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Diffstat (limited to 'crypt.c')
| -rw-r--r-- | crypt.c | 690 |
1 files changed, 690 insertions, 0 deletions
@@ -0,0 +1,690 @@ +/* + Copyright (c) 1990-2008 Info-ZIP. All rights reserved. + + See the accompanying file LICENSE, version 2007-Mar-4 or later + (the contents of which are also included in zip.h) for terms of use. + If, for some reason, all these files are missing, the Info-ZIP license + also may be found at: ftp://ftp.info-zip.org/pub/infozip/license.html +*/ +/* + crypt.c (full version) by Info-ZIP. Last revised: [see crypt.h] + + The main encryption/decryption source code for Info-Zip software was + originally written in Europe. To the best of our knowledge, it can + be freely distributed in both source and object forms from any country, + including the USA under License Exception TSU of the U.S. Export + Administration Regulations (section 740.13(e)) of 6 June 2002. + + NOTE on copyright history: + Previous versions of this source package (up to version 2.8) were + not copyrighted and put in the public domain. If you cannot comply + with the Info-Zip LICENSE, you may want to look for one of those + public domain versions. + */ + +/* + 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). + */ + +#define ZCRYPT_INTERNAL +#include "zip.h" +#include "crypt.h" +#include "ttyio.h" + +#if CRYPT + +#ifndef FALSE +# define FALSE 0 +#endif + +#ifdef ZIP + /* For the encoding task used in Zip (and ZipCloak), we want to initialize + the crypt algorithm with some reasonably unpredictable bytes, see + the crypthead() function. The standard rand() library function is + used to supply these `random' bytes, which in turn is initialized by + a srand() call. The srand() function takes an "unsigned" (at least 16bit) + seed value as argument to determine the starting point of the rand() + pseudo-random number generator. + This seed number is constructed as "Seed = Seed1 .XOR. Seed2" with + Seed1 supplied by the current time (= "(unsigned)time()") and Seed2 + as some (hopefully) nondeterministic bitmask. On many (most) systems, + we use some "process specific" number, as the PID or something similar, + but when nothing unpredictable is available, a fixed number may be + sufficient. + NOTE: + 1.) This implementation requires the availability of the following + standard UNIX C runtime library functions: time(), rand(), srand(). + On systems where some of them are missing, the environment that + incorporates the crypt routines must supply suitable replacement + functions. + 2.) It is a very bad idea to use a second call to time() to set the + "Seed2" number! In this case, both "Seed1" and "Seed2" would be + (almost) identical, resulting in a (mostly) "zero" constant seed + number passed to srand(). + + The implementation environment defined in the "zip.h" header should + supply a reasonable definition for ZCR_SEED2 (an unsigned number; for + most implementations of rand() and srand(), only the lower 16 bits are + significant!). An example that works on many systems would be + "#define ZCR_SEED2 (unsigned)getpid()". + The default definition for ZCR_SEED2 supplied below should be regarded + as a fallback to allow successful compilation in "beta state" + environments. + */ +# include <time.h> /* time() function supplies first part of crypt seed */ + /* "last resort" source for second part of crypt seed pattern */ +# ifndef ZCR_SEED2 +# define ZCR_SEED2 (unsigned)3141592654L /* use PI as default pattern */ +# endif +# ifdef GLOBAL /* used in Amiga system headers, maybe others too */ +# undef GLOBAL +# endif +# define GLOBAL(g) g +#else /* !ZIP */ +# define GLOBAL(g) G.g +#endif /* ?ZIP */ + + +#ifdef UNZIP + /* char *key = (char *)NULL; moved to globals.h */ +# ifndef FUNZIP + local int testp OF((__GPRO__ ZCONST uch *h)); + local int testkey OF((__GPRO__ ZCONST uch *h, ZCONST char *key)); +# endif +#else /* def UNZIP */ /* moved to globals.h for UnZip */ + local z_uint4 keys[3]; /* keys defining the pseudo-random sequence */ +#endif /* def UNZIP [else] */ + +#ifndef Trace +# ifdef CRYPT_DEBUG +# define Trace(x) fprintf x +# else +# define Trace(x) +# endif +#endif + +#include "crc32.h" + +#ifdef IZ_CRC_BE_OPTIMIZ + local z_uint4 near crycrctab[256]; + local z_uint4 near *cry_crctb_p = NULL; + local z_uint4 near *crytab_init OF((__GPRO)); +# define CRY_CRC_TAB cry_crctb_p +# undef CRC32 +# define CRC32(c, b, crctab) (crctab[((int)(c) ^ (b)) & 0xff] ^ ((c) >> 8)) +#else +# define CRY_CRC_TAB CRC_32_TAB +#endif /* ?IZ_CRC_BE_OPTIMIZ */ + +/*********************************************************************** + * Return the next byte in the pseudo-random sequence + */ +int decrypt_byte(__G) + __GDEF +{ + 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)GLOBAL(keys[2]) & 0xffff) | 2; + return (int)(((temp * (temp ^ 1)) >> 8) & 0xff); +} + +/*********************************************************************** + * Update the encryption keys with the next byte of plain text + */ +int update_keys(__G__ c) + __GDEF + int c; /* byte of plain text */ +{ + GLOBAL(keys[0]) = CRC32(GLOBAL(keys[0]), c, CRY_CRC_TAB); + GLOBAL(keys[1]) = (GLOBAL(keys[1]) + + (GLOBAL(keys[0]) & 0xff)) + * 134775813L + 1; + { + register int keyshift = (int)(GLOBAL(keys[1]) >> 24); + GLOBAL(keys[2]) = CRC32(GLOBAL(keys[2]), keyshift, CRY_CRC_TAB); + } + return c; +} + + +/*********************************************************************** + * Initialize the encryption keys and the random header according to + * the given password. + */ +void init_keys(__G__ passwd) + __GDEF + ZCONST char *passwd; /* password string with which to modify keys */ +{ +#ifdef IZ_CRC_BE_OPTIMIZ + if (cry_crctb_p == NULL) { + cry_crctb_p = crytab_init(__G); + } +#endif + GLOBAL(keys[0]) = 305419896L; + GLOBAL(keys[1]) = 591751049L; + GLOBAL(keys[2]) = 878082192L; + while (*passwd != '\0') { + update_keys(__G__ (int)*passwd); + passwd++; + } +} + + +/*********************************************************************** + * Initialize the local copy of the table of precomputed crc32 values. + * Whereas the public crc32-table is optimized for crc32 calculations + * on arrays of bytes, the crypt code needs the crc32 values in an + * byte-order-independent form as 32-bit unsigned numbers. On systems + * with Big-Endian byte order using the optimized crc32 code, this + * requires inverting the byte-order of the values in the + * crypt-crc32-table. + */ +#ifdef IZ_CRC_BE_OPTIMIZ +local z_uint4 near *crytab_init(__G) + __GDEF +{ + int i; + + for (i = 0; i < 256; i++) { + crycrctab[i] = REV_BE(CRC_32_TAB[i]); + } + return crycrctab; +} +#endif + + +#ifdef ZIP + +/*********************************************************************** + * Write encryption header to file zfile using the password passwd + * and the cyclic redundancy check crc. + */ +void crypthead(passwd, crc) + ZCONST char *passwd; /* password string */ + ulg crc; /* crc of file being encrypted */ +{ + int n; /* index in random header */ + int t; /* temporary */ + int c; /* random byte */ + uch header[RAND_HEAD_LEN]; /* random header */ + static unsigned calls = 0; /* ensure different random header each time */ + + /* 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); + for (n = 0; n < RAND_HEAD_LEN-2; n++) { + c = (rand() >> 7) & 0xff; + header[n] = (uch)zencode(c, t); + } + /* Encrypt random header (last two bytes is high word of crc) */ + init_keys(passwd); + for (n = 0; n < RAND_HEAD_LEN-2; n++) { + header[n] = (uch)zencode(header[n], t); + } + header[RAND_HEAD_LEN-2] = (uch)zencode((int)(crc >> 16) & 0xff, t); + header[RAND_HEAD_LEN-1] = (uch)zencode((int)(crc >> 24) & 0xff, t); + bfwrite(header, 1, RAND_HEAD_LEN, BFWRITE_DATA); +} + + +#ifdef UTIL + +/*********************************************************************** + * Encrypt the zip entry described by z from file in_file to file y + * using the password passwd. Return an error code in the ZE_ class. + */ +int zipcloak(z, passwd) + struct zlist far *z; /* zip entry to encrypt */ + ZCONST char *passwd; /* password string */ +{ + int c; /* input byte */ + int res; /* result code */ + zoff_t n; /* holds offset and counts size */ + int t; /* temporary */ + struct zlist far *localz; /* local header */ + uch buf[1024]; /* write buffer */ + int b; /* bytes in buffer */ + + /* Set encrypted bit, clear extended local header bit and write local + header to output file */ + if ((n = (zoff_t)zftello(y)) == (zoff_t)-1L) return ZE_TEMP; + + /* assume this archive is one disk and the file is open */ + + /* read the local header */ + res = readlocal(&localz, z); + + /* update disk and offset */ + z->dsk = 0; + z->off = n; + + /* Set encryption and unset any extended local header */ + z->flg |= 1, z->flg &= ~8; + localz->lflg |= 1, localz->lflg &= ~8; + + /* Add size of encryption header */ + localz->siz += RAND_HEAD_LEN; + z->siz = localz->siz; + + /* Put the local header */ + if ((res = putlocal(localz, PUTLOCAL_WRITE)) != ZE_OK) return res; + + /* Initialize keys with password and write random header */ + crypthead(passwd, localz->crc); + + /* Encrypt data */ + b = 0; + for (n = z->siz - RAND_HEAD_LEN; n; n--) { + if ((c = getc(in_file)) == EOF) { + return ferror(in_file) ? ZE_READ : ZE_EOF; + } + buf[b] = (uch)zencode(c, t); + b++; + if (b >= 1024) { + /* write the buffer */ + bfwrite(buf, 1, b, BFWRITE_DATA); + b = 0; + } + } + if (b) { + /* write the buffer */ + bfwrite(buf, 1, b, BFWRITE_DATA); + b = 0; + } + + /* Since we seek to the start of each local header can skip + reading any extended local header */ + /* + if ((flag & 8) != 0 && zfseeko(in_file, 16L, SEEK_CUR)) { + return ferror(in_file) ? ZE_READ : ZE_EOF; + } + if (fflush(y) == EOF) return ZE_TEMP; + */ + + /* Update number of bytes written to output file */ + tempzn += (4 + LOCHEAD) + localz->nam + localz->ext + localz->siz; + + /* Free local header */ + if (localz->ext) free(localz->extra); + if (localz->nam) free(localz->iname); + if (localz->nam) free(localz->name); +#ifdef UNICODE_SUPPORT + if (localz->uname) free(localz->uname); +#endif + free(localz); + + return ZE_OK; +} + +/*********************************************************************** + * Decrypt the zip entry described by z from file in_file to file y + * using the password passwd. Return an error code in the ZE_ class. + */ +int zipbare(z, passwd) + struct zlist far *z; /* zip entry to encrypt */ + ZCONST char *passwd; /* password string */ +{ +#ifdef ZIP10 + int c0 /* byte preceding the last input byte */ +#endif + int c1; /* last input byte */ + /* all file offset and size now zoff_t - 8/28/04 EG */ + zoff_t size; /* size of input data */ + struct zlist far *localz; /* local header */ + uch buf[1024]; /* write buffer */ + int b; /* bytes in buffer */ + zoff_t n; + int r; /* size of encryption header */ + int res; /* return code */ + + /* Save position */ + if ((n = (zoff_t)zftello(y)) == (zoff_t)-1L) return ZE_TEMP; + + /* Read local header */ + res = readlocal(&localz, z); + + /* Update disk and offset */ + z->dsk = 0; + z->off = n; + + /* Initialize keys with password */ + init_keys(passwd); + + /* Decrypt encryption header, save last two bytes */ + c1 = 0; + for (r = RAND_HEAD_LEN; r; r--) { +#ifdef ZIP10 + c0 = c1; +#endif + if ((c1 = getc(in_file)) == EOF) { + return ferror(in_file) ? ZE_READ : ZE_EOF; + } + Trace((stdout, " (%02x)", c1)); + zdecode(c1); + Trace((stdout, " %02x", c1)); + } + Trace((stdout, "\n")); + + /* If last two bytes of header don't match crc (or file time in the + * case of an extended local header), back up and just copy. For + * pkzip 2.0, the check has been reduced to one byte only. + */ +#ifdef ZIP10 + if ((ush)(c0 | (c1<<8)) != + (z->flg & 8 ? (ush) z->tim & 0xffff : (ush)(z->crc >> 16))) { +#else + if ((ush)c1 != (z->flg & 8 ? (ush) z->tim >> 8 : (ush)(z->crc >> 24))) { +#endif + if (zfseeko(in_file, n, SEEK_SET)) { + return ferror(in_file) ? ZE_READ : ZE_EOF; + } + if ((res = zipcopy(z)) != ZE_OK) { + ziperr(res, "was copying an entry"); + } + return ZE_MISS; + } + + z->siz -= RAND_HEAD_LEN; + localz->siz = z->siz; + + localz->flg = z->flg &= ~9; + z->lflg = localz->lflg &= ~9; + + if ((res = putlocal(localz, PUTLOCAL_WRITE)) != ZE_OK) return res; + + /* Decrypt data */ + b = 0; + for (size = z->siz; size; size--) { + if ((c1 = getc(in_file)) == EOF) { + return ferror(in_file) ? ZE_READ : ZE_EOF; + } + zdecode(c1); + buf[b] = c1; + b++; + if (b >= 1024) { + /* write the buffer */ + bfwrite(buf, 1, b, BFWRITE_DATA); + b = 0; + } + } + if (b) { + /* write the buffer */ + bfwrite(buf, 1, b, BFWRITE_DATA); + b = 0; + } + /* Since we seek to the start of each local header can skip + reading any extended local header */ + + /* Update number of bytes written to output file */ + tempzn += (4 + LOCHEAD) + localz->nam + localz->ext + localz->siz; + + /* Free local header */ + if (localz->ext) free(localz->extra); + if (localz->nam) free(localz->iname); + if (localz->nam) free(localz->name); +#ifdef UNICODE_SUPPORT + if (localz->uname) free(localz->uname); +#endif + free(localz); + + return ZE_OK; +} + + +#else /* !UTIL */ + +/*********************************************************************** + * If requested, encrypt the data in buf, and in any case call fwrite() + * with the arguments to zfwrite(). Return what fwrite() returns. + * + * now write to global y + * + * A bug has been found when encrypting large files that don't + * compress. See trees.c for the details and the fix. + */ +unsigned zfwrite(buf, item_size, nb) + zvoid *buf; /* data buffer */ + extent item_size; /* size of each item in bytes */ + extent nb; /* number of items */ +#if 0 + FILE *f; /* file to write to */ +#endif +{ + int t; /* temporary */ + + if (key != (char *)NULL) { /* key is the global password pointer */ + ulg size; /* buffer size */ + char *p = (char *)buf; /* steps through buffer */ + + /* Encrypt data in buffer */ + for (size = item_size*(ulg)nb; size != 0; p++, size--) { + *p = (char)zencode(*p, t); + } + } + /* Write the buffer out */ + return bfwrite(buf, item_size, nb, BFWRITE_DATA); +} + +#endif /* ?UTIL */ +#endif /* ZIP */ + + +#if (defined(UNZIP) && !defined(FUNZIP)) + +/*********************************************************************** + * Get the password and set up keys for current zipfile member. + * Return PK_ class error. + */ +int decrypt(__G__ passwrd) + __GDEF + ZCONST char *passwrd; +{ + ush b; + int n, r; + uch h[RAND_HEAD_LEN]; + + Trace((stdout, "\n[incnt = %d]: ", GLOBAL(incnt))); + + /* get header once (turn off "encrypted" flag temporarily so we don't + * try to decrypt the same data twice) */ + GLOBAL(pInfo->encrypted) = FALSE; + defer_leftover_input(__G); + for (n = 0; n < RAND_HEAD_LEN; n++) { + b = NEXTBYTE; + h[n] = (uch)b; + Trace((stdout, " (%02x)", h[n])); + } + undefer_input(__G); + GLOBAL(pInfo->encrypted) = TRUE; + + if (GLOBAL(newzip)) { /* this is first encrypted member in this zipfile */ + GLOBAL(newzip) = FALSE; + if (passwrd != (char *)NULL) { /* user gave password on command line */ + if (!GLOBAL(key)) { + if ((GLOBAL(key) = (char *)malloc(strlen(passwrd)+1)) == + (char *)NULL) + return PK_MEM2; + strcpy(GLOBAL(key), passwrd); + GLOBAL(nopwd) = TRUE; /* inhibit password prompting! */ + } + } else if (GLOBAL(key)) { /* get rid of previous zipfile's key */ + free(GLOBAL(key)); + GLOBAL(key) = (char *)NULL; + } + } + + /* if have key already, test it; else allocate memory for it */ + if (GLOBAL(key)) { + if (!testp(__G__ h)) + return PK_COOL; /* existing password OK (else prompt for new) */ + else if (GLOBAL(nopwd)) + return PK_WARN; /* user indicated no more prompting */ + } else if ((GLOBAL(key) = (char *)malloc(IZ_PWLEN+1)) == (char *)NULL) + return PK_MEM2; + + /* try a few keys */ + n = 0; + do { + r = (*G.decr_passwd)((zvoid *)&G, &n, GLOBAL(key), IZ_PWLEN+1, + GLOBAL(zipfn), GLOBAL(filename)); + if (r == IZ_PW_ERROR) { /* internal error in fetch of PW */ + free (GLOBAL(key)); + GLOBAL(key) = NULL; + return PK_MEM2; + } + if (r != IZ_PW_ENTERED) { /* user replied "skip" or "skip all" */ + *GLOBAL(key) = '\0'; /* We try the NIL password, ... */ + n = 0; /* and cancel fetch for this item. */ + } + if (!testp(__G__ h)) + return PK_COOL; + if (r == IZ_PW_CANCELALL) /* User replied "Skip all" */ + GLOBAL(nopwd) = TRUE; /* inhibit any further PW prompt! */ + } while (n > 0); + + return PK_WARN; + +} /* end function decrypt() */ + + + +/*********************************************************************** + * Test the password. Return -1 if bad, 0 if OK. + */ +local int testp(__G__ h) + __GDEF + ZCONST uch *h; +{ + int r; + char *key_translated; + + /* On systems with "obscure" native character coding (e.g., EBCDIC), + * the first test translates the password to the "main standard" + * character coding. */ + +#ifdef STR_TO_CP1 + /* allocate buffer for translated password */ + if ((key_translated = malloc(strlen(GLOBAL(key)) + 1)) == (char *)NULL) + return -1; + /* first try, test password translated "standard" charset */ + r = testkey(__G__ h, STR_TO_CP1(key_translated, GLOBAL(key))); +#else /* !STR_TO_CP1 */ + /* first try, test password as supplied on the extractor's host */ + r = testkey(__G__ h, GLOBAL(key)); +#endif /* ?STR_TO_CP1 */ + +#ifdef STR_TO_CP2 + if (r != 0) { +#ifndef STR_TO_CP1 + /* now prepare for second (and maybe third) test with translated pwd */ + if ((key_translated = malloc(strlen(GLOBAL(key)) + 1)) == (char *)NULL) + return -1; +#endif + /* second try, password translated to alternate ("standard") charset */ + r = testkey(__G__ h, STR_TO_CP2(key_translated, GLOBAL(key))); +#ifdef STR_TO_CP3 + if (r != 0) + /* third try, password translated to another "standard" charset */ + r = testkey(__G__ h, STR_TO_CP3(key_translated, GLOBAL(key))); +#endif +#ifndef STR_TO_CP1 + free(key_translated); +#endif + } +#endif /* STR_TO_CP2 */ + +#ifdef STR_TO_CP1 + free(key_translated); + if (r != 0) { + /* last resort, test password as supplied on the extractor's host */ + r = testkey(__G__ h, GLOBAL(key)); + } +#endif /* STR_TO_CP1 */ + + return r; + +} /* end function testp() */ + + +local int testkey(__G__ h, key) + __GDEF + ZCONST uch *h; /* decrypted header */ + ZCONST char *key; /* decryption password to test */ +{ + ush b; +#ifdef ZIP10 + ush c; +#endif + int n; + uch *p; + uch hh[RAND_HEAD_LEN]; /* decrypted header */ + + /* set keys and save the encrypted header */ + init_keys(__G__ key); + memcpy(hh, h, RAND_HEAD_LEN); + + /* check password */ + for (n = 0; n < RAND_HEAD_LEN; n++) { + zdecode(hh[n]); + Trace((stdout, " %02x", hh[n])); + } + + /* use fzofft to format zoff_t as strings - 10/19/04 from SMS */ + Trace((stdout, + "\n lrec.crc= %08lx crec.crc= %08lx pInfo->ExtLocHdr= %s\n", + GLOBAL(lrec.crc32), GLOBAL(pInfo->crc), + GLOBAL(pInfo->ExtLocHdr) ? "true":"false")); + Trace((stdout, " incnt = %d unzip offset into zipfile = %s\n", + GLOBAL(incnt), + fzofft(GLOBAL(cur_zipfile_bufstart)+(GLOBAL(inptr)-GLOBAL(inbuf)), + NULL, NULL))); + + /* same test as in zipbare(): */ + +#ifdef ZIP10 /* check two bytes */ + c = hh[RAND_HEAD_LEN-2], b = hh[RAND_HEAD_LEN-1]; + Trace((stdout, + " (c | (b<<8)) = %04x (crc >> 16) = %04x lrec.time = %04x\n", + (ush)(c | (b<<8)), (ush)(GLOBAL(lrec.crc32) >> 16), + ((ush)GLOBAL(lrec.last_mod_dos_datetime) & 0xffff)))); + if ((ush)(c | (b<<8)) != (GLOBAL(pInfo->ExtLocHdr) ? + ((ush)GLOBAL(lrec.last_mod_dos_datetime) & 0xffff) : + (ush)(GLOBAL(lrec.crc32) >> 16))) + return -1; /* bad */ +#else + b = hh[RAND_HEAD_LEN-1]; + Trace((stdout, " b = %02x (crc >> 24) = %02x (lrec.time >> 8) = %02x\n", + b, (ush)(GLOBAL(lrec.crc32) >> 24), + ((ush)GLOBAL(lrec.last_mod_dos_datetime) >> 8) & 0xff)); + if (b != (GLOBAL(pInfo->ExtLocHdr) ? + ((ush)GLOBAL(lrec.last_mod_dos_datetime) >> 8) & 0xff : + (ush)(GLOBAL(lrec.crc32) >> 24))) + return -1; /* bad */ +#endif + /* password OK: decrypt current buffer contents before leaving */ + for (n = (zoff_t)GLOBAL(incnt) > GLOBAL(csize) ? + (int)GLOBAL(csize) : GLOBAL(incnt), + p = GLOBAL(inptr); n--; p++) + zdecode(*p); + return 0; /* OK */ + +} /* end function testkey() */ + +#endif /* UNZIP && !FUNZIP */ + +#else /* !CRYPT */ + +/* something "externally visible" to shut up compiler/linker warnings */ +int zcr_dummy; + +#endif /* ?CRYPT */ |