sbt-pgp provides PGP signing for sbt.
Some OSS repositories (e.g. Sonatype) will require that you sign artifacts with publicly available keys prior to release. The primary purpose of sbt-pgp is to let you sign the artifacts using a GPG key.
Add the following to your ~/.sbt/1.0/plugins/gpg.sbt
file:
addSbtPlugin("com.jsuereth" % "sbt-pgp" % "2.0.2")
Add the following to your ~/.sbt/0.13/plugins/gpg.sbt
file:
addSbtPlugin("com.jsuereth" % "sbt-pgp" % "2.0.2")
There are two modes of use:
- By default sbt-pgp 2.0.0+ will use the
gpg
command-line utility (GNU Privary Guard, "GnuPG"). It provides great support and is available on many platforms. You'll need to make sure this is installed prior to usage as this dependency is not provided. - Prior to sbt-pgp 2.0.0,
sbt-pgp
used the Bouncy Castle library, an implementation of PGP that is included with the plugin. It is a Java-only solution that gives the plugin great flexibility in what it can do and how it performs it.
First, please check that you have a recent version of GPG (GNU Privary Guard, "GnuPG") on your system. If not, install it from http://www.gnupg.org/download/ or your favorite package manager. For macOS, we recommend using GPG Suite.
$ gpg --version
gpg (GnuPG/MacGPG2) 2.2.17
libgcrypt 1.8.4
Copyright (C) 2019 Free Software Foundation, Inc.
License GPLv3+: GNU GPL version 3 or later <https://gnu.org/licenses/gpl.html>
This is free software: you are free to change and redistribute it.
There is NO WARRANTY, to the extent permitted by law.
Home: /Users/xxxx/.gnupg
Supported algorithms:
Pubkey: RSA, ELG, DSA, ECDH, ECDSA, EDDSA
Cipher: IDEA, 3DES, CAST5, BLOWFISH, AES, AES192, AES256, TWOFISH,
CAMELLIA128, CAMELLIA192, CAMELLIA256
Hash: SHA1, RIPEMD160, SHA256, SHA384, SHA512, SHA224
Compression: Uncompressed, ZIP, ZLIB, BZIP2
You should also have a program named gpg-agent
running in the background.
$ ps aux | grep gpg
eed3si9n 5157 0.0 0.0 4317860 972 ?? Ss 7:17PM 0:00.02 gpg-agent --homedir /Users/eed3si9n/.gnupg --use-standard-socket --daemon
eed3si9n 2734 0.0 0.0 4300360 732 ?? S 6:56PM 0:00.02 /bin/bash /usr/local/MacGPG2/libexec/shutdown-gpg-agent
eed3si9n 5291 0.0 0.0 4277252 824 s002 S+ 7:24PM 0:00.00 grep gpg
If you're using GPG Suite, navigate to Preferences > GPG Suite, and uncheck "Store in macOS Keychain" to prevent your passphrase from being stored on your laptop.
See Working with PGP Signatures for details.
A key pair allows you to sign artifacts with GPG and users can subsequently validate that artifacts have been signed by you. You can generate a key with.
$ gpg --gen-key
Select the default value when asked for the kind (RSA) and the size (2048bit) of the key. The time of validity for the key defaults to never expire. However it is commonly suggested to use a value of less than 2 years. Once they key is expired you can extend it, provided you own the key and therefore know the passphrase.
Once key pair is generated, we can list them along with any other keys installed:
$ gpg --list-keys
/Users/xxx/.gnupg/pubring.gpg
----------------------------------
pub dsa2048 2010-08-19 [SC] [expires: 2020-06-15]
85E38F69046B44C1EC9FB07B76D78F0500D026C4
uid [ultimate] GPGTools Team <[email protected]>
uid [ultimate] GPGTools Project Team (Official OpenPGP Key) <[email protected]>
uid [ultimate] GPGMail Project Team (Official OpenPGP Key) <[email protected]>
uid [ultimate] [jpeg image of size 5871]
sub elg2048 2010-08-19 [E] [expires: 2020-06-15]
sub rsa4096 2014-04-08 [S] [expires: 2024-01-02]
pub rsa2048 2012-02-14 [SCEA] [expires: 2028-02-09]
2BE67AC00D699E04E840B7FE29967E804D85663F
uid [ultimate] Eugene Yokota <[email protected]>
sub rsa2048 2012-02-14 [SEA] [expires: 2028-02-09]
....
To list the private keys you can use:
$ gpg --list-secret-keys
/Users/xxx/.gnupg/pubring.gpg
----------------------------------
sec rsa2048 2012-02-14 [SCEA] [expires: 2028-02-09]
2BE67AC00D699E04E840B7FE29967E804D85663F
uid [ultimate] Eugene Yokota <[email protected]>
ssb rsa2048 2012-02-14 [SEA] [expires: 2028-02-09]
Since other people need your public key to verify your files, you have to distribute your public key to a key server:
$ gpg --keyserver keyserver.ubuntu.com --send-keys 2BE67AC00D699E04E840B7FE29967E804D85663F
If you have previously created a key pair using sbt-pgp 1.x's pgp-cmd
for example, your secret key should be at $HOME/.sbt/gpg/secring.asc
. You can import this to GnuPG as follows:
$ gpg --import $HOME/.sbt/gpg/secring.asc
gpg: /root/.gnupg/trustdb.gpg: trustdb created
gpg: key 77098E6A92692949: public key "foo <[email protected]>" imported
gpg: key 77098E6A92692949: secret key imported
gpg: Total number processed: 1
gpg: imported: 1
gpg: secret keys read: 1
gpg: secret keys imported:
gpg --list-key
/root/.gnupg/pubring.kbx
------------------------
pub rsa2048 2019-09-15 [SCEA]
965F25CC72DF4F2A4358AC9B77098E6A92692949
uid [ unknown] foo <[email protected]>
Next, see signing key section below to set 965F25CC72DF4F2A4358AC9B77098E6A92692949
as the signing key.
See Tag Driven Releasing.
To publish signed artifacts, use publishSigned
or publishLocalSigned
.
To skip the publish step for a subproject, set publish / skip
to true
.
publish / skip := true
If you've configured your gpg-agent with GPG Suite, it should ask for the passphrase when you run publishLocalSigned
:
Note: It might take 30s or more for the dialog to show up.
Otherwise, add pinentry-program
line in ~/.gnupg/gpg-agent.conf
with the appropriate path to a pinentry program:
pinentry-program /usr/bin/pinentry
default-cache-ttl 600
max-cache-ttl 7200
You might need to restart the gpg-agent for the setting to take effect.
sbt-pgp 1.x has provided ways of storing passphrase using pgpPassphrase
or in the credentials, but we no longer recommend using these methods on your laptop.
On CI environment like Travis CI, you might want to automate passphrase entry. For that purpose sbt-pgp supports PGP_PASSPHRASE
environment variable following olafurpg/sbt-ci-release.
By default, all signing operations will use gpg
's default key. A specific key can be used by setting sbt Credentials
for the host "gpg".
credentials += Credentials(
"GnuPG Key ID",
"gpg",
"2BE67AC00D699E04E840B7FE29967E804D85663F", // key identifier
"ignored" // this field is ignored; passwords are supplied by pinentry
)
Note: This follows the convention set by jodersky/sbt-gpg.
You can also use the usePgpKeyHex
method.
usePgpKeyHex("2BE67AC00D699E04E840B7FE29967E804D85663F")
If you are using a Yubikey 4 or another smartcard that supports OpenPGP, then you may have private keys implemented directly on the smartcard rather than using the gpg keyring. In this situation, you will use gpg-agent
and a pinentry (pinentry-mac
, pinentry-qt
, pinentry-curses
etc) rather than a passphrase. Set useGpgPinentry := true
in your build.sbt
settings to configure sbt-pgp
appropriately.
Global / useGpgPinentry := true
Note that sbt-pgp
only supports OpenPGP through the GPG command line tool -- it is not available through bouncycastle. In addition, you may need to explicitly enable support for OpenPGP on the Yubikey 4.
sbt-pgp
needs to know where the gpg
executable is to run. It will look for a either a gpg
or gpg.exe
executable on your PATH
depdending on your platform. To configure a different location, place the following in your ~/.sbt/gpg.sbt
file:
Global / gpgCommand := "/path/to/gpg"
By default sbt-pgp
will use the default private keys from the standard gpg keyrings.
You can configure the key ring you use with the pgpKeyRing
setting.
Global / pgpKeyRing := Some(file("/home/me/pgp/pubring.gpg"))
If specificied, this is passed to gpg
command as --no-default-keyring --keyring <value>
.
The plugin can be used to validate the PGP signatures of the dependencies of the project you're using. To validate these signatures, simply use the checkPgpSignatures
task:
> checkPgpSignatures
[info] Resolving org.scala-lang#scala-library;2.9.1 ...
...
[info] ----- PGP Signature Results -----
[info] com.novocode : junit-interface : 0.7 : jar [MISSING]
[info] javax.transaction : jta : 1.0.1B : jar [MISSING]
[info] org.scala-lang.plugins : continuations : 2.9.1 : jar [MISSING]
[info] org.apache.derby : derby : 10.5.3.0_1 : jar [UNTRUSTED(0x98e21827)]
[error] {file:/home/josh/projects/typesafe/test-signing/}test-gpg/*:check-pgp-signatures: Some artifacts have bad signatures or are signed by untrusted sources!
[error] Total time: 2 s, completed Jan 23, 2012 12:03:28 PM
In the above output, the signature for derby is from an untrusted key (id: 0x98e21827
). You can import this key into your public key ring, and then the plugin will trust artifacts from that key. The public, by default, accepts any keys included in your public key ring file.
Prior to sbt-pgp 2.0.0, sbt-pgp
used the Bouncy Castle library by default. If you cant to use gpg
command setting useGpg
to false
will use the Bouncy Castle mode:
Global / useGpg := false
Or by setting SBT_PGP_USE_GPG
environment variable to 0
.
When using Bouncy Castle modue, sbt-pgp
will ask for your password once, and cache it for the duration of the sbt process. The prompt will look something like this:
Please enter PGP passphrase (or ENTER to abort): ******