/*
 * Copyright 2003 Sun Microsystems, Inc.  All rights reserved.
 * Use is subject to license terms.
 */

/*      $OpenBSD: bcrypt.c,v 1.16 2002/02/19 19:39:36 millert Exp $     */

/*
 * 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.
 */

/*
 * 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);
 *
 */

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

#include <stdio.h>
#include <stdlib.h>
#include <sys/types.h>
#include <string.h>
#include <pwd.h>
#include <blf.h>

extern uint32_t arc4random();

/*
 * 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_MINLOGROUNDS     4       /* we have log2(rounds) in salt */
#define BCRYPT_MAXLOGROUNDS     31

char   *bcrypt_gensalt(uint8_t);

static void encode_salt(char *, uint8_t *, uint16_t, uint8_t);
static void encode_base64(uint8_t *, uint8_t *, uint16_t);
static void decode_base64(uint8_t *, uint16_t, uint8_t *);

static char    encrypted[128]; /* _PASSWORD_LEN in <pwd.h> on OpenBSD */
static char    gsalt[BCRYPT_MAXSALT * 4 / 3 + 1];
static char    error[] = ":";

static uint8_t Base64Code[] =
"./ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789";

static uint8_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(uint8_t *buffer, uint16_t len, uint8_t *data)
{
        uint8_t *bp = buffer;
        uint8_t *p = data;
        uint8_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, uint8_t *csalt, uint16_t clen, uint8_t logr)
{
        salt[0] = '$';
        salt[1] = BCRYPT_VERSION;
        salt[2] = 'a';
        salt[3] = '$';

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

        encode_base64((uint8_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(uint8_t log_rounds)
{
        uint8_t csalt[BCRYPT_MAXSALT];
        uint16_t i;
        uint32_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 < BCRYPT_MINLOGROUNDS)
                log_rounds = BCRYPT_MINLOGROUNDS;
        else if (log_rounds > BCRYPT_MAXLOGROUNDS)
                log_rounds = BCRYPT_MAXLOGROUNDS;

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

char   *
bcrypt(key, salt)
        const char   *key;
        const char   *salt;
{
        blf_ctx state;
        uint32_t rounds, i, k;
        uint16_t j;
        size_t key_len;
        uint8_t salt_len, logr, minor;
        uint8_t ciphertext[4 * BCRYPT_BLOCKS] = "OrpheanBeholderScryDoubt";
        uint8_t csalt[BCRYPT_MAXSALT];
        uint32_t cdata[BCRYPT_BLOCKS];
        char arounds[3];

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

        if (*salt > BCRYPT_VERSION) {
                /* How do I handle errors ? Return ':' */
                return (error);
        }

        /* Check for minor versions */
        if (salt[1] != '$') {
                switch (salt[1]) {
                    case 'a': /* 'ab' should not yield the same as 'abab' */
                    case 'b': /* cap input length at 72 bytes */
                        minor = salt[1];
                        salt++;
                        break;
                    default:
                        return (error);
                }
        } else
                minor = 0;

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

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

        (void) memcpy(arounds, salt, sizeof (arounds));
        if (arounds[sizeof (arounds) - 1] != '$')
                return (error);
        if ((logr = atoi(arounds)) < BCRYPT_MINLOGROUNDS ||
            logr > BCRYPT_MAXLOGROUNDS)
                return (error);
        /* Computer power doesn't increase linear, 2^x should be fine */
        rounds = 1U << logr;

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

        if (strlen(salt) * 3 / 4 < BCRYPT_MAXSALT)
                return (error);

        /* We dont want the base64 salt but the raw data */
        decode_base64(csalt, BCRYPT_MAXSALT, (uint8_t *)salt);
        salt_len = BCRYPT_MAXSALT;
        if (minor <= 'a')
                key_len = (uint8_t)(strlen(key) + (minor >= 'a' ? 1 : 0));
        else {
                /*
                 * strlen() returns a size_t, but the function calls
                 * below result in implicit casts to a narrower integer
                 * type, so cap key_len at the actual maximum supported
                 * length here to avoid integer wraparound
                 */
                key_len = strlen(key);
                if (key_len > 72)
                        key_len = 72;
                key_len++; /* include the NUL */
        }

        /* Setting up S-Boxes and Subkeys */
        Blowfish_initstate(&state);
        Blowfish_expandstate(&state, csalt, salt_len,
            (uint8_t *)key, key_len);
        for (k = 0; k < rounds; k++) {
                Blowfish_expand0state(&state, (uint8_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++] = '$';
        encrypted[i++] = BCRYPT_VERSION;
        if (minor)
                encrypted[i++] = minor;
        encrypted[i++] = '$';

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

        encode_base64((uint8_t *)encrypted + i + 3, csalt, BCRYPT_MAXSALT);
        encode_base64((uint8_t *)encrypted + strlen(encrypted), ciphertext,
            4 * BCRYPT_BLOCKS - 1);
        return (encrypted);
}

static void
encode_base64(uint8_t *buffer, uint8_t *data, uint16_t len)
{
        uint8_t *bp = buffer;
        uint8_t *p = data;
        uint8_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