diff --git a/go.mod b/go.mod
index 6c27e00..e39416e 100644
--- a/go.mod
+++ b/go.mod
@@ -5,6 +5,7 @@ go 1.15
 require (
 	crawshaw.io/sqlite v0.3.2
 	github.com/matryer/is v1.4.0
+	github.com/matthewhartstonge/argon2 v0.1.4
 	github.com/rickb777/date v1.14.0
 	gitlab.codemonkeysoftware.net/b/hatmill v0.0.6
 )
diff --git a/go.sum b/go.sum
index 0e9138c..510ede8 100644
--- a/go.sum
+++ b/go.sum
@@ -21,6 +21,8 @@ github.com/leanovate/gopter v0.2.4 h1:U4YLBggDFhJdqQsG4Na2zX7joVTky9vHaj/AGEwSuX
 github.com/leanovate/gopter v0.2.4/go.mod h1:gNcbPWNEWRe4lm+bycKqxUYoH5uoVje5SkOJ3uoLer8=
 github.com/matryer/is v1.4.0 h1:sosSmIWwkYITGrxZ25ULNDeKiMNzFSr4V/eqBQP0PeE=
 github.com/matryer/is v1.4.0/go.mod h1:8I/i5uYgLzgsgEloJE1U6xx5HkBQpAZvepWuujKwMRU=
+github.com/matthewhartstonge/argon2 v0.1.4 h1:XalXB/BERpIZbOHV/31FYFFQxsl6GTrTq2N10rwfNGc=
+github.com/matthewhartstonge/argon2 v0.1.4/go.mod h1:ZOSVMa24Ro9NpCjIobiwO49tymOSJ8ZaUmbcdrbrhYQ=
 github.com/nxadm/tail v1.4.4 h1:DQuhQpB1tVlglWS2hLQ5OV6B5r8aGxSrPc5Qo6uTN78=
 github.com/nxadm/tail v1.4.4/go.mod h1:kenIhsEOeOJmVchQTgglprH7qJGnHDVpk1VPCcaMI8A=
 github.com/onsi/ginkgo v1.6.0/go.mod h1:lLunBs/Ym6LB5Z9jYTR76FiuTmxDTDusOGeTQH+WWjE=
@@ -36,6 +38,8 @@ github.com/rickb777/plural v1.2.1/go.mod h1:j058+3M5QQFgcZZ2oKIOekcygoZUL8gKW5yR
 gitlab.codemonkeysoftware.net/b/hatmill v0.0.6 h1:5Vs30ORHoujCYRvtbIwrusGBQgPzbKv011xKrTFa5ng=
 gitlab.codemonkeysoftware.net/b/hatmill v0.0.6/go.mod h1:T19ms3BmsEzy5YTS4icMO1oLC53xWhOP9MFeBv4NcFQ=
 golang.org/x/crypto v0.0.0-20190308221718-c2843e01d9a2/go.mod h1:djNgcEr1/C05ACkg1iLfiJU5Ep61QUkGW8qpdssI0+w=
+golang.org/x/crypto v0.0.0-20200510223506-06a226fb4e37/go.mod h1:LzIPMQfyMNhhGPhUkYOs5KpL4U8rLKemX1yGLhDgUto=
+golang.org/x/crypto v0.0.0-20200622213623-75b288015ac9 h1:psW17arqaxU48Z5kZ0CQnkZWQJsqcURM6tKiBApRjXI=
 golang.org/x/crypto v0.0.0-20200622213623-75b288015ac9/go.mod h1:LzIPMQfyMNhhGPhUkYOs5KpL4U8rLKemX1yGLhDgUto=
 golang.org/x/net v0.0.0-20180906233101-161cd47e91fd/go.mod h1:mL1N/T3taQHkDXs73rZJwtUhF3w3ftmwwsq0BUmARs4=
 golang.org/x/net v0.0.0-20190404232315-eb5bcb51f2a3/go.mod h1:t9HGtf8HONx5eT2rtn7q6eTqICYqUVnKs3thJo3Qplg=
diff --git a/internal/back/store.go b/internal/back/store.go
index b5f9571..85e5284 100644
--- a/internal/back/store.go
+++ b/internal/back/store.go
@@ -9,6 +9,7 @@ import (
 
 	"crawshaw.io/sqlite"
 	"crawshaw.io/sqlite/sqlitex"
+	"github.com/matthewhartstonge/argon2"
 	"github.com/rickb777/date"
 )
 
@@ -23,6 +24,21 @@ func (u UnauthorizedError) Error() string {
 	return fmt.Sprintf("unauthorized: EventID = %s, AdminCode = %s", u.EventID, u.AdminCode)
 }
 
+func hash(password string) (string, error) {
+	hashed, err := (&argon2.Config{
+		HashLength: 32,
+		// We don't need a salt because our random passwords are not
+		// susceptible to dictionary attacks.
+		SaltLength:  0,
+		TimeCost:    3,
+		MemoryCost:  64 * 1024,
+		Parallelism: 4,
+		Mode:        argon2.ModeArgon2id,
+		Version:     argon2.Version13,
+	}).HashEncoded([]byte(password))
+	return string(hashed), err
+}
+
 type GenString func(length int) (string, error)
 
 type Store struct {
@@ -82,7 +98,7 @@ func (s *Store) Close() error {
 const schema = `
 	CREATE TABLE event (
 		id TEXT NOT NULL PRIMARY KEY,
-		admin_code TEXT NOT NULL,
+		admin_code_hash TEXT NOT NULL,
 		name TEXT NOT NULL,
 		description TEXT NOT NULL,
 		earliest_date DATE NOT NULL,
@@ -157,12 +173,17 @@ func (s *Store) CreateEvent(ctx context.Context, cmd CreateEventCommand) (result
 		return
 	}
 
+	adminCodeHash, err := hash(adminCode)
+	if err != nil {
+		return
+	}
+
 	const query = `
-		INSERT INTO event(id, admin_code, name, description, earliest_date, latest_date)
+		INSERT INTO event(id, admin_code_hash, name, description, earliest_date, latest_date)
 		VALUES (?, ?, ?, ?, ?, ?);`
 	err = sqlitex.Exec(conn, query, nil,
 		id,
-		adminCode,
+		adminCodeHash,
 		cmd.Name,
 		cmd.Description,
 		cmd.Earliest.Format(dbDateLayout),
@@ -186,16 +207,21 @@ func (s *Store) AuthorizeEventAdmin(ctx context.Context, query CheckEventAdminCo
 	conn := s.pool.Get(ctx)
 	defer s.pool.Put(conn)
 
+	adminCodeHash, err := hash(query.AdminCode)
+	if err != nil {
+		return err
+	}
+
 	const dbQuery = `
 		SELECT 1
 		FROM event
-		WHERE id = ? AND admin_code = ?;`
+		WHERE id = ? AND admin_code_hash = ?;`
 	var doesMatch bool
-	err := sqlitex.Exec(conn, dbQuery,
+	err = sqlitex.Exec(conn, dbQuery,
 		func(stmt *sqlite.Stmt) error {
 			doesMatch = true
 			return nil
-		}, query.EventID, query.AdminCode)
+		}, query.EventID, adminCodeHash)
 	if err != nil {
 		return err
 	}