#include <config.h>
#ifdef USE_GCC_PRAGMAS
#pragma implementation
#endif
#include <string.h>
#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(Guchar *fileKey, int keyLength, int objNum, int objGen) {
int i;
for (i = 0; i < keyLength; ++i) {
objKey[i] = fileKey[i];
}
objKey[keyLength] = objNum & 0xff;
objKey[keyLength + 1] = (objNum >> 8) & 0xff;
objKey[keyLength + 2] = (objNum >> 16) & 0xff;
objKey[keyLength + 3] = objGen & 0xff;
objKey[keyLength + 4] = (objGen >> 8) & 0xff;
md5(objKey, keyLength + 5, objKey);
x = y = 0;
if ((objKeyLength = keyLength + 5) > 16) {
objKeyLength = 16;
}
rc4InitKey(objKey, objKeyLength, state);
}
void Decrypt::reset() {
x = y = 0;
rc4InitKey(objKey, objKeyLength, state);
}
Guchar Decrypt::decryptByte(Guchar c) {
return rc4DecryptByte(state, &x, &y, c);
}
GBool Decrypt::makeFileKey(int encVersion, int encRevision, int keyLength,
GString *ownerKey, GString *userKey,
int permissions, GString *fileID,
GString *ownerPassword, GString *userPassword,
Guchar *fileKey, GBool encryptMetadata,
GBool *ownerPasswordOk) {
Guchar test[32], test2[32];
GString *userPassword2;
Guchar fState[256];
Guchar tmpKey[16];
Guchar fx, fy;
int len, i, j;
*ownerPasswordOk = gFalse;
if (ownerPassword) {
len = ownerPassword->getLength();
if (len < 32) {
memcpy(test, ownerPassword->getCString(), len);
memcpy(test + len, passwordPad, 32 - len);
} else {
memcpy(test, ownerPassword->getCString(), 32);
}
md5(test, 32, test);
if (encRevision == 3) {
for (i = 0; i < 50; ++i) {
md5(test, 16, test);
}
}
if (encRevision == 2) {
rc4InitKey(test, keyLength, fState);
fx = fy = 0;
for (i = 0; i < 32; ++i) {
test2[i] = rc4DecryptByte(fState, &fx, &fy, ownerKey->getChar(i));
}
} else {
memcpy(test2, ownerKey->getCString(), 32);
for (i = 19; i >= 0; --i) {
for (j = 0; j < keyLength; ++j) {
tmpKey[j] = test[j] ^ i;
}
rc4InitKey(tmpKey, keyLength, fState);
fx = fy = 0;
for (j = 0; j < 32; ++j) {
test2[j] = rc4DecryptByte(fState, &fx, &fy, test2[j]);
}
}
}
userPassword2 = new GString((char *)test2, 32);
if (makeFileKey2(encVersion, encRevision, keyLength, ownerKey, userKey,
permissions, fileID, userPassword2, fileKey,
encryptMetadata)) {
*ownerPasswordOk = gTrue;
delete userPassword2;
return gTrue;
}
delete userPassword2;
}
return makeFileKey2(encVersion, encRevision, keyLength, ownerKey, userKey,
permissions, fileID, userPassword, fileKey,
encryptMetadata);
}
GBool Decrypt::makeFileKey2(int encVersion, int encRevision, int keyLength,
GString *ownerKey, GString *userKey,
int permissions, GString *fileID,
GString *userPassword, Guchar *fileKey,
GBool encryptMetadata) {
Guchar *buf;
Guchar test[32];
Guchar fState[256];
Guchar tmpKey[16];
Guchar fx, fy;
int len, i, j;
GBool ok;
if ( keyLength < 5 || keyLength > 16 ) {
return gFalse;
}
buf = (Guchar *)gmalloc(72 + 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());
len = 68 + fileID->getLength();
if (!encryptMetadata) {
buf[len++] = 0xff;
buf[len++] = 0xff;
buf[len++] = 0xff;
buf[len++] = 0xff;
}
md5(buf, len, fileKey);
if (encRevision == 3) {
for (i = 0; i < 50; ++i) {
md5(fileKey, keyLength, fileKey);
}
}
if (encRevision == 2) {
rc4InitKey(fileKey, keyLength, fState);
fx = fy = 0;
for (i = 0; i < 32; ++i) {
test[i] = rc4DecryptByte(fState, &fx, &fy, userKey->getChar(i));
}
ok = memcmp(test, passwordPad, 32) == 0;
} else if (encRevision == 3) {
memcpy(test, userKey->getCString(), 32);
for (i = 19; i >= 0; --i) {
for (j = 0; j < keyLength; ++j) {
tmpKey[j] = fileKey[j] ^ i;
}
rc4InitKey(tmpKey, keyLength, fState);
fx = fy = 0;
for (j = 0; j < 32; ++j) {
test[j] = rc4DecryptByte(fState, &fx, &fy, test[j]);
}
}
memcpy(buf, passwordPad, 32);
memcpy(buf + 32, fileID->getCString(), fileID->getLength());
md5(buf, 32 + fileID->getLength(), buf);
ok = memcmp(test, buf, 16) == 0;
} else {
ok = gFalse;
}
gfree(buf);
return ok;
}
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];
}
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;
n64 = (msgLen + 1 + 8 + 63) / 64;
a = 0x67452301;
b = 0xefcdab89;
c = 0x98badcfe;
d = 0x10325476;
k = 0;
for (i = 0; i < n64; ++i) {
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;
}
aa = a;
bb = b;
cc = c;
dd = d;
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);
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);
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);
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);
a += aa;
b += bb;
c += cc;
d += dd;
}
digest[0] = (Guchar)(a & 0xff);
digest[1] = (Guchar)((a >>= 8) & 0xff);
digest[2] = (Guchar)((a >>= 8) & 0xff);
digest[3] = (Guchar)((a >>= 8) & 0xff);
digest[4] = (Guchar)(b & 0xff);
digest[5] = (Guchar)((b >>= 8) & 0xff);
digest[6] = (Guchar)((b >>= 8) & 0xff);
digest[7] = (Guchar)((b >>= 8) & 0xff);
digest[8] = (Guchar)(c & 0xff);
digest[9] = (Guchar)((c >>= 8) & 0xff);
digest[10] = (Guchar)((c >>= 8) & 0xff);
digest[11] = (Guchar)((c >>= 8) & 0xff);
digest[12] = (Guchar)(d & 0xff);
digest[13] = (Guchar)((d >>= 8) & 0xff);
digest[14] = (Guchar)((d >>= 8) & 0xff);
digest[15] = (Guchar)((d >>= 8) & 0xff);
}