Stop retrying a PKCS#11 PIN the token rejected

client/internal/certproof/pinlatch.go

@@ -0,0 +1,47 @@
+package certproof
+
+import (
+	"crypto/sha256"
+	"encoding/binary"
+	"errors"
+	"sync"
+)
+
+// errPINRejectedBefore is returned instead of logging in with a PIN the token already
+// refused: every failed login counts towards the token's lockout, which for a TPM is
+// shared with everything else on the machine, and proofs are collected on every sync.
+var errPINRejectedBefore = errors.New("PKCS#11 token rejected this PIN before, not trying it again")
+
+// rejectedPINs outlives a single store, since a store is built for each collection.
+var rejectedPINs = &pinLatch{keys: map[[sha256.Size]byte]struct{}{}}
+
+// pinLatch remembers PINs a token rejected. Keys are hashes, so the PIN itself is not
+// kept in memory any longer than the store that read it.
+type pinLatch struct {
+	mu   sync.Mutex
+	keys map[[sha256.Size]byte]struct{}
+}
+
+func (l *pinLatch) has(key [sha256.Size]byte) bool {
+	l.mu.Lock()
+	defer l.mu.Unlock()
+	_, ok := l.keys[key]
+	return ok
+}
+
+func (l *pinLatch) add(key [sha256.Size]byte) {
+	l.mu.Lock()
+	defer l.mu.Unlock()
+	l.keys[key] = struct{}{}
+}
+
+// rejectedPINKey identifies a PIN for one token of one module, so a PIN another token
+// rejected is still tried on the token it belongs to.
+func rejectedPINKey(module, token string, pin []byte) [sha256.Size]byte {
+	var buf []byte
+	for _, part := range [][]byte{[]byte(module), []byte(token), pin} {
+		buf = binary.BigEndian.AppendUint64(buf, uint64(len(part)))
+		buf = append(buf, part...)
+	}
+	return sha256.Sum256(buf)
+}