Solved Powershell command to generate SHA512 Base64 checksum

Sephirote · Dec 24, 2023

Hi everyone,

Does anyone know the command to generate a SHA512 checksum with Base64 encoding?
Just to clarify, the standard encoding for SHA512 is HEX but the checksum I'm trying to verify was generated Base64 encoding.

Here's the command I'm using to generate the standard SHA512 HEX.

Get-FileHash -Path C:\Users\XXX\Downloads\FILENAME -Algorithm SHA512

But I don't know the command to generate SHA512 Base64.

No need to suggest installing a software, I'm aware of those, I prefer to use a command.

Thanks

x BlueRobot · Dec 24, 2023

PowerShell can interop with .NET so you should be able to use the ToBase64String method: Convert.ToBase64String Method (System)

glasskuter · Dec 24, 2023

I can't testify to it's accuracy but this according to AI. Co-pilot says:
One possible PowerShell command to generate SHA512 Base64 checksum for a file is:

# Get the hash of the file
$hash = Get-FileHash <path to input file> -Algorithm SHA512
# Convert hash to byte representation
$hashBytes = [System.Text.Encoding]::Unicode.GetBytes ($hash.Hash)
# Convert bytes to base64, then output to file
[System.Convert]::ToBase64String ($hashBytes) | Out-File <path to hash output file>

This command is based on the answer from Stack Overflow 1. You can also use other hash algorithms that are supported by PowerShell, such as MD5, SHA1, SHA256, or SHA384. For more information, you can refer to the official documentation of the Get-FileHash cmdlet 2. Alternatively, you can use the certutil.exe tool to generate and verify checksums in Windows 3 4.

FreeBooter · Dec 24, 2023

You can use the attached batch script to add Hash to context menu of files in Windows 8, Windows 10 and Windows 11.

Sephirote · Dec 24, 2023

glasskuter said:
I can't testify to it's accuracy but this according to AI. Co-pilot says:
One possible PowerShell command to generate SHA512 Base64 checksum for a file is:

# Get the hash of the file
$hash = Get-FileHash <path to input file> -Algorithm SHA512
# Convert hash to byte representation
$hashBytes = [System.Text.Encoding]::Unicode.GetBytes ($hash.Hash)
# Convert bytes to base64, then output to file
[System.Convert]::ToBase64String ($hashBytes) | Out-File <path to hash output file>

This command is based on the answer from Stack Overflow 1. You can also use other hash algorithms that are supported by PowerShell, such as MD5, SHA1, SHA256, or SHA384. For more information, you can refer to the official documentation of the Get-FileHash cmdlet 2. Alternatively, you can use the certutil.exe tool to generate and verify checksums in Windows 3 4.

Thanks for the input.

So I got the Hash of the file using

Get-FileHash <path to input file> -Algorithm SHA512

29DA971D3A045CFB1243036BE2158967E22102689B87AAFB0C24A9B8EFC396DA6A88A0318312A24511CF41129AD3BA3FF125A3C75AB84B3FA058C078D01D7797

Then converted to byte representation

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Then converted byte representation to base64

MjlEQTk3MUQzQTA0NUNGQjEyNDMwMzZCRTIxNTg5NjdFMjIxMDI2ODlCODdBQUZCMEMyNEE5QjhFRkMzOTZEQTZBODhBMDMxODMxMkEyNDUxMUNGNDExMjlBRDNCQTNGRjEyNUEzQzc1QUI4NEIzRkEwNThDMDc4RDAxRDc3OTc=

And the base64 hash I get is different than what it should be (downloaded file from the internet)

Unsure if it's an error on my end or if the downloaded file is compromised. Most likely an error on my end.

I would appreciate if someone with a few min to spare could run the command on their end just to see if they end up with the same base64

The SHA512 hash (step 1) should be correct as I also used an online SHA512 checksum tool to double-check and it gave me the same hash as the one I got via powershell

If I made a mistake, it would have occurred when converting to byte representation and then back to base64.

x BlueRobot · Dec 24, 2023

It's because you're encoding the hash as ASCII and then converting that encoded hash to Base64. You should just be able to provide hash directly to ToBase64String.

zebal · Dec 24, 2023

Sephirote said:
Then converted to byte representation

You're using Asci.GetBytes function insteadof Unicode.GetBytes function

Sephirote · Dec 24, 2023

Ok thanks

Hash512 >UTF8 bytes >Base64

Interestingly enough the final hash was really close to the provided base64 hash but not a match

Hash512 >Unicode bytes >Base64

Not a match

The other option suggested is to provide directly the SHA512 hash to ToBase64String but I'm not sure how to do that

zebal · Dec 24, 2023

@Sephirote
Why don't you just follow the example from SO?

Your screenshot shows you're computing hash value of another hash value rather than hash value of the data.

Sephirote · Dec 24, 2023

zebal said:
@Sephirote
Why don't you just follow the example from SO?

Your screenshot shows you're computing hash value of another hash value rather than hash value of the data.

Sorry but the answers provided aren't really clear/helpful. The issue with you guys is that you assume that you're talking to programmers and skip on the small details/steps that may be obvious to you but not to regular people. I'm not familiar with what Unicode or ASCII is, I try to figure it out as I go with Google but if I'm here asking for help, it didn't cross your mind that I may not be fluent in coding, powershell commands and other hash algorithms. I provided the SHA512, wouldn't have been possible to provide me with the commands instead of unhelpful comments instructing me not to use ASCII but Unicode which I have no clue how to do. I mean you have seen the screenshots, I'm trying to be proactive and to find the solution by myself not just waiting to have the solution mouth fed so give me a break with your silly questions like "why don't you do this or that" Because I don't know how to man.

Never mind I found this site where you input the HEX string and it spits out the base64.

Here's the website for anyone who comes across this thread looking for the same thing, because you sure won't find the solutions in the answers I received

Hex to Base64 | Base64 Encode | Base64 Converter | Base64

Free smart tool to convert online Hex to Base64 string

base64.guru

Cheers

zebal · Dec 24, 2023

@Sephirote
Sorry, maybe you missed it but @glasskuter gave you link to SO (in post #3) which has the example, here is the link:

PS SHA512 hash of file, output as base 64 encoded string

I need to take the SHA512 of a file , convert to base 64 encoded string, and output to file. PS > Get-FileHash <path to file> -Algorithm SHA512 I know this function is available [System.

stackoverflow.com

Does following the example work?

You so far have been doing all just not as shown in the example, that why I said why don't you follow the example from SO.

SlicEnDicE · Dec 24, 2023

~~Could you please provide an example file (link to a small file) that uses base64 encoding for it's hashes so I can download and verify my results in PS?~~

Nevermind

SlicEnDicE · Dec 24, 2023

Here is the full solution that should work:

Powershell:

# Getting the HEX-String for SHA512
$HexString = Get-FileHash [Path To Your FILE] -Algorithm SHA512

# Printing out the HEX-String (Using .Hash here because HexString is an object with a lot of data)
$HexString.Hash

# Converting HEX-String to Bytes (as of SO solution provided, but with a small fix)
$bytes = [byte[]] -split ($HexString.Hash -replace '..', '0x$& ')

# Converting the resulting bytes into Base64 encoding and spitting out the result
[System.Convert]::ToBase64String($bytes)

Result:

Code:

582EBD465253994DC564D55F7C4AAD3D7679981A4623DA163F87F7B588E456D76400B79D0741F48B33211347DF05BA5D9900E841DF643CA8D1B2A3582631CC06
WC69RlJTmU3FZNVffEqtPXZ5mBpGI9oWP4f3tYjkVtdkALedB0H0izMhE0ffBbpdmQDoQd9kPKjRsqNYJjHMBg==