x/crypto/openpgp: compression options are not used in Encrypt function

[bytegaurav]

installed Golang version and architecture details :

$ go env
GOARCH="amd64"
GOBIN=""
GOCACHE="/Users/Gaurav.k/Library/Caches/go-build"
GOEXE=""
GOFLAGS=""
GOHOSTARCH="amd64"
GOHOSTOS="darwin"
GOOS="darwin"
GOPATH="/Users/Gaurav.k/Projects/GoProjects/"
GOPROXY=""
GORACE=""
GOROOT="/usr/local/Cellar/go/1.12.4/libexec"
GOTMPDIR=""
GOTOOLDIR="/usr/local/Cellar/go/1.12.4/libexec/pkg/tool/darwin_amd64"
GCCGO="gccgo"
CC="clang"
CXX="clang++"
CGO_ENABLED="1"
GOMOD=""
CGO_CFLAGS="-g -O2"
CGO_CPPFLAGS=""
CGO_CXXFLAGS="-g -O2"
CGO_FFLAGS="-g -O2"
CGO_LDFLAGS="-g -O2"
PKG_CONFIG="pkg-config"
GOGCCFLAGS="-fPIC -m64 -pthread -fno-caret-diagnostics -Qunused-arguments -fmessage-length=0 -fdebug-prefix-map=/var/folders/4_/703g62812t39dfmzfx4l7w3r0000gp/T/go-build267975514=/tmp/go-build -gno-record-gcc-switches -fno-common"

$ go version
go version go1.12.4 darwin/amd64

What did you do?

I'm trying to replicate following gpg command with crypto/openpgp package.

gpg --armor --output <outputfile > --cipher aes256 --compress-algo zip --s2k-digest-algo SHA256 --encrypt --recipient <userkey> --sign -u <privatekeyid>  <inputfile>

I'm using crypto/openpgp package to encrypt message with a public key and sign it with my private key. I'm using the openpgp.Encrypt method and passed following config as parameter:

packetConfig := &packet.Config{
		DefaultCipher:          packet.CipherAES256,
		DefaultCompressionAlgo: packet.CompressionZIP,
		CompressionConfig: &packet.CompressionConfig{
			Level: flate.BestCompression,
		},
	}

What did you expect to see?

I'm expected to see my plain text input message to be PGP encrypted and must have ZIP compression.

What did you see instead?

Message I get from openpgp.Encrypt method, is properly signed and encrypted but not compressed.

Resolution

Upon inspecting the Encrypt function and debugging the code, found out that it's not making use of compression config passed as argument anywhere in the flow. Made a change in write.go and added compression. After this change, the messages are properly encrypted and compressed.

A PR is already raised in golang/crypto repository. golang/crypto#103. This PR and debug info is from last year when i raised it in crypto repo. Posting it here due to inactivity there.

[dmitshur]

/cc @FiloSottile per owners.

[bytegaurav]

@FiloSottile @dmitshur
any update on this issue?

[FiloSottile]

Per the accepted #44226 proposal and due to lack of maintenance, the golang.org/x/crypto/openpgp package is now frozen and deprecated. No new changes will be accepted except for security fixes. The package will not be removed.

If this is a security issue, please email security@golang.org and we will assess it and provide a fix.

If you're looking for alternatives, consider the crypto/ed25519 package for simple signatures, golang.org/x/mod/sumdb/note for inline signatures, or filippo.io/age for encryption. You can read a summary of OpenPGP issues and alternatives here.

If you are required to interoperate with OpenPGP systems and need a maintained package, we suggest considering one of multiple community forks of golang.org/x/crypto/openpgp. We don't endorse any specific one.