decrypt fixed key backups from shield

cmdlist.md

go get golang.org/x/crypto/pbkdf2
go run pbkdf.go
#OUTPUT---
KEY=...
IV=...
#---OUTPUT
FILEIN=2018-12-10-094956-65761430-a301-4203-b3b9-3cff284dac86
FILEOUT=094956-65761430-a301-4203-b3b9-3cff284dac86
openssl enc -d -aes-256-ctr -in $FILEIN -nosalt -p -K $KEY -iv $IV -out $FILEOUT.bz2
bunzip2 $FILEOUT.bz2
tar tf $FILEOUT

pbkdf.go

package main

import "fmt"
import "golang.org/x/crypto/pbkdf2"
import "crypto/sha256"
import "encoding/hex"
import "bytes"

func main() {
	fixedKey := "FIXED_KEY_FROM_SHIELD"
	generatedMaterial := pbkdf2.Key([]byte(fixedKey[32:]), []byte(fixedKey[:32]), 4096, 48, sha256.New)
	key := hex.EncodeToString(generatedMaterial[:32])
	iv := hex.EncodeToString(generatedMaterial[32:])
	fmt.Println("KEY=" + key)
	fmt.Println("IV=" + iv)
}