/**
* Prepare document for encryption.
*
* @param document The document to encrypt.
*
* @ If there is an error accessing data.
*/
public override void PrepareDocumentForEncryption(Document document)
{
PdfEncryption encryptionDictionary = document.File.Encryption;
if (encryptionDictionary == null)
{
encryptionDictionary = new PdfEncryption(document.File);
}
int version = ComputeVersionNumber();
int revision = ComputeRevisionNumber(version);
encryptionDictionary.Filter = FILTER;
encryptionDictionary.Version = version;
if (version != 4 && version != 5)
{
// remove CF, StmF, and StrF entries that may be left from a previous encryption
encryptionDictionary.RemoveV45filters();
}
encryptionDictionary.Revision = revision;
encryptionDictionary.Length = keyLength;
string ownerPassword = policy.OwnerPassword ?? string.Empty;
string userPassword = policy.UserPassword ?? string.Empty;
// If no owner password is set, use the user password instead.
if (ownerPassword.Length == 0)
{
ownerPassword = userPassword;
}
int permissionInt = policy.Permissions.PermissionBytes;
encryptionDictionary.Permissions = permissionInt;
int length = keyLength / 8;
if (revision == 6)
{
// PDFBOX-4155
ownerPassword = SaslPrep.SaslPrepStored(ownerPassword);
userPassword = SaslPrep.SaslPrepStored(userPassword);
PrepareEncryptionDictRev6(ownerPassword, userPassword, encryptionDictionary, permissionInt);
}
else
{
PrepareEncryptionDictRev2345(ownerPassword, userPassword, encryptionDictionary, permissionInt,
document, revision, length);
}
document.File.Encryption = encryptionDictionary;
}
/**
* Prepares everything to decrypt the document.
*
* Only if decryption of single objects is needed this should be called.
*
* @param encryption encryption dictionary
* @param documentIDArray document id
* @param decryptionMaterial Information used to decrypt the document.
*
* @throws InvalidPasswordException If the password is incorrect.
* @ If there is an error accessing data.
*/
public override void PrepareForDecryption(PdfEncryption encryption, PdfArray documentIDArray, DecryptionMaterial decryptionMaterial)
{
if (!(decryptionMaterial is StandardDecryptionMaterial))
{
throw new IOException("Decryption material is not compatible with the document");
}
// This is only used with security version 4 and 5.
if (encryption.Version >= 4)
{
SetStreamFilterName(encryption.StreamFilterName);
SetStringFilterName(encryption.StreamFilterName);
}
SetDecryptMetadata(encryption.IsEncryptMetaData);
StandardDecryptionMaterial material = (StandardDecryptionMaterial)decryptionMaterial;
string password = material.Password ?? string.Empty;
int dicPermissions = encryption.Permissions;
int dicRevision = encryption.Revision;
int dicLength = encryption.Version == 1 ? 5 : encryption.Length / 8;
byte[] documentIDBytes = GetDocumentIDBytes(documentIDArray);
// we need to know whether the meta data was encrypted for password calculation
bool encryptMetadata = encryption.IsEncryptMetaData;
byte[] userKey = encryption.UserKey;
byte[] ownerKey = encryption.OwnerKey;
byte[] ue = null, oe = null;
var passwordCharset = Charset.ISO88591;
if (dicRevision == 6 || dicRevision == 5)
{
passwordCharset = Charset.UTF8;
ue = encryption.UserEncryptionKey;
oe = encryption.OwnerEncryptionKey;
}
if (dicRevision == 6)
{
password = SaslPrep.SaslPrepQuery(password); // PDFBOX-4155
}
AccessPermission currentAccessPermission;
if (IsOwnerPassword(passwordCharset.GetBytes(password), userKey, ownerKey,
dicPermissions, documentIDBytes, dicRevision,
dicLength, encryptMetadata))
{
currentAccessPermission = AccessPermission.getOwnerAccessPermission();
CurrentAccessPermission = currentAccessPermission;
byte[] computedPassword;
if (dicRevision == 6 || dicRevision == 5)
{
computedPassword = passwordCharset.GetBytes(password);
}
else
{
computedPassword = GetUserPassword(passwordCharset.GetBytes(password),
ownerKey, dicRevision, dicLength);
}
encryptionKey =
ComputeEncryptedKey(
computedPassword,
ownerKey, userKey, oe, ue,
dicPermissions,
documentIDBytes,
dicRevision,
dicLength,
encryptMetadata, true);
}
else if (IsUserPassword(passwordCharset.GetBytes(password), userKey, ownerKey,
dicPermissions, documentIDBytes, dicRevision,
dicLength, encryptMetadata))
{
currentAccessPermission = new AccessPermission(dicPermissions);
currentAccessPermission.IsReadOnly = true;
CurrentAccessPermission = currentAccessPermission;
encryptionKey = ComputeEncryptedKey(
passwordCharset.GetBytes(password),
ownerKey, userKey, oe, ue,
dicPermissions,
documentIDBytes,
dicRevision,
dicLength,
encryptMetadata, false);
}
else
{
throw new InvalidPasswordException("Cannot decrypt PDF, the password is incorrect");
}
if (dicRevision == 6 || dicRevision == 5)
{
ValidatePerms(encryption, dicPermissions, encryptMetadata);
}
if (encryption.Version == 4 || encryption.Version == 5)
{
// detect whether AES encryption is used. This assumes that the encryption algo is
// stored in the PDCryptFilterDictionary
// However, crypt filters are used only when V is 4 or 5.
var stdCryptFilterDictionary = encryption.StdCryptFilterDictionary;
if (stdCryptFilterDictionary != null)
{
PdfName cryptFilterMethod = stdCryptFilterDictionary.CryptFilterMethod;
IsAES = PdfName.AESV2.Equals(cryptFilterMethod) ||
PdfName.AESV3.Equals(cryptFilterMethod);
}
}
}
