cannot retrieve crypto/sha256 package using go get

[OonjuoO]

What version of Go are you using (go version)?

go version go1.12 linux/amd64

What operating system and processor architecture are you using (go env)?

GOARCH="amd64"
GOBIN="/home/oonjuoo/projects/bin"
GOCACHE="/home/oonjuoo/.cache/go-build"
GOEXE=""
GOFLAGS=""
GOHOSTARCH="amd64"
GOHOSTOS="linux"
GOOS="linux"
GOPATH="/home/oonjuoo/projects/src"
GOPROXY=""
GORACE=""
GOROOT="/usr/local/go"
GOTMPDIR=""
GOTOOLDIR="/usr/local/go/pkg/tool/linux_amd64"
GCCGO="gccgo"
CC="gcc"
CXX="g++"
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 -fmessage-length=0 -fdebug-prefix-map=/tmp/go-build626961719=/tmp/go-build -gno-record-gcc-switches"

What did you do?

go get golang.org/x/crypto/sha256

What did you expect to see?

successfully fetch this package

What did you see instead?

go: finding golang.org/x/crypto/sha256 latest
go: finding golang.org/x/crypto latest
go get golang.org/x/crypto/sha256: no matching versions for query "latest"

Also see this go doc, https://godoc.org/github.com/golang/go/src/crypto/sha256#pkg-files
Trying to get the package from github.com/golanggo/src/crypto/sha256 but no luck

I can do go get -u golang.org/x/crypto/... but this sha256 package was not inside.