// ExtractDecryptInfo iterates through the header using recipientKey and
// attempts to decrypt any DecryptInfoEntry using the provided ephemeral key.
// If unsuccessful after iterating through all decryptInfo objects, returns ErrCannotDecrypt.
func (hdr *miniLockv1Header) ExtractDecryptInfo(recipientKey *taber.Keys) (nonce []byte, DI *DecryptInfoEntry, err error) {
var (
ephemKey *taber.Keys
encDI []byte
nonceS string
)
ephemKey = new(taber.Keys)
ephemKey.Public = hdr.Ephemeral
if err != nil {
return nil, nil, err
}
// Look for a DI we can decrypt with recipientKey
// TODO: Make this concurrent!
for nonceS, encDI = range hdr.DecryptInfo {
nonce, err := base64.StdEncoding.DecodeString(nonceS)
if err != nil {
return nil, nil, err
}
DI, err = DecryptDecryptInfo(encDI, nonce, ephemKey, recipientKey)
if err == ErrCannotDecrypt {
continue
} else if err != nil {
return nil, nil, err
}
recipID, err := recipientKey.EncodeID()
if err != nil {
return nil, nil, err
}
if DI.RecipientID != recipID {
return nil, nil, ErrBadRecipient
}
return nonce, DI, nil
}
return nil, nil, ErrCannotDecrypt
}
