212 lines
7.0 KiB
Go
212 lines
7.0 KiB
Go
// Copyright 2015 The go-ethereum Authors
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// This file is part of the go-ethereum library.
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//
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// The go-ethereum library is free software: you can redistribute it and/or modify
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// it under the terms of the GNU Lesser General Public License as published by
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// the Free Software Foundation, either version 3 of the License, or
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// (at your option) any later version.
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//
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// The go-ethereum library is distributed in the hope that it will be useful,
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// but WITHOUT ANY WARRANTY; without even the implied warranty of
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// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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// GNU Lesser General Public License for more details.
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//
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// You should have received a copy of the GNU Lesser General Public License
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// along with the go-ethereum library. If not, see <http://www.gnu.org/licenses/>.
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package trie
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import (
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"github.com/ethereum/go-ethereum/common"
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"github.com/ethereum/go-ethereum/logger"
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"github.com/ethereum/go-ethereum/logger/glog"
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)
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var secureKeyPrefix = []byte("secure-key-")
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const secureKeyLength = 11 + 32 // Length of the above prefix + 32byte hash
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// SecureTrie wraps a trie with key hashing. In a secure trie, all
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// access operations hash the key using keccak256. This prevents
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// calling code from creating long chains of nodes that
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// increase the access time.
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//
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// Contrary to a regular trie, a SecureTrie can only be created with
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// New and must have an attached database. The database also stores
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// the preimage of each key.
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//
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// SecureTrie is not safe for concurrent use.
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type SecureTrie struct {
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trie Trie
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hashKeyBuf [secureKeyLength]byte
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secKeyBuf [200]byte
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secKeyCache map[string][]byte
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secKeyCacheOwner *SecureTrie // Pointer to self, replace the key cache on mismatch
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}
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// NewSecure creates a trie with an existing root node from db.
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//
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// If root is the zero hash or the sha3 hash of an empty string, the
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// trie is initially empty. Otherwise, New will panic if db is nil
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// and returns MissingNodeError if the root node cannot be found.
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// Accessing the trie loads nodes from db on demand.
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func NewSecure(root common.Hash, db Database) (*SecureTrie, error) {
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if db == nil {
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panic("NewSecure called with nil database")
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}
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trie, err := New(root, db)
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if err != nil {
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return nil, err
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}
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return &SecureTrie{
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trie: *trie,
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}, nil
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}
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// Get returns the value for key stored in the trie.
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// The value bytes must not be modified by the caller.
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func (t *SecureTrie) Get(key []byte) []byte {
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res, err := t.TryGet(key)
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if err != nil && glog.V(logger.Error) {
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glog.Errorf("Unhandled trie error: %v", err)
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}
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return res
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}
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// TryGet returns the value for key stored in the trie.
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// The value bytes must not be modified by the caller.
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// If a node was not found in the database, a MissingNodeError is returned.
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func (t *SecureTrie) TryGet(key []byte) ([]byte, error) {
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return t.trie.TryGet(t.hashKey(key))
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}
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// Update associates key with value in the trie. Subsequent calls to
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// Get will return value. If value has length zero, any existing value
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// is deleted from the trie and calls to Get will return nil.
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//
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// The value bytes must not be modified by the caller while they are
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// stored in the trie.
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func (t *SecureTrie) Update(key, value []byte) {
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if err := t.TryUpdate(key, value); err != nil && glog.V(logger.Error) {
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glog.Errorf("Unhandled trie error: %v", err)
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}
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}
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// TryUpdate associates key with value in the trie. Subsequent calls to
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// Get will return value. If value has length zero, any existing value
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// is deleted from the trie and calls to Get will return nil.
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//
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// The value bytes must not be modified by the caller while they are
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// stored in the trie.
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//
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// If a node was not found in the database, a MissingNodeError is returned.
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func (t *SecureTrie) TryUpdate(key, value []byte) error {
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hk := t.hashKey(key)
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err := t.trie.TryUpdate(hk, value)
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if err != nil {
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return err
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}
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t.getSecKeyCache()[string(hk)] = common.CopyBytes(key)
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return nil
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}
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// Delete removes any existing value for key from the trie.
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func (t *SecureTrie) Delete(key []byte) {
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if err := t.TryDelete(key); err != nil && glog.V(logger.Error) {
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glog.Errorf("Unhandled trie error: %v", err)
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}
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}
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// TryDelete removes any existing value for key from the trie.
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// If a node was not found in the database, a MissingNodeError is returned.
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func (t *SecureTrie) TryDelete(key []byte) error {
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hk := t.hashKey(key)
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delete(t.getSecKeyCache(), string(hk))
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return t.trie.TryDelete(hk)
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}
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// GetKey returns the sha3 preimage of a hashed key that was
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// previously used to store a value.
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func (t *SecureTrie) GetKey(shaKey []byte) []byte {
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if key, ok := t.getSecKeyCache()[string(shaKey)]; ok {
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return key
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}
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key, _ := t.trie.db.Get(t.secKey(shaKey))
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return key
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}
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// Commit writes all nodes and the secure hash pre-images to the trie's database.
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// Nodes are stored with their sha3 hash as the key.
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//
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// Committing flushes nodes from memory. Subsequent Get calls will load nodes
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// from the database.
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func (t *SecureTrie) Commit() (root common.Hash, err error) {
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return t.CommitTo(t.trie.db)
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}
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func (t *SecureTrie) Hash() common.Hash {
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return t.trie.Hash()
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}
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func (t *SecureTrie) Root() []byte {
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return t.trie.Root()
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}
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func (t *SecureTrie) Iterator() *Iterator {
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return t.trie.Iterator()
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}
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func (t *SecureTrie) NodeIterator() *NodeIterator {
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return NewNodeIterator(&t.trie)
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}
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// CommitTo writes all nodes and the secure hash pre-images to the given database.
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// Nodes are stored with their sha3 hash as the key.
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//
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// Committing flushes nodes from memory. Subsequent Get calls will load nodes from
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// the trie's database. Calling code must ensure that the changes made to db are
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// written back to the trie's attached database before using the trie.
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func (t *SecureTrie) CommitTo(db DatabaseWriter) (root common.Hash, err error) {
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if len(t.getSecKeyCache()) > 0 {
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for hk, key := range t.secKeyCache {
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if err := db.Put(t.secKey([]byte(hk)), key); err != nil {
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return common.Hash{}, err
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}
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}
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t.secKeyCache = make(map[string][]byte)
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}
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return t.trie.CommitTo(db)
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}
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// secKey returns the database key for the preimage of key, as an ephemeral buffer.
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// The caller must not hold onto the return value because it will become
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// invalid on the next call to hashKey or secKey.
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func (t *SecureTrie) secKey(key []byte) []byte {
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buf := append(t.secKeyBuf[:0], secureKeyPrefix...)
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buf = append(buf, key...)
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return buf
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}
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// hashKey returns the hash of key as an ephemeral buffer.
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// The caller must not hold onto the return value because it will become
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// invalid on the next call to hashKey or secKey.
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func (t *SecureTrie) hashKey(key []byte) []byte {
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h := newHasher()
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h.sha.Reset()
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h.sha.Write(key)
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buf := h.sha.Sum(t.hashKeyBuf[:0])
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returnHasherToPool(h)
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return buf
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}
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// getSecKeyCache returns the current secure key cache, creating a new one if
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// ownership changed (i.e. the current secure trie is a copy of another owning
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// the actual cache).
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func (t *SecureTrie) getSecKeyCache() map[string][]byte {
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if t != t.secKeyCacheOwner {
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t.secKeyCacheOwner = t
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t.secKeyCache = make(map[string][]byte)
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}
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return t.secKeyCache
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}
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