here-string literals).
An alternative to explicitly replacing the CRLF sequences with LFs, as shown in Mathias' answer, is to re-save your .ps1 file with LF newlines (PowerShell won't mind).
For better cross-platform compatibility, consider configuring your editor to create LF-format PowerShell scripts by default.