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///////////////////////////////////////////////////////////////////////////////
// Name: pdfencrypt.cpp
// Purpose:
// Author: Ulrich Telle
// Modified by:
// Created: 2005-08-17
// RCS-ID: $$
// Copyright: (c) Ulrich Telle
// Licence: wxWindows licence
///////////////////////////////////////////////////////////////////////////////
/// \file pdfencrypt.cpp Implementation of the wxPdfEncrypt class
// For compilers that support precompilation, includes <wx.h>.
#include <wx/wxprec.h>
#ifdef __BORLANDC__
#pragma hdrstop
#endif
#ifndef WX_PRECOMP
#include <wx/wx.h>
#endif
// includes
#include <wx/log.h>
#include "wx/pdfencrypt.h"
#include "wx/pdfrijndael.h"
#include "wx/pdfutility.h"
#define MD5_HASHBYTES 16
/*
* This is an OpenSSL-compatible implementation of the RSA Data Security, Inc.
* MD5 Message-Digest Algorithm (RFC 1321).
*
* Homepage:
* http://openwall.info/wiki/people/solar/software/public-domain-source-code/md5
*
* Author:
* Alexander Peslyak, better known as Solar Designer <solar at openwall.com>
*
* This software was written by Alexander Peslyak in 2001. No copyright is
* claimed, and the software is hereby placed in the public domain.
* In case this attempt to disclaim copyright and place the software in the
* public domain is deemed null and void, then the software is
* Copyright (c) 2001 Alexander Peslyak and it is hereby released to the
* general public under the following terms:
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted.
*
* There's ABSOLUTELY NO WARRANTY, express or implied.
*
* (This is a heavily cut-down "BSD license".)
*
* This differs from Colin Plumb's older public domain implementation in that
* no exactly 32-bit integer data type is required (any 32-bit or wider
* unsigned integer data type will do), there's no compile-time endianness
* configuration, and the function prototypes match OpenSSL's. No code from
* Colin Plumb's implementation has been reused; this comment merely compares
* the properties of the two independent implementations.
*
* The primary goals of this implementation are portability and ease of use.
* It is meant to be fast, but not as fast as possible. Some known
* optimizations are not included to reduce source code size and avoid
* compile-time configuration.
*/
#include <string.h>
/* Any 32-bit or wider unsigned integer data type will do */
typedef unsigned int MD5_u32plus;
typedef struct {
MD5_u32plus lo, hi;
MD5_u32plus a, b, c, d;
unsigned char buffer[64];
MD5_u32plus block[16];
} MD5_CTX;
static void MD5_Init(MD5_CTX *ctx);
static void MD5_Update(MD5_CTX *ctx, const void *data, unsigned long size);
static void MD5_Final(unsigned char *result, MD5_CTX *ctx);
/*
* The basic MD5 functions.
*
* F and G are optimized compared to their RFC 1321 definitions for
* architectures that lack an AND-NOT instruction, just like in Colin Plumb's
* implementation.
*/
#define F(x, y, z) ((z) ^ ((x) & ((y) ^ (z))))
#define G(x, y, z) ((y) ^ ((z) & ((x) ^ (y))))
#define H(x, y, z) (((x) ^ (y)) ^ (z))
#define H2(x, y, z) ((x) ^ ((y) ^ (z)))
#define I(x, y, z) ((y) ^ ((x) | ~(z)))
/*
* The MD5 transformation for all four rounds.
*/
#define STEP(f, a, b, c, d, x, t, s) \
(a) += f((b), (c), (d)) + (x) + (t); \
(a) = (((a) << (s)) | (((a) & 0xffffffff) >> (32 - (s)))); \
(a) += (b);
/*
* SET reads 4 input bytes in little-endian byte order and stores them
* in a properly aligned word in host byte order.
*
* The check for little-endian architectures that tolerate unaligned
* memory accesses is just an optimization. Nothing will break if it
* doesn't work.
*/
#if defined(__i386__) || defined(__x86_64__) || defined(__vax__)
#define SET(n) \
(*(MD5_u32plus *)&ptr[(n) * 4])
#define GET(n) \
SET(n)
#else
#define SET(n) \
(ctx->block[(n)] = \
(MD5_u32plus)ptr[(n) * 4] | \
((MD5_u32plus)ptr[(n) * 4 + 1] << 8) | \
((MD5_u32plus)ptr[(n) * 4 + 2] << 16) | \
((MD5_u32plus)ptr[(n) * 4 + 3] << 24))
#define GET(n) \
(ctx->block[(n)])
#endif
/*
* This processes one or more 64-byte data blocks, but does NOT update
* the bit counters. There are no alignment requirements.
*/
static const void *body(MD5_CTX *ctx, const void *data, unsigned long size)
{
const unsigned char *ptr;
MD5_u32plus a, b, c, d;
MD5_u32plus saved_a, saved_b, saved_c, saved_d;
ptr = (const unsigned char *)data;
a = ctx->a;
b = ctx->b;
c = ctx->c;
d = ctx->d;
do {
saved_a = a;
saved_b = b;
saved_c = c;
saved_d = d;
/* Round 1 */
STEP(F, a, b, c, d, SET(0), 0xd76aa478, 7)
STEP(F, d, a, b, c, SET(1), 0xe8c7b756, 12)
STEP(F, c, d, a, b, SET(2), 0x242070db, 17)
STEP(F, b, c, d, a, SET(3), 0xc1bdceee, 22)
STEP(F, a, b, c, d, SET(4), 0xf57c0faf, 7)
STEP(F, d, a, b, c, SET(5), 0x4787c62a, 12)
STEP(F, c, d, a, b, SET(6), 0xa8304613, 17)
STEP(F, b, c, d, a, SET(7), 0xfd469501, 22)
STEP(F, a, b, c, d, SET(8), 0x698098d8, 7)
STEP(F, d, a, b, c, SET(9), 0x8b44f7af, 12)
STEP(F, c, d, a, b, SET(10), 0xffff5bb1, 17)
STEP(F, b, c, d, a, SET(11), 0x895cd7be, 22)
STEP(F, a, b, c, d, SET(12), 0x6b901122, 7)
STEP(F, d, a, b, c, SET(13), 0xfd987193, 12)
STEP(F, c, d, a, b, SET(14), 0xa679438e, 17)
STEP(F, b, c, d, a, SET(15), 0x49b40821, 22)
/* Round 2 */
STEP(G, a, b, c, d, GET(1), 0xf61e2562, 5)
STEP(G, d, a, b, c, GET(6), 0xc040b340, 9)
STEP(G, c, d, a, b, GET(11), 0x265e5a51, 14)
STEP(G, b, c, d, a, GET(0), 0xe9b6c7aa, 20)
STEP(G, a, b, c, d, GET(5), 0xd62f105d, 5)
STEP(G, d, a, b, c, GET(10), 0x02441453, 9)
STEP(G, c, d, a, b, GET(15), 0xd8a1e681, 14)
STEP(G, b, c, d, a, GET(4), 0xe7d3fbc8, 20)
STEP(G, a, b, c, d, GET(9), 0x21e1cde6, 5)
STEP(G, d, a, b, c, GET(14), 0xc33707d6, 9)
STEP(G, c, d, a, b, GET(3), 0xf4d50d87, 14)
STEP(G, b, c, d, a, GET(8), 0x455a14ed, 20)
STEP(G, a, b, c, d, GET(13), 0xa9e3e905, 5)
STEP(G, d, a, b, c, GET(2), 0xfcefa3f8, 9)
STEP(G, c, d, a, b, GET(7), 0x676f02d9, 14)
STEP(G, b, c, d, a, GET(12), 0x8d2a4c8a, 20)
/* Round 3 */
STEP(H, a, b, c, d, GET(5), 0xfffa3942, 4)
STEP(H2, d, a, b, c, GET(8), 0x8771f681, 11)
STEP(H, c, d, a, b, GET(11), 0x6d9d6122, 16)
STEP(H2, b, c, d, a, GET(14), 0xfde5380c, 23)
STEP(H, a, b, c, d, GET(1), 0xa4beea44, 4)
STEP(H2, d, a, b, c, GET(4), 0x4bdecfa9, 11)
STEP(H, c, d, a, b, GET(7), 0xf6bb4b60, 16)
STEP(H2, b, c, d, a, GET(10), 0xbebfbc70, 23)
STEP(H, a, b, c, d, GET(13), 0x289b7ec6, 4)
STEP(H2, d, a, b, c, GET(0), 0xeaa127fa, 11)
STEP(H, c, d, a, b, GET(3), 0xd4ef3085, 16)
STEP(H2, b, c, d, a, GET(6), 0x04881d05, 23)
STEP(H, a, b, c, d, GET(9), 0xd9d4d039, 4)
STEP(H2, d, a, b, c, GET(12), 0xe6db99e5, 11)
STEP(H, c, d, a, b, GET(15), 0x1fa27cf8, 16)
STEP(H2, b, c, d, a, GET(2), 0xc4ac5665, 23)
/* Round 4 */
STEP(I, a, b, c, d, GET(0), 0xf4292244, 6)
STEP(I, d, a, b, c, GET(7), 0x432aff97, 10)
STEP(I, c, d, a, b, GET(14), 0xab9423a7, 15)
STEP(I, b, c, d, a, GET(5), 0xfc93a039, 21)
STEP(I, a, b, c, d, GET(12), 0x655b59c3, 6)
STEP(I, d, a, b, c, GET(3), 0x8f0ccc92, 10)
STEP(I, c, d, a, b, GET(10), 0xffeff47d, 15)
STEP(I, b, c, d, a, GET(1), 0x85845dd1, 21)
STEP(I, a, b, c, d, GET(8), 0x6fa87e4f, 6)
STEP(I, d, a, b, c, GET(15), 0xfe2ce6e0, 10)
STEP(I, c, d, a, b, GET(6), 0xa3014314, 15)
STEP(I, b, c, d, a, GET(13), 0x4e0811a1, 21)
STEP(I, a, b, c, d, GET(4), 0xf7537e82, 6)
STEP(I, d, a, b, c, GET(11), 0xbd3af235, 10)
STEP(I, c, d, a, b, GET(2), 0x2ad7d2bb, 15)
STEP(I, b, c, d, a, GET(9), 0xeb86d391, 21)
a += saved_a;
b += saved_b;
c += saved_c;
d += saved_d;
ptr += 64;
} while (size -= 64);
ctx->a = a;
ctx->b = b;
ctx->c = c;
ctx->d = d;
return ptr;
}
void MD5_Init(MD5_CTX *ctx)
{
ctx->a = 0x67452301;
ctx->b = 0xefcdab89;
ctx->c = 0x98badcfe;
ctx->d = 0x10325476;
ctx->lo = 0;
ctx->hi = 0;
}
void MD5_Update(MD5_CTX *ctx, const void *data, unsigned long size)
{
MD5_u32plus saved_lo;
unsigned long used, available;
saved_lo = ctx->lo;
if ((ctx->lo = (saved_lo + size) & 0x1fffffff) < saved_lo)
ctx->hi++;
ctx->hi += size >> 29;
used = saved_lo & 0x3f;
if (used) {
available = 64 - used;
if (size < available) {
memcpy(&ctx->buffer[used], data, size);
return;
}
memcpy(&ctx->buffer[used], data, available);
data = (const unsigned char *)data + available;
size -= available;
body(ctx, ctx->buffer, 64);
}
if (size >= 64) {
data = body(ctx, data, size & ~(unsigned long)0x3f);
size &= 0x3f;
}
memcpy(ctx->buffer, data, size);
}
void MD5_Final(unsigned char *result, MD5_CTX *ctx)
{
unsigned long used, available;
used = ctx->lo & 0x3f;
ctx->buffer[used++] = 0x80;
available = 64 - used;
if (available < 8) {
memset(&ctx->buffer[used], 0, available);
body(ctx, ctx->buffer, 64);
used = 0;
available = 64;
}
memset(&ctx->buffer[used], 0, available - 8);
ctx->lo <<= 3;
ctx->buffer[56] = ctx->lo;
ctx->buffer[57] = ctx->lo >> 8;
ctx->buffer[58] = ctx->lo >> 16;
ctx->buffer[59] = ctx->lo >> 24;
ctx->buffer[60] = ctx->hi;
ctx->buffer[61] = ctx->hi >> 8;
ctx->buffer[62] = ctx->hi >> 16;
ctx->buffer[63] = ctx->hi >> 24;
body(ctx, ctx->buffer, 64);
result[0] = ctx->a;
result[1] = ctx->a >> 8;
result[2] = ctx->a >> 16;
result[3] = ctx->a >> 24;
result[4] = ctx->b;
result[5] = ctx->b >> 8;
result[6] = ctx->b >> 16;
result[7] = ctx->b >> 24;
result[8] = ctx->c;
result[9] = ctx->c >> 8;
result[10] = ctx->c >> 16;
result[11] = ctx->c >> 24;
result[12] = ctx->d;
result[13] = ctx->d >> 8;
result[14] = ctx->d >> 16;
result[15] = ctx->d >> 24;
memset(ctx, 0, sizeof(*ctx));
}
// ---------------------------
// wxPdfEncrypt implementation
// ---------------------------
static unsigned char padding[] =
"\x28\xBF\x4E\x5E\x4E\x75\x8A\x41\x64\x00\x4E\x56\xFF\xFA\x01\x08\x2E\x2E\x00\xB6\xD0\x68\x3E\x80\x2F\x0C\xA9\xFE\x64\x53\x69\x7A";
wxPdfEncrypt::wxPdfEncrypt(int revision, int keyLength)
{
switch (revision)
{
case 4:
m_rValue = 4;
m_keyLength = 128 / 8;
m_aes = new wxPdfRijndael();
break;
case 3:
keyLength = keyLength - keyLength % 8;
keyLength = (keyLength >= 40) ? ((keyLength <= 128) ? keyLength : 128) : 40;
m_rValue = 3;
m_keyLength = keyLength / 8;
break;
case 2:
default:
m_rValue = 2;
m_keyLength = 40 / 8;
break;
}
int j;
for (j = 0; j < 16; j++)
{
m_rc4key[j] = 0;
}
}
wxPdfEncrypt::~wxPdfEncrypt()
{
if (m_rValue == 4)
{
delete m_aes;
}
}
void
wxPdfEncrypt::PadPassword(const wxString& password, unsigned char pswd[32])
{
unsigned int m = (unsigned int) password.Length();
if (m > 32) m = 32;
unsigned int j;
unsigned int p = 0;
wxString::const_iterator ch = password.begin();
for (j = 0; j < m; j++)
{
pswd[p++] = (unsigned char) ((unsigned int) (*ch) & 0xff);
++ch;
}
for (j = 0; p < 32 && j < 32; j++)
{
pswd[p++] = padding[j];
}
}
void
wxPdfEncrypt::GenerateEncryptionKey(const wxString& userPassword,
const wxString& ownerPassword,
int protection,
const wxString& documentId)
{
unsigned char userpswd[32];
unsigned char ownerpswd[32];
// Pad passwords
PadPassword(userPassword, userpswd);
PadPassword(ownerPassword, ownerpswd);
// Compute P value
m_pValue = -((protection ^ 255) + 1);
// Compute O value
ComputeOwnerKey(userpswd, ownerpswd, m_keyLength*8, m_rValue, false, m_oValue);
// Compute encryption key and U value
if (documentId.IsEmpty())
{
m_documentId = CreateDocumentId();
}
else
{
m_documentId = documentId;
}
ComputeEncryptionKey(m_documentId, userpswd,
m_oValue, m_pValue, m_keyLength*8, m_rValue, m_uValue);
}
bool
wxPdfEncrypt::Authenticate(const wxString& documentID, const wxString& password,
const wxString& uValue, const wxString& oValue,
int pValue, int lengthValue, int rValue)
{
unsigned char userKey[32];
bool ok = false;
int j;
wxString::const_iterator uChar = uValue.begin();
wxString::const_iterator oChar = oValue.begin();
for (j = 0; j < 32; j++)
{
m_uValue[j] = (unsigned char) ((unsigned int) (*uChar) & 0xff);
m_oValue[j] = (unsigned char) ((unsigned int) (*oChar) & 0xff);
++uChar;
++oChar;
}
m_pValue = pValue;
m_keyLength = lengthValue / 8;
// Pad password
unsigned char pswd[32];
PadPassword(password, pswd);
// Check password: 1) as user password, 2) as owner password
ComputeEncryptionKey(documentID, pswd, m_oValue, pValue, lengthValue, rValue, userKey);
ok = CheckKey(userKey, m_uValue);
if (!ok)
{
unsigned char userpswd[32];
ComputeOwnerKey(m_oValue, pswd, lengthValue, rValue, true, userpswd);
ComputeEncryptionKey(documentID, userpswd, m_oValue, pValue, lengthValue, rValue, userKey);
ok = CheckKey(userKey, m_uValue);
}
return ok;
}
void
wxPdfEncrypt::ComputeOwnerKey(unsigned char userPad[32], unsigned char ownerPad[32],
unsigned int keyLength, int revision, bool authenticate,
unsigned char ownerKey[32])
{
unsigned char mkey[MD5_HASHBYTES];
unsigned char digest[MD5_HASHBYTES];
unsigned int length = keyLength / 8;
MD5_CTX ctx;
MD5_Init(&ctx);
MD5_Update(&ctx, ownerPad, 32);
MD5_Final(digest,&ctx);
if (revision == 3 || revision == 4)
{
// only use for the input as many bit as the key consists of
unsigned int k;
for (k = 0; k < 50; ++k)
{
MD5_Init(&ctx);
MD5_Update(&ctx, digest, length);
MD5_Final(digest,&ctx);
}
memcpy(ownerKey, userPad, 32);
unsigned int i;
unsigned int j;
for (i = 0; i < 20; ++i)
{
for (j = 0; j < length ; ++j)
{
if (authenticate)
{
mkey[j] = (digest[j] ^ (19-i));
}
else
{
mkey[j] = (digest[j] ^ i);
}
}
RC4(mkey, length, ownerKey, 32, ownerKey);
}
}
else
{
RC4(digest, 5, userPad, 32, ownerKey);
}
}
void
wxPdfEncrypt::ComputeEncryptionKey(const wxString& documentId,
unsigned char userPad[32], unsigned char ownerKey[32],
int pValue, unsigned int keyLength, int revision,
unsigned char userKey[32])
{
unsigned int k;
m_keyLength = keyLength / 8;
MD5_CTX ctx;
MD5_Init(&ctx);
MD5_Update(&ctx, userPad, 32);
MD5_Update(&ctx, ownerKey, 32);
unsigned char ext[4];
ext[0] = (unsigned char) ( pValue & 0xff);
ext[1] = (unsigned char) ((pValue >> 8) & 0xff);
ext[2] = (unsigned char) ((pValue >> 16) & 0xff);
ext[3] = (unsigned char) ((pValue >> 24) & 0xff);
MD5_Update(&ctx, ext, 4);
unsigned int docIdLength = (unsigned int) documentId.Length();
unsigned char* docId = NULL;
if (docIdLength > 0)
{
docId = new unsigned char[docIdLength];
unsigned int j;
wxString::const_iterator dChar = documentId.begin();
for (j = 0; j < docIdLength; j++)
{
docId[j] = (unsigned char) ((unsigned int) (*dChar) & 0xff);
++dChar;
}
MD5_Update(&ctx, docId, docIdLength);
}
// TODO: (Revision 3 or greater) If document metadata is not being encrypted,
// pass 4 bytes with the value 0xFFFFFFFF to the MD5 hash function.
unsigned char digest[MD5_HASHBYTES];
MD5_Final(digest,&ctx);
// only use the really needed bits as input for the hash
if (revision == 3 || revision == 4)
{
for (k = 0; k < 50; ++k)
{
MD5_Init(&ctx);
MD5_Update(&ctx, digest, m_keyLength);
MD5_Final(digest, &ctx);
}
}
memcpy(m_encryptionKey, digest, m_keyLength);
// Setup user key
if (revision == 3 || revision == 4)
{
MD5_Init(&ctx);
MD5_Update(&ctx, padding, 32);
if (docId != NULL)
{
MD5_Update(&ctx, docId, docIdLength);
}
MD5_Final(digest, &ctx);
memcpy(userKey, digest, 16);
for (k = 16; k < 32; ++k)
{
userKey[k] = 0;
}
for (k = 0; k < 20; k++)
{
unsigned int j;
for (j = 0; j < m_keyLength; ++j)
{
digest[j] = (unsigned char)(m_encryptionKey[j] ^ k);
}
RC4(digest, m_keyLength, userKey, 16, userKey);
}
}
else
{
RC4(m_encryptionKey, m_keyLength, padding, 32, userKey);
}
if (docId != NULL)
{
delete [] docId;
}
}
bool
wxPdfEncrypt::CheckKey(unsigned char key1[32], unsigned char key2[32])
{
// Check whether the right password had been given
bool ok = true;
int k;
int kmax = (m_rValue == 3) ? 16 : 32;
for (k = 0; ok && k < kmax; k++)
{
ok = ok && (key1[k] == key2[k]);
}
return ok;
}
void
wxPdfEncrypt::Encrypt(int n, int g, wxString& str)
{
unsigned int len = (unsigned int) str.Length();
unsigned char* data = new unsigned char[len];
unsigned int j;
for (j = 0; j < len; j++)
{
data[j] = (unsigned char) str.GetChar(j);
}
Encrypt(n, g, data, len);
for (j = 0; j < len; j++)
{
str.SetChar(j, data[j]);
}
delete [] data;
}
void
wxPdfEncrypt::Encrypt(int n, int g, unsigned char* str, unsigned int len)
{
unsigned char objkey[MD5_HASHBYTES];
unsigned char nkey[MD5_HASHBYTES+5+4];
unsigned int nkeylen = m_keyLength + 5;
unsigned int j;
for (j = 0; j < m_keyLength; j++)
{
nkey[j] = m_encryptionKey[j];
}
nkey[m_keyLength+0] = 0xff & n;
nkey[m_keyLength+1] = 0xff & (n >> 8);
nkey[m_keyLength+2] = 0xff & (n >> 16);
nkey[m_keyLength+3] = 0xff & g;
nkey[m_keyLength+4] = 0xff & (g >> 8);
if (m_rValue == 4)
{
// AES encryption needs some 'salt'
nkeylen += 4;
nkey[m_keyLength+5] = 0x73;
nkey[m_keyLength+6] = 0x41;
nkey[m_keyLength+7] = 0x6c;
nkey[m_keyLength+8] = 0x54;
}
GetMD5Binary(nkey, nkeylen, objkey);
int keylen = (m_keyLength <= 11) ? m_keyLength+5 : 16;
switch (m_rValue)
{
case 4:
AES(objkey, keylen, str, len, str);
break;
case 3:
case 2:
default:
RC4(objkey, keylen, str, len, str);
break;
}
}
/**
* RC4 is the standard encryption algorithm used in PDF format
*/
void
wxPdfEncrypt::RC4(unsigned char* key, unsigned int keylen,
unsigned char* textin, unsigned int textlen,
unsigned char* textout)
{
unsigned int i;
unsigned int j;
int t;
unsigned char rc4[256];
if (memcmp(key,m_rc4key,keylen) != 0)
{
for (i = 0; i < 256; i++)
{
rc4[i] = i;
}
j = 0;
for (i = 0; i < 256; i++)
{
t = rc4[i];
j = (j + t + key[i % keylen]) % 256;
rc4[i] = rc4[j];
rc4[j] = t;
}
memcpy(m_rc4key,key,keylen);
memcpy(m_rc4last,rc4,256);
}
else
{
memcpy(rc4,m_rc4last,256);
}
int a = 0;
int b = 0;
unsigned char k;
for (i = 0; i < textlen; i++)
{
a = (a + 1) % 256;
t = rc4[a];
b = (b + t) % 256;
rc4[a] = rc4[b];
rc4[b] = t;
k = rc4[(rc4[a] + rc4[b]) % 256];
textout[i] = textin[i] ^ k;
}
}
void
wxPdfEncrypt::GetMD5Binary(const unsigned char* data, unsigned int length, unsigned char* digest)
{
MD5_CTX ctx;
MD5_Init(&ctx);
MD5_Update(&ctx, data, length);
MD5_Final(digest,&ctx);
}
void
wxPdfEncrypt::AES(unsigned char* key, unsigned int keylen,
unsigned char* textin, unsigned int textlen,
unsigned char* textout)
{
wxUnusedVar(keylen);
GenerateInitialVector(textout);
m_aes->init(wxPdfRijndael::CBC, wxPdfRijndael::Encrypt, key, wxPdfRijndael::Key16Bytes, textout);
size_t offset = CalculateStreamOffset();
int len = m_aes->padEncrypt(&textin[offset], textlen, &textout[offset]);
// It is a good idea to check the error code
if (len < 0)
{
wxLogError(wxString(wxT("wxPdfEncrypt::AES: ")) +
wxString(_("Error on encrypting.")));
}
}
void
wxPdfEncrypt::GenerateInitialVector(unsigned char iv[16])
{
wxString keyString = wxPdfUtility::GetUniqueId();
#if wxUSE_UNICODE
wxCharBuffer cb(keyString.ToAscii());
const char* key = (const char*) cb;
#else
const char* key = (const char*) keyString.c_str();
#endif
GetMD5Binary((const unsigned char*) key, (unsigned int) keyString.Length(), iv);
}
size_t
wxPdfEncrypt::CalculateStreamLength(size_t length)
{
size_t realLength = length;
if (m_rValue == 4)
{
// realLength = (length % 0x7ffffff0) + 32;
realLength = ((length + 15) & ~15) + 16;
if (length % 16 == 0)
{
realLength += 16;
}
}
return realLength;
}
size_t
wxPdfEncrypt::CalculateStreamOffset()
{
size_t offset = 0;
if (m_rValue == 4)
{
offset = 16;
}
return offset;
}
wxString
wxPdfEncrypt::CreateDocumentId()
{
wxString documentId;
unsigned char id[16];
GenerateInitialVector(id);
int k;
for (k = 0; k < 16; k++)
{
documentId.Append(wxChar(id[k]));
}
return documentId;
}
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