excelize/crypt.go

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// Copyright 2016 - 2022 The excelize Authors. All rights reserved. Use of
// this source code is governed by a BSD-style license that can be found in
// the LICENSE file.
//
// Package excelize providing a set of functions that allow you to write to and
// read from XLAM / XLSM / XLSX / XLTM / XLTX files. Supports reading and
// writing spreadsheet documents generated by Microsoft Excel™ 2007 and later.
// Supports complex components by high compatibility, and provided streaming
// API for generating or reading data from a worksheet with huge amounts of
// data. This library needs Go version 1.15 or later.
package excelize
import (
"bytes"
"crypto/aes"
"crypto/cipher"
"crypto/md5"
"crypto/rand"
"crypto/sha1"
"crypto/sha256"
"crypto/sha512"
"encoding/base64"
"encoding/binary"
"encoding/xml"
"hash"
"math"
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"reflect"
"strings"
"github.com/richardlehane/mscfb"
"golang.org/x/crypto/md4"
"golang.org/x/crypto/ripemd160"
"golang.org/x/text/encoding/unicode"
)
var (
blockKey = []byte{0x14, 0x6e, 0x0b, 0xe7, 0xab, 0xac, 0xd0, 0xd6} // Block keys used for encryption
oleIdentifier = []byte{0xd0, 0xcf, 0x11, 0xe0, 0xa1, 0xb1, 0x1a, 0xe1}
iterCount = 50000
packageEncryptionChunkSize = 4096
packageOffset = 8 // First 8 bytes are the size of the stream
sheetProtectionSpinCount = 1e5
)
// Encryption specifies the encryption structure, streams, and storages are
// required when encrypting ECMA-376 documents.
type Encryption struct {
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XMLName xml.Name `xml:"encryption"`
KeyData KeyData `xml:"keyData"`
DataIntegrity DataIntegrity `xml:"dataIntegrity"`
KeyEncryptors KeyEncryptors `xml:"keyEncryptors"`
}
// KeyData specifies the cryptographic attributes used to encrypt the data.
type KeyData struct {
SaltSize int `xml:"saltSize,attr"`
BlockSize int `xml:"blockSize,attr"`
KeyBits int `xml:"keyBits,attr"`
HashSize int `xml:"hashSize,attr"`
CipherAlgorithm string `xml:"cipherAlgorithm,attr"`
CipherChaining string `xml:"cipherChaining,attr"`
HashAlgorithm string `xml:"hashAlgorithm,attr"`
SaltValue string `xml:"saltValue,attr"`
}
// DataIntegrity specifies the encrypted copies of the salt and hash values
// used to help ensure that the integrity of the encrypted data has not been
// compromised.
type DataIntegrity struct {
EncryptedHmacKey string `xml:"encryptedHmacKey,attr"`
EncryptedHmacValue string `xml:"encryptedHmacValue,attr"`
}
// KeyEncryptors specifies the key encryptors used to encrypt the data.
type KeyEncryptors struct {
KeyEncryptor []KeyEncryptor `xml:"keyEncryptor"`
}
// KeyEncryptor specifies that the schema used by this encryptor is the schema
// specified for password-based encryptors.
type KeyEncryptor struct {
XMLName xml.Name `xml:"keyEncryptor"`
URI string `xml:"uri,attr"`
EncryptedKey EncryptedKey `xml:"encryptedKey"`
}
// EncryptedKey used to generate the encrypting key.
type EncryptedKey struct {
XMLName xml.Name `xml:"http://schemas.microsoft.com/office/2006/keyEncryptor/password encryptedKey"`
SpinCount int `xml:"spinCount,attr"`
EncryptedVerifierHashInput string `xml:"encryptedVerifierHashInput,attr"`
EncryptedVerifierHashValue string `xml:"encryptedVerifierHashValue,attr"`
EncryptedKeyValue string `xml:"encryptedKeyValue,attr"`
KeyData
}
// StandardEncryptionHeader structure is used by ECMA-376 document encryption
// [ECMA-376] and Office binary document RC4 CryptoAPI encryption, to specify
// encryption properties for an encrypted stream.
type StandardEncryptionHeader struct {
Flags uint32
SizeExtra uint32
AlgID uint32
AlgIDHash uint32
KeySize uint32
ProviderType uint32
Reserved1 uint32
Reserved2 uint32
CspName string
}
// StandardEncryptionVerifier structure is used by Office Binary Document RC4
// CryptoAPI Encryption and ECMA-376 Document Encryption. Every usage of this
// structure MUST specify the hashing algorithm and encryption algorithm used
// in the EncryptionVerifier structure.
type StandardEncryptionVerifier struct {
SaltSize uint32
Salt []byte
EncryptedVerifier []byte
VerifierHashSize uint32
EncryptedVerifierHash []byte
}
// encryptionInfo structure is used for standard encryption with SHA1
// cryptographic algorithm.
type encryption struct {
BlockSize, SaltSize int
EncryptedKeyValue, EncryptedVerifierHashInput, EncryptedVerifierHashValue, SaltValue []byte
KeyBits uint32
}
// Decrypt API decrypts the CFB file format with ECMA-376 agile encryption and
// standard encryption. Support cryptographic algorithm: MD4, MD5, RIPEMD-160,
// SHA1, SHA256, SHA384 and SHA512 currently.
func Decrypt(raw []byte, opt *Options) (packageBuf []byte, err error) {
doc, err := mscfb.New(bytes.NewReader(raw))
if err != nil {
return
}
encryptionInfoBuf, encryptedPackageBuf := extractPart(doc)
mechanism, err := encryptionMechanism(encryptionInfoBuf)
if err != nil || mechanism == "extensible" {
return
}
if mechanism == "agile" {
return agileDecrypt(encryptionInfoBuf, encryptedPackageBuf, opt)
}
return standardDecrypt(encryptionInfoBuf, encryptedPackageBuf, opt)
}
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// Encrypt API encrypt data with the password.
func Encrypt(raw []byte, opt *Options) (packageBuf []byte, err error) {
encryptor := encryption{
EncryptedVerifierHashInput: make([]byte, 16),
EncryptedVerifierHashValue: make([]byte, 32),
SaltValue: make([]byte, 16),
BlockSize: 16,
KeyBits: 128,
SaltSize: 16,
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}
// Key Encryption
encryptionInfoBuffer, err := encryptor.standardKeyEncryption(opt.Password)
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if err != nil {
return nil, err
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}
// Package Encryption
encryptedPackage := make([]byte, 8)
binary.LittleEndian.PutUint64(encryptedPackage, uint64(len(raw)))
encryptedPackage = append(encryptedPackage, encryptor.encrypt(raw)...)
// Create a new CFB
compoundFile := cfb{}
packageBuf = compoundFile.Writer(encryptionInfoBuffer, encryptedPackage)
return packageBuf, nil
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}
// extractPart extract data from storage by specified part name.
func extractPart(doc *mscfb.Reader) (encryptionInfoBuf, encryptedPackageBuf []byte) {
for entry, err := doc.Next(); err == nil; entry, err = doc.Next() {
switch entry.Name {
case "EncryptionInfo":
buf := make([]byte, entry.Size)
i, _ := doc.Read(buf)
if i > 0 {
encryptionInfoBuf = buf
}
case "EncryptedPackage":
buf := make([]byte, entry.Size)
i, _ := doc.Read(buf)
if i > 0 {
encryptedPackageBuf = buf
}
}
}
return
}
// encryptionMechanism parse password-protected documents created mechanism.
func encryptionMechanism(buffer []byte) (mechanism string, err error) {
if len(buffer) < 4 {
err = ErrUnknownEncryptMechanism
return
}
versionMajor, versionMinor := binary.LittleEndian.Uint16(buffer[:2]), binary.LittleEndian.Uint16(buffer[2:4])
if versionMajor == 4 && versionMinor == 4 {
mechanism = "agile"
return
} else if (2 <= versionMajor && versionMajor <= 4) && versionMinor == 2 {
mechanism = "standard"
return
} else if (versionMajor == 3 || versionMajor == 4) && versionMinor == 3 {
mechanism = "extensible"
}
err = ErrUnsupportedEncryptMechanism
return
}
// ECMA-376 Standard Encryption
// standardDecrypt decrypt the CFB file format with ECMA-376 standard encryption.
func standardDecrypt(encryptionInfoBuf, encryptedPackageBuf []byte, opt *Options) ([]byte, error) {
encryptionHeaderSize := binary.LittleEndian.Uint32(encryptionInfoBuf[8:12])
block := encryptionInfoBuf[12 : 12+encryptionHeaderSize]
header := StandardEncryptionHeader{
Flags: binary.LittleEndian.Uint32(block[:4]),
SizeExtra: binary.LittleEndian.Uint32(block[4:8]),
AlgID: binary.LittleEndian.Uint32(block[8:12]),
AlgIDHash: binary.LittleEndian.Uint32(block[12:16]),
KeySize: binary.LittleEndian.Uint32(block[16:20]),
ProviderType: binary.LittleEndian.Uint32(block[20:24]),
Reserved1: binary.LittleEndian.Uint32(block[24:28]),
Reserved2: binary.LittleEndian.Uint32(block[28:32]),
CspName: string(block[32:]),
}
block = encryptionInfoBuf[12+encryptionHeaderSize:]
algIDMap := map[uint32]string{
0x0000660E: "AES-128",
0x0000660F: "AES-192",
0x00006610: "AES-256",
}
algorithm := "AES"
_, ok := algIDMap[header.AlgID]
if !ok {
algorithm = "RC4"
}
verifier := standardEncryptionVerifier(algorithm, block)
secretKey, err := standardConvertPasswdToKey(header, verifier, opt)
if err != nil {
return nil, err
}
// decrypted data
x := encryptedPackageBuf[8:]
blob, err := aes.NewCipher(secretKey)
if err != nil {
return nil, err
}
decrypted := make([]byte, len(x))
size := 16
for bs, be := 0, size; bs < len(x); bs, be = bs+size, be+size {
blob.Decrypt(decrypted[bs:be], x[bs:be])
}
return decrypted, err
}
// standardEncryptionVerifier extract ECMA-376 standard encryption verifier.
func standardEncryptionVerifier(algorithm string, blob []byte) StandardEncryptionVerifier {
verifier := StandardEncryptionVerifier{
SaltSize: binary.LittleEndian.Uint32(blob[:4]),
Salt: blob[4:20],
EncryptedVerifier: blob[20:36],
VerifierHashSize: binary.LittleEndian.Uint32(blob[36:40]),
}
if algorithm == "RC4" {
verifier.EncryptedVerifierHash = blob[40:60]
} else if algorithm == "AES" {
verifier.EncryptedVerifierHash = blob[40:72]
}
return verifier
}
// standardConvertPasswdToKey generate intermediate key from given password.
func standardConvertPasswdToKey(header StandardEncryptionHeader, verifier StandardEncryptionVerifier, opt *Options) ([]byte, error) {
encoder := unicode.UTF16(unicode.LittleEndian, unicode.IgnoreBOM).NewEncoder()
passwordBuffer, err := encoder.Bytes([]byte(opt.Password))
if err != nil {
return nil, err
}
key := hashing("sha1", verifier.Salt, passwordBuffer)
for i := 0; i < iterCount; i++ {
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iterator := createUInt32LEBuffer(i, 4)
key = hashing("sha1", iterator, key)
}
var block int
hFinal := hashing("sha1", key, createUInt32LEBuffer(block, 4))
cbRequiredKeyLength := int(header.KeySize) / 8
cbHash := sha1.Size
buf1 := bytes.Repeat([]byte{0x36}, 64)
buf1 = append(standardXORBytes(hFinal, buf1[:cbHash]), buf1[cbHash:]...)
x1 := hashing("sha1", buf1)
buf2 := bytes.Repeat([]byte{0x5c}, 64)
buf2 = append(standardXORBytes(hFinal, buf2[:cbHash]), buf2[cbHash:]...)
x2 := hashing("sha1", buf2)
x3 := append(x1, x2...)
keyDerived := x3[:cbRequiredKeyLength]
return keyDerived, err
}
// standardXORBytes perform XOR operations for two bytes slice.
func standardXORBytes(a, b []byte) []byte {
r := make([][2]byte, len(a))
for i, e := range a {
r[i] = [2]byte{e, b[i]}
}
buf := make([]byte, len(a))
for p, q := range r {
buf[p] = q[0] ^ q[1]
}
return buf
}
// encrypt provides a function to encrypt given value with AES cryptographic
// algorithm.
func (e *encryption) encrypt(input []byte) []byte {
inputBytes := len(input)
if pad := inputBytes % e.BlockSize; pad != 0 {
inputBytes += e.BlockSize - pad
}
var output, chunk []byte
encryptedChunk := make([]byte, e.BlockSize)
for i := 0; i < inputBytes; i += e.BlockSize {
if i+e.BlockSize <= len(input) {
chunk = input[i : i+e.BlockSize]
} else {
chunk = input[i:]
}
chunk = append(chunk, make([]byte, e.BlockSize-len(chunk))...)
c, _ := aes.NewCipher(e.EncryptedKeyValue)
c.Encrypt(encryptedChunk, chunk)
output = append(output, encryptedChunk...)
}
return output
}
// standardKeyEncryption encrypt convert the password to an encryption key.
func (e *encryption) standardKeyEncryption(password string) ([]byte, error) {
if len(password) == 0 || len(password) > MaxFieldLength {
return nil, ErrPasswordLengthInvalid
}
var storage cfb
storage.writeUint16(0x0003)
storage.writeUint16(0x0002)
storage.writeUint32(0x24)
storage.writeUint32(0xA4)
storage.writeUint32(0x24)
storage.writeUint32(0x00)
storage.writeUint32(0x660E)
storage.writeUint32(0x8004)
storage.writeUint32(0x80)
storage.writeUint32(0x18)
storage.writeUint64(0x00)
providerName := "Microsoft Enhanced RSA and AES Cryptographic Provider (Prototype)"
storage.writeStrings(providerName)
storage.writeUint16(0x00)
storage.writeUint32(0x10)
keyDataSaltValue, _ := randomBytes(16)
verifierHashInput, _ := randomBytes(16)
e.SaltValue = keyDataSaltValue
e.EncryptedKeyValue, _ = standardConvertPasswdToKey(
StandardEncryptionHeader{KeySize: e.KeyBits},
StandardEncryptionVerifier{Salt: e.SaltValue},
&Options{Password: password})
verifierHashInputKey := hashing("sha1", verifierHashInput)
e.EncryptedVerifierHashInput = e.encrypt(verifierHashInput)
e.EncryptedVerifierHashValue = e.encrypt(verifierHashInputKey)
storage.writeBytes(e.SaltValue)
storage.writeBytes(e.EncryptedVerifierHashInput)
storage.writeUint32(0x14)
storage.writeBytes(e.EncryptedVerifierHashValue)
storage.position = 0
return storage.stream, nil
}
// ECMA-376 Agile Encryption
// agileDecrypt decrypt the CFB file format with ECMA-376 agile encryption.
// Support cryptographic algorithm: MD4, MD5, RIPEMD-160, SHA1, SHA256,
// SHA384 and SHA512.
func agileDecrypt(encryptionInfoBuf, encryptedPackageBuf []byte, opt *Options) (packageBuf []byte, err error) {
var encryptionInfo Encryption
if encryptionInfo, err = parseEncryptionInfo(encryptionInfoBuf[8:]); err != nil {
return
}
// Convert the password into an encryption key.
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key, err := convertPasswdToKey(opt.Password, blockKey, encryptionInfo)
if err != nil {
return
}
// Use the key to decrypt the package key.
encryptedKey := encryptionInfo.KeyEncryptors.KeyEncryptor[0].EncryptedKey
saltValue, err := base64.StdEncoding.DecodeString(encryptedKey.SaltValue)
if err != nil {
return
}
encryptedKeyValue, err := base64.StdEncoding.DecodeString(encryptedKey.EncryptedKeyValue)
if err != nil {
return
}
packageKey, _ := decrypt(key, saltValue, encryptedKeyValue)
// Use the package key to decrypt the package.
return decryptPackage(packageKey, encryptedPackageBuf, encryptionInfo)
}
// convertPasswdToKey convert the password into an encryption key.
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func convertPasswdToKey(passwd string, blockKey []byte, encryption Encryption) (key []byte, err error) {
var b bytes.Buffer
saltValue, err := base64.StdEncoding.DecodeString(encryption.KeyEncryptors.KeyEncryptor[0].EncryptedKey.SaltValue)
if err != nil {
return
}
b.Write(saltValue)
encoder := unicode.UTF16(unicode.LittleEndian, unicode.IgnoreBOM).NewEncoder()
passwordBuffer, err := encoder.Bytes([]byte(passwd))
if err != nil {
return
}
b.Write(passwordBuffer)
// Generate the initial hash.
key = hashing(encryption.KeyData.HashAlgorithm, b.Bytes())
// Now regenerate until spin count.
for i := 0; i < encryption.KeyEncryptors.KeyEncryptor[0].EncryptedKey.SpinCount; i++ {
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iterator := createUInt32LEBuffer(i, 4)
key = hashing(encryption.KeyData.HashAlgorithm, iterator, key)
}
// Now generate the final hash.
key = hashing(encryption.KeyData.HashAlgorithm, key, blockKey)
// Truncate or pad as needed to get to length of keyBits.
keyBytes := encryption.KeyEncryptors.KeyEncryptor[0].EncryptedKey.KeyBits / 8
if len(key) < keyBytes {
tmp := make([]byte, 0x36)
key = append(key, tmp...)
} else if len(key) > keyBytes {
key = key[:keyBytes]
}
return
}
// hashing data by specified hash algorithm.
func hashing(hashAlgorithm string, buffer ...[]byte) (key []byte) {
hashMap := map[string]hash.Hash{
"md4": md4.New(),
"md5": md5.New(),
"ripemd-160": ripemd160.New(),
"sha1": sha1.New(),
"sha256": sha256.New(),
"sha384": sha512.New384(),
"sha512": sha512.New(),
}
handler, ok := hashMap[strings.ToLower(hashAlgorithm)]
if !ok {
return key
}
for _, buf := range buffer {
_, _ = handler.Write(buf)
}
key = handler.Sum(nil)
return key
}
// createUInt32LEBuffer create buffer with little endian 32-bit unsigned
// integer.
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func createUInt32LEBuffer(value int, bufferSize int) []byte {
buf := make([]byte, bufferSize)
binary.LittleEndian.PutUint32(buf, uint32(value))
return buf
}
// parseEncryptionInfo parse the encryption info XML into an object.
func parseEncryptionInfo(encryptionInfo []byte) (encryption Encryption, err error) {
err = xml.Unmarshal(encryptionInfo, &encryption)
return
}
// decrypt provides a function to decrypt input by given cipher algorithm,
// cipher chaining, key and initialization vector.
func decrypt(key, iv, input []byte) (packageKey []byte, err error) {
block, err := aes.NewCipher(key)
if err != nil {
return input, err
}
cipher.NewCBCDecrypter(block, iv).CryptBlocks(input, input)
return input, nil
}
// decryptPackage decrypt package by given packageKey and encryption
// info.
func decryptPackage(packageKey, input []byte, encryption Encryption) (outputChunks []byte, err error) {
encryptedKey, offset := encryption.KeyData, packageOffset
var i, start, end int
var iv, outputChunk []byte
for end < len(input) {
start = end
end = start + packageEncryptionChunkSize
if end > len(input) {
end = len(input)
}
// Grab the next chunk
var inputChunk []byte
if (end + offset) < len(input) {
inputChunk = input[start+offset : end+offset]
} else {
inputChunk = input[start+offset : end]
}
// Pad the chunk if it is not an integer multiple of the block size
remainder := len(inputChunk) % encryptedKey.BlockSize
if remainder != 0 {
inputChunk = append(inputChunk, make([]byte, encryptedKey.BlockSize-remainder)...)
}
// Create the initialization vector
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iv, err = createIV(i, encryption)
if err != nil {
return
}
// Decrypt the chunk and add it to the array
outputChunk, err = decrypt(packageKey, iv, inputChunk)
if err != nil {
return
}
outputChunks = append(outputChunks, outputChunk...)
i++
}
return
}
// createIV create an initialization vector (IV).
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func createIV(blockKey interface{}, encryption Encryption) ([]byte, error) {
encryptedKey := encryption.KeyData
// Create the block key from the current index
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var blockKeyBuf []byte
if reflect.TypeOf(blockKey).Kind() == reflect.Int {
blockKeyBuf = createUInt32LEBuffer(blockKey.(int), 4)
} else {
blockKeyBuf = blockKey.([]byte)
}
saltValue, err := base64.StdEncoding.DecodeString(encryptedKey.SaltValue)
if err != nil {
return nil, err
}
// Create the initialization vector by hashing the salt with the block key.
// Truncate or pad as needed to meet the block size.
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iv := hashing(encryptedKey.HashAlgorithm, append(saltValue, blockKeyBuf...))
if len(iv) < encryptedKey.BlockSize {
tmp := make([]byte, 0x36)
iv = append(iv, tmp...)
} else if len(iv) > encryptedKey.BlockSize {
iv = iv[:encryptedKey.BlockSize]
}
return iv, nil
}
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// randomBytes returns securely generated random bytes. It will return an
// error if the system's secure random number generator fails to function
// correctly, in which case the caller should not continue.
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func randomBytes(n int) ([]byte, error) {
b := make([]byte, n)
_, err := rand.Read(b)
return b, err
}
// ISO Write Protection Method
// genISOPasswdHash implements the ISO password hashing algorithm by given
// plaintext password, name of the cryptographic hash algorithm, salt value
// and spin count.
func genISOPasswdHash(passwd, hashAlgorithm, salt string, spinCount int) (hashValue, saltValue string, err error) {
if len(passwd) < 1 || len(passwd) > MaxFieldLength {
err = ErrPasswordLengthInvalid
return
}
algorithmName, ok := map[string]string{
"MD4": "md4",
"MD5": "md5",
"SHA-1": "sha1",
"SHA-256": "sha256",
"SHA-384": "sha384",
"SHA-512": "sha512",
}[hashAlgorithm]
if !ok {
err = ErrUnsupportedHashAlgorithm
return
}
var b bytes.Buffer
s, _ := randomBytes(16)
if salt != "" {
if s, err = base64.StdEncoding.DecodeString(salt); err != nil {
return
}
}
b.Write(s)
encoder := unicode.UTF16(unicode.LittleEndian, unicode.IgnoreBOM).NewEncoder()
passwordBuffer, _ := encoder.Bytes([]byte(passwd))
b.Write(passwordBuffer)
// Generate the initial hash.
key := hashing(algorithmName, b.Bytes())
// Now regenerate until spin count.
for i := 0; i < spinCount; i++ {
iterator := createUInt32LEBuffer(i, 4)
key = hashing(algorithmName, key, iterator)
}
hashValue, saltValue = base64.StdEncoding.EncodeToString(key), base64.StdEncoding.EncodeToString(s)
return
}
// Compound File Binary Implements
// cfb structure is used for the compound file binary (CFB) file format writer.
type cfb struct {
stream []byte
position int
}
// writeBytes write bytes in the stream by a given value with an offset.
func (c *cfb) writeBytes(value []byte) {
pos := c.position
for i := 0; i < len(value); i++ {
for j := len(c.stream); j <= i+pos; j++ {
c.stream = append(c.stream, 0)
}
c.stream[i+pos] = value[i]
}
c.position = pos + len(value)
}
// writeUint16 write an uint16 data type bytes in the stream by a given value
// with an offset.
func (c *cfb) writeUint16(value int) {
buf := make([]byte, 2)
binary.LittleEndian.PutUint16(buf, uint16(value))
c.writeBytes(buf)
}
// writeUint32 write an uint32 data type bytes in the stream by a given value
// with an offset.
func (c *cfb) writeUint32(value int) {
buf := make([]byte, 4)
binary.LittleEndian.PutUint32(buf, uint32(value))
c.writeBytes(buf)
}
// writeUint64 write an uint64 data type bytes in the stream by a given value
// with an offset.
func (c *cfb) writeUint64(value int) {
buf := make([]byte, 8)
binary.LittleEndian.PutUint64(buf, uint64(value))
c.writeBytes(buf)
}
// writeBytes write strings in the stream by a given value with an offset.
func (c *cfb) writeStrings(value string) {
encoder := unicode.UTF16(unicode.LittleEndian, unicode.IgnoreBOM).NewEncoder()
buffer, err := encoder.Bytes([]byte(value))
if err != nil {
return
}
c.writeBytes(buffer)
}
// writeVersionStream provides a function to write compound file version
// stream.
func (c *cfb) writeVersionStream() []byte {
var storage cfb
storage.writeUint32(0x3c)
storage.writeStrings("Microsoft.Container.DataSpaces")
storage.writeUint32(0x01)
storage.writeUint32(0x01)
storage.writeUint32(0x01)
return storage.stream
}
// writeDataSpaceMapStream provides a function to write compound file
// DataSpaceMap stream.
func (c *cfb) writeDataSpaceMapStream() []byte {
var storage cfb
storage.writeUint32(0x08)
storage.writeUint32(0x01)
storage.writeUint32(0x68)
storage.writeUint32(0x01)
storage.writeUint32(0x00)
storage.writeUint32(0x20)
storage.writeStrings("EncryptedPackage")
storage.writeUint32(0x32)
storage.writeStrings("StrongEncryptionDataSpace")
storage.writeUint16(0x00)
return storage.stream
}
// writeStrongEncryptionDataSpaceStream provides a function to write compound
// file StrongEncryptionDataSpace stream.
func (c *cfb) writeStrongEncryptionDataSpaceStream() []byte {
var storage cfb
storage.writeUint32(0x08)
storage.writeUint32(0x01)
storage.writeUint32(0x32)
storage.writeStrings("StrongEncryptionTransform")
storage.writeUint16(0x00)
return storage.stream
}
// writePrimaryStream provides a function to write compound file Primary
// stream.
func (c *cfb) writePrimaryStream() []byte {
var storage cfb
storage.writeUint32(0x6C)
storage.writeUint32(0x01)
storage.writeUint32(0x4C)
storage.writeStrings("{FF9A3F03-56EF-4613-BDD5-5A41C1D07246}")
storage.writeUint32(0x4E)
storage.writeUint16(0x00)
storage.writeUint32(0x01)
storage.writeUint32(0x01)
storage.writeUint32(0x01)
storage.writeStrings("AES128")
storage.writeUint32(0x00)
storage.writeUint32(0x04)
return storage.stream
}
// writeFileStream provides a function to write encrypted package in compound
// file by a given buffer and the short sector allocation table.
func (c *cfb) writeFileStream(encryptionInfoBuffer []byte, SSAT []int) ([]byte, []int) {
var (
storage cfb
miniProperties int
stream = make([]byte, 0x100)
)
if encryptionInfoBuffer != nil {
copy(stream, encryptionInfoBuffer)
}
storage.writeBytes(stream)
streamBlocks := len(stream) / 64
if len(stream)%64 > 0 {
streamBlocks++
}
for i := 1; i < streamBlocks; i++ {
SSAT = append(SSAT, i)
}
SSAT = append(SSAT, -2)
miniProperties += streamBlocks
versionStream := make([]byte, 0x80)
version := c.writeVersionStream()
copy(versionStream, version)
storage.writeBytes(versionStream)
versionBlocks := len(versionStream) / 64
if len(versionStream)%64 > 0 {
versionBlocks++
}
for i := 1; i < versionBlocks; i++ {
SSAT = append(SSAT, i+miniProperties)
}
SSAT = append(SSAT, -2)
miniProperties += versionBlocks
dataSpaceMap := make([]byte, 0x80)
dataStream := c.writeDataSpaceMapStream()
copy(dataSpaceMap, dataStream)
storage.writeBytes(dataSpaceMap)
dataSpaceMapBlocks := len(dataSpaceMap) / 64
if len(dataSpaceMap)%64 > 0 {
dataSpaceMapBlocks++
}
for i := 1; i < dataSpaceMapBlocks; i++ {
SSAT = append(SSAT, i+miniProperties)
}
SSAT = append(SSAT, -2)
miniProperties += dataSpaceMapBlocks
dataSpaceStream := c.writeStrongEncryptionDataSpaceStream()
storage.writeBytes(dataSpaceStream)
dataSpaceStreamBlocks := len(dataSpaceStream) / 64
if len(dataSpaceStream)%64 > 0 {
dataSpaceStreamBlocks++
}
for i := 1; i < dataSpaceStreamBlocks; i++ {
SSAT = append(SSAT, i+miniProperties)
}
SSAT = append(SSAT, -2)
miniProperties += dataSpaceStreamBlocks
primaryStream := make([]byte, 0x1C0)
primary := c.writePrimaryStream()
copy(primaryStream, primary)
storage.writeBytes(primaryStream)
primaryBlocks := len(primary) / 64
if len(primary)%64 > 0 {
primaryBlocks++
}
for i := 1; i < primaryBlocks; i++ {
SSAT = append(SSAT, i+miniProperties)
}
SSAT = append(SSAT, -2)
if len(SSAT) < 128 {
for i := len(SSAT); i < 128; i++ {
SSAT = append(SSAT, -1)
}
}
storage.position = 0
return storage.stream, SSAT
}
// writeRootEntry provides a function to write compound file root directory
// entry. The first entry in the first sector of the directory chain
// (also referred to as the first element of the directory array, or stream
// ID #0) is known as the root directory entry, and it is reserved for two
// purposes. First, it provides a root parent for all objects that are
// stationed at the root of the compound file. Second, its function is
// overloaded to store the size and starting sector for the mini stream.
func (c *cfb) writeRootEntry(customSectID int) []byte {
storage := cfb{stream: make([]byte, 128)}
storage.writeStrings("Root Entry")
storage.position = 0x40
storage.writeUint16(0x16)
storage.writeBytes([]byte{5, 0})
storage.writeUint32(-1)
storage.writeUint32(-1)
storage.writeUint32(1)
storage.position = 0x64
storage.writeUint32(0)
storage.writeUint32(0)
storage.writeUint32(0)
storage.writeUint32(0)
storage.writeUint32(customSectID)
storage.writeUint32(0x340)
return storage.stream
}
// writeEncryptionInfo provides a function to write compound file
// writeEncryptionInfo stream. The writeEncryptionInfo stream contains
// detailed information that is used to initialize the cryptography used to
// encrypt the EncryptedPackage stream.
func (c *cfb) writeEncryptionInfo() []byte {
storage := cfb{stream: make([]byte, 128)}
storage.writeStrings("EncryptionInfo")
storage.position = 0x40
storage.writeUint16(0x1E)
storage.writeBytes([]byte{2, 1})
storage.writeUint32(0x03)
storage.writeUint32(0x02)
storage.writeUint32(-1)
storage.position = 0x64
storage.writeUint32(0)
storage.writeUint32(0)
storage.writeUint32(0)
storage.writeUint32(0)
storage.writeUint32(0)
storage.writeUint32(0xF8)
return storage.stream
}
// writeEncryptedPackage provides a function to write compound file
// writeEncryptedPackage stream. The writeEncryptedPackage stream is an
// encrypted stream of bytes containing the entire ECMA-376 source file in
// compressed form.
func (c *cfb) writeEncryptedPackage(propertyCount, size int) []byte {
storage := cfb{stream: make([]byte, 128)}
storage.writeStrings("EncryptedPackage")
storage.position = 0x40
storage.writeUint16(0x22)
storage.writeBytes([]byte{2, 0})
storage.writeUint32(-1)
storage.writeUint32(-1)
storage.writeUint32(-1)
storage.position = 0x64
storage.writeUint32(0)
storage.writeUint32(0)
storage.writeUint32(0)
storage.writeUint32(0)
storage.writeUint32(propertyCount)
storage.writeUint32(size)
return storage.stream
}
// writeDataSpaces provides a function to write compound file writeDataSpaces
// stream. The data spaces structure consists of a set of interrelated
// storages and streams in an OLE compound file.
func (c *cfb) writeDataSpaces() []byte {
storage := cfb{stream: make([]byte, 128)}
storage.writeUint16(0x06)
storage.position = 0x40
storage.writeUint16(0x18)
storage.writeBytes([]byte{1, 0})
storage.writeUint32(-1)
storage.writeUint32(-1)
storage.writeUint32(5)
storage.position = 0x64
storage.writeUint32(0)
storage.writeUint32(0)
storage.writeUint32(0)
storage.writeUint32(0)
storage.writeUint32(0)
storage.writeUint32(0)
return storage.stream
}
// writeVersion provides a function to write compound file version. The
// writeVersion structure specifies the version of a product or feature. It
// contains a major and a minor version number.
func (c *cfb) writeVersion() []byte {
storage := cfb{stream: make([]byte, 128)}
storage.writeStrings("Version")
storage.position = 0x40
storage.writeUint16(0x10)
storage.writeBytes([]byte{2, 1})
storage.writeUint32(-1)
storage.writeUint32(-1)
storage.writeUint32(-1)
storage.position = 0x64
storage.writeUint32(0)
storage.writeUint32(0)
storage.writeUint32(0)
storage.writeUint32(0)
storage.writeUint32(4)
storage.writeUint32(76)
return storage.stream
}
// writeDataSpaceMap provides a function to write compound file
// writeDataSpaceMap stream. The writeDataSpaceMap structure associates
// protected content with data space definitions. The data space definition,
// in turn, describes the series of transforms that MUST be applied to that
// protected content to restore it to its original form. By using a map to
// associate data space definitions with content, a single data space
// definition can be used to define the transforms applied to more than one
// piece of protected content. However, a given piece of protected content can
// be referenced only by a single data space definition.
func (c *cfb) writeDataSpaceMap() []byte {
storage := cfb{stream: make([]byte, 128)}
storage.writeStrings("DataSpaceMap")
storage.position = 0x40
storage.writeUint16(0x1A)
storage.writeBytes([]byte{2, 1})
storage.writeUint32(0x04)
storage.writeUint32(0x06)
storage.writeUint32(-1)
storage.position = 0x64
storage.writeUint32(0)
storage.writeUint32(0)
storage.writeUint32(0)
storage.writeUint32(0)
storage.writeUint32(6)
storage.writeUint32(112)
return storage.stream
}
// writeDataSpaceInfo provides a function to write compound file
// writeDataSpaceInfo storage. The writeDataSpaceInfo is a storage containing
// the data space definitions used in the file. This storage must contain one
// or more streams, each of which contains a DataSpaceDefinition structure.
// The storage must contain exactly one stream for each DataSpaceMapEntry
// structure in the DataSpaceMap stream. The name of each stream must be equal
// to the DataSpaceName field of exactly one DataSpaceMapEntry structure
// contained in the DataSpaceMap stream.
func (c *cfb) writeDataSpaceInfo() []byte {
storage := cfb{stream: make([]byte, 128)}
storage.writeStrings("DataSpaceInfo")
storage.position = 0x40
storage.writeUint16(0x1C)
storage.writeBytes([]byte{1, 1})
storage.writeUint32(-1)
storage.writeUint32(8)
storage.writeUint32(7)
storage.position = 0x64
storage.writeUint32(0)
storage.writeUint32(0)
storage.writeUint32(0)
storage.writeUint32(0)
storage.writeUint32(0)
storage.writeUint32(0)
return storage.stream
}
// writeStrongEncryptionDataSpace provides a function to write compound file
// writeStrongEncryptionDataSpace stream.
func (c *cfb) writeStrongEncryptionDataSpace() []byte {
storage := cfb{stream: make([]byte, 128)}
storage.writeStrings("StrongEncryptionDataSpace")
storage.position = 0x40
storage.writeUint16(0x34)
storage.writeBytes([]byte{2, 1})
storage.writeUint32(-1)
storage.writeUint32(-1)
storage.writeUint32(-1)
storage.position = 0x64
storage.writeUint32(0)
storage.writeUint32(0)
storage.writeUint32(0)
storage.writeUint32(0)
storage.writeUint32(8)
storage.writeUint32(64)
return storage.stream
}
// writeTransformInfo provides a function to write compound file
// writeTransformInfo storage. writeTransformInfo is a storage containing
// definitions for the transforms used in the data space definitions stored in
// the DataSpaceInfo storage. The stream contains zero or more definitions for
// the possible transforms that can be applied to the data in content
// streams.
func (c *cfb) writeTransformInfo() []byte {
storage := cfb{stream: make([]byte, 128)}
storage.writeStrings("TransformInfo")
storage.position = 0x40
storage.writeUint16(0x1C)
storage.writeBytes([]byte{1, 0})
storage.writeUint32(-1)
storage.writeUint32(-1)
storage.writeUint32(9)
storage.position = 0x64
storage.writeUint32(0)
storage.writeUint32(0)
storage.writeUint32(0)
storage.writeUint32(0)
storage.writeUint32(0)
storage.writeUint32(0)
return storage.stream
}
// writeStrongEncryptionTransform provides a function to write compound file
// writeStrongEncryptionTransform storage.
func (c *cfb) writeStrongEncryptionTransform() []byte {
storage := cfb{stream: make([]byte, 128)}
storage.writeStrings("StrongEncryptionTransform")
storage.position = 0x40
storage.writeUint16(0x34)
storage.writeBytes([]byte{1})
storage.writeBytes([]byte{1})
storage.writeUint32(-1)
storage.writeUint32(-1)
storage.writeUint32(0x0A)
storage.position = 0x64
storage.writeUint32(0)
storage.writeUint32(0)
storage.writeUint32(0)
storage.writeUint32(0)
storage.writeUint32(0)
storage.writeUint32(0)
return storage.stream
}
// writePrimary provides a function to write compound file writePrimary stream.
func (c *cfb) writePrimary() []byte {
storage := cfb{stream: make([]byte, 128)}
storage.writeUint16(0x06)
storage.writeStrings("Primary")
storage.position = 0x40
storage.writeUint16(0x12)
storage.writeBytes([]byte{2, 1})
storage.writeUint32(-1)
storage.writeUint32(-1)
storage.writeUint32(-1)
storage.position = 0x64
storage.writeUint32(0)
storage.writeUint32(0)
storage.writeUint32(0)
storage.writeUint32(0)
storage.writeUint32(9)
storage.writeUint32(208)
return storage.stream
}
// writeNoneDir provides a function to write compound file writeNoneDir stream.
func (c *cfb) writeNoneDir() []byte {
storage := cfb{stream: make([]byte, 128)}
storage.position = 0x40
storage.writeUint16(0x00)
storage.writeUint16(0x00)
storage.writeUint32(-1)
storage.writeUint32(-1)
storage.writeUint32(-1)
return storage.stream
}
// writeDirectoryEntry provides a function to write compound file directory
// entries. The directory entry array is an array of directory entries that
// are grouped into a directory sector. Each storage object or stream object
// within a compound file is represented by a single directory entry. The
// space for the directory sectors that are holding the array is allocated
// from the FAT.
func (c *cfb) writeDirectoryEntry(propertyCount, customSectID, size int) []byte {
var storage cfb
if size < 0 {
size = 0
}
for _, entry := range [][]byte{
c.writeRootEntry(customSectID),
c.writeEncryptionInfo(),
c.writeEncryptedPackage(propertyCount, size),
c.writeDataSpaces(),
c.writeVersion(),
c.writeDataSpaceMap(),
c.writeDataSpaceInfo(),
c.writeStrongEncryptionDataSpace(),
c.writeTransformInfo(),
c.writeStrongEncryptionTransform(),
c.writePrimary(),
c.writeNoneDir(),
} {
storage.writeBytes(entry)
}
return storage.stream
}
// writeMSAT provides a function to write compound file master sector allocation
// table.
func (c *cfb) writeMSAT(MSATBlocks, SATBlocks int, MSAT []int) []int {
if MSATBlocks > 0 {
cnt, MSATIdx := MSATBlocks*128+109, 0
for i := 0; i < cnt; i++ {
if i < SATBlocks {
bufferSize := i - 109
if bufferSize > 0 && bufferSize%0x80 == 0 {
MSATIdx++
MSAT = append(MSAT, MSATIdx)
}
MSAT = append(MSAT, i+MSATBlocks)
continue
}
MSAT = append(MSAT, -1)
}
return MSAT
}
for i := 0; i < 109; i++ {
if i < SATBlocks {
MSAT = append(MSAT, i)
continue
}
MSAT = append(MSAT, -1)
}
return MSAT
}
// writeSAT provides a function to write compound file sector allocation
// table.
func (c *cfb) writeSAT(MSATBlocks, SATBlocks, SSATBlocks, directoryBlocks, fileBlocks, streamBlocks int, SAT []int) (int, []int) {
var blocks int
if SATBlocks > 0 {
for i := 1; i <= MSATBlocks; i++ {
SAT = append(SAT, -4)
}
blocks = MSATBlocks
for i := 1; i <= SATBlocks; i++ {
SAT = append(SAT, -3)
}
blocks += SATBlocks
for i := 1; i < SSATBlocks; i++ {
SAT = append(SAT, i)
}
SAT = append(SAT, -2)
blocks += SSATBlocks
for i := 1; i < directoryBlocks; i++ {
SAT = append(SAT, i+blocks)
}
SAT = append(SAT, -2)
blocks += directoryBlocks
for i := 1; i < fileBlocks; i++ {
SAT = append(SAT, i+blocks)
}
SAT = append(SAT, -2)
blocks += fileBlocks
for i := 1; i < streamBlocks; i++ {
SAT = append(SAT, i+blocks)
}
SAT = append(SAT, -2)
}
return blocks, SAT
}
// Writer provides a function to create compound file with given info stream
// and package stream.
//
// MSAT - The master sector allocation table
// SSAT - The short sector allocation table
// SAT - The sector allocation table
func (c *cfb) Writer(encryptionInfoBuffer, encryptedPackage []byte) []byte {
var (
storage cfb
MSAT, SAT, SSAT []int
directoryBlocks, fileBlocks, SSATBlocks = 3, 2, 1
size = int(math.Max(float64(len(encryptedPackage)), float64(packageEncryptionChunkSize)))
streamBlocks = len(encryptedPackage) / 0x200
)
if len(encryptedPackage)%0x200 > 0 {
streamBlocks++
}
propertyBlocks := directoryBlocks + fileBlocks + SSATBlocks
blockSize := (streamBlocks + propertyBlocks) * 4
SATBlocks := blockSize / 0x200
if blockSize%0x200 > 0 {
SATBlocks++
}
MSATBlocks, blocksChanged := 0, true
for blocksChanged {
var SATCap, MSATCap int
blocksChanged = false
blockSize = (streamBlocks + propertyBlocks + SATBlocks + MSATBlocks) * 4
SATCap = blockSize / 0x200
if blockSize%0x200 > 0 {
SATCap++
}
if SATCap > SATBlocks {
SATBlocks, blocksChanged = SATCap, true
continue
}
if SATBlocks > 109 {
blockRemains := (SATBlocks - 109) * 4
blockBuffer := blockRemains % 0x200
MSATCap = blockRemains / 0x200
if blockBuffer > 0 {
MSATCap++
}
if blockBuffer+(4*MSATCap) > 0x200 {
MSATCap++
}
if MSATCap > MSATBlocks {
MSATBlocks, blocksChanged = MSATCap, true
}
}
}
MSAT = c.writeMSAT(MSATBlocks, SATBlocks, MSAT)
blocks, SAT := c.writeSAT(MSATBlocks, SATBlocks, SSATBlocks, directoryBlocks, fileBlocks, streamBlocks, SAT)
for i := 0; i < 8; i++ {
storage.writeBytes([]byte{oleIdentifier[i]})
}
storage.writeBytes(make([]byte, 16))
storage.writeUint16(0x003E)
storage.writeUint16(0x0003)
storage.writeUint16(-2)
storage.writeUint16(9)
storage.writeUint32(6)
storage.writeUint32(0)
storage.writeUint32(0)
storage.writeUint32(SATBlocks)
storage.writeUint32(MSATBlocks + SATBlocks + SSATBlocks)
storage.writeUint32(0)
storage.writeUint32(0x00001000)
storage.writeUint32(SATBlocks + MSATBlocks)
storage.writeUint32(SSATBlocks)
if MSATBlocks > 0 {
storage.writeUint32(0)
storage.writeUint32(MSATBlocks)
} else {
storage.writeUint32(-2)
storage.writeUint32(0)
}
for _, block := range MSAT {
storage.writeUint32(block)
}
for i := 0; i < SATBlocks*128; i++ {
if i < len(SAT) {
storage.writeUint32(SAT[i])
continue
}
storage.writeUint32(-1)
}
fileStream, SSATStream := c.writeFileStream(encryptionInfoBuffer, SSAT)
for _, block := range SSATStream {
storage.writeUint32(block)
}
directoryEntry := c.writeDirectoryEntry(blocks, blocks-fileBlocks, size)
storage.writeBytes(directoryEntry)
storage.writeBytes(fileStream)
storage.writeBytes(encryptedPackage)
return storage.stream
}