diff --git a/nip44/nip44.go b/nip44/nip44.go index 3c036c1..96d94ae 100644 --- a/nip44/nip44.go +++ b/nip44/nip44.go @@ -25,24 +25,24 @@ const ( ) type encryptOptions struct { - err error - salt []byte + err error + nonce []byte } -func WithCustomSalt(salt []byte) func(opts *encryptOptions) { +// Deprecated: use WithCustomNonce instead of WithCustomSalt, so the naming is less confusing +var WithCustomSalt = WithCustomNonce + +func WithCustomNonce(salt []byte) func(opts *encryptOptions) { return func(opts *encryptOptions) { if len(salt) != 32 { opts.err = errors.New("salt must be 32 bytes") } - opts.salt = salt + opts.nonce = salt } } func Encrypt(plaintext string, conversationKey []byte, applyOptions ...func(opts *encryptOptions)) (string, error) { - opts := encryptOptions{ - salt: nil, - } - + opts := encryptOptions{} for _, apply := range applyOptions { apply(&opts) } @@ -51,53 +51,59 @@ func Encrypt(plaintext string, conversationKey []byte, applyOptions ...func(opts return "", opts.err } - salt := opts.salt - if salt == nil { - salt := make([]byte, 32) - if _, err := rand.Read(salt); err != nil { + nonce := opts.nonce + if nonce == nil { + nonce := make([]byte, 32) + if _, err := rand.Read(nonce); err != nil { return "", err } } - enc, nonce, auth, err := messageKeys(conversationKey, salt) + enc, cc20nonce, auth, err := messageKeys(conversationKey, nonce) if err != nil { return "", err } - padded, err := pad(plaintext) + plain := []byte(plaintext) + size := len(plain) + if size < MinPlaintextSize || size > MaxPlaintextSize { + return "", errors.New("plaintext should be between 1b and 64kB") + } + + padding := calcPadding(size) + padded := make([]byte, 2+padding) + binary.BigEndian.PutUint16(padded, uint16(size)) + copy(padded[2:], plain) + + ciphertext, err := chacha(enc, cc20nonce, []byte(padded)) if err != nil { return "", err } - ciphertext, err := chacha20_(enc, nonce, []byte(padded)) + mac, err := sha256Hmac(auth, ciphertext, nonce) if err != nil { return "", err } - hmac_, err := sha256Hmac(auth, ciphertext, salt) - if err != nil { - return "", err - } - - concat := make([]byte, 1+len(salt)+len(ciphertext)+len(hmac_)) + concat := make([]byte, 1+32+len(ciphertext)+32) concat[0] = version - copy(concat[1:], salt) - copy(concat[1+len(salt):], ciphertext) - copy(concat[1+len(salt)+len(ciphertext):], hmac_) + copy(concat[1:], nonce) + copy(concat[1+32:], ciphertext) + copy(concat[1+32+len(ciphertext):], mac) return base64.StdEncoding.EncodeToString(concat), nil } -func Decrypt(ciphertext string, conversationKey []byte) (string, error) { - cLen := len(ciphertext) +func Decrypt(b64ciphertextWrapped string, conversationKey []byte) (string, error) { + cLen := len(b64ciphertextWrapped) if cLen < 132 || cLen > 87472 { return "", errors.New(fmt.Sprintf("invalid payload length: %d", cLen)) } - if ciphertext[0:1] == "#" { + if b64ciphertextWrapped[0:1] == "#" { return "", errors.New("unknown version") } - decoded, err := base64.StdEncoding.DecodeString(ciphertext) + decoded, err := base64.StdEncoding.DecodeString(b64ciphertextWrapped) if err != nil { return "", errors.New("invalid base64") } @@ -111,33 +117,33 @@ func Decrypt(ciphertext string, conversationKey []byte) (string, error) { return "", errors.New(fmt.Sprintf("invalid data length: %d", dLen)) } - salt, ciphertext_, hmac_ := decoded[1:33], decoded[33:dLen-32], decoded[dLen-32:] - enc, nonce, auth, err := messageKeys(conversationKey, salt) + nonce, ciphertext, givenMac := decoded[1:33], decoded[33:dLen-32], decoded[dLen-32:] + enc, cc20nonce, auth, err := messageKeys(conversationKey, nonce) if err != nil { return "", err } - hmac, err := sha256Hmac(auth, ciphertext_, salt) + expectedMac, err := sha256Hmac(auth, ciphertext, nonce) if err != nil { return "", err } - if !bytes.Equal(hmac_, hmac) { + if !bytes.Equal(givenMac, expectedMac) { return "", errors.New("invalid hmac") } - padded, err := chacha20_(enc, nonce, ciphertext_) + padded, err := chacha(enc, cc20nonce, ciphertext) if err != nil { return "", err } unpaddedLen := binary.BigEndian.Uint16(padded[0:2]) - if unpaddedLen < uint16(MinPlaintextSize) || - unpaddedLen > uint16(MaxPlaintextSize) || len(padded) != 2+calcPadding(int(unpaddedLen)) { + if unpaddedLen < uint16(MinPlaintextSize) || unpaddedLen > uint16(MaxPlaintextSize) || + len(padded) != 2+calcPadding(int(unpaddedLen)) { return "", errors.New("invalid padding") } - unpadded := padded[2 : unpaddedLen+2] + unpadded := padded[2:][:unpaddedLen] if len(unpadded) == 0 || len(unpadded) != int(unpaddedLen) { return "", errors.New("invalid padding") } @@ -157,7 +163,7 @@ func GenerateConversationKey(pub string, sk string) ([]byte, error) { return hkdf.Extract(sha256.New, shared, []byte("nip44-v2")), nil } -func chacha20_(key []byte, nonce []byte, message []byte) ([]byte, error) { +func chacha(key []byte, nonce []byte, message []byte) ([]byte, error) { cipher, err := chacha20.NewUnauthenticatedCipher(key, nonce) if err != nil { return nil, err @@ -168,32 +174,32 @@ func chacha20_(key []byte, nonce []byte, message []byte) ([]byte, error) { return dst, nil } -func sha256Hmac(key []byte, ciphertext []byte, aad []byte) ([]byte, error) { - if len(aad) != 32 { - return nil, errors.New("aad data must be 32 bytes") +func sha256Hmac(key []byte, ciphertext []byte, nonce []byte) ([]byte, error) { + if len(nonce) != 32 { + return nil, errors.New("nonce aad must be 32 bytes") } h := hmac.New(sha256.New, key) - h.Write(aad) + h.Write(nonce) h.Write(ciphertext) return h.Sum(nil), nil } -func messageKeys(conversationKey []byte, salt []byte) ([]byte, []byte, []byte, error) { +func messageKeys(conversationKey []byte, nonce []byte) ([]byte, []byte, []byte, error) { if len(conversationKey) != 32 { return nil, nil, nil, errors.New("conversation key must be 32 bytes") } - if len(salt) != 32 { - return nil, nil, nil, errors.New("salt must be 32 bytes") + if len(nonce) != 32 { + return nil, nil, nil, errors.New("nonce must be 32 bytes") } - r := hkdf.Expand(sha256.New, conversationKey, salt) + r := hkdf.Expand(sha256.New, conversationKey, nonce) enc := make([]byte, 32) if _, err := io.ReadFull(r, enc); err != nil { return nil, nil, nil, err } - nonce := make([]byte, 12) - if _, err := io.ReadFull(r, nonce); err != nil { + cc20nonce := make([]byte, 12) + if _, err := io.ReadFull(r, cc20nonce); err != nil { return nil, nil, nil, err } @@ -202,21 +208,7 @@ func messageKeys(conversationKey []byte, salt []byte) ([]byte, []byte, []byte, e return nil, nil, nil, err } - return enc, nonce, auth, nil -} - -func pad(s string) ([]byte, error) { - sb := []byte(s) - sbLen := len(sb) - if sbLen < 1 || sbLen > MaxPlaintextSize { - return nil, errors.New("plaintext should be between 1b and 64kB") - } - padding := calcPadding(sbLen) - result := make([]byte, 2) - binary.BigEndian.PutUint16(result, uint16(sbLen)) - result = append(result, sb...) - result = append(result, make([]byte, padding-sbLen)...) - return result, nil + return enc, cc20nonce, auth, nil } func calcPadding(sLen int) int { diff --git a/nip44/nip44_test.go b/nip44/nip44_test.go index 5f3576a..f31084a 100644 --- a/nip44/nip44_test.go +++ b/nip44/nip44_test.go @@ -1,9 +1,12 @@ package nip44 import ( + "crypto/rand" "crypto/sha256" "encoding/hex" + "fmt" "hash" + "strings" "testing" "github.com/nbd-wtf/go-nostr" @@ -30,41 +33,7 @@ func assertCryptPriv(t *testing.T, sk1 string, sk2 string, conversationKey strin if ok = assert.NoErrorf(t, err, "hex decode failed for salt: %v", err); !ok { return } - actual, err = Encrypt(plaintext, k1, WithCustomSalt(s)) - if ok = assert.NoError(t, err, "encryption failed: %v", err); !ok { - return - } - if ok = assert.Equalf(t, expected, actual, "wrong encryption"); !ok { - return - } - decrypted, err = Decrypt(expected, k1) - if ok = assert.NoErrorf(t, err, "decryption failed: %v", err); !ok { - return - } - assert.Equal(t, decrypted, plaintext, "wrong decryption") -} - -func assertCryptPub(t *testing.T, sk1 string, pub2 string, conversationKey string, salt string, plaintext string, expected string) { - var ( - k1 []byte - s []byte - actual string - decrypted string - ok bool - err error - ) - k1, err = hex.DecodeString(conversationKey) - if ok = assert.NoErrorf(t, err, "hex decode failed for conversation key: %v", err); !ok { - return - } - if ok = assertConversationKeyGenerationPub(t, sk1, pub2, conversationKey); !ok { - return - } - s, err = hex.DecodeString(salt) - if ok = assert.NoErrorf(t, err, "hex decode failed for salt: %v", err); !ok { - return - } - actual, err = Encrypt(plaintext, k1, WithCustomSalt(s)) + actual, err = Encrypt(plaintext, k1, WithCustomNonce(s)) if ok = assert.NoError(t, err, "encryption failed: %v", err); !ok { return } @@ -209,7 +178,7 @@ func assertCryptLong(t *testing.T, conversationKey string, salt string, pattern if ok = assert.Equalf(t, plaintextSha256, actualPlaintextSha256, "invalid plaintext sha256 hash: %v", err); !ok { return } - actualPayload, err = Encrypt(plaintext, convKey, WithCustomSalt(convSalt)) + actualPayload, err = Encrypt(plaintext, convKey, WithCustomNonce(convSalt)) if ok = assert.NoErrorf(t, err, "encryption failed: %v", err); !ok { return } @@ -1169,3 +1138,60 @@ func TestMessageKeyGeneration033(t *testing.T) { "47b89da97f68d389867b5d8a2d7ba55715a30e3d88a3cc11f3646bc2af5580ef", ) } + +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, + sk1, + pub2, + fmt.Sprintf("%x", conversationKey), + fmt.Sprintf("%x", salt), + plaintext, + encrypted, + ) +} + +func assertCryptPub(t *testing.T, sk1 string, pub2 string, conversationKey string, salt string, plaintext string, expected string) { + var ( + k1 []byte + s []byte + actual string + decrypted string + ok bool + err error + ) + k1, err = hex.DecodeString(conversationKey) + if ok = assert.NoErrorf(t, err, "hex decode failed for conversation key: %v", err); !ok { + return + } + if ok = assertConversationKeyGenerationPub(t, sk1, pub2, conversationKey); !ok { + return + } + s, err = hex.DecodeString(salt) + if ok = assert.NoErrorf(t, err, "hex decode failed for salt: %v", err); !ok { + return + } + actual, err = Encrypt(plaintext, k1, WithCustomNonce(s)) + if ok = assert.NoError(t, err, "encryption failed: %v", err); !ok { + return + } + if ok = assert.Equalf(t, expected, actual, "wrong encryption"); !ok { + return + } + decrypted, err = Decrypt(expected, k1) + if ok = assert.NoErrorf(t, err, "decryption failed: %v", err); !ok { + return + } + assert.Equal(t, decrypted, plaintext, "wrong decryption") +}