code: func (k *EcdsaKey) GenSKI() (ski []byte) {
  	if k.PubKey == nil {
  		return nil
  	}
  
  	// Marshall the public key
  	raw := elliptic.Marshal(k.PubKey.Curve, k.PubKey.X, k.PubKey.Y)
  
  	// Hash it
  	hash := sha256.New()
  	hash.Write(raw)
  	k.SKI.Sha256Bytes = hash.Sum(nil)
  	k.SKI.Sha256 = hex.EncodeToString(k.SKI.Sha256Bytes)
  
  	hash = sha1.New()
  	hash.Write(raw)
  	k.SKI.Sha1Bytes = hash.Sum(nil)
  	k.SKI.Sha1 = hex.EncodeToString(k.SKI.Sha1Bytes)
  
  	return
  }
docs: // SKI returns the subject key identifier of this key.