Mercurial > vim
view src/crypt_zip.c @ 7093:503f4e8f86c4
Added tag v7.4.858 for changeset 64e30831fa4253f18f1a781d25f5c2518f190deb
author | Christian Brabandt <cb@256bit.org> |
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date | Tue, 08 Sep 2015 19:00:05 +0200 |
parents | 18ac55444b37 |
children | af3c41a3c53f |
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/* vi:set ts=8 sts=4 sw=4: * * VIM - Vi IMproved by Bram Moolenaar * * Do ":help uganda" in Vim to read copying and usage conditions. * Do ":help credits" in Vim to see a list of people who contributed. * See README.txt for an overview of the Vim source code. */ /* * crypt_zip.c: Zip encryption support. */ #include "vim.h" #if defined(FEAT_CRYPT) || defined(PROTO) /* * Optional encryption support. * Mohsin Ahmed, mosh@sasi.com, 98-09-24 * Based on zip/crypt sources. * * NOTE FOR USA: Since 2000 exporting this code from the USA is allowed to * most countries. There are a few exceptions, but that still should not be a * problem since this code was originally created in Europe and India. */ /* Need a type that should be 32 bits. 64 also works but wastes space. */ # if VIM_SIZEOF_INT >= 4 typedef unsigned int u32_T; /* int is at least 32 bits */ # else typedef unsigned long u32_T; /* long should be 32 bits or more */ # endif /* The state of encryption, referenced by cryptstate_T. */ typedef struct { u32_T keys[3]; } zip_state_T; static void make_crc_tab __ARGS((void)); static u32_T crc_32_table[256]; /* * Fill the CRC table, if not done already. */ static void make_crc_tab() { u32_T s, t, v; static int done = FALSE; if (done) return; for (t = 0; t < 256; t++) { v = t; for (s = 0; s < 8; s++) v = (v >> 1) ^ ((v & 1) * (u32_T)0xedb88320L); crc_32_table[t] = v; } done = TRUE; } #define CRC32(c, b) (crc_32_table[((int)(c) ^ (b)) & 0xff] ^ ((c) >> 8)) /* * Return the next byte in the pseudo-random sequence. */ #define DECRYPT_BYTE_ZIP(keys, t) { \ short_u temp = (short_u)keys[2] | 2; \ t = (int)(((unsigned)(temp * (temp ^ 1U)) >> 8) & 0xff); \ } /* * Update the encryption keys with the next byte of plain text. */ #define UPDATE_KEYS_ZIP(keys, c) { \ keys[0] = CRC32(keys[0], (c)); \ keys[1] += keys[0] & 0xff; \ keys[1] = keys[1] * 134775813L + 1; \ keys[2] = CRC32(keys[2], (int)(keys[1] >> 24)); \ } /* * Initialize for encryption/decryption. */ void crypt_zip_init(state, key, salt, salt_len, seed, seed_len) cryptstate_T *state; char_u *key; char_u *salt UNUSED; int salt_len UNUSED; char_u *seed UNUSED; int seed_len UNUSED; { char_u *p; zip_state_T *zs; zs = (zip_state_T *)alloc(sizeof(zip_state_T)); state->method_state = zs; make_crc_tab(); zs->keys[0] = 305419896L; zs->keys[1] = 591751049L; zs->keys[2] = 878082192L; for (p = key; *p != NUL; ++p) { UPDATE_KEYS_ZIP(zs->keys, (int)*p); } } /* * Encrypt "from[len]" into "to[len]". * "from" and "to" can be equal to encrypt in place. */ void crypt_zip_encode(state, from, len, to) cryptstate_T *state; char_u *from; size_t len; char_u *to; { zip_state_T *zs = state->method_state; size_t i; int ztemp, t; for (i = 0; i < len; ++i) { ztemp = from[i]; DECRYPT_BYTE_ZIP(zs->keys, t); UPDATE_KEYS_ZIP(zs->keys, ztemp); to[i] = t ^ ztemp; } } /* * Decrypt "from[len]" into "to[len]". */ void crypt_zip_decode(state, from, len, to) cryptstate_T *state; char_u *from; size_t len; char_u *to; { zip_state_T *zs = state->method_state; size_t i; short_u temp; for (i = 0; i < len; ++i) { temp = (short_u)zs->keys[2] | 2; temp = (int)(((unsigned)(temp * (temp ^ 1U)) >> 8) & 0xff); UPDATE_KEYS_ZIP(zs->keys, to[i] = from[i] ^ temp); } } #endif /* FEAT_CRYPT */