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Diffstat (limited to 'lib/zlib/contrib/minizip/crypt.h')
-rw-r--r-- | lib/zlib/contrib/minizip/crypt.h | 132 |
1 files changed, 132 insertions, 0 deletions
diff --git a/lib/zlib/contrib/minizip/crypt.h b/lib/zlib/contrib/minizip/crypt.h new file mode 100644 index 0000000000..622f4bc2ec --- /dev/null +++ b/lib/zlib/contrib/minizip/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 |