Simplify the password hash and get rid of pbkdf2

Since the password already has 16 bytes of security, pbkdf2 isn't
necessary here. We can use a simple sha256. I promise to pick a
secure password.

7 files changed, 7 insertions, 120 deletions

diff --git a/flake.nix b/flake.nix
index 6fa885a..5e3a2ce 100644
--- a/flake.nix
+++ b/flake.nix
@@ -48,7 +48,7 @@
             # remember to bump this hash when your dependencies change.
             # vendorHash = pkgs.lib.fakeHash;
 
-            vendorHash = "sha256-/Ciog57YcusaM8PvTRnBgxKcbNgxot4R8PhImu5m3Us=";
+            vendorHash = "sha256-Rrtcdtprg0y3oNtCbxvF4QVIGFbx+je6BcQGymsxpIA=";
           };
         });
 
diff --git a/go.mod b/go.mod
index c67fe11..ad0556c 100644
--- a/go.mod
+++ b/go.mod
@@ -4,9 +4,6 @@ go 1.24.0
 
 require (
 	github.com/skip2/go-qrcode v0.0.0-20200617195104-da1b6568686e
-	golang.org/x/term v0.36.0
 	roseh.moe/pkg/ccl v0.1.1
 	roseh.moe/pkg/wordlist v1.0.2
 )
-
-require golang.org/x/sys v0.37.0 // indirect
diff --git a/go.sum b/go.sum
index 7fd2131..8e8e2b8 100644
--- a/go.sum
+++ b/go.sum
@@ -2,10 +2,6 @@ github.com/google/go-cmp v0.7.0 h1:wk8382ETsv4JYUZwIsn6YpYiWiBsYLSJiTsyBybVuN8=
 github.com/google/go-cmp v0.7.0/go.mod h1:pXiqmnSA92OHEEa9HXL2W4E7lf9JzCmGVUdgjX3N/iU=
 github.com/skip2/go-qrcode v0.0.0-20200617195104-da1b6568686e h1:MRM5ITcdelLK2j1vwZ3Je0FKVCfqOLp5zO6trqMLYs0=
 github.com/skip2/go-qrcode v0.0.0-20200617195104-da1b6568686e/go.mod h1:XV66xRDqSt+GTGFMVlhk3ULuV0y9ZmzeVGR4mloJI3M=
-golang.org/x/sys v0.37.0 h1:fdNQudmxPjkdUTPnLn5mdQv7Zwvbvpaxqs831goi9kQ=
-golang.org/x/sys v0.37.0/go.mod h1:OgkHotnGiDImocRcuBABYBEXf8A9a87e/uXjp9XT3ks=
-golang.org/x/term v0.36.0 h1:zMPR+aF8gfksFprF/Nc/rd1wRS1EI6nDBGyWAvDzx2Q=
-golang.org/x/term v0.36.0/go.mod h1:Qu394IJq6V6dCBRgwqshf3mPF85AqzYEzofzRdZkWss=
 roseh.moe/pkg/ccl v0.1.1 h1:WSrG+AqOlUymdbeCD4D22zEvQ8fJLNU4SLQW6WtvL0Y=
 roseh.moe/pkg/ccl v0.1.1/go.mod h1:OCcZ30pQDtjXgqgpN8eLo6f/pTi6XVKIHPs1k+gups0=
 roseh.moe/pkg/wordlist v1.0.2 h1:riB2RqCU5zXfCQjaPHYTXV/688FV9/Bp6Hnb0IAkP9c=
diff --git a/internal/pwhash/pwhash.go b/internal/pwhash/pwhash.go
deleted file mode 100644
index 576d052..0000000
--- a/internal/pwhash/pwhash.go
+++ /dev/null
@@ -1,18 +0,0 @@
-package pwhash
-
-import (
-	"crypto/pbkdf2"
-	"crypto/sha512"
-)
-
-const SaltSize = 8
-
-const defaultIter = 12059332 // from tools/finditer
-
-func HashIter(password string, salt []byte, iter int) ([]byte, error) {
-	return pbkdf2.Key(sha512.New, password, salt, iter, 32)
-}
-
-func Hash(password string, salt []byte) ([]byte, error) {
-	return HashIter(password, salt, defaultIter)
-}
diff --git a/roseh.moe.go b/roseh.moe.go
index 64d5e83..ffca9d5 100644
--- a/roseh.moe.go
+++ b/roseh.moe.go
@@ -25,7 +25,6 @@ import (
 
 	"github.com/skip2/go-qrcode"
 	"roseh.moe/pkg/ccl"
-	"roseh.moe/pkg/roseh.moe/internal/pwhash"
 	"roseh.moe/pkg/wordlist"
 )
 
@@ -40,6 +39,8 @@ var (
 	serverStartTime = time.Now()
 )
 
+const targetSecurityLevel = 16
+
 var notepadPassword, secretKey []byte
 
 func loadSecrets() error {
@@ -322,7 +323,7 @@ func wormholeQR(w http.ResponseWriter, r *http.Request) {
 	w.Write(qr)
 }
 
-const macSize = 16 // sorry
+const macSize = targetSecurityLevel
 
 func mac(msg []byte) []byte {
 	mac := hmac.New(sha256.New, secretKey)
@@ -473,9 +474,9 @@ func checkCSRFToken(r *http.Request) error {
 }
 
 func checkPassword(password string) bool {
-	expectedHash, salt := notepadPassword[:len(notepadPassword)-pwhash.SaltSize], notepadPassword[len(notepadPassword)-pwhash.SaltSize:]
-	hash, err := pwhash.Hash(password, salt)
-	return err == nil && subtle.ConstantTimeCompare(hash, expectedHash) != 0
+	const pwHashSize = targetSecurityLevel
+	hash := sha256.Sum256([]byte(password))
+	return subtle.ConstantTimeCompare(hash[:pwHashSize], notepadPassword) != 0
 }
 
 var (
diff --git a/tools/finditer/finditer.go b/tools/finditer/finditer.go
deleted file mode 100644
index 114785d..0000000
--- a/tools/finditer/finditer.go
+++ /dev/null
@@ -1,43 +0,0 @@
-package main
-
-import (
-	"encoding/hex"
-	"fmt"
-	"sort"
-	"testing"
-	"time"
-
-	"roseh.moe/pkg/roseh.moe/internal/pwhash"
-)
-
-func mustHex(s string) []byte {
-	b, err := hex.DecodeString(s)
-	if err != nil {
-		panic(err)
-	}
-	return b
-}
-
-const password = "emcee polio cardiac disclose superglue clapper cruelness stonework tingly unarmored"
-
-var salt = mustHex("a0aa6971f38827e5")
-
-var iterations int
-
-func BenchmarkHashIter(b *testing.B) {
-	for b.Loop() {
-		pwhash.HashIter(password, salt, iterations)
-	}
-}
-
-func main() {
-	const targetDuration = 5 * time.Second
-	for iterations = 8192; time.Duration(testing.Benchmark(BenchmarkHashIter).NsPerOp()) < targetDuration; iterations *= 2 {
-	}
-	lo := iterations / 2
-	hi := iterations
-	fmt.Println(lo + sort.Search(hi-lo, func(i int) bool {
-		iterations = lo + i
-		return time.Duration(testing.Benchmark(BenchmarkHashIter).NsPerOp()) > targetDuration
-	}))
-}
diff --git a/tools/hashpw/hashpw.go b/tools/hashpw/hashpw.go
deleted file mode 100644
index f1e76db..0000000
--- a/tools/hashpw/hashpw.go
+++ /dev/null
@@ -1,46 +0,0 @@
-package main
-
-import (
-	"bytes"
-	"crypto/rand"
-	"encoding/base64"
-	"fmt"
-	"os"
-	"slices"
-
-	"golang.org/x/term"
-	"roseh.moe/pkg/roseh.moe/internal/pwhash"
-)
-
-func hashpw() error {
-	fmt.Fprint(os.Stderr, "Enter password: ")
-	password, err := term.ReadPassword(int(os.Stdin.Fd()))
-	fmt.Fprintln(os.Stderr)
-	if err != nil {
-		return err
-	}
-	fmt.Fprint(os.Stderr, "Confirm password: ")
-	pwConfirm, err := term.ReadPassword(int(os.Stdin.Fd()))
-	fmt.Fprintln(os.Stderr)
-	if err != nil {
-		return err
-	}
-	if !bytes.Equal(password, pwConfirm) {
-		return fmt.Errorf("passwords do not match")
-	}
-	salt := make([]byte, pwhash.SaltSize)
-	rand.Read(salt)
-	hash, err := pwhash.Hash(string(password), salt)
-	if err != nil {
-		return err
-	}
-	fmt.Printf("NotepadPassword:%q\n", base64.StdEncoding.EncodeToString(slices.Concat(hash, salt)))
-	return nil
-}
-
-func main() {
-	if err := hashpw(); err != nil {
-		fmt.Fprintln(os.Stderr, err)
-		os.Exit(1)
-	}
-}