From 0349c6d6572f59770898d3f40287ebdcd2f8ed30 Mon Sep 17 00:00:00 2001
From: Gentoo <installgentoo@endianness.com>
Date: Sat, 27 Mar 2021 10:36:05 +1100
Subject: initial commit

---
 source/unzip/crypt.h | 132 +++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 132 insertions(+)
 create mode 100644 source/unzip/crypt.h

(limited to 'source/unzip/crypt.h')

diff --git a/source/unzip/crypt.h b/source/unzip/crypt.h
new file mode 100644
index 0000000..f14a628
--- /dev/null
+++ b/source/unzip/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
-- 
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