FreeBSD/Linux Kernel Cross Reference
sys/opencrypto/gfmult.h

     /*-
      * Copyright (c) 2014 The FreeBSD Foundation
      *
      * This software was developed by John-Mark Gurney under
      * the sponsorship of the FreeBSD Foundation and
      * Rubicon Communications, LLC (Netgate).
      * Redistribution and use in source and binary forms, with or without
      * modification, are permitted provided that the following conditions
      * are met:
     * 1.  Redistributions of source code must retain the above copyright
     *     notice, this list of conditions and the following disclaimer.
     * 2.  Redistributions in binary form must reproduce the above copyright
     *     notice, this list of conditions and the following disclaimer in the
     *     documentation and/or other materials provided with the distribution.
     *
     * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
     * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
     * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
     * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
     * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
     * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
     * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
     * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
     * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
     * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
     * SUCH DAMAGE.
     *
     *      $FreeBSD$
     *
     */
    
    #ifndef _GFMULT_H_
    #define _GFMULT_H_
    
    #ifdef __APPLE__
    #define __aligned(x)    __attribute__((__aligned__(x)))
    #define be64dec(buf)    __builtin_bswap64(*(uint64_t *)buf)
    #define be64enc(buf, x) (*(uint64_t *)buf = __builtin_bswap64(x))
    #else
    #include <sys/endian.h>
    #endif
    
    #ifdef _KERNEL
    #include <sys/types.h>
    #else
    #include <stdint.h>
    #include <strings.h>
    #endif
    
    #define REQ_ALIGN       (16 * 4)
    /*
     * The rows are striped across cache lines.  Note that the indexes
     * are bit reversed to make accesses quicker.
     */
    struct gf128table {
            uint32_t a[16] __aligned(REQ_ALIGN);    /* bits   0 - 31 */
            uint32_t b[16] __aligned(REQ_ALIGN);    /* bits  63 - 32 */
            uint32_t c[16] __aligned(REQ_ALIGN);    /* bits  95 - 64 */
            uint32_t d[16] __aligned(REQ_ALIGN);    /* bits 127 - 96 */
    } __aligned(REQ_ALIGN);
    
    /*
     * A set of tables that contain h, h^2, h^3, h^4.  To be used w/ gf128_mul4.
     */
    struct gf128table4 {
            struct gf128table       tbls[4];
    };
    
    /*
     * GCM per spec is bit reversed in memory.  So byte 0 is really bit reversed
     * and contains bits 0-7.  We can deal w/ this by using right shifts and
     * related math instead of having to bit reverse everything.  This means that
     * the low bits are in v[0] (bits 0-63) and reverse order, while the high
     * bits are in v[1] (bits 64-127) and reverse order.  The high bit of v[0] is
     * bit 0, and the low bit of v[1] is bit 127.
     */
    struct gf128 {
            uint64_t v[2];
    };
    
    /* Note that we don't bit reverse in MAKE_GF128. */
    #define MAKE_GF128(a, b)        ((struct gf128){.v = { (a), (b) } })
    #define GF128_EQ(a, b)          ((((a).v[0] ^ (b).v[0]) | \
                                        ((a).v[1] ^ (b).v[1])) == 0)
    
    static inline struct gf128
    gf128_read(const uint8_t *buf)
    {
            struct gf128 r;
    
            r.v[0] = be64dec(buf);
            buf += sizeof(uint64_t);
    
            r.v[1] = be64dec(buf);
    
            return r;
    }
    
    static inline void
   gf128_write(struct gf128 v, uint8_t *buf)
   {
           uint64_t tmp;
   
           be64enc(buf, v.v[0]);
           buf += sizeof tmp;
   
           be64enc(buf, v.v[1]);
   }
   
   static inline struct gf128 __pure /* XXX - __pure2 instead */
   gf128_add(struct gf128 a, struct gf128 b)
   {
           a.v[0] ^= b.v[0];
           a.v[1] ^= b.v[1];
   
           return a;
   }
   
   void gf128_genmultable(struct gf128 h, struct gf128table *t);
   void gf128_genmultable4(struct gf128 h, struct gf128table4 *t);
   struct gf128 gf128_mul(struct gf128 v, struct gf128table *tbl);
   struct gf128 gf128_mul4(struct gf128 a, struct gf128 b, struct gf128 c,
       struct gf128 d, struct gf128table4 *tbl);
   struct gf128 gf128_mul4b(struct gf128 r, const uint8_t *v,
       struct gf128table4 *tbl);
   
   #endif /* _GFMULT_H_ */

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