// Sign performs a signature using the PKCS #11 key.
func (ps *PKCS11Key) Sign(rand io.Reader, msg []byte, opts crypto.SignerOpts) (signature []byte, err error) {
// Verify that the length of the hash is as expected
hash := opts.HashFunc()
hashLen := hash.Size()
if len(msg) != hashLen {
err = errors.New("input size does not match hash function output size")
return
}
// Add DigestInfo prefix
// TODO: Switch mechanisms based on CKA_KEY_TYPE
mechanism := []*pkcs11.Mechanism{pkcs11.NewMechanism(pkcs11.CKM_RSA_PKCS, nil)}
prefix, ok := hashPrefixes[hash]
if !ok {
err = errors.New("unknown hash function")
return
}
signatureInput := append(prefix, msg...)
// Open a session
session, err := ps.openSession()
if err != nil {
return
}
defer ps.closeSession(session)
// Perform the sign operation
err = ps.module.SignInit(session, mechanism, ps.privateKeyHandle)
if err != nil {
return
}
signature, err = ps.module.Sign(session, signatureInput)
return
}
// Sign performs a signature using the PKCS #11 key.
func (ps *Key) Sign(rand io.Reader, msg []byte, opts crypto.SignerOpts) (signature []byte, err error) {
ps.sessionMu.Lock()
defer ps.sessionMu.Unlock()
if ps.session == nil {
return nil, errors.New("Session was nil")
}
// When the alwaysAuthenticate bit is true (e.g. on a Yubikey NEO in PIV mode),
// each Sign has to include a Logout/Login, or the next Sign request will get
// CKR_USER_NOT_LOGGED_IN. This is very slow, but on the NEO it's not possible
// to clear the CKA_ALWAYS_AUTHENTICATE bit, so this is the only available
// workaround.
// Also, since logged in / logged out is application state rather than session
// state, we take a global lock while we do the logout and login, and during
// the signing.
if ps.alwaysAuthenticate {
modulesMu.Lock()
defer modulesMu.Unlock()
if err := ps.module.Logout(*ps.session); err != nil {
return nil, fmt.Errorf("logout: %s", err)
}
if err = ps.module.Login(*ps.session, pkcs11.CKU_USER, ps.pin); err != nil {
return nil, fmt.Errorf("login: %s", err)
}
}
// Verify that the length of the hash is as expected
hash := opts.HashFunc()
hashLen := hash.Size()
if len(msg) != hashLen {
err = fmt.Errorf("input size does not match hash function output size: %d vs %d", len(msg), hashLen)
return
}
// Add DigestInfo prefix
// TODO: Switch mechanisms based on CKA_KEY_TYPE
mechanism := []*pkcs11.Mechanism{pkcs11.NewMechanism(pkcs11.CKM_RSA_PKCS, nil)}
prefix, ok := hashPrefixes[hash]
if !ok {
err = errors.New("unknown hash function")
return
}
signatureInput := append(prefix, msg...)
// Perform the sign operation
err = ps.module.SignInit(*ps.session, mechanism, ps.privateKeyHandle)
if err != nil {
return nil, fmt.Errorf("sign init: %s", err)
}
signature, err = ps.module.Sign(*ps.session, signatureInput)
if err != nil {
return nil, fmt.Errorf("sign: %s", err)
}
return
}