Synched with Xpdf 0.92

this adds "decryption" support
testing this code after six weeks immediately gives me segfaults (image drawing) :-O
must have fixed that later without knowing :-O

1 files changed, 304 insertions, 0 deletions

diff --git a/pdf/xpdf/Decrypt.cc b/pdf/xpdf/Decrypt.cc
new file mode 100644
index 0000000..ae9b732
--- /dev/null
+++ b/pdf/xpdf/Decrypt.cc
@@ -0,0 +1,304 @@
+//========================================================================
+//
+// Decrypt.cc
+//
+// Copyright 1996 Derek B. Noonburg
+//
+//========================================================================
+
+#ifdef __GNUC__
+#pragma implementation
+#endif
+
+#include "gmem.h"
+#include "Decrypt.h"
+
+static void rc4InitKey(Guchar *key, int keyLen, Guchar *state);
+static Guchar rc4DecryptByte(Guchar *state, Guchar *x, Guchar *y, Guchar c);
+static void md5(Guchar *msg, int msgLen, Guchar *digest);
+
+static Guchar passwordPad[32] = {
+  0x28, 0xbf, 0x4e, 0x5e, 0x4e, 0x75, 0x8a, 0x41,
+  0x64, 0x00, 0x4e, 0x56, 0xff, 0xfa, 0x01, 0x08, 
+  0x2e, 0x2e, 0x00, 0xb6, 0xd0, 0x68, 0x3e, 0x80, 
+  0x2f, 0x0c, 0xa9, 0xfe, 0x64, 0x53, 0x69, 0x7a
+};
+
+//------------------------------------------------------------------------
+// Decrypt
+//------------------------------------------------------------------------
+
+Decrypt::Decrypt(Guchar *fileKey, int objNum, int objGen) {
+  // construct object key
+  objKey[0] = fileKey[0];
+  objKey[1] = fileKey[1];
+  objKey[2] = fileKey[2];
+  objKey[3] = fileKey[3];
+  objKey[4] = fileKey[4];
+  objKey[5] = objNum & 0xff;
+  objKey[6] = (objNum >> 8) & 0xff;
+  objKey[7] = (objNum >> 16) & 0xff;
+  objKey[8] = objGen & 0xff;
+  objKey[9] = (objGen >> 8) & 0xff;
+  md5(objKey, 10, objKey);
+
+  // set up for decryption
+  x = y = 0;
+  rc4InitKey(objKey, 10, state);
+}
+
+void Decrypt::reset() {
+  x = y = 0;
+  rc4InitKey(objKey, 10, state);
+}
+
+Guchar Decrypt::decryptByte(Guchar c) {
+  return rc4DecryptByte(state, &x, &y, c);
+}
+
+GBool Decrypt::makeFileKey(GString *ownerKey, GString *userKey,
+			   int permissions, GString *fileID,
+			   GString *userPassword, Guchar *fileKey) {
+  Guchar *buf;
+  Guchar userTest[32];
+  Guchar fState[256];
+  Guchar fx, fy;
+  int len, i;
+  GBool ok;
+
+  // generate file key
+  buf = (Guchar *)gmalloc(68 + fileID->getLength());
+  if (userPassword) {
+    len = userPassword->getLength();
+    if (len < 32) {
+      memcpy(buf, userPassword->getCString(), len);
+      memcpy(buf + len, passwordPad, 32 - len);
+    } else {
+      memcpy(buf, userPassword->getCString(), 32);
+    }
+  } else {
+    memcpy(buf, passwordPad, 32);
+  }
+  memcpy(buf + 32, ownerKey->getCString(), 32);
+  buf[64] = permissions & 0xff;
+  buf[65] = (permissions >> 8) & 0xff;
+  buf[66] = (permissions >> 16) & 0xff;
+  buf[67] = (permissions >> 24) & 0xff;
+  memcpy(buf + 68, fileID->getCString(), fileID->getLength());
+  md5(buf, 68 + fileID->getLength(), fileKey);
+
+  // test user key
+  fx = fy = 0;
+  rc4InitKey(fileKey, 5, fState);
+  for (i = 0; i < 32; ++i) {
+    userTest[i] = rc4DecryptByte(fState, &fx, &fy, userKey->getChar(i));
+  }
+  ok = memcmp(userTest, passwordPad, 32) == 0;
+  gfree(buf);
+
+  return ok;
+}
+
+//------------------------------------------------------------------------
+// RC4-compatible decryption
+//------------------------------------------------------------------------
+
+static void rc4InitKey(Guchar *key, int keyLen, Guchar *state) {
+  Guchar index1, index2;
+  Guchar t;
+  int i;
+
+  for (i = 0; i < 256; ++i)
+    state[i] = i;
+  index1 = index2 = 0;
+  for (i = 0; i < 256; ++i) {
+    index2 = (key[index1] + state[i] + index2) % 256;
+    t = state[i];
+    state[i] = state[index2];
+    state[index2] = t;
+    index1 = (index1 + 1) % keyLen;
+  }
+}
+
+static Guchar rc4DecryptByte(Guchar *state, Guchar *x, Guchar *y, Guchar c) {
+  Guchar x1, y1, tx, ty;
+
+  x1 = *x = (*x + 1) % 256;
+  y1 = *y = (state[*x] + *y) % 256;
+  tx = state[x1];
+  ty = state[y1];
+  state[x1] = ty;
+  state[y1] = tx;
+  return c ^ state[(tx + ty) % 256];
+}
+
+//------------------------------------------------------------------------
+// MD5 message digest
+//------------------------------------------------------------------------
+
+static inline Gulong rotateLeft(Gulong x, int r) {
+  x &= 0xffffffff;
+  return ((x << r) | (x >> (32 - r))) & 0xffffffff;
+}
+
+static inline Gulong md5Round1(Gulong a, Gulong b, Gulong c, Gulong d,
+			       Gulong Xk,  Gulong s, Gulong Ti) {
+  return b + rotateLeft((a + ((b & c) | (~b & d)) + Xk + Ti), s);
+}
+
+static inline Gulong md5Round2(Gulong a, Gulong b, Gulong c, Gulong d,
+			       Gulong Xk,  Gulong s, Gulong Ti) {
+  return b + rotateLeft((a + ((b & d) | (c & ~d)) + Xk + Ti), s);
+}
+
+static inline Gulong md5Round3(Gulong a, Gulong b, Gulong c, Gulong d,
+			       Gulong Xk,  Gulong s, Gulong Ti) {
+  return b + rotateLeft((a + (b ^ c ^ d) + Xk + Ti), s);
+}
+
+static inline Gulong md5Round4(Gulong a, Gulong b, Gulong c, Gulong d,
+			       Gulong Xk,  Gulong s, Gulong Ti) {
+  return b + rotateLeft((a + (c ^ (b | ~d)) + Xk + Ti), s);
+}
+
+static void md5(Guchar *msg, int msgLen, Guchar *digest) {
+  Gulong x[16];
+  Gulong a, b, c, d, aa, bb, cc, dd;
+  int n64;
+  int i, j, k;
+
+  // compute number of 64-byte blocks
+  // (length + pad byte (0x80) + 8 bytes for length)
+  n64 = (msgLen + 1 + 8 + 63) / 64;
+
+  // initialize a, b, c, d
+  a = 0x67452301;
+  b = 0xefcdab89;
+  c = 0x98badcfe;
+  d = 0x10325476;
+
+  // loop through blocks
+  k = 0;
+  for (i = 0; i < n64; ++i) {
+
+    // grab a 64-byte block
+    for (j = 0; j < 16 && k < msgLen - 3; ++j, k += 4)
+      x[j] = (((((msg[k+3] << 8) + msg[k+2]) << 8) + msg[k+1]) << 8) + msg[k];
+    if (i == n64 - 1) {
+      if (k == msgLen - 3)
+	x[j] = 0x80000000 + (((msg[k+2] << 8) + msg[k+1]) << 8) + msg[k];
+      else if (k == msgLen - 2)
+	x[j] = 0x800000 + (msg[k+1] << 8) + msg[k];
+      else if (k == msgLen - 1)
+	x[j] = 0x8000 + msg[k];
+      else
+	x[j] = 0x80;
+      ++j;
+      while (j < 16)
+	x[j++] = 0;
+      x[14] = msgLen << 3;
+    }
+
+    // save a, b, c, d
+    aa = a;
+    bb = b;
+    cc = c;
+    dd = d;
+
+    // round 1
+    a = md5Round1(a, b, c, d, x[0],   7, 0xd76aa478);
+    d = md5Round1(d, a, b, c, x[1],  12, 0xe8c7b756);
+    c = md5Round1(c, d, a, b, x[2],  17, 0x242070db);
+    b = md5Round1(b, c, d, a, x[3],  22, 0xc1bdceee);
+    a = md5Round1(a, b, c, d, x[4],   7, 0xf57c0faf);
+    d = md5Round1(d, a, b, c, x[5],  12, 0x4787c62a);
+    c = md5Round1(c, d, a, b, x[6],  17, 0xa8304613);
+    b = md5Round1(b, c, d, a, x[7],  22, 0xfd469501);
+    a = md5Round1(a, b, c, d, x[8],   7, 0x698098d8);
+    d = md5Round1(d, a, b, c, x[9],  12, 0x8b44f7af);
+    c = md5Round1(c, d, a, b, x[10], 17, 0xffff5bb1);
+    b = md5Round1(b, c, d, a, x[11], 22, 0x895cd7be);
+    a = md5Round1(a, b, c, d, x[12],  7, 0x6b901122);
+    d = md5Round1(d, a, b, c, x[13], 12, 0xfd987193);
+    c = md5Round1(c, d, a, b, x[14], 17, 0xa679438e);
+    b = md5Round1(b, c, d, a, x[15], 22, 0x49b40821);
+
+    // round 2
+    a = md5Round2(a, b, c, d, x[1],   5, 0xf61e2562);
+    d = md5Round2(d, a, b, c, x[6],   9, 0xc040b340);
+    c = md5Round2(c, d, a, b, x[11], 14, 0x265e5a51);
+    b = md5Round2(b, c, d, a, x[0],  20, 0xe9b6c7aa);
+    a = md5Round2(a, b, c, d, x[5],   5, 0xd62f105d);
+    d = md5Round2(d, a, b, c, x[10],  9, 0x02441453);
+    c = md5Round2(c, d, a, b, x[15], 14, 0xd8a1e681);
+    b = md5Round2(b, c, d, a, x[4],  20, 0xe7d3fbc8);
+    a = md5Round2(a, b, c, d, x[9],   5, 0x21e1cde6);
+    d = md5Round2(d, a, b, c, x[14],  9, 0xc33707d6);
+    c = md5Round2(c, d, a, b, x[3],  14, 0xf4d50d87);
+    b = md5Round2(b, c, d, a, x[8],  20, 0x455a14ed);
+    a = md5Round2(a, b, c, d, x[13],  5, 0xa9e3e905);
+    d = md5Round2(d, a, b, c, x[2],   9, 0xfcefa3f8);
+    c = md5Round2(c, d, a, b, x[7],  14, 0x676f02d9);
+    b = md5Round2(b, c, d, a, x[12], 20, 0x8d2a4c8a);
+
+    // round 3
+    a = md5Round3(a, b, c, d, x[5],   4, 0xfffa3942);
+    d = md5Round3(d, a, b, c, x[8],  11, 0x8771f681);
+    c = md5Round3(c, d, a, b, x[11], 16, 0x6d9d6122);
+    b = md5Round3(b, c, d, a, x[14], 23, 0xfde5380c);
+    a = md5Round3(a, b, c, d, x[1],   4, 0xa4beea44);
+    d = md5Round3(d, a, b, c, x[4],  11, 0x4bdecfa9);
+    c = md5Round3(c, d, a, b, x[7],  16, 0xf6bb4b60);
+    b = md5Round3(b, c, d, a, x[10], 23, 0xbebfbc70);
+    a = md5Round3(a, b, c, d, x[13],  4, 0x289b7ec6);
+    d = md5Round3(d, a, b, c, x[0],  11, 0xeaa127fa);
+    c = md5Round3(c, d, a, b, x[3],  16, 0xd4ef3085);
+    b = md5Round3(b, c, d, a, x[6],  23, 0x04881d05);
+    a = md5Round3(a, b, c, d, x[9],   4, 0xd9d4d039);
+    d = md5Round3(d, a, b, c, x[12], 11, 0xe6db99e5);
+    c = md5Round3(c, d, a, b, x[15], 16, 0x1fa27cf8);
+    b = md5Round3(b, c, d, a, x[2],  23, 0xc4ac5665);
+
+    // round 4
+    a = md5Round4(a, b, c, d, x[0],   6, 0xf4292244);
+    d = md5Round4(d, a, b, c, x[7],  10, 0x432aff97);
+    c = md5Round4(c, d, a, b, x[14], 15, 0xab9423a7);
+    b = md5Round4(b, c, d, a, x[5],  21, 0xfc93a039);
+    a = md5Round4(a, b, c, d, x[12],  6, 0x655b59c3);
+    d = md5Round4(d, a, b, c, x[3],  10, 0x8f0ccc92);
+    c = md5Round4(c, d, a, b, x[10], 15, 0xffeff47d);
+    b = md5Round4(b, c, d, a, x[1],  21, 0x85845dd1);
+    a = md5Round4(a, b, c, d, x[8],   6, 0x6fa87e4f);
+    d = md5Round4(d, a, b, c, x[15], 10, 0xfe2ce6e0);
+    c = md5Round4(c, d, a, b, x[6],  15, 0xa3014314);
+    b = md5Round4(b, c, d, a, x[13], 21, 0x4e0811a1);
+    a = md5Round4(a, b, c, d, x[4],   6, 0xf7537e82);
+    d = md5Round4(d, a, b, c, x[11], 10, 0xbd3af235);
+    c = md5Round4(c, d, a, b, x[2],  15, 0x2ad7d2bb);
+    b = md5Round4(b, c, d, a, x[9],  21, 0xeb86d391);
+
+    // increment a, b, c, d
+    a += aa;
+    b += bb;
+    c += cc;
+    d += dd;
+  }
+
+  // break digest into bytes
+  digest[0] = a & 0xff;
+  digest[1] = (a >>= 8) & 0xff;
+  digest[2] = (a >>= 8) & 0xff;
+  digest[3] = (a >>= 8) & 0xff;
+  digest[4] = b & 0xff;
+  digest[5] = (b >>= 8) & 0xff;
+  digest[6] = (b >>= 8) & 0xff;
+  digest[7] = (b >>= 8) & 0xff;
+  digest[8] = c & 0xff;
+  digest[9] = (c >>= 8) & 0xff;
+  digest[10] = (c >>= 8) & 0xff;
+  digest[11] = (c >>= 8) & 0xff;
+  digest[12] = d & 0xff;
+  digest[13] = (d >>= 8) & 0xff;
+  digest[14] = (d >>= 8) & 0xff;
+  digest[15] = (d >>= 8) & 0xff;
+}