diff options
Diffstat (limited to 'src/zlib/crypt.h')
| -rw-r--r-- | src/zlib/crypt.h | 132 |
1 files changed, 132 insertions, 0 deletions
diff --git a/src/zlib/crypt.h b/src/zlib/crypt.h new file mode 100644 index 000000000..f14a628b4 --- /dev/null +++ b/src/zlib/crypt.h @@ -0,0 +1,132 @@ +/* crypt.h -- base code for crypt/uncrypt ZIPfile
+
+
+ Version 1.01e, February 12th, 2005
+
+ Copyright (C) 1998-2005 Gilles Vollant
+
+ This code is a modified version of crypting code in Infozip distribution
+
+ The encryption/decryption parts of this source code (as opposed to the
+ non-echoing password parts) were originally written in Europe. The
+ whole source package can be freely distributed, including from the USA.
+ (Prior to January 2000, re-export from the US was a violation of US law.)
+
+ This encryption code is a direct transcription of the algorithm from
+ Roger Schlafly, described by Phil Katz in the file appnote.txt. This
+ file (appnote.txt) is distributed with the PKZIP program (even in the
+ version without encryption capabilities).
+
+ If you don't need crypting in your application, just define symbols
+ NOCRYPT and NOUNCRYPT.
+
+ This code support the "Traditional PKWARE Encryption".
+
+ The new AES encryption added on Zip format by Winzip (see the page
+ http://www.winzip.com/aes_info.htm ) and PKWare PKZip 5.x Strong
+ Encryption is not supported.
+*/
+
+#define CRC32(c, b) ((*(pcrc_32_tab+(((int)(c) ^ (b)) & 0xff))) ^ ((c) >> 8))
+
+/***********************************************************************
+ * Return the next byte in the pseudo-random sequence
+ */
+static int decrypt_byte(unsigned long* pkeys, const unsigned long* pcrc_32_tab)
+{
+ unsigned temp; /* POTENTIAL BUG: temp*(temp^1) may overflow in an
+ * unpredictable manner on 16-bit systems; not a problem
+ * with any known compiler so far, though */
+
+ temp = ((unsigned)(*(pkeys+2)) & 0xffff) | 2;
+ return (int)(((temp * (temp ^ 1)) >> 8) & 0xff);
+}
+
+/***********************************************************************
+ * Update the encryption keys with the next byte of plain text
+ */
+static int update_keys(unsigned long* pkeys,const unsigned long* pcrc_32_tab,int c)
+{
+ (*(pkeys+0)) = CRC32((*(pkeys+0)), c);
+ (*(pkeys+1)) += (*(pkeys+0)) & 0xff;
+ (*(pkeys+1)) = (*(pkeys+1)) * 134775813L + 1;
+ {
+ register int keyshift = (int)((*(pkeys+1)) >> 24);
+ (*(pkeys+2)) = CRC32((*(pkeys+2)), keyshift);
+ }
+ return c;
+}
+
+
+/***********************************************************************
+ * Initialize the encryption keys and the random header according to
+ * the given password.
+ */
+static void init_keys(const char* passwd,unsigned long* pkeys,const unsigned long* pcrc_32_tab)
+{
+ *(pkeys+0) = 305419896L;
+ *(pkeys+1) = 591751049L;
+ *(pkeys+2) = 878082192L;
+ while (*passwd != '\0') {
+ update_keys(pkeys,pcrc_32_tab,(int)*passwd);
+ passwd++;
+ }
+}
+
+#define zdecode(pkeys,pcrc_32_tab,c) \
+ (update_keys(pkeys,pcrc_32_tab,c ^= decrypt_byte(pkeys,pcrc_32_tab)))
+
+#define zencode(pkeys,pcrc_32_tab,c,t) \
+ (t=decrypt_byte(pkeys,pcrc_32_tab), update_keys(pkeys,pcrc_32_tab,c), t^(c))
+
+#ifdef INCLUDECRYPTINGCODE_IFCRYPTALLOWED
+
+#define RAND_HEAD_LEN 12
+ /* "last resort" source for second part of crypt seed pattern */
+# ifndef ZCR_SEED2
+# define ZCR_SEED2 3141592654UL /* use PI as default pattern */
+# endif
+
+static int crypthead(passwd, buf, bufSize, pkeys, pcrc_32_tab, crcForCrypting)
+ const char *passwd; /* password string */
+ unsigned char *buf; /* where to write header */
+ int bufSize;
+ unsigned long* pkeys;
+ const unsigned long* pcrc_32_tab;
+ unsigned long crcForCrypting;
+{
+ int n; /* index in random header */
+ int t; /* temporary */
+ int c; /* random byte */
+ unsigned char header[RAND_HEAD_LEN-2]; /* random header */
+ static unsigned calls = 0; /* ensure different random header each time */
+
+ if (bufSize<RAND_HEAD_LEN)
+ return 0;
+
+ /* First generate RAND_HEAD_LEN-2 random bytes. We encrypt the
+ * output of rand() to get less predictability, since rand() is
+ * often poorly implemented.
+ */
+ if (++calls == 1)
+ {
+ srand((unsigned)(time(NULL) ^ ZCR_SEED2));
+ }
+ init_keys(passwd, pkeys, pcrc_32_tab);
+ for (n = 0; n < RAND_HEAD_LEN-2; n++)
+ {
+ c = (rand() >> 7) & 0xff;
+ header[n] = (unsigned char)zencode(pkeys, pcrc_32_tab, c, t);
+ }
+ /* Encrypt random header (last two bytes is high word of crc) */
+ init_keys(passwd, pkeys, pcrc_32_tab);
+ for (n = 0; n < RAND_HEAD_LEN-2; n++)
+ {
+ buf[n] = (unsigned char)zencode(pkeys, pcrc_32_tab, header[n], t);
+ }
+ buf[n++] = zencode(pkeys, pcrc_32_tab, (int)(crcForCrypting >> 16) & 0xff, t);
+ buf[n++] = zencode(pkeys, pcrc_32_tab, (int)(crcForCrypting >> 24) & 0xff, t);
+ return n;
+}
+
+#endif
|