func DecodeKey(csid uint8, pub, prv string) (Key, error) {
c := ciphers[csid]
pubKey, err := base32util.DecodeString(pub)
if err != nil {
return nil, ErrInvalidKey
}
prvKey, err := base32util.DecodeString(prv)
if err != nil {
return nil, ErrInvalidKey
}
if c == nil {
return opaqueKey{csid, pubKey, prvKey}, nil
}
return c.DecodeKeyBytes(pubKey, prvKey)
}
// FromIntermediates derives a hashname from its intermediate parts.
func FromIntermediates(parts cipherset.Parts) (H, error) {
if len(parts) == 0 {
return "", ErrNoIntermediateParts
}
var (
hash = sha256.New()
ids = make([]int, 0, len(parts))
buf [32]byte
)
for id := range parts {
ids = append(ids, int(id))
}
sort.Ints(ids)
for _, id := range ids {
// decode intermediate part
partString := parts[uint8(id)]
if len(partString) != 52 {
return "", ErrInvalidIntermediatePart
}
part, err := base32util.DecodeString(partString)
if err != nil {
return "", ErrInvalidIntermediatePart
}
buf[0] = byte(id)
hash.Write(buf[:1])
hash.Sum(buf[:0])
hash.Reset()
hash.Write(buf[:32])
hash.Write(part)
hash.Sum(buf[:0])
hash.Reset()
hash.Write(buf[:32])
}
return H(base32util.EncodeToString(buf[:32])), nil
}