From 7aac8dc8533347e21311b15186e0af82f1b22fd6 Mon Sep 17 00:00:00 2001 From: Martin Kretzschmar Date: Wed, 18 Sep 2002 20:32:18 +0000 Subject: 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 --- (limited to 'pdf/xpdf/Decrypt.cc') 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; +} -- cgit v0.9.1