private void SetProtectionAttribute(DocumentProtectionValues value)
{
var mainDocumentPart = _wordDocument.MainDocumentPart;
var settingsPart = mainDocumentPart.DocumentSettingsPart ??
CreateDocumentSettingsPart(mainDocumentPart);
var protectionTag = settingsPart.Settings.GetFirstChild <DocumentProtection>() ??
settingsPart.Settings.AppendChild(new DocumentProtection());
protectionTag.Edit = value;
}
private void SetProtectionAttribute(DocumentProtectionValues value)
{
var mainDocumentPart = _wordDocument.MainDocumentPart;
var settingsPart = mainDocumentPart.DocumentSettingsPart ??
CreateDocumentSettingsPart(mainDocumentPart);
var protectionTag = settingsPart.Settings.GetFirstChild<DocumentProtection>() ??
settingsPart.Settings.AppendChild(new DocumentProtection());
protectionTag.Edit = value;
}
public string SetLock(string szFilePath, DocumentProtectionValues objLockType, string strPwd = "")
{
string strResult = string.Empty;
try
{
using (WordprocessingDocument _objDoc = WordprocessingDocument.Open(szFilePath, true))
{
DocumentProtection documentProtection = new DocumentProtection();
documentProtection.Edit = objLockType;
// Generate the Salt
byte[] arrSalt = new byte[16];
RandomNumberGenerator rand = new RNGCryptoServiceProvider();
rand.GetNonZeroBytes(arrSalt);
//Array to hold Key Values
byte[] generatedKey = new byte[4];
//Maximum length of the password is 15 chars.
int intMaxPasswordLength = 15;
if (!string.IsNullOrEmpty(strPwd))
{
// Truncate the password to 15 characters
strPwd = strPwd.Substring(0, Math.Min(strPwd.Length, intMaxPasswordLength));
// Construct a new NULL-terminated string consisting of single-byte characters:
// -- > Get the single-byte values by iterating through the Unicode characters of the truncated Password.
// --> For each character, if the low byte is not equal to 0, take it. Otherwise, take the high byte.
byte[] arrByteChars = new byte[strPwd.Length];
for (int intLoop = 0; intLoop < strPwd.Length; intLoop++)
{
int intTemp = Convert.ToInt32(strPwd[intLoop]);
arrByteChars[intLoop] = Convert.ToByte(intTemp & 0x00FF);
if (arrByteChars[intLoop] == 0)
{
arrByteChars[intLoop] = Convert.ToByte((intTemp & 0xFF00) >> 8);
}
}
// Compute the high-order word of the new key:
// --> Initialize from the initial code array (see below), depending on the strPassword’s length.
int intHighOrderWord = InitialCodeArray[arrByteChars.Length - 1];
// --> For each character in the strPassword:
// --> For every bit in the character, starting with the least significant and progressing to (but excluding)
// the most significant, if the bit is set, XOR the key’s high-order word with the corresponding word from
// the Encryption Matrix
for (int intLoop = 0; intLoop < arrByteChars.Length; intLoop++)
{
int tmp = intMaxPasswordLength - arrByteChars.Length + intLoop;
for (int intBit = 0; intBit < 7; intBit++)
{
if ((arrByteChars[intLoop] & (0x0001 << intBit)) != 0)
{
intHighOrderWord ^= EncryptionMatrix[tmp, intBit];
}
}
}
// Compute the low-order word of the new key:
// Initialize with 0
int intLowOrderWord = 0;
// For each character in the strPassword, going backwards
for (int intLoopChar = arrByteChars.Length - 1; intLoopChar >= 0; intLoopChar--)
{
// low-order word = (((low-order word SHR 14) AND 0x0001) OR (low-order word SHL 1) AND 0x7FFF)) XOR character
intLowOrderWord = (((intLowOrderWord >> 14) & 0x0001) | ((intLowOrderWord << 1) & 0x7FFF)) ^ arrByteChars[intLoopChar];
}
// Lastly,low-order word = (((low-order word SHR 14) AND 0x0001) OR (low-order word SHL 1) AND 0x7FFF)) XOR strPassword length XOR 0xCE4B.
intLowOrderWord = (((intLowOrderWord >> 14) & 0x0001) | ((intLowOrderWord << 1) & 0x7FFF)) ^ arrByteChars.Length ^ 0xCE4B;
// Combine the Low and High Order Word
int intCombinedkey = (intHighOrderWord << 16) + intLowOrderWord;
// The byte order of the result shall be reversed [Example: 0x64CEED7E becomes 7EEDCE64. end example],
// and that value shall be hashed as defined by the attribute values.
for (int intTemp = 0; intTemp < 4; intTemp++)
{
generatedKey[intTemp] = Convert.ToByte(((uint)(intCombinedkey & (0x000000FF << (intTemp * 8)))) >> (intTemp * 8));
}
}
// Implementation Notes List:
// --> In this third stage, the reversed byte order legacy hash from the second stage shall be converted to Unicode hex
// --> string representation
StringBuilder sb = new StringBuilder();
for (int intTemp = 0; intTemp < 4; intTemp++)
{
sb.Append(Convert.ToString(generatedKey[intTemp], 16));
}
generatedKey = Encoding.Unicode.GetBytes(sb.ToString().ToUpper());
// Implementation Notes List:
//Word appends the binary form of the salt attribute and not the base64 string representation when hashing
// Before calculating the initial hash, you are supposed to prepend (not append) the salt to the key
byte[] tmpArray1 = generatedKey;
byte[] tmpArray2 = arrSalt;
byte[] tempKey = new byte[tmpArray1.Length + tmpArray2.Length];
Buffer.BlockCopy(tmpArray2, 0, tempKey, 0, tmpArray2.Length);
Buffer.BlockCopy(tmpArray1, 0, tempKey, tmpArray2.Length, tmpArray1.Length);
generatedKey = tempKey;
// Iterations specifies the number of times the hashing function shall be iteratively run (using each
// iteration's result as the input for the next iteration).
int iterations = 50000;
// Implementation Notes List:
//Word requires that the initial hash of the password with the salt not be considered in the count.
// The initial hash of salt + key is not included in the iteration count.
HashAlgorithm sha1 = new SHA1Managed();
generatedKey = sha1.ComputeHash(generatedKey);
byte[] iterator = new byte[4];
for (int intTmp = 0; intTmp < iterations; intTmp++)
{
//When iterating on the hash, you are supposed to append the current iteration number.
iterator[0] = Convert.ToByte((intTmp & 0x000000FF) >> 0);
iterator[1] = Convert.ToByte((intTmp & 0x0000FF00) >> 8);
iterator[2] = Convert.ToByte((intTmp & 0x00FF0000) >> 16);
iterator[3] = Convert.ToByte((intTmp & 0xFF000000) >> 24);
generatedKey = concatByteArrays(iterator, generatedKey);
generatedKey = sha1.ComputeHash(generatedKey);
}
DocumentFormat.OpenXml.OnOffValue docProtection = new DocumentFormat.OpenXml.OnOffValue(true);
documentProtection.Enforcement = docProtection;
documentProtection.CryptographicAlgorithmClass = CryptAlgorithmClassValues.Hash;
documentProtection.CryptographicProviderType = CryptProviderValues.RsaFull;
documentProtection.CryptographicAlgorithmType = CryptAlgorithmValues.TypeAny;
documentProtection.CryptographicAlgorithmSid = 4; // SHA1
// The iteration count is unsigned
UInt32 uintVal = new UInt32();
uintVal = (uint)iterations;
documentProtection.CryptographicSpinCount = uintVal;
documentProtection.Hash = Convert.ToBase64String(generatedKey);
documentProtection.Salt = Convert.ToBase64String(arrSalt);
_objDoc.MainDocumentPart.DocumentSettingsPart.Settings.AppendChild(documentProtection);
_objDoc.MainDocumentPart.DocumentSettingsPart.Settings.Save();
_objDoc.Close();
}
}
catch (Exception ex)
{
strResult = ex.Message;
}
return(strResult);
}
