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putty/sshdes.c

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C
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#include <assert.h>
#include "ssh.h"
/* des.c - implementation of DES
*/
/*
* Description of DES
* ------------------
*
* Unlike the description in FIPS 46, I'm going to use _sensible_ indices:
* bits in an n-bit word are numbered from 0 at the LSB to n-1 at the MSB.
* And S-boxes are indexed by six consecutive bits, not by the outer two
* followed by the middle four.
*
* The DES encryption routine requires a 64-bit input, and a key schedule K
* containing 16 48-bit elements.
*
* First the input is permuted by the initial permutation IP.
* Then the input is split into 32-bit words L and R. (L is the MSW.)
* Next, 16 rounds. In each round:
* (L, R) <- (R, L xor f(R, K[i]))
* Then the pre-output words L and R are swapped.
* Then L and R are glued back together into a 64-bit word. (L is the MSW,
* again, but since we just swapped them, the MSW is the R that came out
* of the last round.)
* The 64-bit output block is permuted by the inverse of IP and returned.
*
* Decryption is identical except that the elements of K are used in the
* opposite order. (This wouldn't work if that word swap didn't happen.)
*
* The function f, used in each round, accepts a 32-bit word R and a
* 48-bit key block K. It produces a 32-bit output.
*
* First R is expanded to 48 bits using the bit-selection function E.
* The resulting 48-bit block is XORed with the key block K to produce
* a 48-bit block X.
* This block X is split into eight groups of 6 bits. Each group of 6
* bits is then looked up in one of the eight S-boxes to convert
* it to 4 bits. These eight groups of 4 bits are glued back
* together to produce a 32-bit preoutput block.
* The preoutput block is permuted using the permutation P and returned.
*
* Key setup maps a 64-bit key word into a 16x48-bit key schedule. Although
* the approved input format for the key is a 64-bit word, eight of the
* bits are discarded, so the actual quantity of key used is 56 bits.
*
* First the input key is converted to two 28-bit words C and D using
* the bit-selection function PC1.
* Then 16 rounds of key setup occur. In each round, C and D are each
* rotated left by either 1 or 2 bits (depending on which round), and
* then converted into a key schedule element using the bit-selection
* function PC2.
*
* That's the actual algorithm. Now for the tedious details: all those
* painful permutations and lookup tables.
*
* IP is a 64-to-64 bit permutation. Its output contains the following
* bits of its input (listed in order MSB to LSB of output).
*
* 6 14 22 30 38 46 54 62 4 12 20 28 36 44 52 60
* 2 10 18 26 34 42 50 58 0 8 16 24 32 40 48 56
* 7 15 23 31 39 47 55 63 5 13 21 29 37 45 53 61
* 3 11 19 27 35 43 51 59 1 9 17 25 33 41 49 57
*
* E is a 32-to-48 bit selection function. Its output contains the following
* bits of its input (listed in order MSB to LSB of output).
*
* 0 31 30 29 28 27 28 27 26 25 24 23 24 23 22 21 20 19 20 19 18 17 16 15
* 16 15 14 13 12 11 12 11 10 9 8 7 8 7 6 5 4 3 4 3 2 1 0 31
*
* The S-boxes are arbitrary table-lookups each mapping a 6-bit input to a
* 4-bit output. In other words, each S-box is an array[64] of 4-bit numbers.
* The S-boxes are listed below. The first S-box listed is applied to the
* most significant six bits of the block X; the last one is applied to the
* least significant.
*
* 14 0 4 15 13 7 1 4 2 14 15 2 11 13 8 1
* 3 10 10 6 6 12 12 11 5 9 9 5 0 3 7 8
* 4 15 1 12 14 8 8 2 13 4 6 9 2 1 11 7
* 15 5 12 11 9 3 7 14 3 10 10 0 5 6 0 13
*
* 15 3 1 13 8 4 14 7 6 15 11 2 3 8 4 14
* 9 12 7 0 2 1 13 10 12 6 0 9 5 11 10 5
* 0 13 14 8 7 10 11 1 10 3 4 15 13 4 1 2
* 5 11 8 6 12 7 6 12 9 0 3 5 2 14 15 9
*
* 10 13 0 7 9 0 14 9 6 3 3 4 15 6 5 10
* 1 2 13 8 12 5 7 14 11 12 4 11 2 15 8 1
* 13 1 6 10 4 13 9 0 8 6 15 9 3 8 0 7
* 11 4 1 15 2 14 12 3 5 11 10 5 14 2 7 12
*
* 7 13 13 8 14 11 3 5 0 6 6 15 9 0 10 3
* 1 4 2 7 8 2 5 12 11 1 12 10 4 14 15 9
* 10 3 6 15 9 0 0 6 12 10 11 1 7 13 13 8
* 15 9 1 4 3 5 14 11 5 12 2 7 8 2 4 14
*
* 2 14 12 11 4 2 1 12 7 4 10 7 11 13 6 1
* 8 5 5 0 3 15 15 10 13 3 0 9 14 8 9 6
* 4 11 2 8 1 12 11 7 10 1 13 14 7 2 8 13
* 15 6 9 15 12 0 5 9 6 10 3 4 0 5 14 3
*
* 12 10 1 15 10 4 15 2 9 7 2 12 6 9 8 5
* 0 6 13 1 3 13 4 14 14 0 7 11 5 3 11 8
* 9 4 14 3 15 2 5 12 2 9 8 5 12 15 3 10
* 7 11 0 14 4 1 10 7 1 6 13 0 11 8 6 13
*
* 4 13 11 0 2 11 14 7 15 4 0 9 8 1 13 10
* 3 14 12 3 9 5 7 12 5 2 10 15 6 8 1 6
* 1 6 4 11 11 13 13 8 12 1 3 4 7 10 14 7
* 10 9 15 5 6 0 8 15 0 14 5 2 9 3 2 12
*
* 13 1 2 15 8 13 4 8 6 10 15 3 11 7 1 4
* 10 12 9 5 3 6 14 11 5 0 0 14 12 9 7 2
* 7 2 11 1 4 14 1 7 9 4 12 10 14 8 2 13
* 0 15 6 12 10 9 13 0 15 3 3 5 5 6 8 11
*
* P is a 32-to-32 bit permutation. Its output contains the following
* bits of its input (listed in order MSB to LSB of output).
*
* 16 25 12 11 3 20 4 15 31 17 9 6 27 14 1 22
* 30 24 8 18 0 5 29 23 13 19 2 26 10 21 28 7
*
* PC1 is a 64-to-56 bit selection function. Its output is in two words,
* C and D. The word C contains the following bits of its input (listed
* in order MSB to LSB of output).
*
* 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
*
* And the word D contains these bits.
*
* 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
*
* PC2 is a 56-to-48 bit selection function. Its input is in two words,
* C and D. These are treated as one 56-bit word (with C more significant,
* so that bits 55 to 28 of the word are bits 27 to 0 of C, and bits 27 to
* 0 of the word are bits 27 to 0 of D). The output contains the following
* bits of this 56-bit input word (listed in order MSB to LSB of output).
*
* 42 39 45 32 55 51 53 28 41 50 35 46 33 37 44 52 30 48 40 49 29 36 43 54
* 15 4 25 19 9 1 26 16 5 11 23 8 12 7 17 0 22 3 10 14 6 20 27 24
*/
/*
* Implementation details
* ----------------------
*
* If you look at the code in this module, you'll find it looks
* nothing _like_ the above algorithm. Here I explain the
* differences...
*
* Key setup has not been heavily optimised here. We are not
* concerned with key agility: we aren't codebreakers. We don't
* mind a little delay (and it really is a little one; it may be a
* factor of five or so slower than it could be but it's still not
* an appreciable length of time) while setting up. The only tweaks
* in the key setup are ones which change the format of the key
* schedule to speed up the actual encryption. I'll describe those
* below.
*
* The first and most obvious optimisation is the S-boxes. Since
* each S-box always targets the same four bits in the final 32-bit
* word, so the output from (for example) S-box 0 must always be
* shifted left 28 bits, we can store the already-shifted outputs
* in the lookup tables. This reduces lookup-and-shift to lookup,
* so the S-box step is now just a question of ORing together eight
* table lookups.
*
* The permutation P is just a bit order change; it's invariant
* with respect to OR, in that P(x)|P(y) = P(x|y). Therefore, we
* can apply P to every entry of the S-box tables and then we don't
* have to do it in the code of f(). This yields a set of tables
* which might be called SP-boxes.
*
* The bit-selection function E is our next target. Note that E is
* immediately followed by the operation of splitting into 6-bit
* chunks. Examining the 6-bit chunks coming out of E we notice
* they're all contiguous within the word (speaking cyclically -
* the end two wrap round); so we can extract those bit strings
* individually rather than explicitly running E. This would yield
* code such as
*
* y |= SPboxes[0][ (rotl(R, 5) ^ top6bitsofK) & 0x3F ];
* t |= SPboxes[1][ (rotl(R,11) ^ next6bitsofK) & 0x3F ];
*
* and so on; and the key schedule preparation would have to
* provide each 6-bit chunk separately.
*
* Really we'd like to XOR in the key schedule element before
* looking up bit strings in R. This we can't do, naively, because
* the 6-bit strings we want overlap. But look at the strings:
*
* 3322222222221111111111
* bit 10987654321098765432109876543210
*
* box0 XXXXX X
* box1 XXXXXX
* box2 XXXXXX
* box3 XXXXXX
* box4 XXXXXX
* box5 XXXXXX
* box6 XXXXXX
* box7 X XXXXX
*
* The bit strings we need to XOR in for boxes 0, 2, 4 and 6 don't
* overlap with each other. Neither do the ones for boxes 1, 3, 5
* and 7. So we could provide the key schedule in the form of two
* words that we can separately XOR into R, and then every S-box
* index is available as a (cyclically) contiguous 6-bit substring
* of one or the other of the results.
*
* The comments in Eric Young's libdes implementation point out
* that two of these bit strings require a rotation (rather than a
* simple shift) to extract. It's unavoidable that at least _one_
* must do; but we can actually run the whole inner algorithm (all
* 16 rounds) rotated one bit to the left, so that what the `real'
* DES description sees as L=0x80000001 we see as L=0x00000003.
* This requires rotating all our SP-box entries one bit to the
* left, and rotating each word of the key schedule elements one to
* the left, and rotating L and R one bit left just after IP and
* one bit right again just before FP. And in each round we convert
* a rotate into a shift, so we've saved a few per cent.
*
* That's about it for the inner loop; the SP-box tables as listed
* below are what I've described here (the original S value,
* shifted to its final place in the input to P, run through P, and
* then rotated one bit left). All that remains is to optimise the
* initial permutation IP.
*
* IP is not an arbitrary permutation. It has the nice property
* that if you take any bit number, write it in binary (6 bits),
* permute those 6 bits and invert some of them, you get the final
* position of that bit. Specifically, the bit whose initial
* position is given (in binary) as fedcba ends up in position
* AcbFED (where a capital letter denotes the inverse of a bit).
*
* We have the 64-bit data in two 32-bit words L and R, where bits
* in L are those with f=1 and bits in R are those with f=0. We
* note that we can do a simple transformation: suppose we exchange
* the bits with f=1,c=0 and the bits with f=0,c=1. This will cause
* the bit fedcba to be in position cedfba - we've `swapped' bits c
* and f in the position of each bit!
*
* Better still, this transformation is easy. In the example above,
* bits in L with c=0 are bits 0x0F0F0F0F, and those in R with c=1
* are 0xF0F0F0F0. So we can do
*
* difference = ((R >> 4) ^ L) & 0x0F0F0F0F
* R ^= (difference << 4)
* L ^= difference
*
* to perform the swap. Let's denote this by bitswap(4,0x0F0F0F0F).
* Also, we can invert the bit at the top just by exchanging L and
* R. So in a few swaps and a few of these bit operations we can
* do:
*
* Initially the position of bit fedcba is fedcba
* Swap L with R to make it Fedcba
* Perform bitswap( 4,0x0F0F0F0F) to make it cedFba
* Perform bitswap(16,0x0000FFFF) to make it ecdFba
* Swap L with R to make it EcdFba
* Perform bitswap( 2,0x33333333) to make it bcdFEa
* Perform bitswap( 8,0x00FF00FF) to make it dcbFEa
* Swap L with R to make it DcbFEa
* Perform bitswap( 1,0x55555555) to make it acbFED
* Swap L with R to make it AcbFED
*
* (In the actual code the four swaps are implicit: R and L are
* simply used the other way round in the first, second and last
* bitswap operations.)
*
* The final permutation is just the inverse of IP, so it can be
* performed by a similar set of operations.
*/
typedef struct {
word32 k0246[16], k1357[16];
word32 eiv0, eiv1;
word32 div0, div1;
} DESContext;
#define rotl(x, c) ( (x << c) | (x >> (32-c)) )
#define rotl28(x, c) ( ( (x << c) | (x >> (28-c)) ) & 0x0FFFFFFF)
static word32 bitsel(word32 *input, const int *bitnums, int size) {
word32 ret = 0;
while (size--) {
int bitpos = *bitnums++;
ret <<= 1;
if (bitpos >= 0)
ret |= 1 & (input[bitpos / 32] >> (bitpos % 32));
}
return ret;
}
void des_key_setup(word32 key_msw, word32 key_lsw, DESContext *sched) {
static const int PC1_Cbits[] = {
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
};
static const int PC1_Dbits[] = {
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
};
/*
* The bit numbers in the two lists below don't correspond to
* the ones in the above description of PC2, because in the
* above description C and D are concatenated so `bit 28' means
* bit 0 of C. In this implementation we're using the standard
* `bitsel' function above and C is in the second word, so bit
* 0 of C is addressed by writing `32' here.
*/
static const int PC2_0246[] = {
49, 36, 59, 55, -1, -1, 37, 41, 48, 56, 34, 52, -1, -1, 15, 4,
25, 19, 9, 1, -1, -1, 12, 7, 17, 0, 22, 3, -1, -1, 46, 43
};
static const int PC2_1357[] = {
-1, -1, 57, 32, 45, 54, 39, 50, -1, -1, 44, 53, 33, 40, 47, 58,
-1, -1, 26, 16, 5, 11, 23, 8, -1, -1, 10, 14, 6, 20, 27, 24
};
static const int leftshifts[] = {1,1,2,2,2,2,2,2,1,2,2,2,2,2,2,1};
word32 C, D;
word32 buf[2];
int i;
buf[0] = key_lsw;
buf[1] = key_msw;
C = bitsel(buf, PC1_Cbits, 28);
D = bitsel(buf, PC1_Dbits, 28);
for (i = 0; i < 16; i++) {
C = rotl28(C, leftshifts[i]);
D = rotl28(D, leftshifts[i]);
buf[0] = D;
buf[1] = C;
sched->k0246[i] = bitsel(buf, PC2_0246, 32);
sched->k1357[i] = bitsel(buf, PC2_1357, 32);
}
sched->eiv0 = sched->eiv1 = 0;
sched->div0 = sched->div1 = 0; /* for good measure */
}
static const word32 SPboxes[8][64] = {
{0x01010400, 0x00000000, 0x00010000, 0x01010404,
0x01010004, 0x00010404, 0x00000004, 0x00010000,
0x00000400, 0x01010400, 0x01010404, 0x00000400,
0x01000404, 0x01010004, 0x01000000, 0x00000004,
0x00000404, 0x01000400, 0x01000400, 0x00010400,
0x00010400, 0x01010000, 0x01010000, 0x01000404,
0x00010004, 0x01000004, 0x01000004, 0x00010004,
0x00000000, 0x00000404, 0x00010404, 0x01000000,
0x00010000, 0x01010404, 0x00000004, 0x01010000,
0x01010400, 0x01000000, 0x01000000, 0x00000400,
0x01010004, 0x00010000, 0x00010400, 0x01000004,
0x00000400, 0x00000004, 0x01000404, 0x00010404,
0x01010404, 0x00010004, 0x01010000, 0x01000404,
0x01000004, 0x00000404, 0x00010404, 0x01010400,
0x00000404, 0x01000400, 0x01000400, 0x00000000,
0x00010004, 0x00010400, 0x00000000, 0x01010004L},
{0x80108020, 0x80008000, 0x00008000, 0x00108020,
0x00100000, 0x00000020, 0x80100020, 0x80008020,
0x80000020, 0x80108020, 0x80108000, 0x80000000,
0x80008000, 0x00100000, 0x00000020, 0x80100020,
0x00108000, 0x00100020, 0x80008020, 0x00000000,
0x80000000, 0x00008000, 0x00108020, 0x80100000,
0x00100020, 0x80000020, 0x00000000, 0x00108000,
0x00008020, 0x80108000, 0x80100000, 0x00008020,
0x00000000, 0x00108020, 0x80100020, 0x00100000,
0x80008020, 0x80100000, 0x80108000, 0x00008000,
0x80100000, 0x80008000, 0x00000020, 0x80108020,
0x00108020, 0x00000020, 0x00008000, 0x80000000,
0x00008020, 0x80108000, 0x00100000, 0x80000020,
0x00100020, 0x80008020, 0x80000020, 0x00100020,
0x00108000, 0x00000000, 0x80008000, 0x00008020,
0x80000000, 0x80100020, 0x80108020, 0x00108000L},
{0x00000208, 0x08020200, 0x00000000, 0x08020008,
0x08000200, 0x00000000, 0x00020208, 0x08000200,
0x00020008, 0x08000008, 0x08000008, 0x00020000,
0x08020208, 0x00020008, 0x08020000, 0x00000208,
0x08000000, 0x00000008, 0x08020200, 0x00000200,
0x00020200, 0x08020000, 0x08020008, 0x00020208,
0x08000208, 0x00020200, 0x00020000, 0x08000208,
0x00000008, 0x08020208, 0x00000200, 0x08000000,
0x08020200, 0x08000000, 0x00020008, 0x00000208,
0x00020000, 0x08020200, 0x08000200, 0x00000000,
0x00000200, 0x00020008, 0x08020208, 0x08000200,
0x08000008, 0x00000200, 0x00000000, 0x08020008,
0x08000208, 0x00020000, 0x08000000, 0x08020208,
0x00000008, 0x00020208, 0x00020200, 0x08000008,
0x08020000, 0x08000208, 0x00000208, 0x08020000,
0x00020208, 0x00000008, 0x08020008, 0x00020200L},
{0x00802001, 0x00002081, 0x00002081, 0x00000080,
0x00802080, 0x00800081, 0x00800001, 0x00002001,
0x00000000, 0x00802000, 0x00802000, 0x00802081,
0x00000081, 0x00000000, 0x00800080, 0x00800001,
0x00000001, 0x00002000, 0x00800000, 0x00802001,
0x00000080, 0x00800000, 0x00002001, 0x00002080,
0x00800081, 0x00000001, 0x00002080, 0x00800080,
0x00002000, 0x00802080, 0x00802081, 0x00000081,
0x00800080, 0x00800001, 0x00802000, 0x00802081,
0x00000081, 0x00000000, 0x00000000, 0x00802000,
0x00002080, 0x00800080, 0x00800081, 0x00000001,
0x00802001, 0x00002081, 0x00002081, 0x00000080,
0x00802081, 0x00000081, 0x00000001, 0x00002000,
0x00800001, 0x00002001, 0x00802080, 0x00800081,
0x00002001, 0x00002080, 0x00800000, 0x00802001,
0x00000080, 0x00800000, 0x00002000, 0x00802080L},
{0x00000100, 0x02080100, 0x02080000, 0x42000100,
0x00080000, 0x00000100, 0x40000000, 0x02080000,
0x40080100, 0x00080000, 0x02000100, 0x40080100,
0x42000100, 0x42080000, 0x00080100, 0x40000000,
0x02000000, 0x40080000, 0x40080000, 0x00000000,
0x40000100, 0x42080100, 0x42080100, 0x02000100,
0x42080000, 0x40000100, 0x00000000, 0x42000000,
0x02080100, 0x02000000, 0x42000000, 0x00080100,
0x00080000, 0x42000100, 0x00000100, 0x02000000,
0x40000000, 0x02080000, 0x42000100, 0x40080100,
0x02000100, 0x40000000, 0x42080000, 0x02080100,
0x40080100, 0x00000100, 0x02000000, 0x42080000,
0x42080100, 0x00080100, 0x42000000, 0x42080100,
0x02080000, 0x00000000, 0x40080000, 0x42000000,
0x00080100, 0x02000100, 0x40000100, 0x00080000,
0x00000000, 0x40080000, 0x02080100, 0x40000100L},
{0x20000010, 0x20400000, 0x00004000, 0x20404010,
0x20400000, 0x00000010, 0x20404010, 0x00400000,
0x20004000, 0x00404010, 0x00400000, 0x20000010,
0x00400010, 0x20004000, 0x20000000, 0x00004010,
0x00000000, 0x00400010, 0x20004010, 0x00004000,
0x00404000, 0x20004010, 0x00000010, 0x20400010,
0x20400010, 0x00000000, 0x00404010, 0x20404000,
0x00004010, 0x00404000, 0x20404000, 0x20000000,
0x20004000, 0x00000010, 0x20400010, 0x00404000,
0x20404010, 0x00400000, 0x00004010, 0x20000010,
0x00400000, 0x20004000, 0x20000000, 0x00004010,
0x20000010, 0x20404010, 0x00404000, 0x20400000,
0x00404010, 0x20404000, 0x00000000, 0x20400010,
0x00000010, 0x00004000, 0x20400000, 0x00404010,
0x00004000, 0x00400010, 0x20004010, 0x00000000,
0x20404000, 0x20000000, 0x00400010, 0x20004010L},
{0x00200000, 0x04200002, 0x04000802, 0x00000000,
0x00000800, 0x04000802, 0x00200802, 0x04200800,
0x04200802, 0x00200000, 0x00000000, 0x04000002,
0x00000002, 0x04000000, 0x04200002, 0x00000802,
0x04000800, 0x00200802, 0x00200002, 0x04000800,
0x04000002, 0x04200000, 0x04200800, 0x00200002,
0x04200000, 0x00000800, 0x00000802, 0x04200802,
0x00200800, 0x00000002, 0x04000000, 0x00200800,
0x04000000, 0x00200800, 0x00200000, 0x04000802,
0x04000802, 0x04200002, 0x04200002, 0x00000002,
0x00200002, 0x04000000, 0x04000800, 0x00200000,
0x04200800, 0x00000802, 0x00200802, 0x04200800,
0x00000802, 0x04000002, 0x04200802, 0x04200000,
0x00200800, 0x00000000, 0x00000002, 0x04200802,
0x00000000, 0x00200802, 0x04200000, 0x00000800,
0x04000002, 0x04000800, 0x00000800, 0x00200002L},
{0x10001040, 0x00001000, 0x00040000, 0x10041040,
0x10000000, 0x10001040, 0x00000040, 0x10000000,
0x00040040, 0x10040000, 0x10041040, 0x00041000,
0x10041000, 0x00041040, 0x00001000, 0x00000040,
0x10040000, 0x10000040, 0x10001000, 0x00001040,
0x00041000, 0x00040040, 0x10040040, 0x10041000,
0x00001040, 0x00000000, 0x00000000, 0x10040040,
0x10000040, 0x10001000, 0x00041040, 0x00040000,
0x00041040, 0x00040000, 0x10041000, 0x00001000,
0x00000040, 0x10040040, 0x00001000, 0x00041040,
0x10001000, 0x00000040, 0x10000040, 0x10040000,
0x10040040, 0x10000000, 0x00040000, 0x10001040,
0x00000000, 0x10041040, 0x00040040, 0x10000040,
0x10040000, 0x10001000, 0x10001040, 0x00000000,
0x10041040, 0x00041000, 0x00041000, 0x00001040,
0x00001040, 0x00040040, 0x10000000, 0x10041000L}
};
#define f(R, K0246, K1357) (\
s0246 = R ^ K0246, \
s1357 = R ^ K1357, \
s0246 = rotl(s0246, 28), \
SPboxes[0] [(s0246 >> 24) & 0x3F] | \
SPboxes[1] [(s1357 >> 24) & 0x3F] | \
SPboxes[2] [(s0246 >> 16) & 0x3F] | \
SPboxes[3] [(s1357 >> 16) & 0x3F] | \
SPboxes[4] [(s0246 >> 8) & 0x3F] | \
SPboxes[5] [(s1357 >> 8) & 0x3F] | \
SPboxes[6] [(s0246 ) & 0x3F] | \
SPboxes[7] [(s1357 ) & 0x3F])
#define bitswap(L, R, n, mask) (\
swap = mask & ( (R >> n) ^ L ), \
R ^= swap << n, \
L ^= swap)
/* Initial permutation */
#define IP(L, R) (\
bitswap(R, L, 4, 0x0F0F0F0F), \
bitswap(R, L, 16, 0x0000FFFF), \
bitswap(L, R, 2, 0x33333333), \
bitswap(L, R, 8, 0x00FF00FF), \
bitswap(R, L, 1, 0x55555555))
/* Final permutation */
#define FP(L, R) (\
bitswap(R, L, 1, 0x55555555), \
bitswap(L, R, 8, 0x00FF00FF), \
bitswap(L, R, 2, 0x33333333), \
bitswap(R, L, 16, 0x0000FFFF), \
bitswap(R, L, 4, 0x0F0F0F0F))
void des_encipher(word32 *output, word32 L, word32 R, DESContext *sched) {
word32 swap, s0246, s1357;
IP(L, R);
L = rotl(L, 1);
R = rotl(R, 1);
L ^= f(R, sched->k0246[ 0], sched->k1357[ 0]);
R ^= f(L, sched->k0246[ 1], sched->k1357[ 1]);
L ^= f(R, sched->k0246[ 2], sched->k1357[ 2]);
R ^= f(L, sched->k0246[ 3], sched->k1357[ 3]);
L ^= f(R, sched->k0246[ 4], sched->k1357[ 4]);
R ^= f(L, sched->k0246[ 5], sched->k1357[ 5]);
L ^= f(R, sched->k0246[ 6], sched->k1357[ 6]);
R ^= f(L, sched->k0246[ 7], sched->k1357[ 7]);
L ^= f(R, sched->k0246[ 8], sched->k1357[ 8]);
R ^= f(L, sched->k0246[ 9], sched->k1357[ 9]);
L ^= f(R, sched->k0246[10], sched->k1357[10]);
R ^= f(L, sched->k0246[11], sched->k1357[11]);
L ^= f(R, sched->k0246[12], sched->k1357[12]);
R ^= f(L, sched->k0246[13], sched->k1357[13]);
L ^= f(R, sched->k0246[14], sched->k1357[14]);
R ^= f(L, sched->k0246[15], sched->k1357[15]);
L = rotl(L, 31);
R = rotl(R, 31);
swap = L; L = R; R = swap;
FP(L, R);
output[0] = L;
output[1] = R;
}
void des_decipher(word32 *output, word32 L, word32 R, DESContext *sched) {
word32 swap, s0246, s1357;
IP(L, R);
L = rotl(L, 1);
R = rotl(R, 1);
L ^= f(R, sched->k0246[15], sched->k1357[15]);
R ^= f(L, sched->k0246[14], sched->k1357[14]);
L ^= f(R, sched->k0246[13], sched->k1357[13]);
R ^= f(L, sched->k0246[12], sched->k1357[12]);
L ^= f(R, sched->k0246[11], sched->k1357[11]);
R ^= f(L, sched->k0246[10], sched->k1357[10]);
L ^= f(R, sched->k0246[ 9], sched->k1357[ 9]);
R ^= f(L, sched->k0246[ 8], sched->k1357[ 8]);
L ^= f(R, sched->k0246[ 7], sched->k1357[ 7]);
R ^= f(L, sched->k0246[ 6], sched->k1357[ 6]);
L ^= f(R, sched->k0246[ 5], sched->k1357[ 5]);
R ^= f(L, sched->k0246[ 4], sched->k1357[ 4]);
L ^= f(R, sched->k0246[ 3], sched->k1357[ 3]);
R ^= f(L, sched->k0246[ 2], sched->k1357[ 2]);
L ^= f(R, sched->k0246[ 1], sched->k1357[ 1]);
R ^= f(L, sched->k0246[ 0], sched->k1357[ 0]);
L = rotl(L, 31);
R = rotl(R, 31);
swap = L; L = R; R = swap;
FP(L, R);
output[0] = L;
output[1] = R;
}
#define GET_32BIT_MSB_FIRST(cp) \
(((unsigned long)(unsigned char)(cp)[3]) | \
((unsigned long)(unsigned char)(cp)[2] << 8) | \
((unsigned long)(unsigned char)(cp)[1] << 16) | \
((unsigned long)(unsigned char)(cp)[0] << 24))
#define PUT_32BIT_MSB_FIRST(cp, value) do { \
(cp)[3] = (value); \
(cp)[2] = (value) >> 8; \
(cp)[1] = (value) >> 16; \
(cp)[0] = (value) >> 24; } while (0)
static void des_cbc_encrypt(unsigned char *dest, const unsigned char *src,
unsigned int len, DESContext *sched) {
word32 out[2], iv0, iv1;
unsigned int i;
assert((len & 7) == 0);
iv0 = sched->eiv0;
iv1 = sched->eiv1;
for (i = 0; i < len; i += 8) {
iv0 ^= GET_32BIT_MSB_FIRST(src); src += 4;
iv1 ^= GET_32BIT_MSB_FIRST(src); src += 4;
des_encipher(out, iv0, iv1, sched);
iv0 = out[0];
iv1 = out[1];
PUT_32BIT_MSB_FIRST(dest, iv0); dest += 4;
PUT_32BIT_MSB_FIRST(dest, iv1); dest += 4;
}
sched->eiv0 = iv0;
sched->eiv1 = iv1;
}
static void des_cbc_decrypt(unsigned char *dest, const unsigned char *src,
unsigned int len, DESContext *sched) {
word32 out[2], iv0, iv1, xL, xR;
unsigned int i;
assert((len & 7) == 0);
iv0 = sched->div0;
iv1 = sched->div1;
for (i = 0; i < len; i += 8) {
xL = GET_32BIT_MSB_FIRST(src); src += 4;
xR = GET_32BIT_MSB_FIRST(src); src += 4;
des_decipher(out, xL, xR, sched);
iv0 ^= out[0];
iv1 ^= out[1];
PUT_32BIT_MSB_FIRST(dest, iv0); dest += 4;
PUT_32BIT_MSB_FIRST(dest, iv1); dest += 4;
iv0 = xL;
iv1 = xR;
}
sched->div0 = iv0;
sched->div1 = iv1;
}
static void des_3cbc_encrypt(unsigned char *dest, const unsigned char *src,
unsigned int len, DESContext *scheds) {
des_cbc_encrypt(dest, src, len, &scheds[0]);
des_cbc_decrypt(dest, src, len, &scheds[1]);
des_cbc_encrypt(dest, src, len, &scheds[2]);
}
static void des_cbc3_encrypt(unsigned char *dest, const unsigned char *src,
unsigned int len, DESContext *scheds) {
word32 out[2], iv0, iv1;
unsigned int i;
assert((len & 7) == 0);
iv0 = scheds->eiv0;
iv1 = scheds->eiv1;
for (i = 0; i < len; i += 8) {
iv0 ^= GET_32BIT_MSB_FIRST(src); src += 4;
iv1 ^= GET_32BIT_MSB_FIRST(src); src += 4;
des_encipher(out, iv0, iv1, &scheds[0]);
des_decipher(out, out[0], out[1], &scheds[1]);
des_encipher(out, out[0], out[1], &scheds[2]);
iv0 = out[0];
iv1 = out[1];
PUT_32BIT_MSB_FIRST(dest, iv0); dest += 4;
PUT_32BIT_MSB_FIRST(dest, iv1); dest += 4;
}
scheds->eiv0 = iv0;
scheds->eiv1 = iv1;
}
static void des_3cbc_decrypt(unsigned char *dest, const unsigned char *src,
unsigned int len, DESContext *scheds) {
des_cbc_decrypt(dest, src, len, &scheds[2]);
des_cbc_encrypt(dest, src, len, &scheds[1]);
des_cbc_decrypt(dest, src, len, &scheds[0]);
}
static void des_cbc3_decrypt(unsigned char *dest, const unsigned char *src,
unsigned int len, DESContext *scheds) {
word32 out[2], iv0, iv1, xL, xR;
unsigned int i;
assert((len & 7) == 0);
iv0 = scheds->div0;
iv1 = scheds->div1;
for (i = 0; i < len; i += 8) {
xL = GET_32BIT_MSB_FIRST(src); src += 4;
xR = GET_32BIT_MSB_FIRST(src); src += 4;
des_decipher(out, xL, xR, &scheds[2]);
des_encipher(out, out[0], out[1], &scheds[1]);
des_decipher(out, out[0], out[1], &scheds[0]);
iv0 ^= out[0];
iv1 ^= out[1];
PUT_32BIT_MSB_FIRST(dest, iv0); dest += 4;
PUT_32BIT_MSB_FIRST(dest, iv1); dest += 4;
iv0 = xL;
iv1 = xR;
}
scheds->div0 = iv0;
scheds->div1 = iv1;
}
static DESContext cskeys[3], sckeys[3];
static void des3_cskey(unsigned char *key) {
des_key_setup(GET_32BIT_MSB_FIRST(key),
GET_32BIT_MSB_FIRST(key+4), &cskeys[0]);
des_key_setup(GET_32BIT_MSB_FIRST(key+8),
GET_32BIT_MSB_FIRST(key+12), &cskeys[1]);
des_key_setup(GET_32BIT_MSB_FIRST(key+16),
GET_32BIT_MSB_FIRST(key+20), &cskeys[2]);
logevent("Initialised triple-DES client->server encryption");
}
static void des3_csiv(unsigned char *key) {
cskeys[0].eiv0 = GET_32BIT_MSB_FIRST(key);
cskeys[0].eiv1 = GET_32BIT_MSB_FIRST(key+4);
}
static void des3_sciv(unsigned char *key) {
sckeys[0].div0 = GET_32BIT_MSB_FIRST(key);
sckeys[0].div1 = GET_32BIT_MSB_FIRST(key+4);
}
static void des3_sckey(unsigned char *key) {
des_key_setup(GET_32BIT_MSB_FIRST(key),
GET_32BIT_MSB_FIRST(key+4), &sckeys[0]);
des_key_setup(GET_32BIT_MSB_FIRST(key+8),
GET_32BIT_MSB_FIRST(key+12), &sckeys[1]);
des_key_setup(GET_32BIT_MSB_FIRST(key+16),
GET_32BIT_MSB_FIRST(key+20), &sckeys[2]);
logevent("Initialised triple-DES server->client encryption");
}
static void des3_sesskey(unsigned char *key) {
des3_cskey(key);
des3_sckey(key);
}
static void des3_encrypt_blk(unsigned char *blk, int len) {
des_3cbc_encrypt(blk, blk, len, cskeys);
}
static void des3_decrypt_blk(unsigned char *blk, int len) {
des_3cbc_decrypt(blk, blk, len, sckeys);
}
static void des3_ssh2_encrypt_blk(unsigned char *blk, int len) {
des_cbc3_encrypt(blk, blk, len, cskeys);
}
static void des3_ssh2_decrypt_blk(unsigned char *blk, int len) {
des_cbc3_decrypt(blk, blk, len, sckeys);
}
void des3_decrypt_pubkey(unsigned char *key,
unsigned char *blk, int len) {
DESContext ourkeys[3];
des_key_setup(GET_32BIT_MSB_FIRST(key),
GET_32BIT_MSB_FIRST(key+4), &ourkeys[0]);
des_key_setup(GET_32BIT_MSB_FIRST(key+8),
GET_32BIT_MSB_FIRST(key+12), &ourkeys[1]);
des_key_setup(GET_32BIT_MSB_FIRST(key),
GET_32BIT_MSB_FIRST(key+4), &ourkeys[2]);
des_3cbc_decrypt(blk, blk, len, ourkeys);
}
struct ssh_cipher ssh_3des_ssh2 = {
NULL,
des3_csiv, des3_cskey,
des3_sciv, des3_sckey,
des3_ssh2_encrypt_blk,
des3_ssh2_decrypt_blk,
"3des-cbc",
8
};
struct ssh_cipher ssh_3des = {
des3_sesskey,
NULL, NULL, NULL, NULL,
des3_encrypt_blk,
des3_decrypt_blk,
"3des-cbc",
8
};
static void des_sesskey(unsigned char *key) {
des_key_setup(GET_32BIT_MSB_FIRST(key),
GET_32BIT_MSB_FIRST(key+4), &cskeys[0]);
logevent("Initialised single-DES encryption");
}
static void des_encrypt_blk(unsigned char *blk, int len) {
des_cbc_encrypt(blk, blk, len, cskeys);
}
static void des_decrypt_blk(unsigned char *blk, int len) {
des_cbc_decrypt(blk, blk, len, cskeys);
}
struct ssh_cipher ssh_des = {
des_sesskey,
NULL, NULL, NULL, NULL, /* SSH 2 bits - unused */
des_encrypt_blk,
des_decrypt_blk,
"des-cbc", /* should never be used - not a valid cipher in ssh2 */
8
};
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