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Credential stores

There are several options for storing credentials that GCM Core supports:

The default credential stores on macOS and Windows are the macOS Keychain and the Windows Credential Manager, respectively.

GCM comes without a default store on Linux distributions.

You can select which credential store to use by setting the GCM_CREDENTIAL_STORE environment variable, or the credential.credentialStore Git configuration setting.

Some credential stores have limitations, or further configuration required depending on your particular setup. See more detailed information below for each credential store.

Windows Credential Manager

Available on: Windows

This is the default store on Windows.

⚠️ Does not work over a network/SSH session.

SET GCM_CREDENTIAL_STORE="wincredman"

or

git config --global credential.credentialStore wincredman

This credential store uses the Windows Credential APIs (wincred.h) to store data securely in the Windows Credential Manager (also known as the Windows Credential Vault in earlier versions of Windows).

You can access and manage data in the credential manager from the control panel, or via the cmdkey command-line tool.

When connecting to a Windows machine over a network session (such as SSH), GCM is unable to persist credentials to the Windows Credential Manager due to limitations in Windows. Connecting by Remote Desktop doesn't suffer from this limitation.

DPAPI protected files

Available on: Windows

SET GCM_CREDENTIAL_STORE="dpapi"

or

git config --global credential.credentialStore dpapi

This credential store uses Windows DPAPI to encrypt credentials which are stored as files in your file system. The file structure is the same as the plaintext files credential store except the first line (the secret value) is protected by DPAPI.

By default files are stored in %USERPROFILE%\.gcm\dpapi_store. This can be configured using the environment variable GCM_DPAPI_STORE_PATH environment variable.

If the directory doesn't exist it will be created.

macOS Keychain

Available on: macOS

This is the default store on macOS.

export GCM_CREDENTIAL_STORE=keychain
# or
git config --global credential.credentialStore keychain

This credential store uses the default macOS Keychain, which is typically the login keychain.

You can manage data stored in the keychain using the Keychain Access application.

freedesktop.org Secret Service API

Available on: Linux

⚠️ Requires a graphical user interface session.

export GCM_CREDENTIAL_STORE=secretservice
# or
git config --global credential.credentialStore secretservice

This credential store uses the libsecret library to interact with the Secret Service. It stores credentials securely in 'collections', which can be viewed by tools such as secret-tool and seahorse.

A graphical user interface is required in order to show a secure prompt to request a secret collection be unlocked.

GPG/pass compatible files

Available on: macOS, Linux

⚠️ Requires gpg, pass, and a GPG key pair.

export GCM_CREDENTIAL_STORE=gpg
# or
git config --global credential.credentialStore gpg

This credential store uses GPG to encrypt files containing credentials which are stored in your file system. The file structure is compatible with the popular pass tool. By default files are stored in ~/.password-store but this can be configured using the pass environment variable PASSWORD_STORE_DIR.

Before you can use this credential store, it must be initialized by the pass utility, which in-turn requires a valid GPG key pair. To initalize the store, run:

pass init <gpg-id>

..where <gpg-id> is the user ID of a GPG key pair on your system. To create a new GPG key pair, run:

gpg --gen-key

..and follow the prompts.

Headless/TTY-only sessions

If you are using the gpg credential store in a headless/TTY-only environment, you must ensure you have configured the GPG Agent (gpg-agent) with a suitable pin-entry program for the terminal such as pinentry-tty or pinentry-curses.

If you are connecting to your system via SSH, then the SSH_TTY variable should automatically be set. GCM Core will pass the value of SSH_TTY to GPG/GPG Agent as the TTY device to use for prompting for a passphrase.

If you are not connecting via SSH, or otherwise do not have the SSH_TTY environment variable set, you must set the GPG_TTY environment variable before running GCM Core. The easiest way to do this is by adding the following to your profile (~/.bashrc, ~/.profile etc):

export GPG_TTY=$(tty)

Note: Using /dev/tty does not appear to work here - you must use the real TTY device path, as returned by the tty utility.

Git's built-in credential cache

Available on: Windows, macOS, Linux

export GCM_CREDENTIAL_STORE=cache
# or
git config --global credential.credentialStore cache

This credential store uses Git's built-in ephemeral in-memory credential cache. This helps you reduce the number of times you have to authenticate but doesn't require storing credentials on persistent storage. It's good for scenarios like Azure Cloud Shell or AWS CloudShell, where you don't want to leave credentials on disk but also don't want to re-authenticate on every Git operation.

By default, git credential-cache stores your credentials for 900 seconds. That, and any other options it accepts, may be altered by setting them in the environment variable GCM_CREDENTIAL_CACHE_OPTIONS or the Git config value credential.cacheOptions. (Using the --socket option is untested and unsupported, but there's no reason it shouldn't work.)

export GCM_CREDENTIAL_CACHE_OPTIONS="--timeout 300"
# or
git config --global credential.cacheOptions "--timeout 300"

Plaintext files

Available on: Windows, macOS, Linux

⚠️ This is not a secure method of credential storage!

export GCM_CREDENTIAL_STORE=plaintext
# or
git config --global credential.credentialStore plaintext

This credential store saves credentials to plaintext files in your file system. By default files are stored in ~/.gcm/store or %USERPROFILE%\.gcm\store. This can be configured using the environment variable GCM_PLAINTEXT_STORE_PATH environment variable.

If the directory doesn't exist it will be created.

On POSIX platforms the newly created store directory will have permissions set such that only the owner can read/write/execute (700 or drwx---). Permissions on existing directories will not be modified.

⚠️ WARNING ⚠️

This storage mechanism is NOT secure!

Secrets and credentials are stored in plaintext files without any security!

It is HIGHLY RECOMMENDED to always use one of the other credential store options above. This option is only provided for compatibility and use in environments where no other secure option is available.

If you chose to use this credential store, it is recommended you set the permissions on this directory such that no other users or applications can access files within. If possible, use a path that exists on an external volume that you take with you and use full-disk encryption.