gc__gvmi_hash

Summary: computes the hash of a gvmi image file. Extra: optionally queries the Golem network to confirm that gvmi image is available from golem's central repository (i.e. to see if the hash link has been created)

Usage:

git clone https://github.com/krunch3r76/gc__gvmi_hash.git
python3 gc__gvmi_hash/gc__gvmi_hash.py <gvmi-image>

Example:BASH

(cracker-venv)$ git clone https://github.com/krunch3r76/gc__gvmi_hash.git
(cracker-venv)$ alias gvmi_hash="python3 $PWD/gc__gvmi_hash/gc__gvmi_hash.py" #BASH alias
(cracker-venv)$ krunch3r@crystalcavern:~/hash-cracker$ gvmi_hash *.gvmi
SHA3-224(docker-hash-cracker-latest-363b2e9df2.gvmi)= e1a95ab266977b857ae1c59942ebc7384a72359840b452c2e5293737
SHA3-224(docker-hash-cracker-latest-e93d21fba0.gvmi)= 4c9778760794a5fa6b8461ed2654c09cbc20f16edd3ec687c3289db8

Example:Powershell

cracker-venv > git clone https://github.com/krunch3r76/gc__gvmi_hash.git
cracker-venv > $gvmi_hash="${PWD}\gc__gvmi_hash\gc__gvmi_hash.py"
cracker-venv > python $gvmi_hash docker-hash-cracker-latest-363b2e9df2.gvmi
SHA3-224(docker-hash-cracker-latest-363b2e9df2.gvmi)= e1a95ab266977b857ae1c59942ebc7384a72359840b452c2e5293737

Example:Powershell: alternatively edit $PROFILE

set $gvmi_hash to absolute path to\gc__gvmi_hash\gc__gvmi_hash.py

example $profile

oh-my-posh init pwsh --config $env:POSH_THEMES_PATH/space.omp.json | Invoke-Expression
$gvmi_hash="C:\Users\krunch3r\golem\gc__gvmi_hash\gc__gvmi_hash.py"

somewhere > . $profile
cracker-venv > python $gvmi_hash docker-hash-cracker-latest-363b2e9df2.gvmi
SHA3-224(docker-hash-cracker-latest-363b2e9df2.gvmi)= e1a95ab266977b857ae1c59942ebc7384a72359840b452c2e5293737

Extra Usage (Linux):

$ alias gvmi_hash="python3 $PWD/gc__gvmi_hash/gc__gvmi_hash.py" #BASH alias
$ gvmi_hash --check-hash-link 4c9778760794a5fa6b8461ed2654c09cbc20f16edd3ec687c3289db8
The link exists on the central repository.

$ gvmi_hash docker-hash-cracker-latest-e93d21fba0.gvmi | cut -f2 -d ' ' | gvmi_hash --check-hash-link-stdin
The link exists on the central repository.

Problem:

The gvmkit-build Python package/script outputs the hash of a gvmi image only after its initial push operation. However, a Requestor is required to provide the pushed image hash in its requestor script, and if lost, has no means provided by gvmkit-build to re-output the image hash. Additionally, the current Golem documentation neither specifies the hashing algorithm used (sha3-224) nor suggests a tool for recomputation.

The supplied gv__gvmi_hash.py solves a lost hash problem by hashing the input image file using the same algorithm as, and with no additional runtime dependencies than those already satisfied by, the gvmkit-build package -- namely the Python Standard Library + OpenSSL libraries.

Note, the script is equivalent to invoking openssl dgst -sha3-224 <gvmi-image> on systems where openssl executables have been installed. Also, the hash algorithm is indeed SHA3-224 and the reader is encouraged to see the code in gvmkit-build itself (viz Credits) to convince oneself of this.

--Note: to understand better what problem this script solves, it is recommended the reader follow the Provider Flash Tutorial (Python) at https://handbook.golem.network/requestor-tutorials/flash-tutorial-of-requestor-development. --

NOTE:

The script's extra functionality (viz Extra Usage) to query the repo for the hash link makes an outside network connection. The routine is safe (HTTP/1.1 HEAD request), short, and can be quickly audited for peace of mind in the context of security concerns. viz (__check_for_hash_link in gc__gvmi_has.py)

Credits:

Adapted from the source code in the Python package gvmkit-build, which is viewable in the tarbell via https://pypi.org/project/gvmkit-build/#files (file: repo.py, function: upload_image). Formatting of output should be credited to openssl.org.

Tips:

Consider placing community scripts on linux such as this in $HOME/.local/bin/golem-community and adding it to your path. You may also consider adding said community scripts path to the environment variable PYTHONPATH and calling from gc__gvmi_hash import gc__gvmi_hash in order to utilize the function from within scripts, e.g. requestor.py.

Additional:

primary function inputs,process,and outputs:

def gc__gvmi_hash(filename: str): # gc for golem community
MEBIBYTES=1024*1024 # one mebibyte ie megabyte, always a multiple of typical block sizes 4096,8192
# input: path to file as string
# pre: file is readable, MEBIBYTES defined
# process:
#   open gvmi image
#   on each chunk
#       send to hasher
#   query hasher
# output: hash as string
# post: none
# notes: additional details of the hashlib implementation may be discoverable via https://www.openssl.org/docs/manmaster/man3/EVP_DigestInit.html

Alternatives:

Besides the openssl dgst command mentioned in the problem statement, a simple command line tool and call may be preferred if extra features of gc__gvmi_hash are not needed. See https://handbook.golem.network/requestor-tutorials/vm-runtime/self-hosted-vm-images for details.

figurestudios / gc__gvmi_image_handler