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249 строки
10 KiB
C
249 строки
10 KiB
C
/*
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* Copyright (c) 1989, 1993
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* The Regents of the University of California. All rights reserved.
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*
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* This code is derived from software contributed to Berkeley by
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* Tom Truscott.
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions
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* are met:
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* 1. Redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer.
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* 2. Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in the
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* documentation and/or other materials provided with the distribution.
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* 3. Neither the name of the University nor the names of its contributors
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* may be used to endorse or promote products derived from this software
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* without specific prior written permission.
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*
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* THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
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* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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* ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
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* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
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* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
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* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
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* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
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* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
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* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
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* SUCH DAMAGE.
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*/
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#ifndef CRYPT_H
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#define CRYPT_H 1
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/* ===== Configuration ==================== */
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#ifdef CHAR_BITS
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#if CHAR_BITS != 8
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#error C_block structure assumes 8 bit characters
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#endif
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#endif
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#ifndef LONG_LONG
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# if SIZEOF_LONG_LONG > 0
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# define LONG_LONG long long
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# elif SIZEOF___INT64 > 0
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# define HAVE_LONG_LONG 1
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# define LONG_LONG __int64
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# undef SIZEOF_LONG_LONG
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# define SIZEOF_LONG_LONG SIZEOF___INT64
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# endif
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#endif
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/*
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* define "LONG_IS_32_BITS" only if sizeof(long)==4.
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* This avoids use of bit fields (your compiler may be sloppy with them).
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*/
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#if SIZEOF_LONG == 4
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#define LONG_IS_32_BITS
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#endif
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/*
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* define "B64" to be the declaration for a 64 bit integer.
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* XXX this feature is currently unused, see "endian" comment below.
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*/
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#if SIZEOF_LONG == 8
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#define B64 long
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#elif SIZEOF_LONG_LONG == 8
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#define B64 LONG_LONG
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#endif
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/*
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* define "LARGEDATA" to get faster permutations, by using about 72 kilobytes
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* of lookup tables. This speeds up des_setkey() and des_cipher(), but has
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* little effect on crypt().
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*/
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#if defined(notdef)
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#define LARGEDATA
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#endif
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/* compile with "-DSTATIC=int" when profiling */
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#ifndef STATIC
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#define STATIC static
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#endif
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/* ==================================== */
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/*
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* Cipher-block representation (Bob Baldwin):
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*
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* DES operates on groups of 64 bits, numbered 1..64 (sigh). One
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* representation is to store one bit per byte in an array of bytes. Bit N of
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* the NBS spec is stored as the LSB of the Nth byte (index N-1) in the array.
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* Another representation stores the 64 bits in 8 bytes, with bits 1..8 in the
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* first byte, 9..16 in the second, and so on. The DES spec apparently has
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* bit 1 in the MSB of the first byte, but that is particularly noxious so we
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* bit-reverse each byte so that bit 1 is the LSB of the first byte, bit 8 is
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* the MSB of the first byte. Specifically, the 64-bit input data and key are
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* converted to LSB format, and the output 64-bit block is converted back into
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* MSB format.
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*
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* DES operates internally on groups of 32 bits which are expanded to 48 bits
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* by permutation E and shrunk back to 32 bits by the S boxes. To speed up
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* the computation, the expansion is applied only once, the expanded
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* representation is maintained during the encryption, and a compression
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* permutation is applied only at the end. To speed up the S-box lookups,
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* the 48 bits are maintained as eight 6 bit groups, one per byte, which
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* directly feed the eight S-boxes. Within each byte, the 6 bits are the
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* most significant ones. The low two bits of each byte are zero. (Thus,
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* bit 1 of the 48 bit E expansion is stored as the "4"-valued bit of the
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* first byte in the eight byte representation, bit 2 of the 48 bit value is
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* the "8"-valued bit, and so on.) In fact, a combined "SPE"-box lookup is
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* used, in which the output is the 64 bit result of an S-box lookup which
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* has been permuted by P and expanded by E, and is ready for use in the next
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* iteration. Two 32-bit wide tables, SPE[0] and SPE[1], are used for this
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* lookup. Since each byte in the 48 bit path is a multiple of four, indexed
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* lookup of SPE[0] and SPE[1] is simple and fast. The key schedule and
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* "salt" are also converted to this 8*(6+2) format. The SPE table size is
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* 8*64*8 = 4K bytes.
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*
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* To speed up bit-parallel operations (such as XOR), the 8 byte
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* representation is "union"ed with 32 bit values "i0" and "i1", and, on
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* machines which support it, a 64 bit value "b64". This data structure,
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* "C_block", has two problems. First, alignment restrictions must be
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* honored. Second, the byte-order (e.g. little-endian or big-endian) of
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* the architecture becomes visible.
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*
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* The byte-order problem is unfortunate, since on the one hand it is good
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* to have a machine-independent C_block representation (bits 1..8 in the
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* first byte, etc.), and on the other hand it is good for the LSB of the
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* first byte to be the LSB of i0. We cannot have both these things, so we
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* currently use the "little-endian" representation and avoid any multi-byte
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* operations that depend on byte order. This largely precludes use of the
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* 64-bit datatype since the relative order of i0 and i1 are unknown. It
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* also inhibits grouping the SPE table to look up 12 bits at a time. (The
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* 12 bits can be stored in a 16-bit field with 3 low-order zeroes and 1
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* high-order zero, providing fast indexing into a 64-bit wide SPE.) On the
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* other hand, 64-bit datatypes are currently rare, and a 12-bit SPE lookup
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* requires a 128 kilobyte table, so perhaps this is not a big loss.
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*
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* Permutation representation (Jim Gillogly):
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*
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* A transformation is defined by its effect on each of the 8 bytes of the
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* 64-bit input. For each byte we give a 64-bit output that has the bits in
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* the input distributed appropriately. The transformation is then the OR
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* of the 8 sets of 64-bits. This uses 8*256*8 = 16K bytes of storage for
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* each transformation. Unless LARGEDATA is defined, however, a more compact
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* table is used which looks up 16 4-bit "chunks" rather than 8 8-bit chunks.
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* The smaller table uses 16*16*8 = 2K bytes for each transformation. This
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* is slower but tolerable, particularly for password encryption in which
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* the SPE transformation is iterated many times. The small tables total 9K
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* bytes, the large tables total 72K bytes.
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*
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* The transformations used are:
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* IE3264: MSB->LSB conversion, initial permutation, and expansion.
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* This is done by collecting the 32 even-numbered bits and applying
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* a 32->64 bit transformation, and then collecting the 32 odd-numbered
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* bits and applying the same transformation. Since there are only
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* 32 input bits, the IE3264 transformation table is half the size of
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* the usual table.
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* CF6464: Compression, final permutation, and LSB->MSB conversion.
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* This is done by two trivial 48->32 bit compressions to obtain
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* a 64-bit block (the bit numbering is given in the "CIFP" table)
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* followed by a 64->64 bit "cleanup" transformation. (It would
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* be possible to group the bits in the 64-bit block so that 2
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* identical 32->32 bit transformations could be used instead,
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* saving a factor of 4 in space and possibly 2 in time, but
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* byte-ordering and other complications rear their ugly head.
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* Similar opportunities/problems arise in the key schedule
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* transforms.)
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* PC1ROT: MSB->LSB, PC1 permutation, rotate, and PC2 permutation.
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* This admittedly baroque 64->64 bit transformation is used to
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* produce the first code (in 8*(6+2) format) of the key schedule.
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* PC2ROT[0]: Inverse PC2 permutation, rotate, and PC2 permutation.
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* It would be possible to define 15 more transformations, each
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* with a different rotation, to generate the entire key schedule.
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* To save space, however, we instead permute each code into the
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* next by using a transformation that "undoes" the PC2 permutation,
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* rotates the code, and then applies PC2. Unfortunately, PC2
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* transforms 56 bits into 48 bits, dropping 8 bits, so PC2 is not
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* invertible. We get around that problem by using a modified PC2
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* which retains the 8 otherwise-lost bits in the unused low-order
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* bits of each byte. The low-order bits are cleared when the
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* codes are stored into the key schedule.
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* PC2ROT[1]: Same as PC2ROT[0], but with two rotations.
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* This is faster than applying PC2ROT[0] twice,
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*
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* The Bell Labs "salt" (Bob Baldwin):
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*
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* The salting is a simple permutation applied to the 48-bit result of E.
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* Specifically, if bit i (1 <= i <= 24) of the salt is set then bits i and
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* i+24 of the result are swapped. The salt is thus a 24 bit number, with
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* 16777216 possible values. (The original salt was 12 bits and could not
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* swap bits 13..24 with 36..48.)
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*
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* It is possible, but ugly, to warp the SPE table to account for the salt
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* permutation. Fortunately, the conditional bit swapping requires only
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* about four machine instructions and can be done on-the-fly with about an
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* 8% performance penalty.
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*/
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typedef union {
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unsigned char b[8];
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struct {
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#if defined(LONG_IS_32_BITS)
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/* long is often faster than a 32-bit bit field */
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long i0;
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long i1;
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#else
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long i0: 32;
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long i1: 32;
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#endif
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} b32;
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#if defined(B64)
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B64 b64;
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#endif
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} C_block;
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#if defined(LARGEDATA)
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/* Waste memory like crazy. Also, do permutations in line */
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#define LGCHUNKBITS 3
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#define CHUNKBITS (1<<LGCHUNKBITS)
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#else
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/* "small data" */
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#define LGCHUNKBITS 2
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#define CHUNKBITS (1<<LGCHUNKBITS)
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#endif
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struct crypt_data {
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/* The Key Schedule, filled in by des_setkey() or setkey(). */
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#define KS_SIZE 16
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C_block KS[KS_SIZE];
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/* ==================================== */
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char cryptresult[1+4+4+11+1]; /* encrypted result */
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};
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char *crypt(const char *key, const char *setting);
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void setkey(const char *key);
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void encrypt(char *block, int flag);
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char *crypt_r(const char *key, const char *setting, struct crypt_data *data);
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void setkey_r(const char *key, struct crypt_data *data);
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void encrypt_r(char *block, int flag, struct crypt_data *data);
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#endif /* CRYPT_H */
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