src/lib-otp/otp-hash.c

/*
 * OTP hash generation.
 *
 * Copyright (c) 2006 Andrey Panin <pazke@donpac.ru>
 *
 * This software is released under the MIT license.
 */

#include "lib.h"
#include "md4.h"
#include "md5.h"
#include "sha1.h"

#include "otp.h"

struct digest {
    const char *name;
    void (*init)(void *ctx);
    void (*update)(void *ctx, const void *data, const size_t size);
    void (*final)(void *ctx, void *res);
    void (*otp_final)(void *ctx, void *res);
};

struct digest_context {
    const struct digest *digest;
    union {
        struct md4_context md4_ctx;
        struct md5_context md5_ctx;
        struct sha1_ctxt sha1_ctx;
    } ctx;
};

static void md4_fold(struct md4_context *ctx, void *res)
{
    uint32_t tmp[4], *p = res;

    md4_final(ctx, (unsigned char *) tmp);

    *p++ = tmp[0] ^ tmp[2];
    *p = tmp[1] ^ tmp[3];
}

static void md5_fold(struct md5_context *ctx, void *res)
{
    uint32_t tmp[4], *p = res;

    md5_final(ctx, (unsigned char *) tmp);

    *p++ = tmp[0] ^ tmp[2];
    *p = tmp[1] ^ tmp[3];
}

/*
 * Sometimes I simply can't look at code generated by gcc.
 */
static inline uint32_t swab_uint32(uint32_t val)
{
#if defined(__GNUC__) && defined(__i386__)
    asm("xchgb %b0, %h0\n"
        "rorl $16, %0\n"
        "xchgb %b0, %h0\n"
        :"=q" (val)
        : "0" (val));
#else
    val = ((val & 0xff) << 24) | ((val & 0xff00) << 8) |
        ((val & 0xff0000) >> 8) | ((val >> 24) & 0xff);
#endif
    return val;
}

static void sha1_fold(struct sha1_ctxt *ctx, void *res)
{
    uint32_t tmp[5], *p = res;

    sha1_result(ctx, tmp);

    *p++ = swab_uint32(tmp[0] ^ tmp[2] ^ tmp[4]);
    *p = swab_uint32(tmp[1] ^ tmp[3]);
}


#define F_INIT(name) ((void (*)(void *)) (name))
#define F_UPDATE(name) ((void (*)(void *, const void *, size_t)) (name))
#define F_FINAL(name) ((void (*)(void *, void *)) (name))
#define F_FOLD(name) ((void (*)(void *, void *)) (name))

static const struct digest digests[] = {
    { "md4",  F_INIT(md4_init),  F_UPDATE(md4_update), F_FINAL(md4_final),   F_FOLD(md4_fold) },
    { "md5",  F_INIT(md5_init),  F_UPDATE(md5_update), F_FINAL(md5_final),   F_FOLD(md5_fold) },
    { "sha1", F_INIT(sha1_init), F_UPDATE(sha1_loop),  F_FINAL(sha1_result), F_FOLD(sha1_fold) },
};

#undef F_INIT
#undef F_UPDATE
#undef F_FINAL
#undef F_FOLD

const char *digest_name(unsigned int algo)
{
    i_assert(algo < N_ELEMENTS(digests));

    return digests[algo].name;
}

int digest_find(const char *name)
{
    unsigned int i;

    for (i = 0; i < N_ELEMENTS(digests); i++)
        if (strcmp(name, digests[i].name) == 0)
            return i;

    return -1;
}

void digest_init(struct digest_context *ctx, const unsigned int algo)
{
    i_assert(algo < N_ELEMENTS(digests));

    ctx->digest = digests + algo;
    ctx->digest->init(&ctx->ctx);
}

void digest_update(struct digest_context *ctx, const void *data,
         const size_t size)
{
    ctx->digest->update(&ctx->ctx, data, size);
}

void digest_final(struct digest_context *ctx, unsigned char *result)
{
    ctx->digest->final(&ctx->ctx, result);
}

void digest_otp_final(struct digest_context *ctx, unsigned char *result)
{
    ctx->digest->otp_final(&ctx->ctx, result);
}

void otp_hash(unsigned int algo, const char *seed, const char *passphrase,
          unsigned int step, unsigned char *result)
{
    struct digest_context ctx;

    digest_init(&ctx, algo);
    digest_update(&ctx, seed, strlen(seed));
    digest_update(&ctx, passphrase, strlen(passphrase));
    digest_otp_final(&ctx, result);

    while (step-- > 0) {
        digest_init(&ctx, algo);
        digest_update(&ctx, result, OTP_HASH_SIZE);
        digest_otp_final(&ctx, result);
    }
}

void otp_next_hash(unsigned int algo, const unsigned char *prev,
           unsigned char *result)
{
    struct digest_context ctx;

    digest_init(&ctx, algo);
    digest_update(&ctx, prev, OTP_HASH_SIZE);
    digest_otp_final(&ctx, result);
}