Add principal types.

principal/principal.go

@@ -13,7 +13,7 @@ import (
 )
 
 // AnonymousID is used for the anonymous caller. It can be used in call and query requests without a signature.
-var AnonymousID = Principal{[]byte{0x04}}
+var AnonymousID = Principal{Raw: []byte{0x04}}
 
 var encoding = base32.StdEncoding.WithPadding(base32.NoPadding)
 
@@ -46,6 +46,38 @@ func MustDecode(s string) Principal {
 	return p
 }
 
+// IsOpaque checks if the principal is opaque, these are always generated by the IC and have no structure of interest
+// outside of it.
+func (p Principal) IsOpaque() bool {
+	return p.Raw[len(p.Raw)-1] == 0x01
+}
+
+// IsSelfAuthenticating checks if the principal is self authenticating, an external user can use these ids as the sender
+// of a request if they own the corresponding private key.
+func (p Principal) IsSelfAuthenticating() bool {
+	return p.Raw[len(p.Raw)-1] == 0x02
+}
+
+// IsDerived checks if the principal is derived.
+func (p Principal) IsDerived() bool {
+	return p.Raw[len(p.Raw)-1] == 0x03
+}
+
+// IsAnonymous checks if the principal is the anonymous id.
+func (p Principal) IsAnonymous() bool {
+	return bytes.Equal(p.Raw, AnonymousID.Raw)
+}
+
+// IsReserved checks if the principal is reserved. These ids can be useful for applications that want to re-use the
+// Textual representation of principals but want to indicate explicitly that the blob does not address any canisters or
+// a user.
+func (p Principal) IsReserved() bool {
+	if 29 < len(p.Raw) {
+		return false
+	}
+	return p.Raw[len(p.Raw)-1] == 0x7f
+}
+
 // Decode converts a textual representation into a principal.
 func Decode(s string) (Principal, error) {
 	p := strings.Split(s, "-")

principal/principal_test.go

@@ -3,6 +3,8 @@ package principal_test
 import (
 	"encoding/hex"
 	"fmt"
+	"github.com/aviate-labs/agent-go/ic"
+	"testing"
 
 	"github.com/aviate-labs/agent-go/principal"
 )
@@ -16,8 +18,23 @@ func ExampleDecode() {
 
 func ExamplePrincipal() {
 	raw, _ := hex.DecodeString("abcd01")
-	p := principal.Principal{raw}
+	p := principal.Principal{Raw: raw}
 	fmt.Println(p.Encode())
 	// Output:
 	// em77e-bvlzu-aq
 }
+
+func TestPrincipal(t *testing.T) {
+	if !ic.LEDGER_PRINCIPAL.IsOpaque() {
+		t.Fatal("expected opaque principal")
+	}
+	if !principal.MustDecode("g27xm-fnyhk-uu73a-njpqd-hec7y-syhwe-bd45b-qm6yc-xikg5-cylqt-iae").IsSelfAuthenticating() {
+		t.Fatal("expected derived principal")
+	}
+	if !principal.AnonymousID.IsAnonymous() {
+		t.Fatal("expected anonymous principal")
+	}
+	if !(principal.Principal{Raw: append([]byte("random"), 0x7f)}).IsReserved() {
+		t.Fatal("expected reserved principal")
+	}
+}