diff options
Diffstat (limited to 'sshdes.c')
| -rw-r--r-- | sshdes.c | 1048 |
1 files changed, 0 insertions, 1048 deletions
diff --git a/sshdes.c b/sshdes.c deleted file mode 100644 index d2ba9825..00000000 --- a/sshdes.c +++ /dev/null @@ -1,1048 +0,0 @@ -/* - * sshdes.c: implementation of DES. - */ - -/* - * Background - * ---------- - * - * The basic structure of DES is a Feistel network: the 64-bit cipher - * block is divided into two 32-bit halves L and R, and in each round, - * a mixing function is applied to one of them, the result is XORed - * into the other, and then the halves are swapped so that the other - * one will be the input to the mixing function next time. (This - * structure guarantees reversibility no matter whether the mixing - * function itself is bijective.) - * - * The mixing function for DES goes like this: - * + Extract eight contiguous 6-bit strings from the 32-bit word. - * They start at positions 4 bits apart, so each string overlaps - * the next one by one bit. At least one has to wrap cyclically - * round the end of the word. - * + XOR each of those strings with 6 bits of data from the key - * schedule (which consists of 8 x 6-bit strings per round). - * + Use the resulting 6-bit numbers as the indices into eight - * different lookup tables ('S-boxes'), each of which delivers a - * 4-bit output. - * + Concatenate those eight 4-bit values into a 32-bit word. - * + Finally, apply a fixed permutation P to that word. - * - * DES adds one more wrinkle on top of this structure, which is to - * conjugate it by a bitwise permutation of the cipher block. That is, - * before starting the main cipher rounds, the input bits are permuted - * according to a 64-bit permutation called IP, and after the rounds - * are finished, the output bits are permuted back again by applying - * the inverse of IP. - * - * This gives a lot of leeway to redefine the components of the cipher - * without actually changing the input and output. You could permute - * the bits in the output of any or all of the S-boxes, or reorder the - * S-boxes among themselves, and adjust the following permutation P to - * compensate. And you could adjust IP by post-composing a rotation of - * each 32-bit half, and adjust the starting offsets of the 6-bit - * S-box indices to compensate. - * - * test/desref.py demonstrates this by providing two equivalent forms - * of the cipher, called DES and SGTDES, which give the same output. - * DES is the form described in the original spec: if you make it - * print diagnostic output during the cipher and check it against the - * original, you should recognise the S-box outputs as matching the - * ones you expect. But SGTDES, which I egotistically name after - * myself, is much closer to the form implemented here: I've changed - * the permutation P to suit my implementation strategy and - * compensated by permuting the S-boxes, and also I've added a - * rotation right by 1 bit to IP so that only one S-box index has to - * wrap round the word and also so that the indices are nicely aligned - * for the constant-time selection system I'm using. - */ - -#include <stdio.h> - -#include "ssh.h" -#include "mpint_i.h" /* we reuse the BignumInt system */ - -/* If you compile with -DDES_DIAGNOSTICS, intermediate results will be - * sent to debug() (so you also need to compile with -DDEBUG). - * Otherwise this ifdef will condition away all the debug() calls. */ -#ifndef DES_DIAGNOSTICS -#undef debug -#define debug(...) ((void)0) -#endif - -/* - * General utility functions. - */ -static inline uint32_t rol(uint32_t x, unsigned c) -{ - return (x << (31 & c)) | (x >> (31 & -c)); -} -static inline uint32_t ror(uint32_t x, unsigned c) -{ - return rol(x, -c); -} - -/* - * The hard part of doing DES in constant time is the S-box lookup. - * - * My strategy is to iterate over the whole lookup table! That's slow, - * but I don't see any way to avoid _something_ along those lines: in - * every round, every entry in every S-box is potentially needed, and - * if you can't change your memory access pattern based on the input - * data, it follows that you have to read a quantity of information - * equal to the size of all the S-boxes. (Unless they were to turn out - * to be significantly compressible, but I for one couldn't show them - * to be.) - * - * In more detail, I construct a sort of counter-based 'selection - * gadget', which is 15 bits wide and starts off with the top bit - * zero, the next eight bits all 1, and the bottom six set to the - * input S-box index: - * - * 011111111xxxxxx - * - * Now if you add 1 in the lowest bit position, then either it carries - * into the top section (resetting it to 100000000), or it doesn't do - * that yet. If you do that 64 times, then it will _guarantee_ to have - * ticked over into 100000000. In between those increments, the eight - * bits that started off as 11111111 will have stayed that way for - * some number of iterations and then become 00000000, and exactly how - * many iterations depends on the input index. - * - * The purpose of the 0 bit at the top is to absorb the carry when the - * switch happens, which means you can pack more than one gadget into - * the same machine word and have them all work in parallel without - * each one intefering with the next. - * - * The next step is to use each of those 8-bit segments as a bit mask: - * each one is ANDed with a lookup table entry, and all the results - * are XORed together. So you end up with the bitwise XOR of some - * initial segment of the table entries. And the stored S-box tables - * are transformed in such a way that the real S-box values are given - * not by the individual entries, but by the cumulative XORs - * constructed in this way. - * - * A refinement is that I increment each gadget by 2 rather than 1 - * each time, so I only iterate 32 times instead of 64. That's why - * there are 8 selection bits instead of 4: each gadget selects enough - * bits to reconstruct _two_ S-box entries, for a pair of indices - * (2n,2n+1), and then finally I use the low bit of the index to do a - * parallel selection between each of those pairs. - * - * The selection gadget is not quite 16 bits wide. So you can fit four - * of them across a 64-bit word at 16-bit intervals, which is also - * convenient because the place the S-box indices are coming from also - * has pairs of them separated by 16-bit distances, so it's easy to - * copy them into the gadgets in the first place. - */ - -/* - * The S-box data. Each pair of nonzero columns here describes one of - * the S-boxes, corresponding to the SGTDES tables in test/desref.py, - * under the following transformation. - * - * Take S-box #3 as an example. Its values in successive rows of this - * table are eb,e8,54,3d, ... So the cumulative XORs of initial - * sequences of those values are eb,(eb^e8),(eb^e8^54), ... which - * comes to eb,03,57,... Of _those_ values, the top nibble (e,0,5,...) - * gives the even-numbered entries in the S-box, in _reverse_ order - * (because a lower input index selects the XOR of a longer - * subsequence). The odd-numbered entries are given by XORing the two - * digits together: (e^b),(0^3),(5^7),... = 5,3,2,... And indeed, if - * you check SGTDES.sboxes[3] you find it ends ... 52 03 e5. - */ -#define SBOX_ITERATION(X) \ - /* 66 22 44 00 77 33 55 11 */ \ - X(0xf600970083008500, 0x0e00eb007b002e00) \ - X(0xda00e4009000e000, 0xad00e800a700b400) \ - X(0x1a009d003f003600, 0xf60054004300cd00) \ - X(0xaf00c500e900a900, 0x63003d00f2005900) \ - X(0xf300750079001400, 0x80005000a2008900) \ - X(0xa100d400d6007b00, 0xd3009000d300e100) \ - X(0x450087002600ac00, 0xae003c0031009c00) \ - X(0xd000b100b6003600, 0x3e006f0092005900) \ - X(0x4d008a0026001000, 0x89007a00b8004a00) \ - X(0xca00f5003f00ac00, 0x6f00f0003c009400) \ - X(0x92008d0090001000, 0x8c00c600ce004a00) \ - X(0xe2005900e9006d00, 0x790078007800fa00) \ - X(0x1300b10090008d00, 0xa300170027001800) \ - X(0xc70058005f006a00, 0x9c00c100e0006300) \ - X(0x9b002000f000f000, 0xf70057001600f900) \ - X(0xeb00b0009000af00, 0xa9006300b0005800) \ - X(0xa2001d00cf000000, 0x3800b00066000000) \ - X(0xf100da007900d000, 0xbc00790094007900) \ - X(0x570015001900ad00, 0x6f00ef005100cb00) \ - X(0xc3006100e9006d00, 0xc000b700f800f200) \ - X(0x1d005800b600d000, 0x67004d00cd002c00) \ - X(0xf400b800d600e000, 0x5e00a900b000e700) \ - X(0x5400d1003f009c00, 0xc90069002c005300) \ - X(0xe200e50060005900, 0x6a00b800c500f200) \ - X(0xdf0047007900d500, 0x7000ec004c00ea00) \ - X(0x7100d10060009c00, 0x3f00b10095005e00) \ - X(0x82008200f0002000, 0x87001d00cd008000) \ - X(0xd0007000af00c000, 0xe200be006100f200) \ - X(0x8000930060001000, 0x36006e0081001200) \ - X(0x6500a300d600ac00, 0xcf003d007d00c000) \ - X(0x9000700060009800, 0x62008100ad009200) \ - X(0xe000e4003f00f400, 0x5a00ed009000f200) \ - /* end of list */ - -/* - * The S-box mapping function. Expects two 32-bit input words: si6420 - * contains the table indices for S-boxes 0,2,4,6 with their low bits - * starting at position 2 (for S-box 0) and going up in steps of 8. - * si7531 has indices 1,3,5,7 in the same bit positions. - */ -static inline uint32_t des_S(uint32_t si6420, uint32_t si7531) -{ - debug("sindices: %02x %02x %02x %02x %02x %02x %02x %02x\n", - 0x3F & (si6420 >> 2), 0x3F & (si7531 >> 2), - 0x3F & (si6420 >> 10), 0x3F & (si7531 >> 10), - 0x3F & (si6420 >> 18), 0x3F & (si7531 >> 18), - 0x3F & (si6420 >> 26), 0x3F & (si7531 >> 26)); - -#ifdef SIXTY_FOUR_BIT - /* - * On 64-bit machines, we store the table in exactly the form - * shown above, and make two 64-bit words containing four - * selection gadgets each. - */ - - /* Set up the gadgets. The 'cNNNN' variables will be gradually - * incremented, and the bits in positions FF00FF00FF00FF00 will - * act as selectors for the words in the table. - * - * A side effect of moving the input indices further apart is that - * they change order, because it's easier to keep a pair that were - * originally 16 bits apart still 16 bits apart, which now makes - * them adjacent instead of separated by one. So the fact that - * si6420 turns into c6240 (with the 2,4 reversed) is not a typo! - * This will all be undone when we rebuild the output word later. - */ - uint64_t c6240 = ((si6420 | ((uint64_t)si6420 << 24)) - & 0x00FC00FC00FC00FC) | 0xFF00FF00FF00FF00; - uint64_t c7351 = ((si7531 | ((uint64_t)si7531 << 24)) - & 0x00FC00FC00FC00FC) | 0xFF00FF00FF00FF00; - debug("S in: c6240=%016"PRIx64" c7351=%016"PRIx64"\n", c6240, c7351); - - /* Iterate over the table. The 'sNNNN' variables accumulate the - * XOR of all the table entries not masked out. */ - static const struct tbl { uint64_t t6240, t7351; } tbl[32] = { -#define TABLE64(a, b) { a, b }, - SBOX_ITERATION(TABLE64) -#undef TABLE64 - }; - uint64_t s6240 = 0, s7351 = 0; - for (const struct tbl *t = tbl, *limit = tbl + 32; t < limit; t++) { - s6240 ^= c6240 & t->t6240; c6240 += 0x0008000800080008; - s7351 ^= c7351 & t->t7351; c7351 += 0x0008000800080008; - } - debug("S out: s6240=%016"PRIx64" s7351=%016"PRIx64"\n", s6240, s7351); - - /* Final selection between each even/odd pair: mask off the low - * bits of all the input indices (which haven't changed throughout - * the iteration), and multiply by a bit mask that will turn each - * set bit into a mask covering the upper nibble of the selected - * pair. Then use those masks to control which set of lower - * nibbles is XORed into the upper nibbles. */ - s6240 ^= (s6240 << 4) & ((0xf000/0x004) * (c6240 & 0x0004000400040004)); - s7351 ^= (s7351 << 4) & ((0xf000/0x004) * (c7351 & 0x0004000400040004)); - - /* Now the eight final S-box outputs are in the upper nibble of - * each selection position. Mask away the rest of the clutter. */ - s6240 &= 0xf000f000f000f000; - s7351 &= 0xf000f000f000f000; - debug("s0=%x s1=%x s2=%x s3=%x s4=%x s5=%x s6=%x s7=%x\n", - (unsigned)(0xF & (s6240 >> 12)), - (unsigned)(0xF & (s7351 >> 12)), - (unsigned)(0xF & (s6240 >> 44)), - (unsigned)(0xF & (s7351 >> 44)), - (unsigned)(0xF & (s6240 >> 28)), - (unsigned)(0xF & (s7351 >> 28)), - (unsigned)(0xF & (s6240 >> 60)), - (unsigned)(0xF & (s7351 >> 60))); - - /* Combine them all into a single 32-bit output word, which will - * come out in the order 76543210. */ - uint64_t combined = (s6240 >> 12) | (s7351 >> 8); - return combined | (combined >> 24); - -#else /* SIXTY_FOUR_BIT */ - /* - * For 32-bit platforms, we do the same thing but in four 32-bit - * words instead of two 64-bit ones, so the CPU doesn't have to - * waste time propagating carries or shifted bits between the two - * halves of a uint64 that weren't needed anyway. - */ - - /* Set up the gadgets */ - uint32_t c40 = ((si6420 ) & 0x00FC00FC) | 0xFF00FF00; - uint32_t c62 = ((si6420 >> 8) & 0x00FC00FC) | 0xFF00FF00; - uint32_t c51 = ((si7531 ) & 0x00FC00FC) | 0xFF00FF00; - uint32_t c73 = ((si7531 >> 8) & 0x00FC00FC) | 0xFF00FF00; - debug("S in: c40=%08"PRIx32" c62=%08"PRIx32 - " c51=%08"PRIx32" c73=%08"PRIx32"\n", c40, c62, c51, c73); - - /* Iterate over the table */ - static const struct tbl { uint32_t t40, t62, t51, t73; } tbl[32] = { -#define TABLE32(a, b) { ((uint32_t)a), (a>>32), ((uint32_t)b), (b>>32) }, - SBOX_ITERATION(TABLE32) -#undef TABLE32 - }; - uint32_t s40 = 0, s62 = 0, s51 = 0, s73 = 0; - for (const struct tbl *t = tbl, *limit = tbl + 32; t < limit; t++) { - s40 ^= c40 & t->t40; c40 += 0x00080008; - s62 ^= c62 & t->t62; c62 += 0x00080008; - s51 ^= c51 & t->t51; c51 += 0x00080008; - s73 ^= c73 & t->t73; c73 += 0x00080008; - } - debug("S out: s40=%08"PRIx32" s62=%08"PRIx32 - " s51=%08"PRIx32" s73=%08"PRIx32"\n", s40, s62, s51, s73); - - /* Final selection within each pair */ - s40 ^= (s40 << 4) & ((0xf000/0x004) * (c40 & 0x00040004)); - s62 ^= (s62 << 4) & ((0xf000/0x004) * (c62 & 0x00040004)); - s51 ^= (s51 << 4) & ((0xf000/0x004) * (c51 & 0x00040004)); - s73 ^= (s73 << 4) & ((0xf000/0x004) * (c73 & 0x00040004)); - - /* Clean up the clutter */ - s40 &= 0xf000f000; - s62 &= 0xf000f000; - s51 &= 0xf000f000; - s73 &= 0xf000f000; - debug("s0=%x s1=%x s2=%x s3=%x s4=%x s5=%x s6=%x s7=%x\n", - (unsigned)(0xF & (s40 >> 12)), - (unsigned)(0xF & (s51 >> 12)), - (unsigned)(0xF & (s62 >> 12)), - (unsigned)(0xF & (s73 >> 12)), - (unsigned)(0xF & (s40 >> 28)), - (unsigned)(0xF & (s51 >> 28)), - (unsigned)(0xF & (s62 >> 28)), - (unsigned)(0xF & (s73 >> 28))); - - /* Recombine and return */ - return (s40 >> 12) | (s62 >> 4) | (s51 >> 8) | (s73); - -#endif /* SIXTY_FOUR_BIT */ - -} - -/* - * Now for the permutation P. The basic strategy here is to use a - * Benes network: in each stage, the bit at position i is allowed to - * either stay where it is or swap with i ^ D, where D is a power of 2 - * that varies with each phase. (So when D=1, pairs of the form - * {2n,2n+1} can swap; when D=2, the pairs are {4n+j,4n+j+2} for - * j={0,1}, and so on.) - * - * You can recursively construct a Benes network for an arbitrary - * permutation, in which the values of D iterate across all the powers - * of 2 less than the permutation size and then go back again. For - * example, the typical presentation for 32 bits would have D iterate - * over 16,8,4,2,1,2,4,8,16, and there's an easy algorithm that can - * express any permutation in that form by deciding which pairs of - * bits to swap in the outer pair of stages and then recursing to do - * all the stages in between. - * - * Actually implementing the swaps is easy when they're all between - * bits at the same separation: make the value x ^ (x >> D), mask out - * just the bits in the low position of a pair that needs to swap, and - * then use the resulting value y to make x ^ y ^ (y << D) which is - * the swapped version. - * - * In this particular case, I processed the bit indices in the other - * order (going 1,2,4,8,16,8,4,2,1), which makes no significant - * difference to the construction algorithm (it's just a relabelling), - * but it now means that the first two steps only permute entries - * within the output of each S-box - and therefore we can leave them - * completely out, in favour of just defining the S-boxes so that - * those permutation steps are already applied. Furthermore, by - * exhaustive search over the rest of the possible bit-orders for each - * S-box, I was able to find a version of P which could be represented - * in such a way that two further phases had all their control bits - * zero and could be skipped. So the number of swap stages is reduced - * to 5 from the 9 that might have been needed. - */ - -static inline uint32_t des_benes_step(uint32_t v, unsigned D, uint32_t mask) -{ - uint32_t diff = (v ^ (v >> D)) & mask; - return v ^ diff ^ (diff << D); -} - -static inline uint32_t des_P(uint32_t v_orig) -{ - uint32_t v = v_orig; - - /* initial stages with distance 1,2 are part of the S-box data table */ - v = des_benes_step(v, 4, 0x07030702); - v = des_benes_step(v, 8, 0x004E009E); - v = des_benes_step(v, 16, 0x0000D9D3); -/* v = des_benes_step(v, 8, 0x00000000); no-op, so we can skip it */ - v = des_benes_step(v, 4, 0x05040004); -/* v = des_benes_step(v, 2, 0x00000000); no-op, so we can skip it */ - v = des_benes_step(v, 1, 0x04045015); - - debug("P(%08"PRIx32") = %08"PRIx32"\n", v_orig, v); - - return v; -} - -/* - * Putting the S and P functions together, and adding in the round key - * as well, gives us the full mixing function f. - */ - -static inline uint32_t des_f(uint32_t R, uint32_t K7531, uint32_t K6420) -{ - uint32_t s7531 = R ^ K7531, s6420 = rol(R, 4) ^ K6420; - return des_P(des_S(s6420, s7531)); -} - -/* - * The key schedule, and the function to set it up. - */ - -typedef struct des_keysched des_keysched; -struct des_keysched { - uint32_t k7531[16], k6420[16]; -}; - -/* - * Simplistic function to select an arbitrary sequence of bits from - * one value and glue them together into another value. bitnums[] - * gives the sequence of bit indices of the input, from the highest - * output bit downwards. An index of -1 means that output bit is left - * at zero. - * - * This function is only used during key setup, so it doesn't need to - * be highly optimised. - */ -static inline uint64_t bitsel( - uint64_t input, const int8_t *bitnums, size_t size) -{ - uint64_t ret = 0; - while (size-- > 0) { - int bitpos = *bitnums++; - ret <<= 1; - if (bitpos >= 0) - ret |= 1 & (input >> bitpos); - } - return ret; -} - -static void des_key_setup(uint64_t key, des_keysched *sched) -{ - static const int8_t PC1[] = { - 7, 15, 23, 31, 39, 47, 55, 63, 6, 14, 22, 30, 38, 46, - 54, 62, 5, 13, 21, 29, 37, 45, 53, 61, 4, 12, 20, 28, - -1, -1, -1, -1, - 1, 9, 17, 25, 33, 41, 49, 57, 2, 10, 18, 26, 34, 42, - 50, 58, 3, 11, 19, 27, 35, 43, 51, 59, 36, 44, 52, 60, - }; - static const int8_t PC2_7531[] = { - 46, 43, 49, 36, 59, 55, -1, -1, /* index into S-box 7 */ - 37, 41, 48, 56, 34, 52, -1, -1, /* index into S-box 5 */ - 15, 4, 25, 19, 9, 1, -1, -1, /* index into S-box 3 */ - 12, 7, 17, 0, 22, 3, -1, -1, /* index into S-box 1 */ - }; - static const int8_t PC2_6420[] = { - 57, 32, 45, 54, 39, 50, -1, -1, /* index into S-box 6 */ - 44, 53, 33, 40, 47, 58, -1, -1, /* index into S-box 4 */ - 26, 16, 5, 11, 23, 8, -1, -1, /* index into S-box 2 */ - 10, 14, 6, 20, 27, 24, -1, -1, /* index into S-box 0 */ - }; - static const int leftshifts[] = {1,1,2,2,2,2,2,2,1,2,2,2,2,2,2,1}; - - /* Select 56 bits from the 64-bit input key integer (the low bit - * of each input byte is unused), into a word consisting of two - * 28-bit integers starting at bits 0 and 32. */ - uint64_t CD = bitsel(key, PC1, lenof(PC1)); - - for (size_t i = 0; i < 16; i++) { - /* Rotate each 28-bit half of CD left by 1 or 2 bits (varying - * between rounds) */ - CD <<= leftshifts[i]; - CD = (CD & 0x0FFFFFFF0FFFFFFF) | ((CD & 0xF0000000F0000000) >> 28); - - /* Select key bits from the rotated word to use during the - * actual cipher */ - sched->k7531[i] = bitsel(CD, PC2_7531, lenof(PC2_7531)); - sched->k6420[i] = bitsel(CD, PC2_6420, lenof(PC2_6420)); - } -} - -/* - * Helper routines for dealing with 64-bit blocks in the form of an L - * and R word. - */ - -typedef struct LR LR; -struct LR { uint32_t L, R; }; - -static inline LR des_load_lr(const void *vp) -{ - const uint8_t *p = (const uint8_t *)vp; - LR out; - out.L = GET_32BIT_MSB_FIRST(p); - out.R = GET_32BIT_MSB_FIRST(p+4); - return out; -} - -static inline void des_store_lr(void *vp, LR lr) -{ - uint8_t *p = (uint8_t *)vp; - PUT_32BIT_MSB_FIRST(p, lr.L); - PUT_32BIT_MSB_FIRST(p+4, lr.R); -} - -static inline LR des_xor_lr(LR a, LR b) -{ - a.L ^= b.L; - a.R ^= b.R; - return a; -} - -static inline LR des_swap_lr(LR in) -{ - LR out; - out.L = in.R; - out.R = in.L; - return out; -} - -/* - * The initial and final permutations of official DES are in a - * restricted form, in which the 'before' and 'after' positions of a - * given data bit are derived from each other by permuting the bits of - * the _index_ and flipping some of them. This allows the permutation - * to be performed effectively by a method that looks rather like - * _half_ of a general Benes network, because the restricted form - * means only half of it is actually needed. - * - * _Our_ initial and final permutations include a rotation by 1 bit, - * but it's still easier to just suffix that to the standard IP/FP - * than to regenerate everything using a more general method. - * - * Because we're permuting 64 bits in this case, between two 32-bit - * words, there's a separate helper function for this code that - * doesn't look quite like des_benes_step() above. - */ - -static inline void des_bitswap_IP_FP(uint32_t *L, uint32_t *R, - unsigned D, uint32_t mask) -{ - uint32_t diff = mask & ((*R >> D) ^ *L); - *R ^= diff << D; - *L ^= diff; -} - -static inline LR des_IP(LR lr) -{ - des_bitswap_IP_FP(&lr.R, &lr.L, 4, 0x0F0F0F0F); - des_bitswap_IP_FP(&lr.R, &lr.L, 16, 0x0000FFFF); - des_bitswap_IP_FP(&lr.L, &lr.R, 2, 0x33333333); - des_bitswap_IP_FP(&lr.L, &lr.R, 8, 0x00FF00FF); - des_bitswap_IP_FP(&lr.R, &lr.L, 1, 0x55555555); - - lr.L = ror(lr.L, 1); - lr.R = ror(lr.R, 1); - - return lr; -} - -static inline LR des_FP(LR lr) -{ - lr.L = rol(lr.L, 1); - lr.R = rol(lr.R, 1); - - des_bitswap_IP_FP(&lr.R, &lr.L, 1, 0x55555555); - des_bitswap_IP_FP(&lr.L, &lr.R, 8, 0x00FF00FF); - des_bitswap_IP_FP(&lr.L, &lr.R, 2, 0x33333333); - des_bitswap_IP_FP(&lr.R, &lr.L, 16, 0x0000FFFF); - des_bitswap_IP_FP(&lr.R, &lr.L, 4, 0x0F0F0F0F); - - return lr; -} - -/* - * The main cipher functions, which are identical except that they use - * the key schedule in opposite orders. - * - * We provide a version without the initial and final permutations, - * for use in triple-DES mode (no sense undoing and redoing it in - * between the phases). - */ - -static inline LR des_round(LR in, const des_keysched *sched, size_t round) -{ - LR out; - out.L = in.R; - out.R = in.L ^ des_f(in.R, sched->k7531[round], sched->k6420[round]); - return out; -} - -static inline LR des_inner_cipher(LR lr, const des_keysched *sched, - size_t start, size_t step) -{ - lr = des_round(lr, sched, start+0x0*step); - lr = des_round(lr, sched, start+0x1*step); - lr = des_round(lr, sched, start+0x2*step); - lr = des_round(lr, sched, start+0x3*step); - lr = des_round(lr, sched, start+0x4*step); - lr = des_round(lr, sched, start+0x5*step); - lr = des_round(lr, sched, start+0x6*step); - lr = des_round(lr, sched, start+0x7*step); - lr = des_round(lr, sched, start+0x8*step); - lr = des_round(lr, sched, start+0x9*step); - lr = des_round(lr, sched, start+0xa*step); - lr = des_round(lr, sched, start+0xb*step); - lr = des_round(lr, sched, start+0xc*step); - lr = des_round(lr, sched, start+0xd*step); - lr = des_round(lr, sched, start+0xe*step); - lr = des_round(lr, sched, start+0xf*step); - return des_swap_lr(lr); -} - -static inline LR des_full_cipher(LR lr, const des_keysched *sched, - size_t start, size_t step) -{ - lr = des_IP(lr); - lr = des_inner_cipher(lr, sched, start, step); - lr = des_FP(lr); - return lr; -} - -/* - * Parameter pairs for the start,step arguments to the cipher routines - * above, causing them to use the same key schedule in opposite orders. - */ -#define ENCIPHER 0, 1 /* for encryption */ -#define DECIPHER 15, -1 /* for decryption */ - -/* ---------------------------------------------------------------------- - * Single-DES - */ - -struct des_cbc_ctx { - des_keysched sched; - LR iv; - ssh_cipher ciph; -}; - -static ssh_cipher *des_cbc_new(const ssh_cipheralg *alg) -{ - struct des_cbc_ctx *ctx = snew(struct des_cbc_ctx); - ctx->ciph.vt = alg; - return &ctx->ciph; -} - -static void des_cbc_free(ssh_cipher *ciph) -{ - struct des_cbc_ctx *ctx = container_of(ciph, struct des_cbc_ctx, ciph); - smemclr(ctx, sizeof(*ctx)); - sfree(ctx); -} - -static void des_cbc_setkey(ssh_cipher *ciph, const void *vkey) -{ - struct des_cbc_ctx *ctx = container_of(ciph, struct des_cbc_ctx, ciph); - const uint8_t *key = (const uint8_t *)vkey; - des_key_setup(GET_64BIT_MSB_FIRST(key), &ctx->sched); -} - -static void des_cbc_setiv(ssh_cipher *ciph, const void *iv) -{ - struct des_cbc_ctx *ctx = container_of(ciph, struct des_cbc_ctx, ciph); - ctx->iv = des_load_lr(iv); -} - -static void des_cbc_encrypt(ssh_cipher *ciph, void *vdata, int len) -{ - struct des_cbc_ctx *ctx = container_of(ciph, struct des_cbc_ctx, ciph); - uint8_t *data = (uint8_t *)vdata; - for (; len > 0; len -= 8, data += 8) { - LR plaintext = des_load_lr(data); - LR cipher_in = des_xor_lr(plaintext, ctx->iv); - LR ciphertext = des_full_cipher(cipher_in, &ctx->sched, ENCIPHER); - des_store_lr(data, ciphertext); - ctx->iv = ciphertext; - } -} - -static void des_cbc_decrypt(ssh_cipher *ciph, void *vdata, int len) -{ - struct des_cbc_ctx *ctx = container_of(ciph, struct des_cbc_ctx, ciph); - uint8_t *data = (uint8_t *)vdata; - for (; len > 0; len -= 8, data += 8) { - LR ciphertext = des_load_lr(data); - LR cipher_out = des_full_cipher(ciphertext, &ctx->sched, DECIPHER); - LR plaintext = des_xor_lr(cipher_out, ctx->iv); - des_store_lr(data, plaintext); - ctx->iv = ciphertext; - } -} - -const ssh_cipheralg ssh_des = { - .new = des_cbc_new, - .free = des_cbc_free, - .setiv = des_cbc_setiv, - .setkey = des_cbc_setkey, - .encrypt = des_cbc_encrypt, - .decrypt = des_cbc_decrypt, - .ssh2_id = "des-cbc", - .blksize = 8, - .real_keybits = 56, - .padded_keybytes = 8, - .flags = SSH_CIPHER_IS_CBC, - .text_name = "single-DES CBC", -}; - -const ssh_cipheralg ssh_des_sshcom_ssh2 = { - /* Same as ssh_des_cbc, but with a different SSH-2 ID */ - .new = des_cbc_new, - .free = des_cbc_free, - .setiv = des_cbc_setiv, - .setkey = des_cbc_setkey, - .encrypt = des_cbc_encrypt, - .decrypt = des_cbc_decrypt, - .ssh2_id = "des-cbc@ssh.com", - .blksize = 8, - .real_keybits = 56, - .padded_keybytes = 8, - .flags = SSH_CIPHER_IS_CBC, - .text_name = "single-DES CBC", -}; - -static const ssh_cipheralg *const des_list[] = { - &ssh_des, - &ssh_des_sshcom_ssh2 -}; - -const ssh2_ciphers ssh2_des = { lenof(des_list), des_list }; - -/* ---------------------------------------------------------------------- - * Triple-DES CBC, SSH-2 style. The CBC mode treats the three - * invocations of DES as a single unified cipher, and surrounds it - * with just one layer of CBC, so only one IV is needed. - */ - -struct des3_cbc1_ctx { - des_keysched sched[3]; - LR iv; - ssh_cipher ciph; -}; - -static ssh_cipher *des3_cbc1_new(const ssh_cipheralg *alg) -{ - struct des3_cbc1_ctx *ctx = snew(struct des3_cbc1_ctx); - ctx->ciph.vt = alg; - return &ctx->ciph; -} - -static void des3_cbc1_free(ssh_cipher *ciph) -{ - struct des3_cbc1_ctx *ctx = container_of(ciph, struct des3_cbc1_ctx, ciph); - smemclr(ctx, sizeof(*ctx)); - sfree(ctx); -} - -static void des3_cbc1_setkey(ssh_cipher *ciph, const void *vkey) -{ - struct des3_cbc1_ctx *ctx = container_of(ciph, struct des3_cbc1_ctx, ciph); - const uint8_t *key = (const uint8_t *)vkey; - for (size_t i = 0; i < 3; i++) - des_key_setup(GET_64BIT_MSB_FIRST(key + 8*i), &ctx->sched[i]); -} - -static void des3_cbc1_setiv(ssh_cipher *ciph, const void *iv) -{ - struct des3_cbc1_ctx *ctx = container_of(ciph, struct des3_cbc1_ctx, ciph); - ctx->iv = des_load_lr(iv); -} - -static void des3_cbc1_cbc_encrypt(ssh_cipher *ciph, void *vdata, int len) -{ - struct des3_cbc1_ctx *ctx = container_of(ciph, struct des3_cbc1_ctx, ciph); - uint8_t *data = (uint8_t *)vdata; - for (; len > 0; len -= 8, data += 8) { - LR plaintext = des_load_lr(data); - LR cipher_in = des_xor_lr(plaintext, ctx->iv); - - /* Run three copies of the cipher, without undoing and redoing - * IP/FP in between. */ - LR lr = des_IP(cipher_in); - lr = des_inner_cipher(lr, &ctx->sched[0], ENCIPHER); - lr = des_inner_cipher(lr, &ctx->sched[1], DECIPHER); - lr = des_inner_cipher(lr, &ctx->sched[2], ENCIPHER); - LR ciphertext = des_FP(lr); - - des_store_lr(data, ciphertext); - ctx->iv = ciphertext; - } -} - -static void des3_cbc1_cbc_decrypt(ssh_cipher *ciph, void *vdata, int len) -{ - struct des3_cbc1_ctx *ctx = container_of(ciph, struct des3_cbc1_ctx, ciph); - uint8_t *data = (uint8_t *)vdata; - for (; len > 0; len -= 8, data += 8) { - LR ciphertext = des_load_lr(data); - - /* Similarly to encryption, but with the order reversed. */ - LR lr = des_IP(ciphertext); - lr = des_inner_cipher(lr, &ctx->sched[2], DECIPHER); - lr = des_inner_cipher(lr, &ctx->sched[1], ENCIPHER); - lr = des_inner_cipher(lr, &ctx->sched[0], DECIPHER); - LR cipher_out = des_FP(lr); - - LR plaintext = des_xor_lr(cipher_out, ctx->iv); - des_store_lr(data, plaintext); - ctx->iv = ciphertext; - } -} - -const ssh_cipheralg ssh_3des_ssh2 = { - .new = des3_cbc1_new, - .free = des3_cbc1_free, - .setiv = des3_cbc1_setiv, - .setkey = des3_cbc1_setkey, - .encrypt = des3_cbc1_cbc_encrypt, - .decrypt = des3_cbc1_cbc_decrypt, - .ssh2_id = "3des-cbc", - .blksize = 8, - .real_keybits = 168, - .padded_keybytes = 24, - .flags = SSH_CIPHER_IS_CBC, - .text_name = "triple-DES CBC", -}; - -/* ---------------------------------------------------------------------- - * Triple-DES in SDCTR mode. Again, the three DES instances are - * treated as one big cipher, with a single counter encrypted through - * all three. - */ - -#define SDCTR_WORDS (8 / BIGNUM_INT_BYTES) - -struct des3_sdctr_ctx { - des_keysched sched[3]; - BignumInt counter[SDCTR_WORDS]; - ssh_cipher ciph; -}; - -static ssh_cipher *des3_sdctr_new(const ssh_cipheralg *alg) -{ - struct des3_sdctr_ctx *ctx = snew(struct des3_sdctr_ctx); - ctx->ciph.vt = alg; - return &ctx->ciph; -} - -static void des3_sdctr_free(ssh_cipher *ciph) -{ - struct des3_sdctr_ctx *ctx = container_of( - ciph, struct des3_sdctr_ctx, ciph); - smemclr(ctx, sizeof(*ctx)); - sfree(ctx); -} - -static void des3_sdctr_setkey(ssh_cipher *ciph, const void *vkey) -{ - struct des3_sdctr_ctx *ctx = container_of( - ciph, struct des3_sdctr_ctx, ciph); - const uint8_t *key = (const uint8_t *)vkey; - for (size_t i = 0; i < 3; i++) - des_key_setup(GET_64BIT_MSB_FIRST(key + 8*i), &ctx->sched[i]); -} - -static void des3_sdctr_setiv(ssh_cipher *ciph, const void *viv) -{ - struct des3_sdctr_ctx *ctx = container_of( - ciph, struct des3_sdctr_ctx, ciph); - const uint8_t *iv = (const uint8_t *)viv; - - /* Import the initial counter value into the internal representation */ - for (unsigned i = 0; i < SDCTR_WORDS; i++) - ctx->counter[i] = GET_BIGNUMINT_MSB_FIRST( - iv + 8 - BIGNUM_INT_BYTES - i*BIGNUM_INT_BYTES); -} - -static void des3_sdctr_encrypt_decrypt(ssh_cipher *ciph, void *vdata, int len) -{ - struct des3_sdctr_ctx *ctx = container_of( - ciph, struct des3_sdctr_ctx, ciph); - uint8_t *data = (uint8_t *)vdata; - uint8_t iv_buf[8]; - for (; len > 0; len -= 8, data += 8) { - /* Format the counter value into the buffer. */ - for (unsigned i = 0; i < SDCTR_WORDS; i++) - PUT_BIGNUMINT_MSB_FIRST( - iv_buf + 8 - BIGNUM_INT_BYTES - i*BIGNUM_INT_BYTES, - ctx->counter[i]); - - /* Increment the counter. */ - BignumCarry carry = 1; - for (unsigned i = 0; i < SDCTR_WORDS; i++) - BignumADC(ctx->counter[i], carry, ctx->counter[i], 0, carry); - - /* Triple-encrypt the counter value from the IV. */ - LR lr = des_IP(des_load_lr(iv_buf)); - lr = des_inner_cipher(lr, &ctx->sched[0], ENCIPHER); - lr = des_inner_cipher(lr, &ctx->sched[1], DECIPHER); - lr = des_inner_cipher(lr, &ctx->sched[2], ENCIPHER); - LR keystream = des_FP(lr); - - LR input = des_load_lr(data); - LR output = des_xor_lr(input, keystream); - des_store_lr(data, output); - } - smemclr(iv_buf, sizeof(iv_buf)); -} - -const ssh_cipheralg ssh_3des_ssh2_ctr = { - .new = des3_sdctr_new, - .free = des3_sdctr_free, - .setiv = des3_sdctr_setiv, - .setkey = des3_sdctr_setkey, - .encrypt = des3_sdctr_encrypt_decrypt, - .decrypt = des3_sdctr_encrypt_decrypt, - .ssh2_id = "3des-ctr", - .blksize = 8, - .real_keybits = 168, - .padded_keybytes = 24, - .flags = 0, - .text_name = "triple-DES SDCTR", -}; - -static const ssh_cipheralg *const des3_list[] = { - &ssh_3des_ssh2_ctr, - &ssh_3des_ssh2 -}; - -const ssh2_ciphers ssh2_3des = { lenof(des3_list), des3_list }; - -/* ---------------------------------------------------------------------- - * Triple-DES, SSH-1 style. SSH-1 replicated the whole CBC structure - * three times, so there have to be three separate IVs, one in each - * layer. - */ - -struct des3_cbc3_ctx { - des_keysched sched[3]; - LR iv[3]; - ssh_cipher ciph; -}; - -static ssh_cipher *des3_cbc3_new(const ssh_cipheralg *alg) -{ - struct des3_cbc3_ctx *ctx = snew(struct des3_cbc3_ctx); - ctx->ciph.vt = alg; - return &ctx->ciph; -} - -static void des3_cbc3_free(ssh_cipher *ciph) -{ - struct des3_cbc3_ctx *ctx = container_of(ciph, struct des3_cbc3_ctx, ciph); - smemclr(ctx, sizeof(*ctx)); - sfree(ctx); -} - -static void des3_cbc3_setkey(ssh_cipher *ciph, const void *vkey) -{ - struct des3_cbc3_ctx *ctx = container_of(ciph, struct des3_cbc3_ctx, ciph); - const uint8_t *key = (const uint8_t *)vkey; - for (size_t i = 0; i < 3; i++) - des_key_setup(GET_64BIT_MSB_FIRST(key + 8*i), &ctx->sched[i]); -} - -static void des3_cbc3_setiv(ssh_cipher *ciph, const void *viv) -{ - struct des3_cbc3_ctx *ctx = container_of(ciph, struct des3_cbc3_ctx, ciph); - - /* - * In principle, we ought to provide an interface for the user to - * input 24 instead of 8 bytes of IV. But that would make this an - * ugly exception to the otherwise universal rule that IV size = - * cipher block size, and there's really no need to violate that - * rule given that this is a historical one-off oddity and SSH-1 - * always initialises all three IVs to zero anyway. So we fudge it - * by just setting all the IVs to the same value. - */ - - LR iv = des_load_lr(viv); - - /* But we store the IVs in permuted form, so that we can handle - * all three CBC layers without having to do IP/FP in between. */ - iv = des_IP(iv); - for (size_t i = 0; i < 3; i++) - ctx->iv[i] = iv; -} - -static void des3_cbc3_cbc_encrypt(ssh_cipher *ciph, void *vdata, int len) -{ - struct des3_cbc3_ctx *ctx = container_of(ciph, struct des3_cbc3_ctx, ciph); - uint8_t *data = (uint8_t *)vdata; - for (; len > 0; len -= 8, data += 8) { - /* Load and IP the input. */ - LR plaintext = des_IP(des_load_lr(data)); - LR lr = plaintext; - - /* Do three passes of CBC, with the middle one inverted. */ - - lr = des_xor_lr(lr, ctx->iv[0]); - lr = des_inner_cipher(lr, &ctx->sched[0], ENCIPHER); - ctx->iv[0] = lr; - - LR ciphertext = lr; - lr = des_inner_cipher(ciphertext, &ctx->sched[1], DECIPHER); - lr = des_xor_lr(lr, ctx->iv[1]); - ctx->iv[1] = ciphertext; - - lr = des_xor_lr(lr, ctx->iv[2]); - lr = des_inner_cipher(lr, &ctx->sched[2], ENCIPHER); - ctx->iv[2] = lr; - - des_store_lr(data, des_FP(lr)); - } -} - -static void des3_cbc3_cbc_decrypt(ssh_cipher *ciph, void *vdata, int len) -{ - struct des3_cbc3_ctx *ctx = container_of(ciph, struct des3_cbc3_ctx, ciph); - uint8_t *data = (uint8_t *)vdata; - for (; len > 0; len -= 8, data += 8) { - /* Load and IP the input */ - LR lr = des_IP(des_load_lr(data)); - LR ciphertext; - - /* Do three passes of CBC, with the middle one inverted. */ - ciphertext = lr; - lr = des_inner_cipher(ciphertext, &ctx->sched[2], DECIPHER); - lr = des_xor_lr(lr, ctx->iv[2]); - ctx->iv[2] = ciphertext; - - lr = des_xor_lr(lr, ctx->iv[1]); - lr = des_inner_cipher(lr, &ctx->sched[1], ENCIPHER); - ctx->iv[1] = lr; - - ciphertext = lr; - lr = des_inner_cipher(ciphertext, &ctx->sched[0], DECIPHER); - lr = des_xor_lr(lr, ctx->iv[0]); - ctx->iv[0] = ciphertext; - - des_store_lr(data, des_FP(lr)); - } -} - -const ssh_cipheralg ssh_3des_ssh1 = { - .new = des3_cbc3_new, - .free = des3_cbc3_free, - .setiv = des3_cbc3_setiv, - .setkey = des3_cbc3_setkey, - .encrypt = des3_cbc3_cbc_encrypt, - .decrypt = des3_cbc3_cbc_decrypt, - .blksize = 8, - .real_keybits = 168, - .padded_keybytes = 24, - .flags = SSH_CIPHER_IS_CBC, - .text_name = "triple-DES inner-CBC", -}; |