/*
 * Copyright 1997 Niels Provos <provos@physnet.uni-hamburg.de>
 * All rights reserved.
 *
 * 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.
 * 3. All advertising materials mentioning features or use of this software
 *    must display the following acknowledgement:
 *      This product includes software developed by Niels Provos.
 * 4. The name of the author may not be used to endorse or promote products
 *    derived from this software without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``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 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: src/secure/lib/libcrypt/crypt-blowfish.c,v 1.1.2.1 2001/05/24 12:20:03 markm Exp $
 */

/* This password hashing algorithm was designed by David Mazieres
 * <dm@lcs.mit.edu> and works as follows:
 *
 * 1. state := InitState ()
 * 2. state := ExpandKey (state, salt, password) 3.
 * REPEAT rounds:
 *      state := ExpandKey (state, 0, salt)
 *      state := ExpandKey(state, 0, password)
 * 4. ctext := "OrpheanBeholderScryDoubt"
 * 5. REPEAT 64:
 *      ctext := Encrypt_ECB (state, ctext);
 * 6. RETURN Concatenate (salt, ctext);
 *
 */

/*
 * FreeBSD implementation by Paul Herman <pherman@frenchfries.net>
 */

#if 0
#include <stdio.h>
#endif

#include <stdio.h>
#include <stdlib.h>
#include <sys/types.h>
#include <string.h>
#include <pwd.h>
#include "blowfish.h"
#include "crypt.h"

/* This implementation is adaptable to current computing power.
 * You can have up to 2^31 rounds which should be enough for some
 * time to come.
 */

#define BCRYPT_VERSION '2'
#define BCRYPT_MAXSALT 16       /* Precomputation is just so nice */
#define BCRYPT_BLOCKS 6         /* Ciphertext blocks */
#define BCRYPT_MINROUNDS 16     /* we have log2(rounds) in salt */

char   *bcrypt_gensalt (u_int8_t);

static void encode_salt (char *, u_int8_t *, u_int16_t, u_int8_t);
static void encode_base64 (u_int8_t *, u_int8_t *, u_int16_t);
static void decode_base64 (u_int8_t *, u_int16_t, u_int8_t *);

static char    encrypted[_PASSWORD_LEN];
static char    gsalt[BCRYPT_MAXSALT * 4 / 3 + 1];

static const u_int8_t Base64Code[] =
"./ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789";

static const u_int8_t index_64[128] =
{
        255, 255, 255, 255, 255, 255, 255, 255, 255, 255,
        255, 255, 255, 255, 255, 255, 255, 255, 255, 255,
        255, 255, 255, 255, 255, 255, 255, 255, 255, 255,
        255, 255, 255, 255, 255, 255, 255, 255, 255, 255,
        255, 255, 255, 255, 255, 255, 0, 1, 54, 55,
        56, 57, 58, 59, 60, 61, 62, 63, 255, 255,
        255, 255, 255, 255, 255, 2, 3, 4, 5, 6,
        7, 8, 9, 10, 11, 12, 13, 14, 15, 16,
        17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27,
        255, 255, 255, 255, 255, 255, 28, 29, 30,
        31, 32, 33, 34, 35, 36, 37, 38, 39, 40,
        41, 42, 43, 44, 45, 46, 47, 48, 49, 50,
        51, 52, 53, 255, 255, 255, 255, 255
};
#define CHAR64(c)  ( (c) > 127 ? 255 : index_64[(c)])

static void
decode_base64(u_int8_t *buffer, u_int16_t len, u_int8_t *data)
{
        u_int8_t *bp = buffer;
        u_int8_t *p = data;
        u_int8_t c1, c2, c3, c4;
        while (bp < buffer + len) {
                c1 = CHAR64(*p);
                c2 = CHAR64(*(p + 1));

                /* Invalid data */
                if (c1 == 255 || c2 == 255)
                        break;

                *bp++ = (c1 << 2) | ((c2 & 0x30) >> 4);
                if (bp >= buffer + len)
                        break;

                c3 = CHAR64(*(p + 2));
                if (c3 == 255)
                        break;

                *bp++ = ((c2 & 0x0f) << 4) | ((c3 & 0x3c) >> 2);
                if (bp >= buffer + len)
                        break;

                c4 = CHAR64(*(p + 3));
                if (c4 == 255)
                        break;
                *bp++ = ((c3 & 0x03) << 6) | c4;

                p += 4;
        }
}

static void
encode_salt(char *salt, u_int8_t *csalt, u_int16_t clen, u_int8_t logr)
{
        salt[0] = '$';
        salt[1] = BCRYPT_VERSION;
        salt[2] = 'a';
        salt[3] = '$';

        snprintf(salt + 4, 4, "%2.2u$", logr);

        encode_base64((u_int8_t *) salt + 7, csalt, clen);
}
/* Generates a salt for this version of crypt.
   Since versions may change. Keeping this here
   seems sensible.
 */

char *
bcrypt_gensalt(u_int8_t log_rounds)
{
        u_int8_t csalt[BCRYPT_MAXSALT];
        u_int16_t i;
        u_int32_t seed = 0;

        for (i = 0; i < BCRYPT_MAXSALT; i++) {
                if (i % 4 == 0)
                        seed = arc4random();
                csalt[i] = seed & 0xff;
                seed = seed >> 8;
        }

        if (log_rounds < 4)
                log_rounds = 4;

        encode_salt(gsalt, csalt, BCRYPT_MAXSALT, log_rounds);
        return gsalt;
}
/* We handle $Vers$log2(NumRounds)$salt+passwd$
   i.e. $2$04$iwouldntknowwhattosayetKdJ6iFtacBqJdKe6aW7ou */

char   *
crypt_blowfish(const char *key, const char *salt)
{
        blf_ctx state;
        u_int32_t rounds, i, k;
        u_int16_t j;
        u_int8_t key_len, salt_len, logr, minor;
        u_int8_t ciphertext[4 * BCRYPT_BLOCKS] = "OrpheanBeholderScryDoubt";
        u_int8_t csalt[BCRYPT_MAXSALT];
        u_int32_t cdata[BCRYPT_BLOCKS];
        static const char *magic = "$2a$04$";

                /* Defaults */
        minor = 'a';
        logr = 4;
        rounds = 1 << logr;

        /* If it starts with the magic string, then skip that */
        if(!strncmp(salt, magic, strlen(magic))) {
                salt += strlen(magic);
        }
        else if (*salt == '$') {

                /* Discard "$" identifier */
                salt++;

                if (*salt > BCRYPT_VERSION) {
                        /* How do I handle errors ? Return NULL according to
                           crypt(3) */
                        return NULL;
                }

                /* Check for minor versions */
                if (salt[1] != '$') {
                         switch (salt[1]) {
                         case 'a':
                                 /* 'ab' should not yield the same as 'abab' */
                                 minor = salt[1];
                                 salt++;
                                 break;
                         default:
                                 return NULL;
                         }
                } else
                         minor = 0;

                /* Discard version + "$" identifier */
                salt += 2;

                if (salt[2] != '$')
                        /* Out of sync with passwd entry */
                        return NULL;

                /* Computer power doesnt increase linear, 2^x should be fine */
                if ((rounds = (u_int32_t) 1 << (logr = atoi(salt))) < BCRYPT_MINROUNDS)
                        return NULL;

                /* Discard num rounds + "$" identifier */
                salt += 3;
        }


        /* We dont want the base64 salt but the raw data */
        decode_base64(csalt, BCRYPT_MAXSALT, (u_int8_t *) salt);
        salt_len = BCRYPT_MAXSALT;
        key_len = strlen(key) + (minor >= 'a' ? 1 : 0);

        /* Setting up S-Boxes and Subkeys */
        Blowfish_initstate(&state);
        Blowfish_expandstate(&state, csalt, salt_len,
            (u_int8_t *) key, key_len);
        for (k = 0; k < rounds; k++) {
                Blowfish_expand0state(&state, (u_int8_t *) key, key_len);
                Blowfish_expand0state(&state, csalt, salt_len);
        }

        /* This can be precomputed later */
        j = 0;
        for (i = 0; i < BCRYPT_BLOCKS; i++)
                cdata[i] = Blowfish_stream2word(ciphertext, 4 * BCRYPT_BLOCKS, &j);

        /* Now do the encryption */
        for (k = 0; k < 64; k++)
                blf_enc(&state, cdata, BCRYPT_BLOCKS / 2);

        for (i = 0; i < BCRYPT_BLOCKS; i++) {
                ciphertext[4 * i + 3] = cdata[i] & 0xff;
                cdata[i] = cdata[i] >> 8;
                ciphertext[4 * i + 2] = cdata[i] & 0xff;
                cdata[i] = cdata[i] >> 8;
                ciphertext[4 * i + 1] = cdata[i] & 0xff;
                cdata[i] = cdata[i] >> 8;
                ciphertext[4 * i + 0] = cdata[i] & 0xff;
        }


        i = 0;
        encrypted[i++] = '$';
        encrypted[i++] = BCRYPT_VERSION;
        if (minor)
                encrypted[i++] = minor;
        encrypted[i++] = '$';

        snprintf(encrypted + i, 4, "%2.2u$", logr);

        encode_base64((u_int8_t *) encrypted + i + 3, csalt, BCRYPT_MAXSALT);
        encode_base64((u_int8_t *) encrypted + strlen(encrypted), ciphertext,
            4 * BCRYPT_BLOCKS - 1);
        return encrypted;
}

static void
encode_base64(u_int8_t *buffer, u_int8_t *data, u_int16_t len)
{
        u_int8_t *bp = buffer;
        u_int8_t *p = data;
        u_int8_t c1, c2;
        while (p < data + len) {
                c1 = *p++;
                *bp++ = Base64Code[(c1 >> 2)];
                c1 = (c1 & 0x03) << 4;
                if (p >= data + len) {
                        *bp++ = Base64Code[c1];
                        break;
                }
                c2 = *p++;
                c1 |= (c2 >> 4) & 0x0f;
                *bp++ = Base64Code[c1];
                c1 = (c2 & 0x0f) << 2;
                if (p >= data + len) {
                        *bp++ = Base64Code[c1];
                        break;
                }
                c2 = *p++;
                c1 |= (c2 >> 6) & 0x03;
                *bp++ = Base64Code[c1];
                *bp++ = Base64Code[c2 & 0x3f];
        }
        *bp = '\0';
}
#if 0
void
main()
{
        char    blubber[73];
        char    salt[100];
        char   *p;
        salt[0] = '$';
        salt[1] = BCRYPT_VERSION;
        salt[2] = '$';

        snprintf(salt + 3, 4, "%2.2u$", 5);

        printf("24 bytes of salt: ");
        fgets(salt + 6, 94, stdin);
        salt[99] = 0;
        printf("72 bytes of password: ");
        fpurge(stdin);
        fgets(blubber, 73, stdin);
        blubber[72] = 0;

        p = crypt(blubber, salt);
        printf("Passwd entry: %s\n\n", p);

        p = bcrypt_gensalt(5);
        printf("Generated salt: %s\n", p);
        p = crypt(blubber, p);
        printf("Passwd entry: %s\n", p);
}
#endif