diff --git a/lib/security/audit/principal.go b/lib/security/audit/principal.go
index 81d7211..95dd8cc 100644
--- a/lib/security/audit/principal.go
+++ b/lib/security/audit/principal.go
@@ -75,15 +75,6 @@
 func (p *auditingPrincipal) Roots() security.BlessingRoots         { return p.principal.Roots() }
 func (p *auditingPrincipal) BlessingStore() security.BlessingStore { return p.principal.BlessingStore() }
 
-func (p *auditingPrincipal) Encrypter() security.BlessingsBasedEncrypter {
-	return p.principal.Encrypter()
-}
-
-// TODO(ataly): Return an auditing decrypter instead.
-func (p *auditingPrincipal) Decrypter() security.BlessingsBasedDecrypter {
-	return p.principal.Decrypter()
-}
-
 func (p *auditingPrincipal) audit(err error, method string, args args, result interface{}) error {
 	if err != nil {
 		return err
diff --git a/lib/security/audit/principal_test.go b/lib/security/audit/principal_test.go
index 5fa6f2f..75148b6 100644
--- a/lib/security/audit/principal_test.go
+++ b/lib/security/audit/principal_test.go
@@ -202,8 +202,6 @@
 func (p *mockPrincipal) PublicKey() security.PublicKey               { return p.NextResult.(security.PublicKey) }
 func (p *mockPrincipal) Roots() security.BlessingRoots               { return nil }
 func (p *mockPrincipal) BlessingStore() security.BlessingStore       { return nil }
-func (p *mockPrincipal) Encrypter() security.BlessingsBasedEncrypter { return nil }
-func (p *mockPrincipal) Decrypter() security.BlessingsBasedDecrypter { return nil }
 
 type mockAuditor struct {
 	LastEntry audit.Entry
@@ -257,7 +255,7 @@
 		t.Fatal(err)
 	}
 	signer := security.NewInMemoryECDSASigner(key)
-	p, err := security.CreatePrincipal(signer, nil, nil, nil, nil)
+	p, err := security.CreatePrincipal(signer, nil, nil)
 	if err != nil {
 		t.Fatal(err)
 	}
diff --git a/lib/security/principal.go b/lib/security/principal.go
index 39d3dfb..9532970 100644
--- a/lib/security/principal.go
+++ b/lib/security/principal.go
@@ -44,7 +44,7 @@
 	if err != nil {
 		return nil, err
 	}
-	return security.CreatePrincipal(security.NewInMemoryECDSASigner(priv), newInMemoryBlessingStore(pub), newInMemoryBlessingRoots(), nil, nil)
+	return security.CreatePrincipal(security.NewInMemoryECDSASigner(priv), newInMemoryBlessingStore(pub), newInMemoryBlessingRoots())
 }
 
 // PrincipalStateSerializer is used to persist BlessingRoots/BlessingStore state for
@@ -73,9 +73,9 @@
 // same serializers. Otherwise, the state (ie: BlessingStore, BlessingRoots) is kept in memory.
 func NewPrincipalFromSigner(signer security.Signer, state *PrincipalStateSerializer) (security.Principal, error) {
 	if state == nil {
-		return security.CreatePrincipal(signer, newInMemoryBlessingStore(signer.PublicKey()), newInMemoryBlessingRoots(), nil, nil)
+		return security.CreatePrincipal(signer, newInMemoryBlessingStore(signer.PublicKey()), newInMemoryBlessingRoots())
 	}
-	serializationSigner, err := security.CreatePrincipal(signer, nil, nil, nil, nil)
+	serializationSigner, err := security.CreatePrincipal(signer, nil, nil)
 	if err != nil {
 		return nil, verror.New(errCantCreateSigner, nil, err)
 	}
@@ -87,7 +87,7 @@
 	if err != nil {
 		return nil, verror.New(errCantLoadBlessingStore, nil, err)
 	}
-	return security.CreatePrincipal(signer, blessingStore, blessingRoots, nil, nil)
+	return security.CreatePrincipal(signer, blessingStore, blessingRoots)
 }
 
 // LoadPersistentPrincipal reads state for a principal (private key, BlessingRoots, BlessingStore)
diff --git a/lib/security/serialization/serialization_test.go b/lib/security/serialization/serialization_test.go
index 241b3e2..3ed62a7 100644
--- a/lib/security/serialization/serialization_test.go
+++ b/lib/security/serialization/serialization_test.go
@@ -68,7 +68,7 @@
 	if err != nil {
 		panic(err)
 	}
-	p, err := security.CreatePrincipal(security.NewInMemoryECDSASigner(key), nil, nil, nil, nil)
+	p, err := security.CreatePrincipal(security.NewInMemoryECDSASigner(key), nil, nil)
 	if err != nil {
 		panic(err)
 	}
diff --git a/services/agent/agentlib/client.go b/services/agent/agentlib/client.go
index 396df74..8cc257f 100644
--- a/services/agent/agentlib/client.go
+++ b/services/agent/agentlib/client.go
@@ -257,16 +257,6 @@
 	return &blessingRoots{c.caller}
 }
 
-// TODO(ataly): Implement this method.
-func (c *client) Encrypter() security.BlessingsBasedEncrypter {
-	return nil
-}
-
-// TODO(ataly): Implement this method.
-func (c *client) Decrypter() security.BlessingsBasedDecrypter {
-	return nil
-}
-
 type blessingStore struct {
 	caller caller
 	key    security.PublicKey
diff --git a/services/agent/internal/cache/cache.go b/services/agent/internal/cache/cache.go
index 4c8ec1d..ea2e8cb 100644
--- a/services/agent/internal/cache/cache.go
+++ b/services/agent/internal/cache/cache.go
@@ -410,7 +410,7 @@
 		cachedRoots.flush()
 		cachedStore.flush()
 	}
-	sp, err := security.CreatePrincipal(dummySigner{impl.PublicKey()}, cachedStore, cachedRoots, impl.Encrypter(), impl.Decrypter())
+	sp, err := security.CreatePrincipal(dummySigner{impl.PublicKey()}, cachedStore, cachedRoots)
 	if err != nil {
 		return
 	}
diff --git a/services/wspr/internal/principal/cache_test.go b/services/wspr/internal/principal/cache_test.go
index d2141d1..73be928 100644
--- a/services/wspr/internal/principal/cache_test.go
+++ b/services/wspr/internal/principal/cache_test.go
@@ -89,7 +89,7 @@
 	bc := NewBlessingsCache(notifier, onDemandGCPolicy)
 
 	// Blessings for the tests.
-	p, err := security.CreatePrincipal(newSigner(), nil, nil, nil, nil)
+	p, err := security.CreatePrincipal(newSigner(), nil, nil)
 	if err != nil {
 		t.Fatal("Failed to create principal: ", err)
 	}