nip44: simplify slightly.

nip44/nip44.go

@@ -22,7 +22,6 @@ import (
 const version byte = 2
 
 const (
-	MinPlaintextSize = 0x0001 // 1b msg => padded to 32b
 	MaxPlaintextSize = 0xffff // 65535 (64kb-1) => padded to 64kb
 )
 
@@ -59,14 +58,14 @@ func Encrypt(plaintext string, conversationKey [32]byte, applyOptions ...func(op
 		}
 	}
 
-	cc20key, cc20nonce, hmackey, err := messageKeys(conversationKey, nonce)
+	cc20key, cc20nonce, hmacKey, err := messageKeys(conversationKey, nonce)
 	if err != nil {
 		return "", err
 	}
 
 	plain := []byte(plaintext)
 	size := len(plain)
-	if size < MinPlaintextSize || size > MaxPlaintextSize {
+	if size == 0 || size > MaxPlaintextSize {
 		return "", fmt.Errorf("plaintext should be between 1b and 64kB")
 	}
 
@@ -80,7 +79,7 @@ func Encrypt(plaintext string, conversationKey [32]byte, applyOptions ...func(op
 		return "", err
 	}
 
-	mac, err := sha256Hmac(hmackey, ciphertext, nonce)
+	mac, err := sha256Hmac(hmacKey, ciphertext, nonce)
 	if err != nil {
 		return "", err
 	}
@@ -97,7 +96,7 @@ func Encrypt(plaintext string, conversationKey [32]byte, applyOptions ...func(op
 func Decrypt(b64ciphertextWrapped string, conversationKey [32]byte) (string, error) {
 	cLen := len(b64ciphertextWrapped)
 	if cLen < 132 || cLen > 87472 {
-		return "", fmt.Errorf(fmt.Sprintf("invalid payload length: %d", cLen))
+		return "", fmt.Errorf("invalid payload length: %d", cLen)
 	}
 	if b64ciphertextWrapped[0:1] == "#" {
 		return "", fmt.Errorf("unknown version")
@@ -109,24 +108,24 @@ func Decrypt(b64ciphertextWrapped string, conversationKey [32]byte) (string, err
 	}
 
 	if decoded[0] != version {
-		return "", fmt.Errorf(fmt.Sprintf("unknown version %d", decoded[0]))
+		return "", fmt.Errorf("unknown version %d", decoded[0])
 	}
 
 	dLen := len(decoded)
 	if dLen < 99 || dLen > 65603 {
-		return "", fmt.Errorf(fmt.Sprintf("invalid data length: %d", dLen))
+		return "", fmt.Errorf("invalid data length: %d", dLen)
 	}
 
 	var nonce [32]byte
 	copy(nonce[:], decoded[1:33])
 	ciphertext := decoded[33 : dLen-32]
 	givenMac := decoded[dLen-32:]
-	cc20key, cc20nonce, hmackey, err := messageKeys(conversationKey, nonce)
+	cc20key, cc20nonce, hmacKey, err := messageKeys(conversationKey, nonce)
 	if err != nil {
 		return "", err
 	}
 
-	expectedMac, err := sha256Hmac(hmackey, ciphertext, nonce)
+	expectedMac, err := sha256Hmac(hmacKey, ciphertext, nonce)
 	if err != nil {
 		return "", err
 	}
@@ -141,8 +140,7 @@ func Decrypt(b64ciphertextWrapped string, conversationKey [32]byte) (string, err
 	}
 
 	unpaddedLen := binary.BigEndian.Uint16(padded[0:2])
-	if unpaddedLen < uint16(MinPlaintextSize) || unpaddedLen > uint16(MaxPlaintextSize) ||
+	if unpaddedLen == 0 || unpaddedLen > MaxPlaintextSize || len(padded) != 2+calcPadding(int(unpaddedLen)) {
-		len(padded) != 2+calcPadding(int(unpaddedLen)) {
 		return "", fmt.Errorf("invalid padding")
 	}
 
@@ -160,7 +158,7 @@ func GenerateConversationKey(pub nostr.PubKey, sk [32]byte) ([32]byte, error) {
 	var ck [32]byte
 
 	if bytes.Compare(sk[:], maxThreshold) != -1 || sk == [32]byte{} {
-		return ck, fmt.Errorf("invalid private key: x coordinate %s is not on the secp256k1 curve", sk)
+		return ck, fmt.Errorf("invalid private key: x coordinate %x is not on the secp256k1 curve", sk)
 	}
 
 	shared, err := computeSharedSecret(pub, sk)

nip44/nip44_test.go

@@ -1,11 +1,8 @@
 package nip44
 
 import (
-	"crypto/rand"
 	"crypto/sha256"
 	"encoding/hex"
-	"fmt"
-	"strings"
 	"testing"
 
 	"fiatjaf.com/nostr"
@@ -1072,48 +1069,6 @@ func TestMessageKeyGeneration033(t *testing.T) {
 	)
 }
 
-func TestMaxLength(t *testing.T) {
-	sk1 := nostr.GeneratePrivateKey()
-	sk2 := nostr.GeneratePrivateKey()
-	pub2 := nostr.GetPublicKey(sk2)
-	salt := make([]byte, 32)
-	rand.Read(salt)
-	conversationKey, _ := GenerateConversationKey(pub2, sk1)
-	plaintext := strings.Repeat("a", MaxPlaintextSize)
-	encrypted, err := Encrypt(plaintext, conversationKey, WithCustomNonce(salt))
-	if err != nil {
-		t.Error(err)
-	}
-
-	assertCryptPub(t,
-		hex.EncodeToString(sk1[:]),
-		hex.EncodeToString(pub2[:]),
-		fmt.Sprintf("%x", conversationKey),
-		fmt.Sprintf("%x", salt),
-		plaintext,
-		encrypted,
-	)
-}
-
-func assertCryptPub(t *testing.T, sk1 string, pub2 string, conversationKey string, customNonce string, plaintext string, expected string) {
-	k1, err := hexDecode32Array(conversationKey)
-	require.NoErrorf(t, err, "hex decode failed for conversation key: %v", err)
-
-	assertConversationKeyGenerationPub(t, sk1, pub2, conversationKey)
-
-	s, err := hex.DecodeString(customNonce)
-	require.NoErrorf(t, err, "hex decode failed for salt: %v", err)
-
-	actual, err := Encrypt(plaintext, k1, WithCustomNonce(s))
-	require.NoError(t, err, "encryption failed: %v", err)
-	require.Equalf(t, expected, actual, "wrong encryption")
-
-	decrypted, err := Decrypt(expected, k1)
-	require.NoErrorf(t, err, "decryption failed: %v", err)
-
-	require.Equal(t, decrypted, plaintext, "wrong decryption")
-}
-
 func hexDecode32Array(hexString string) (res [32]byte, err error) {
 	_, err = hex.Decode(res[:], []byte(hexString))
 	return res, err