diff --git a/config_example.yaml b/config_example.yaml
index 664f2e6..5a3e064 100644
--- a/config_example.yaml
+++ b/config_example.yaml
@@ -25,6 +25,7 @@ chihaya:
         write_timeout: 10s
         client_store: memory
         ip_store: memory
+        string_store: memory
         peer_store: memory
         peer_store_config:
           gcAfter: 30m
diff --git a/server/store/memory/string_store.go b/server/store/memory/string_store.go
new file mode 100644
index 0000000..e1bb0ce
--- /dev/null
+++ b/server/store/memory/string_store.go
@@ -0,0 +1,57 @@
+// Copyright 2016 The Chihaya Authors. All rights reserved.
+// Use of this source code is governed by the BSD 2-Clause license,
+// which can be found in the LICENSE file.
+
+package memory
+
+import (
+	"sync"
+
+	"github.com/chihaya/chihaya/server/store"
+)
+
+func init() {
+	store.RegisterStringStoreDriver("memory", &stringStoreDriver{})
+}
+
+type stringStoreDriver struct{}
+
+func (d *stringStoreDriver) New(cfg *store.Config) (store.StringStore, error) {
+	return &stringStore{
+		strings: make(map[string]struct{}),
+	}, nil
+}
+
+type stringStore struct {
+	strings map[string]struct{}
+	sync.RWMutex
+}
+
+var _ store.StringStore = &stringStore{}
+
+func (ss *stringStore) PutString(s string) error {
+	ss.Lock()
+	defer ss.Unlock()
+
+	ss.strings[s] = struct{}{}
+
+	return nil
+}
+
+func (ss *stringStore) HasString(s string) (bool, error) {
+	ss.RLock()
+	defer ss.RUnlock()
+
+	_, ok := ss.strings[s]
+
+	return ok, nil
+}
+
+func (ss *stringStore) RemoveString(s string) error {
+	ss.Lock()
+	defer ss.Unlock()
+
+	delete(ss.strings, s)
+
+	return nil
+}
diff --git a/server/store/memory/string_store_test.go b/server/store/memory/string_store_test.go
new file mode 100644
index 0000000..49e56c8
--- /dev/null
+++ b/server/store/memory/string_store_test.go
@@ -0,0 +1,73 @@
+// Copyright 2016 The Chihaya Authors. All rights reserved.
+// Use of this source code is governed by the BSD 2-Clause license,
+// which can be found in the LICENSE file.
+
+package memory
+
+import (
+	"github.com/chihaya/chihaya/server/store"
+	"github.com/stretchr/testify/assert"
+	"testing"
+)
+
+var (
+	driver = &stringStoreDriver{}
+	s1     = "abc"
+	s2     = "def"
+)
+
+func TestStringStore(t *testing.T) {
+	ss, err := driver.New(&store.Config{})
+	assert.Nil(t, err)
+	assert.NotNil(t, ss)
+
+	has, err := ss.HasString(s1)
+	assert.Nil(t, err)
+	assert.False(t, has)
+
+	has, err = ss.HasString(s2)
+	assert.Nil(t, err)
+	assert.False(t, has)
+
+	err = ss.RemoveString(s1)
+	assert.Nil(t, err)
+
+	err = ss.PutString(s1)
+	assert.Nil(t, err)
+
+	has, err = ss.HasString(s1)
+	assert.Nil(t, err)
+	assert.True(t, has)
+
+	has, err = ss.HasString(s2)
+	assert.Nil(t, err)
+	assert.False(t, has)
+
+	err = ss.PutString(s1)
+	assert.Nil(t, err)
+
+	err = ss.PutString(s2)
+	assert.Nil(t, err)
+
+	has, err = ss.HasString(s1)
+	assert.Nil(t, err)
+	assert.True(t, has)
+
+	has, err = ss.HasString(s2)
+	assert.Nil(t, err)
+	assert.True(t, has)
+
+	err = ss.RemoveString(s1)
+	assert.Nil(t, err)
+
+	err = ss.RemoveString(s2)
+	assert.Nil(t, err)
+
+	has, err = ss.HasString(s1)
+	assert.Nil(t, err)
+	assert.False(t, has)
+
+	has, err = ss.HasString(s2)
+	assert.Nil(t, err)
+	assert.False(t, has)
+}
diff --git a/server/store/store.go b/server/store/store.go
index 801cd56..df5dfe3 100644
--- a/server/store/store.go
+++ b/server/store/store.go
@@ -45,6 +45,11 @@ func constructor(srvcfg *chihaya.ServerConfig, tkr *tracker.Tracker) (server.Ser
 			return nil, err
 		}
 
+		ss, err := OpenStringStore(cfg)
+		if err != nil {
+			return nil, err
+		}
+
 		theStore = &Store{
 			cfg:         cfg,
 			tkr:         tkr,
@@ -52,6 +57,7 @@ func constructor(srvcfg *chihaya.ServerConfig, tkr *tracker.Tracker) (server.Ser
 			ClientStore: cs,
 			PeerStore:   ps,
 			IPStore:     ips,
+			StringStore: ss,
 		}
 	}
 	return theStore, nil
@@ -69,6 +75,8 @@ type Config struct {
 	PeerStoreConfig   interface{}   `yaml:"peer_store_config"`
 	IPStore           string        `yaml:"ip_store"`
 	IPStoreConfig     interface{}   `yaml:"ip_store_config"`
+	StringStore       string        `yaml:"string_store"`
+	StringStoreConfig interface{}   `yaml:"string_store_config"`
 }
 
 func newConfig(srvcfg *chihaya.ServerConfig) (*Config, error) {
@@ -106,6 +114,7 @@ type Store struct {
 	PeerStore
 	ClientStore
 	IPStore
+	StringStore
 }
 
 func (s *Store) Start() {
diff --git a/server/store/string_store.go b/server/store/string_store.go
new file mode 100644
index 0000000..1f530e9
--- /dev/null
+++ b/server/store/string_store.go
@@ -0,0 +1,49 @@
+// Copyright 2016 The Chihaya Authors. All rights reserved.
+// Use of this source code is governed by the BSD 2-Clause license,
+// which can be found in the LICENSE file.
+
+package store
+
+import "fmt"
+
+// PrefixInfohash is the prefix to be used for infohashes.
+const PrefixInfohash = "ih-"
+
+var stringStoreDrivers = make(map[string]StringStoreDriver)
+
+// StringStore represents an interface for manipulating strings.
+type StringStore interface {
+	PutString(s string) error
+	HasString(s string) (bool, error)
+	RemoveString(s string) error
+}
+
+// StringStoreDriver represents an interface for creating a handle to the
+// storage of swarms.
+type StringStoreDriver interface {
+	New(*Config) (StringStore, error)
+}
+
+// RegisterStringStoreDriver makes a driver available by the provided name.
+//
+// If this function is called twice with the same name or if the driver is nil,
+// it panics.
+func RegisterStringStoreDriver(name string, driver StringStoreDriver) {
+	if driver == nil {
+		panic("store: could not register nil StringStoreDriver")
+	}
+	if _, dup := stringStoreDrivers[name]; dup {
+		panic("store: could not register duplicate StringStoreDriver: " + name)
+	}
+	stringStoreDrivers[name] = driver
+}
+
+// OpenStringStore returns a StringStore specified by a configuration.
+func OpenStringStore(cfg *Config) (StringStore, error) {
+	driver, ok := stringStoreDrivers[cfg.StringStore]
+	if !ok {
+		return nil, fmt.Errorf("store: unknown driver %q (forgotten import?)", cfg.StringStore)
+	}
+
+	return driver.New(cfg)
+}