If two factor authentication is enabled on GitHub , then when trying to commit to a git repository , you might face the following error message :

remote: Invalid username or password.
fatal: Authentication failed for 'https://github.com/mohamad-wael/tmp.git/'

A possible solution to such an error message , is to use ssh ,to commit to your git repository , as follows .

First , start by generating your public , and private ssh , key pairs :

# Select only one of the following commands , the
# first one uses a newer algorithm , which might
# not yet be supported by the client.


$ ssh-keygen -t ed25519 -C "your_email@example.com"
# Generate user own ssh public , and private
# key pairs , using the algorithm ed25519 ,
# with a comment of user email .
Generating public/private ed25519 key pair.
Enter file in which to save the key (/Users/difyel/.ssh/id_ed25519):
Enter passphrase (empty for no passphrase):
Enter same passphrase again:
Your identification has been saved in /Users/difyel/.ssh/id_ed25519.
Your public key has been saved in /Users/difyel/.ssh/id_ed25519.pub.
The key fingerprint is:
SHA256:a9JAoN2pwMcYaYxNsi0shyqGmVl0ZeG8YMV2KuQiDcw your_email@example.com
The key s randomart image is:
+--[ED25519 256]--+
|+=+.oo=.         |
|+E=B.Bo..        |
|==Oo*.*o         |
|=Bo+o+..         |
|Bo ...o S        |
|o      o .       |
|      . +        |
|       o         |
|                 |
+----[SHA256]-----+


$ ssh-keygen -t rsa -b 4096 -C "your_email@example.com"
# uses the rsa algorithm with a key size of 4096 ,
# with a comment containing an email .
Generating public/private rsa key pair.
Enter file in which to save the key (/Users/difyel/.ssh/id_rsa):
Enter passphrase (empty for no passphrase):
Enter same passphrase again:
Your identification has been saved in /Users/difyel/.ssh/id_rsa.
Your public key has been saved in /Users/difyel/.ssh/id_rsa.pub.
The key fingerprint is:
SHA256:GDdMlCeNp/+xc9EuxTmSvEgaMeKc/pe/km/0Lycrr4s your_email@example.com
The key s randomart image is:
+---[RSA 4096]----+
|       .o+       |
|       o+ +      |
|      . +=       |
|       =.+       |
|      + S.o . .o.|
|       + ....=.o+|
|      .   +.=o++.|
|       . . B=o=.o|
|        ..E B@+*o|
+----[SHA256]-----+

This will create the following files in the ~./ssh/ folder :

$ ls -al ~/.ssh
# list the content of the ~/.ssh
# folder .

# If the ed25519 algorithm was used to 
# generate keys , and the default name
# was selected , then these two files 
# will be created . 
id_ed25519
id_ed25519.pub

# If the rsa algorithm was used to 
# generate keys , and the default
# name was selected , then these 
# files will be created .
id_rsa
id_rsa.pub

Copy the generated , public key to the clipboard , for example by first echoing it , and then copying it .

$ cat ~/.ssh/id_ed25519.pub 
# If the chosen algorithm is ed25519 .
ssh-ed25519 AAAAC3NzaC1lZDI1NTE5AAAAIMa4Mrn6kaZXEsbhTQqvkFYUQN1d1exvauDut1ssD8np your_email@example.com

$ cat ~/.ssh/id_rsa.pub
# If the chosen algorithm was rsa .
ssh-rsa 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 your_email@example.com

And add it to GitHub , by going to ssh and gpg keys , and creating , a new ssh key :

To change from https , to ssh , in your local computer , go to where you have stored your repository , and issue the following commands :

$ git remote -v
# Check the configured protocol .
origin	https://github.com/mohamad-wael/tmp.git (fetch)
origin	https://github.com/mohamad-wael/tmp.git (push)

$ git remote set-url origin git@github.com:mohamad-wael/tmp.git
# Switch to ssh , by replacing https://github.com/ ,
# with git@github.com:


$ git remote -v
# Check the configured protocol .
origin	git@github.com:mohamad-wael/tmp.git (fetch)
origin	git@github.com:mohamad-wael/tmp.git (push)

$ git push origin main
# Push to GitHub 
The authenticity of host 'github.com (140.82.121.4)' can't be established.
RSA key fingerprint is SHA256:nThbg6kXUpJWGl7E1IGOCspRomTxdCARLviKw6E5SY8.
Are you sure you want to continue connecting (yes/no)? yes
Warning: Permanently added 'github.com,140.82.121.4' (RSA) to the list of known hosts.
Branch main set up to track remote branch main from origin.
Everything up-to-date

To switch back to https , issue :

$ git remote set-url origin https://github.com/:mohamad-wael/tmp.git