func verifyDetachedSignature(key *packet.PublicKey, contentf, sigf io.Reader) error {
var hashFunc crypto.Hash
packets := packet.NewReader(sigf)
p, err := packets.Next()
if err != nil {
return err
}
switch sig := p.(type) {
case *packet.Signature:
hashFunc = sig.Hash
case *packet.SignatureV3:
hashFunc = sig.Hash
default:
return errors.UnsupportedError("unrecognized signature")
}
h := hashFunc.New()
if _, err := io.Copy(h, contentf); err != nil && err != io.EOF {
return err
}
switch sig := p.(type) {
case *packet.Signature:
err = key.VerifySignature(h, sig)
case *packet.SignatureV3:
err = key.VerifySignatureV3(h, sig)
default:
panic("unreachable")
}
return err
}
