Imports upspin.io/pack/internal upspin.io/bind upspin.io/pack/packutil upspin.io/factotum golang.org/x/crypto/hkdf upspin.io/pack upspin.io/errors upspin.io/log upspin.io/path upspin.io/upspin Standard library imports crypto/elliptic crypto/sha256 crypto/cipher bytes crypto/aes crypto/ecdsa crypto/rand encoding/binary fmt io math/big