siyuan-note/siyuan · error

encrypted envelope too short

Error message

encrypted envelope too short

What it means

EncryptionNonce found the 'SENC' magic but the buffer is shorter than the 7-byte envelope header (magic 4B + spec 1B + algorithm 1B + nonceLength 1B), so the spec/algorithm/nonce-length fields cannot be read. The input is a truncated envelope.

Solutions

1. Pass the complete envelope bytes as returned by Encrypt/EncryptWithAAD (never a manual slice)
2. Check the read path that produced the bytes for truncation (compare against expected envelope length)
3. Restore the original file from backup/sync if stored data is corrupted

Example fix

// before
nonce, err := util.EncryptionNonce(envelope[:5]) // truncated header

// after
nonce, err := util.EncryptionNonce(envelope) // full envelope bytes

if len(data) < 7 {
    return errors.New("ciphertext shorter than envelope header")
}

func isCompleteHeader(b []byte) bool { return len(b) >= 7 }

nonce, err := util.EncryptionNonce(ciphertext)
if err != nil {
    return fmt.Errorf("envelope truncated or malformed: %w", err)
}

When it happens

Trigger: Calling EncryptionNonce with a byte slice of length 4-6 that starts with 'SENC' — a header that was cut off mid-read, a manually sliced envelope, or corrupted storage.

Common situations: Partial file reads, copying only part of the ciphertext, slicing the envelope into header + body and passing the wrong part, or disk corruption of stored encrypted blobs.

Understand the failure class

Background: "Invalid ... format", "must be in format X", "does not look like a ..." — invalid argument format errors across CLI tools and libraries — this error's family across 17 libraries.

Related errors

• invalid encrypted envelope magic
• invalid encrypted envelope nonce length
• unsupported encrypted envelope algorithm
• Decryption failed: incorrect key or corrupted data
• unsupported encrypted envelope spec

AI-assisted analysis of siyuan-note/siyuan@9f775e8a12 (2026-09-19). Data as JSON: /api/errors/336ce7e953f0e6f7. Report an issue: GitHub.

Appendix: source

Thrown at kernel/util/kdf.go:107

// Encrypt 用 AES-256-GCM 加密。每次调用生成随机 nonce，因此同一明文多次加密结果不同。
// 返回格式：magic(4B) || spec(1B) || algorithm(1B) || nonceLength(1B) || nonce || ciphertext || GCM tag(16B)。
func Encrypt(key, plaintext []byte) ([]byte, error) {
	return encryptGCM(key, plaintext, nil, "Encrypt")
}

// Decrypt 对应 Encrypt 的解密。密钥错误、格式无效或密文被篡改时返回错误。
func Decrypt(key, ciphertext []byte) ([]byte, error) {
	return decryptGCM(key, ciphertext, nil, "Decrypt")
}

// EncryptionNonce 从 AES-GCM 密文信封中提取 nonce。
func EncryptionNonce(ciphertext []byte) ([]byte, error) {
	if !hasEncryptionMagic(ciphertext) {
		return nil, errors.New("invalid encrypted envelope magic")
	}
	if len(ciphertext) < encryptionEnvelopeHeaderSize {
		return nil, errors.New("encrypted envelope too short")
	}
	if ciphertext[len(encryptionMagic)] != EncryptionSpec {
		return nil, errors.New("unsupported encrypted envelope spec")
	}
	if ciphertext[len(encryptionMagic)+1] != encryptionAlgorithmAES256GCM {
		return nil, errors.New("unsupported encrypted envelope algorithm")
	}
	nonceLength := int(ciphertext[len(encryptionMagic)+2])
	if nonceLength == 0 || len(ciphertext) < encryptionEnvelopeHeaderSize+nonceLength {
		return nil, errors.New("invalid encrypted envelope nonce length")
	}
	return append([]byte(nil), ciphertext[encryptionEnvelopeHeaderSize:encryptionEnvelopeHeaderSize+nonceLength]...), nil
}

// DeriveSubKey 用 HKDF-SHA256 从主 DEK 派生用途隔离的子密钥。
// 同一 (dek, purpose) 多次调用结果一致；不同 purpose 派生出相互独立的子密钥，
// 实现用途分离——.sy/assets/AV 各用独立子密钥，互不可替代，限制单点密钥泄漏的影响面。
func DeriveSubKey(dek []byte, purpose string) []byte {

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