SHA256 hash doesn't match download - what now?

Question

Hello stackoverflow World,

I'm investigating using the miniconda package manager for the first time.

I downloaded the files from here: https://docs.conda.io/en/latest/miniconda.html

I'm on a windows machine so downloaded the following file:

As I am hoping is obvious from my title, the check sum that my machine produces using the Windows certUtil -hashfile function produces a different check sum.

Now, my main issue is what to do now...!

Do I run screaming to the hills burning all my IT kit as I go, or is there a way to get to the bottom of this?

Thanks in advance

Answer 1

So interestingly, using the PowerShell approach rather than the cmd line, as specified in the miniconda download reference did result in a matching Hash key.

I thought that these were supposed to be independent of the program used to unpack the HASH...?

Answer 2

hash is not a universally defined algorithm:

A hash function is any function that can be used to map data of arbitrary size to fixed-size values (https://en.wikipedia.org/wiki/Hash_function)

So when you use a program to hash a file and want to compare it to a published value, you must make sure that you are using the same hash function. In your case, the miniconda download page already clarifies that it is a SHA256 hash, which you need to specify when calling certutil.

Proof:

Without specifying the hash function (SHA1 is used and - as expected - produces a different hash value):

certutil -hashfile Miniconda3-latest-Windows-x86_64.exe
SHA1 hash of Miniconda3-latest-Windows-x86_64.exe:
0b553f6b77926db707c4406cafc612d74301b24e
CertUtil: -hashfile command completed successfully.

Specifying the correct function produces the right hash value:

certutil -hashfile Miniconda3-latest-Windows-x86_64.exe SHA256
SHA256 hash of Miniconda3-latest-Windows-x86_64.exe:
6013152b169c2c2d4bcd75bb03a1b8bf208b8545d69116a59351af695d9a0081
CertUtil: -hashfile command completed successfully.