feat: add vault module

x/did/keeper/macaroon.go

@@ -0,0 +1,29 @@
+package keeper
+
+import (
+	"crypto/sha256"
+	"fmt"
+
+	sdk "github.com/cosmos/cosmos-sdk/types"
+	"gopkg.in/macaroon.v2"
+)
+
+// IssueMacaroon creates a macaroon with the specified parameters.
+func (k Keeper) IssueMacaroon(ctx sdk.Context, sharedMPCPubKey, location, id string, blockExpiry uint64) (*macaroon.Macaroon, error) {
+	// Derive the root key by hashing the shared MPC public key
+	rootKey := sha256.Sum256([]byte(sharedMPCPubKey))
+	// Create the macaroon
+	m, err := macaroon.New(rootKey[:], []byte(id), location, macaroon.LatestVersion)
+	if err != nil {
+		return nil, err
+	}
+
+	// Add the block expiry caveat
+	caveat := fmt.Sprintf("block-expiry=%d", blockExpiry)
+	err = m.AddFirstPartyCaveat([]byte(caveat))
+	if err != nil {
+		return nil, err
+	}
+
+	return m, nil
+}