xref: /freebsd-9.3-release/crypto/heimdal/lib/krb5/crypto.c

/*
 * Copyright (c) 1997, 1998, 1999 Kungliga Tekniska H�gskolan
 * (Royal Institute of Technology, Stockholm, Sweden).
 * 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. Neither the name of the Institute nor the names of its contributors
 *    may be used to endorse or promote products derived from this software
 *    without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE INSTITUTE 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 INSTITUTE 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.
 */

#include "krb5_locl.h"
RCSID("$Id: crypto.c,v 1.28 2000/01/06 20:21:13 assar Exp $");

#undef CRYPTO_DEBUG
#ifdef CRYPTO_DEBUG
static void krb5_crypto_debug(krb5_context, int, size_t, krb5_keyblock*);
#endif


struct key_data {
    krb5_keyblock *key;
    krb5_data *schedule;
};

struct key_usage {
    unsigned usage;
    struct key_data key;
};

struct krb5_crypto_data {
    struct encryption_type *et;
    struct key_data key;
    int num_key_usage;
    struct key_usage *key_usage;
};

#define CRYPTO_ETYPE(C) ((C)->et->type)

/* bits for `flags' below */
#define F_KEYED		 1	/* checksum is keyed */
#define F_CPROOF	 2	/* checksum is collision proof */
#define F_DERIVED	 4	/* uses derived keys */
#define F_VARIANT	 8	/* uses `variant' keys (6.4.3) */
#define F_PSEUDO	16	/* not a real protocol type */

struct salt_type {
    krb5_salttype type;
    const char *name;
    krb5_error_code (*string_to_key)(krb5_context, krb5_enctype, krb5_data,
				     krb5_salt, krb5_keyblock*);
};

struct key_type {
    krb5_keytype type; /* XXX */
    const char *name;
    size_t bits;
    size_t size;
    size_t schedule_size;
#if 0
    krb5_enctype best_etype;
#endif
    void (*random_key)(krb5_context, krb5_keyblock*);
    void (*schedule)(krb5_context, struct key_data *);
    struct salt_type *string_to_key;
};

struct checksum_type {
    krb5_cksumtype type;
    const char *name;
    size_t blocksize;
    size_t checksumsize;
    unsigned flags;
    void (*checksum)(krb5_context, struct key_data*, void*, size_t, Checksum*);
    krb5_error_code (*verify)(krb5_context, struct key_data*,
			      void*, size_t, Checksum*);
};

struct encryption_type {
    krb5_enctype type;
    const char *name;
    size_t blocksize;
    size_t confoundersize;
    struct key_type *keytype;
    struct checksum_type *cksumtype;
    struct checksum_type *keyed_checksum;
    unsigned flags;
    void (*encrypt)(struct key_data *, void *, size_t, int);
};

#define ENCRYPTION_USAGE(U) (((U) << 8) | 0xAA)
#define INTEGRITY_USAGE(U) (((U) << 8) | 0x55)
#define CHECKSUM_USAGE(U) (((U) << 8) | 0x99)

static struct checksum_type *_find_checksum(krb5_cksumtype type);
static struct encryption_type *_find_enctype(krb5_enctype type);
static struct key_type *_find_keytype(krb5_keytype type);
static krb5_error_code _get_derived_key(krb5_context, krb5_crypto,
					unsigned, struct key_data**);
static struct key_data *_new_derived_key(krb5_crypto crypto, unsigned usage);

/************************************************************
 *                                                          *
 ************************************************************/

static void
DES_random_key(krb5_context context,
	       krb5_keyblock *key)
{
    des_cblock *k = key->keyvalue.data;
    do {
	krb5_generate_random_block(k, sizeof(des_cblock));
	des_set_odd_parity(k);
    } while(des_is_weak_key(k));
}

static void
DES_schedule(krb5_context context,
	     struct key_data *key)
{
    des_set_key(key->key->keyvalue.data, key->schedule->data);
}

static krb5_error_code
DES_string_to_key(krb5_context context,
		  krb5_enctype enctype,
		  krb5_data password,
		  krb5_salt salt,
		  krb5_keyblock *key)
{
    char *s;
    size_t len;
    des_cblock tmp;

    len = password.length + salt.saltvalue.length + 1;
    s = malloc(len);
    if(s == NULL)
	return ENOMEM;
    memcpy(s, password.data, password.length);
    memcpy(s + password.length, salt.saltvalue.data, salt.saltvalue.length);
    s[len - 1] = '\0';
    des_string_to_key(s, &tmp);
    key->keytype = enctype;
    krb5_data_copy(&key->keyvalue, tmp, sizeof(tmp));
    memset(&tmp, 0, sizeof(tmp));
    memset(s, 0, len);
    free(s);
    return 0;
}

/* This defines the Andrew string_to_key function.  It accepts a password
 * string as input and converts its via a one-way encryption algorithm to a DES
 * encryption key.  It is compatible with the original Andrew authentication
 * service password database.
 */

/*
 * Short passwords, i.e 8 characters or less.
 */
static void
DES_AFS3_CMU_string_to_key (krb5_data pw,
			    krb5_data cell,
			    des_cblock *key)
{
    char  password[8+1];	/* crypt is limited to 8 chars anyway */
    int   i;

    for(i = 0; i < 8; i++) {
	char c = ((i < pw.length) ? ((char*)pw.data)[i] : 0) ^
		 ((i < cell.length) ? ((char*)cell.data)[i] : 0);
	password[i] = c ? c : 'X';
    }
    password[8] = '\0';

    memcpy(key, crypt(password, "#~") + 2, sizeof(des_cblock));

    /* parity is inserted into the LSB so left shift each byte up one
       bit. This allows ascii characters with a zero MSB to retain as
       much significance as possible. */
    for (i = 0; i < sizeof(des_cblock); i++)
	((unsigned char*)key)[i] <<= 1;
    des_set_odd_parity (key);
}

/*
 * Long passwords, i.e 9 characters or more.
 */
static void
DES_AFS3_Transarc_string_to_key (krb5_data pw,
				 krb5_data cell,
				 des_cblock *key)
{
    des_key_schedule schedule;
    des_cblock temp_key;
    des_cblock ivec;
    char password[512];
    size_t passlen;

    memcpy(password, pw.data, min(pw.length, sizeof(password)));
    if(pw.length < sizeof(password))
	memcpy(password + pw.length,
	       cell.data, min(cell.length,
			      sizeof(password) - pw.length));
    passlen = min(sizeof(password), pw.length + cell.length);
    memcpy(&ivec, "kerberos", 8);
    memcpy(&temp_key, "kerberos", 8);
    des_set_odd_parity (&temp_key);
    des_set_key (&temp_key, schedule);
    des_cbc_cksum ((des_cblock *)password, &ivec, passlen, schedule, &ivec);

    memcpy(&temp_key, &ivec, 8);
    des_set_odd_parity (&temp_key);
    des_set_key (&temp_key, schedule);
    des_cbc_cksum ((des_cblock *)password, key, passlen, schedule, &ivec);
    memset(&schedule, 0, sizeof(schedule));
    memset(&temp_key, 0, sizeof(temp_key));
    memset(&ivec, 0, sizeof(ivec));
    memset(password, 0, sizeof(password));

    des_set_odd_parity (key);
}

static krb5_error_code
DES_AFS3_string_to_key(krb5_context context,
		       krb5_enctype enctype,
		       krb5_data password,
		       krb5_salt salt,
		       krb5_keyblock *key)
{
    des_cblock tmp;
    if(password.length > 8)
	DES_AFS3_Transarc_string_to_key(password, salt.saltvalue, &tmp);
    else
	DES_AFS3_CMU_string_to_key(password, salt.saltvalue, &tmp);
    key->keytype = enctype;
    krb5_data_copy(&key->keyvalue, tmp, sizeof(tmp));
    memset(&key, 0, sizeof(key));
    return 0;
}

static void
DES3_random_key(krb5_context context,
		krb5_keyblock *key)
{
    des_cblock *k = key->keyvalue.data;
    do {
	krb5_generate_random_block(k, 3 * sizeof(des_cblock));
	des_set_odd_parity(&k[0]);
	des_set_odd_parity(&k[1]);
	des_set_odd_parity(&k[2]);
    } while(des_is_weak_key(&k[0]) ||
	    des_is_weak_key(&k[1]) ||
	    des_is_weak_key(&k[2]));
}

static void
DES3_schedule(krb5_context context,
	      struct key_data *key)
{
    des_cblock *k = key->key->keyvalue.data;
    des_key_schedule *s = key->schedule->data;
    des_set_key(&k[0], s[0]);
    des_set_key(&k[1], s[1]);
    des_set_key(&k[2], s[2]);
}

/*
 * A = A xor B. A & B are 8 bytes.
 */

static void
xor (des_cblock *key, const unsigned char *b)
{
    unsigned char *a = (unsigned char*)key;
    a[0] ^= b[0];
    a[1] ^= b[1];
    a[2] ^= b[2];
    a[3] ^= b[3];
    a[4] ^= b[4];
    a[5] ^= b[5];
    a[6] ^= b[6];
    a[7] ^= b[7];
}

static krb5_error_code
DES3_string_to_key(krb5_context context,
		   krb5_enctype enctype,
		   krb5_data password,
		   krb5_salt salt,
		   krb5_keyblock *key)
{
    char *str;
    size_t len;
    unsigned char tmp[24];
    des_cblock keys[3];

    len = password.length + salt.saltvalue.length;
    str = malloc(len);
    if(len != 0 && str == NULL)
	return ENOMEM;
    memcpy(str, password.data, password.length);
    memcpy(str + password.length, salt.saltvalue.data, salt.saltvalue.length);
    {
	des_cblock ivec;
	des_key_schedule s[3];
	int i;

	_krb5_n_fold(str, len, tmp, 24);

	for(i = 0; i < 3; i++){
	    memcpy(keys + i, tmp + i * 8, sizeof(keys[i]));
	    des_set_odd_parity(keys + i);
	    if(des_is_weak_key(keys + i))
		xor(keys + i, (unsigned char*)"\0\0\0\0\0\0\0\xf0");
	    des_set_key(keys + i, s[i]);
	}
	memset(&ivec, 0, sizeof(ivec));
	des_ede3_cbc_encrypt((void*)tmp, (void*)tmp, sizeof(tmp),
			     s[0], s[1], s[2], &ivec, DES_ENCRYPT);
	memset(s, 0, sizeof(s));
	memset(&ivec, 0, sizeof(ivec));
	for(i = 0; i < 3; i++){
	    memcpy(keys + i, tmp + i * 8, sizeof(keys[i]));
	    des_set_odd_parity(keys + i);
	    if(des_is_weak_key(keys + i))
		xor(keys + i, (unsigned char*)"\0\0\0\0\0\0\0\xf0");
	}
	memset(tmp, 0, sizeof(tmp));
    }
    key->keytype = enctype;
    krb5_data_copy(&key->keyvalue, keys, sizeof(keys));
    memset(keys, 0, sizeof(keys));
    memset(str, 0, len);
    free(str);
    return 0;
}

static krb5_error_code
DES3_string_to_key_derived(krb5_context context,
			   krb5_enctype enctype,
			   krb5_data password,
			   krb5_salt salt,
			   krb5_keyblock *key)
{
    krb5_error_code ret;
    size_t len = password.length + salt.saltvalue.length;
    char *s;

    s = malloc(len);
    if(len != 0 && s == NULL)
	return ENOMEM;
    memcpy(s, password.data, password.length);
    memcpy(s + password.length, salt.saltvalue.data, salt.saltvalue.length);
    ret = krb5_string_to_key_derived(context,
				     s,
				     len,
				     enctype,
				     key);
    memset(s, 0, len);
    free(s);
    return ret;
}

/*
 * ARCFOUR
 */

static void
ARCFOUR_random_key(krb5_context context, krb5_keyblock *key)
{
    krb5_generate_random_block (key->keyvalue.data,
				key->keyvalue.length);
}

static void
ARCFOUR_schedule(krb5_context context, struct key_data *kd)
{
    RC4_set_key (kd->schedule->data,
		 kd->key->keyvalue.length, kd->key->keyvalue.data);
}

static krb5_error_code
ARCFOUR_string_to_key(krb5_context context,
		  krb5_enctype enctype,
		  krb5_data password,
		  krb5_salt salt,
		  krb5_keyblock *key)
{
    char *s, *p;
    size_t len;
    int i;
    struct md4 m;

    len = 2 * (password.length + salt.saltvalue.length);
    s = malloc (len);
    if (len != 0 && s == NULL)
	return ENOMEM;
    for (p = s, i = 0; i < password.length; ++i) {
	*p++ = ((char *)password.data)[i];
	*p++ = 0;
    }
    for (i = 0; i < salt.saltvalue.length; ++i) {
	*p++ = ((char *)salt.saltvalue.data)[i];
	*p++ = 0;
    }
    md4_init(&m);
    md4_update(&m, s, len);
    key->keytype = enctype;
    krb5_data_alloc (&key->keyvalue, 16);
    md4_finito(&m, key->keyvalue.data);
    memset (s, 0, len);
    free (s);
    return 0;
}

extern struct salt_type des_salt[],
    des3_salt[], des3_salt_derived[], arcfour_salt[];

struct key_type keytype_null = {
    KEYTYPE_NULL,
    "null",
    0,
    0,
    0,
    NULL,
    NULL,
    NULL
};

struct key_type keytype_des = {
    KEYTYPE_DES,
    "des",
    56,
    sizeof(des_cblock),
    sizeof(des_key_schedule),
    DES_random_key,
    DES_schedule,
    des_salt
};

struct key_type keytype_des3 = {
    KEYTYPE_DES3,
    "des3",
    168,
    3 * sizeof(des_cblock),
    3 * sizeof(des_key_schedule),
    DES3_random_key,
    DES3_schedule,
    des3_salt
};

struct key_type keytype_des3_derived = {
    KEYTYPE_DES3,
    "des3",
    168,
    3 * sizeof(des_cblock),
    3 * sizeof(des_key_schedule),
    DES3_random_key,
    DES3_schedule,
    des3_salt_derived
};

struct key_type keytype_arcfour = {
    KEYTYPE_ARCFOUR,
    "arcfour",
    128,
    16,
    sizeof(RC4_KEY),
    ARCFOUR_random_key,
    ARCFOUR_schedule,
    arcfour_salt
};

struct key_type *keytypes[] = {
    &keytype_null,
    &keytype_des,
    &keytype_des3_derived,
    &keytype_des3,
    &keytype_arcfour
};

static int num_keytypes = sizeof(keytypes) / sizeof(keytypes[0]);

static struct key_type *
_find_keytype(krb5_keytype type)
{
    int i;
    for(i = 0; i < num_keytypes; i++)
	if(keytypes[i]->type == type)
	    return keytypes[i];
    return NULL;
}


struct salt_type des_salt[] = {
    {
	KRB5_PW_SALT,
	"pw-salt",
	DES_string_to_key
    },
    {
	KRB5_AFS3_SALT,
	"afs3-salt",
	DES_AFS3_string_to_key
    },
    { 0 }
};

struct salt_type des3_salt[] = {
    {
	KRB5_PW_SALT,
	"pw-salt",
	DES3_string_to_key
    },
    { 0 }
};

struct salt_type des3_salt_derived[] = {
    {
	KRB5_PW_SALT,
	"pw-salt",
	DES3_string_to_key_derived
    },
    { 0 }
};

struct salt_type arcfour_salt[] = {
    {
	KRB5_PW_SALT,
	"pw-salt",
	ARCFOUR_string_to_key
    },
    { 0 }
};

krb5_error_code
krb5_salttype_to_string (krb5_context context,
			 krb5_enctype etype,
			 krb5_salttype stype,
			 char **string)
{
    struct encryption_type *e;
    struct salt_type *st;

    e = _find_enctype (etype);
    if (e == NULL)
	return KRB5_PROG_ETYPE_NOSUPP;
    for (st = e->keytype->string_to_key; st && st->type; st++) {
	if (st->type == stype) {
	    *string = strdup (st->name);
	    if (*string == NULL)
		return ENOMEM;
	    return 0;
	}
    }
    return HEIM_ERR_SALTTYPE_NOSUPP;
}

krb5_error_code
krb5_string_to_salttype (krb5_context context,
			 krb5_enctype etype,
			 const char *string,
			 krb5_salttype *salttype)
{
    struct encryption_type *e;
    struct salt_type *st;

    e = _find_enctype (etype);
    if (e == NULL)
	return KRB5_PROG_ETYPE_NOSUPP;
    for (st = e->keytype->string_to_key; st && st->type; st++) {
	if (strcasecmp (st->name, string) == 0) {
	    *salttype = st->type;
	    return 0;
	}
    }
    return HEIM_ERR_SALTTYPE_NOSUPP;
}

krb5_error_code
krb5_get_pw_salt(krb5_context context,
		 krb5_const_principal principal,
		 krb5_salt *salt)
{
    size_t len;
    int i;
    krb5_error_code ret;
    char *p;

    salt->salttype = KRB5_PW_SALT;
    len = strlen(principal->realm);
    for (i = 0; i < principal->name.name_string.len; ++i)
	len += strlen(principal->name.name_string.val[i]);
    ret = krb5_data_alloc (&salt->saltvalue, len);
    if (ret)
	return ret;
    p = salt->saltvalue.data;
    memcpy (p, principal->realm, strlen(principal->realm));
    p += strlen(principal->realm);
    for (i = 0; i < principal->name.name_string.len; ++i) {
	memcpy (p,
		principal->name.name_string.val[i],
		strlen(principal->name.name_string.val[i]));
	p += strlen(principal->name.name_string.val[i]);
    }
    return 0;
}

krb5_error_code
krb5_free_salt(krb5_context context,
	       krb5_salt salt)
{
    krb5_data_free(&salt.saltvalue);
    return 0;
}

krb5_error_code
krb5_string_to_key_data (krb5_context context,
			 krb5_enctype enctype,
			 krb5_data password,
			 krb5_principal principal,
			 krb5_keyblock *key)
{
    krb5_error_code ret;
    krb5_salt salt;

    ret = krb5_get_pw_salt(context, principal, &salt);
    if(ret)
	return ret;
    ret = krb5_string_to_key_data_salt(context, enctype, password, salt, key);
    krb5_free_salt(context, salt);
    return ret;
}

krb5_error_code
krb5_string_to_key (krb5_context context,
		    krb5_enctype enctype,
		    const char *password,
		    krb5_principal principal,
		    krb5_keyblock *key)
{
    krb5_data pw;
    pw.data = (void*)password;
    pw.length = strlen(password);
    return krb5_string_to_key_data(context, enctype, pw, principal, key);
}

krb5_error_code
krb5_string_to_key_data_salt (krb5_context context,
			      krb5_enctype enctype,
			      krb5_data password,
			      krb5_salt salt,
			      krb5_keyblock *key)
{
    struct encryption_type *et =_find_enctype(enctype);
    struct salt_type *st;
    if(et == NULL)
	return KRB5_PROG_ETYPE_NOSUPP;
    for(st = et->keytype->string_to_key; st && st->type; st++)
	if(st->type == salt.salttype)
	    return (*st->string_to_key)(context, enctype, password, salt, key);
    return HEIM_ERR_SALTTYPE_NOSUPP;
}

krb5_error_code
krb5_string_to_key_salt (krb5_context context,
			 krb5_enctype enctype,
			 const char *password,
			 krb5_salt salt,
			 krb5_keyblock *key)
{
    krb5_data pw;
    pw.data = (void*)password;
    pw.length = strlen(password);
    return krb5_string_to_key_data_salt(context, enctype, pw, salt, key);
}

krb5_error_code
krb5_keytype_to_string(krb5_context context,
		       krb5_keytype keytype,
		       char **string)
{
    struct key_type *kt = _find_keytype(keytype);
    if(kt == NULL)
	return KRB5_PROG_KEYTYPE_NOSUPP;
    *string = strdup(kt->name);
    if(*string == NULL)
	return ENOMEM;
    return 0;
}

krb5_error_code
krb5_string_to_keytype(krb5_context context,
		       const char *string,
		       krb5_keytype *keytype)
{
    int i;
    for(i = 0; i < num_keytypes; i++)
	if(strcasecmp(keytypes[i]->name, string) == 0){
	    *keytype = keytypes[i]->type;
	    return 0;
	}
    return KRB5_PROG_KEYTYPE_NOSUPP;
}

krb5_error_code
krb5_generate_random_keyblock(krb5_context context,
			      krb5_enctype type,
			      krb5_keyblock *key)
{
    krb5_error_code ret;
    struct encryption_type *et = _find_enctype(type);
    if(et == NULL)
	return KRB5_PROG_ETYPE_NOSUPP;
    ret = krb5_data_alloc(&key->keyvalue, et->keytype->size);
    if(ret)
	return ret;
    key->keytype = type;
    if(et->keytype->random_key)
	(*et->keytype->random_key)(context, key);
    else
	krb5_generate_random_block(key->keyvalue.data,
				   key->keyvalue.length);
    return 0;
}

static krb5_error_code
_key_schedule(krb5_context context,
	      struct key_data *key)
{
    krb5_error_code ret;
    struct encryption_type *et = _find_enctype(key->key->keytype);
    struct key_type *kt = et->keytype;

    if(kt->schedule == NULL)
	return 0;
    ALLOC(key->schedule, 1);
    if(key->schedule == NULL)
	return ENOMEM;
    ret = krb5_data_alloc(key->schedule, kt->schedule_size);
    if(ret) {
	free(key->schedule);
	key->schedule = NULL;
	return ret;
    }
    (*kt->schedule)(context, key);
    return 0;
}

/************************************************************
 *                                                          *
 ************************************************************/

static void
NONE_checksum(krb5_context context,
	      struct key_data *key,
	      void *data,
	      size_t len,
	      Checksum *C)
{
}

static void
CRC32_checksum(krb5_context context,
	       struct key_data *key,
	       void *data,
	       size_t len,
	       Checksum *C)
{
    u_int32_t crc;
    unsigned char *r = C->checksum.data;
    _krb5_crc_init_table ();
    crc = _krb5_crc_update (data, len, 0);
    r[0] = crc & 0xff;
    r[1] = (crc >> 8)  & 0xff;
    r[2] = (crc >> 16) & 0xff;
    r[3] = (crc >> 24) & 0xff;
}

static void
RSA_MD4_checksum(krb5_context context,
		 struct key_data *key,
		 void *data,
		 size_t len,
		 Checksum *C)
{
    struct md4 m;
    md4_init(&m);
    md4_update(&m, data, len);
    md4_finito(&m, C->checksum.data);
}

static void
RSA_MD4_DES_checksum(krb5_context context,
		     struct key_data *key,
		     void *data,
		     size_t len,
		     Checksum *cksum)
{
    struct md4 md4;
    des_cblock ivec;
    unsigned char *p = cksum->checksum.data;

    krb5_generate_random_block(p, 8);
    md4_init(&md4);
    md4_update(&md4, p, 8);
    md4_update(&md4, data, len);
    md4_finito(&md4, p + 8);
    memset (&ivec, 0, sizeof(ivec));
    des_cbc_encrypt((des_cblock*)p,
		    (des_cblock*)p,
		    24,
		    key->schedule->data,
		    &ivec,
		    DES_ENCRYPT);
}

static krb5_error_code
RSA_MD4_DES_verify(krb5_context context,
		   struct key_data *key,
		   void *data,
		   size_t len,
		   Checksum *C)
{
    struct md4 md4;
    unsigned char tmp[24];
    unsigned char res[16];
    des_cblock ivec;
    krb5_error_code ret = 0;

    memset(&ivec, 0, sizeof(ivec));
    des_cbc_encrypt(C->checksum.data,
		    (void*)tmp,
		    C->checksum.length,
		    key->schedule->data,
		    &ivec,
		    DES_DECRYPT);
    md4_init(&md4);
    md4_update(&md4, tmp, 8); /* confounder */
    md4_update(&md4, data, len);
    md4_finito(&md4, res);
    if(memcmp(res, tmp + 8, sizeof(res)) != 0)
	ret = KRB5KRB_AP_ERR_BAD_INTEGRITY;
    memset(tmp, 0, sizeof(tmp));
    memset(res, 0, sizeof(res));
    return ret;
}

static void
RSA_MD5_checksum(krb5_context context,
		 struct key_data *key,
		 void *data,
		 size_t len,
		 Checksum *C)
{
    struct md5 m;
    md5_init(&m);
    md5_update(&m, data, len);
    md5_finito(&m, C->checksum.data);
}

static void
RSA_MD5_DES_checksum(krb5_context context,
		     struct key_data *key,
		     void *data,
		     size_t len,
		     Checksum *C)
{
    struct md5 md5;
    des_cblock ivec;
    unsigned char *p = C->checksum.data;

    krb5_generate_random_block(p, 8);
    md5_init(&md5);
    md5_update(&md5, p, 8);
    md5_update(&md5, data, len);
    md5_finito(&md5, p + 8);
    memset (&ivec, 0, sizeof(ivec));
    des_cbc_encrypt((des_cblock*)p,
		    (des_cblock*)p,
		    24,
		    key->schedule->data,
		    &ivec,
		    DES_ENCRYPT);
}

static krb5_error_code
RSA_MD5_DES_verify(krb5_context context,
		   struct key_data *key,
		   void *data,
		   size_t len,
		   Checksum *C)
{
    struct md5 md5;
    unsigned char tmp[24];
    unsigned char res[16];
    des_cblock ivec;
    des_key_schedule *sched = key->schedule->data;
    krb5_error_code ret = 0;

    memset(&ivec, 0, sizeof(ivec));
    des_cbc_encrypt(C->checksum.data,
		    (void*)tmp,
		    C->checksum.length,
		    sched[0],
		    &ivec,
		    DES_DECRYPT);
    md5_init(&md5);
    md5_update(&md5, tmp, 8); /* confounder */
    md5_update(&md5, data, len);
    md5_finito(&md5, res);
    if(memcmp(res, tmp + 8, sizeof(res)) != 0)
	ret = KRB5KRB_AP_ERR_BAD_INTEGRITY;
    memset(tmp, 0, sizeof(tmp));
    memset(res, 0, sizeof(res));
    return ret;
}

static void
RSA_MD5_DES3_checksum(krb5_context context,
		      struct key_data *key,
		      void *data,
		      size_t len,
		      Checksum *C)
{
    struct md5 md5;
    des_cblock ivec;
    unsigned char *p = C->checksum.data;
    des_key_schedule *sched = key->schedule->data;

    krb5_generate_random_block(p, 8);
    md5_init(&md5);
    md5_update(&md5, p, 8);
    md5_update(&md5, data, len);
    md5_finito(&md5, p + 8);
    memset (&ivec, 0, sizeof(ivec));
    des_ede3_cbc_encrypt((des_cblock*)p,
			 (des_cblock*)p,
			 24,
			 sched[0], sched[1], sched[2],
			 &ivec,
			 DES_ENCRYPT);
}

static krb5_error_code
RSA_MD5_DES3_verify(krb5_context context,
		    struct key_data *key,
		    void *data,
		    size_t len,
		    Checksum *C)
{
    struct md5 md5;
    unsigned char tmp[24];
    unsigned char res[16];
    des_cblock ivec;
    des_key_schedule *sched = key->schedule->data;
    krb5_error_code ret = 0;

    memset(&ivec, 0, sizeof(ivec));
    des_ede3_cbc_encrypt(C->checksum.data,
			 (void*)tmp,
			 C->checksum.length,
			 sched[0], sched[1], sched[2],
			 &ivec,
			 DES_DECRYPT);
    md5_init(&md5);
    md5_update(&md5, tmp, 8); /* confounder */
    md5_update(&md5, data, len);
    md5_finito(&md5, res);
    if(memcmp(res, tmp + 8, sizeof(res)) != 0)
	ret = KRB5KRB_AP_ERR_BAD_INTEGRITY;
    memset(tmp, 0, sizeof(tmp));
    memset(res, 0, sizeof(res));
    return ret;
}

static void
SHA1_checksum(krb5_context context,
	      struct key_data *key,
	      void *data,
	      size_t len,
	      Checksum *C)
{
    struct sha m;
    sha_init(&m);
    sha_update(&m, data, len);
    sha_finito(&m, C->checksum.data);
}

/* HMAC according to RFC2104 */
static void
hmac(krb5_context context,
     struct checksum_type *cm,
     void *data,
     size_t len,
     struct key_data *keyblock,
     Checksum *result)
{
    unsigned char *ipad, *opad;
    unsigned char *key;
    size_t key_len;
    int i;

    if(keyblock->key->keyvalue.length > cm->blocksize){
	(*cm->checksum)(context,
			keyblock,
			keyblock->key->keyvalue.data,
			keyblock->key->keyvalue.length,
			result);
	key = result->checksum.data;
	key_len = result->checksum.length;
    } else {
	key = keyblock->key->keyvalue.data;
	key_len = keyblock->key->keyvalue.length;
    }
    ipad = malloc(cm->blocksize + len);
    opad = malloc(cm->blocksize + cm->checksumsize);
    memset(ipad, 0x36, cm->blocksize);
    memset(opad, 0x5c, cm->blocksize);
    for(i = 0; i < key_len; i++){
	ipad[i] ^= key[i];
	opad[i] ^= key[i];
    }
    memcpy(ipad + cm->blocksize, data, len);
    (*cm->checksum)(context, keyblock, ipad, cm->blocksize + len, result);
    memcpy(opad + cm->blocksize, result->checksum.data,
	   result->checksum.length);
    (*cm->checksum)(context, keyblock, opad,
		    cm->blocksize + cm->checksumsize, result);
    memset(ipad, 0, cm->blocksize + len);
    free(ipad);
    memset(opad, 0, cm->blocksize + cm->checksumsize);
    free(opad);
}

static void
HMAC_SHA1_DES3_checksum(krb5_context context,
			struct key_data *key,
			void *data,
			size_t len,
			Checksum *result)
{
    struct checksum_type *c = _find_checksum(CKSUMTYPE_SHA1);

    hmac(context, c, data, len, key, result);
}

struct checksum_type checksum_none = {
    CKSUMTYPE_NONE,
    "none",
    1,
    0,
    0,
    NONE_checksum,
    NULL
};
struct checksum_type checksum_crc32 = {
    CKSUMTYPE_CRC32,
    "crc32",
    1,
    4,
    0,
    CRC32_checksum,
    NULL
};
struct checksum_type checksum_rsa_md4 = {
    CKSUMTYPE_RSA_MD4,
    "rsa-md4",
    64,
    16,
    F_CPROOF,
    RSA_MD4_checksum,
    NULL
};
struct checksum_type checksum_rsa_md4_des = {
    CKSUMTYPE_RSA_MD4_DES,
    "rsa-md4-des",
    64,
    24,
    F_KEYED | F_CPROOF | F_VARIANT,
    RSA_MD4_DES_checksum,
    RSA_MD4_DES_verify
};
#if 0
struct checksum_type checksum_des_mac = {
    CKSUMTYPE_DES_MAC,
    "des-mac",
    0,
    0,
    0,
    DES_MAC_checksum,
};
struct checksum_type checksum_des_mac_k = {
    CKSUMTYPE_DES_MAC_K,
    "des-mac-k",
    0,
    0,
    0,
    DES_MAC_K_checksum,
};
struct checksum_type checksum_rsa_md4_des_k = {
    CKSUMTYPE_RSA_MD4_DES_K,
    "rsa-md4-des-k",
    0,
    0,
    0,
    RSA_MD4_DES_K_checksum,
    RSA_MD4_DES_K_verify,
};
#endif
struct checksum_type checksum_rsa_md5 = {
    CKSUMTYPE_RSA_MD5,
    "rsa-md5",
    64,
    16,
    F_CPROOF,
    RSA_MD5_checksum,
    NULL
};
struct checksum_type checksum_rsa_md5_des = {
    CKSUMTYPE_RSA_MD5_DES,
    "rsa-md5-des",
    64,
    24,
    F_KEYED | F_CPROOF | F_VARIANT,
    RSA_MD5_DES_checksum,
    RSA_MD5_DES_verify,
};
struct checksum_type checksum_rsa_md5_des3 = {
    CKSUMTYPE_RSA_MD5_DES3,
    "rsa-md5-des3",
    64,
    24,
    F_KEYED | F_CPROOF | F_VARIANT,
    RSA_MD5_DES3_checksum,
    RSA_MD5_DES3_verify,
};
struct checksum_type checksum_sha1 = {
    CKSUMTYPE_SHA1,
    "sha1",
    64,
    20,
    F_CPROOF,
    SHA1_checksum,
    NULL
};
struct checksum_type checksum_hmac_sha1_des3 = {
    CKSUMTYPE_HMAC_SHA1_DES3,
    "hmac-sha1-des3",
    64,
    20,
    F_KEYED | F_CPROOF | F_DERIVED,
    HMAC_SHA1_DES3_checksum,
    NULL
};

struct checksum_type *checksum_types[] = {
    &checksum_none,
    &checksum_crc32,
    &checksum_rsa_md4,
    &checksum_rsa_md4_des,
#if 0
    &checksum_des_mac,
    &checksum_des_mac_k,
    &checksum_rsa_md4_des_k,
#endif
    &checksum_rsa_md5,
    &checksum_rsa_md5_des,
    &checksum_rsa_md5_des3,
    &checksum_sha1,
    &checksum_hmac_sha1_des3
};

static int num_checksums = sizeof(checksum_types) / sizeof(checksum_types[0]);

static struct checksum_type *
_find_checksum(krb5_cksumtype type)
{
    int i;
    for(i = 0; i < num_checksums; i++)
	if(checksum_types[i]->type == type)
	    return checksum_types[i];
    return NULL;
}

static krb5_error_code
get_checksum_key(krb5_context context,
		 krb5_crypto crypto,
		 unsigned usage,  /* not krb5_key_usage */
		 struct checksum_type *ct,
		 struct key_data **key)
{
    krb5_error_code ret = 0;

    if(ct->flags & F_DERIVED)
	ret = _get_derived_key(context, crypto, usage, key);
    else if(ct->flags & F_VARIANT) {
	int i;

	*key = _new_derived_key(crypto, 0xff/* KRB5_KU_RFC1510_VARIANT */);
	if(*key == NULL)
	    return ENOMEM;
	ret = krb5_copy_keyblock(context, crypto->key.key, &(*key)->key);
	if(ret)
	    return ret;
	for(i = 0; i < (*key)->key->keyvalue.length; i++)
	    ((unsigned char*)(*key)->key->keyvalue.data)[i] ^= 0xF0;
    } else {
	*key = &crypto->key;
    }
    if(ret == 0)
	ret = _key_schedule(context, *key);
    return ret;
}

static krb5_error_code
do_checksum (krb5_context context,
	     struct checksum_type *ct,
	     krb5_crypto crypto,
	     unsigned usage,
	     void *data,
	     size_t len,
	     Checksum *result)
{
    krb5_error_code ret;
    struct key_data *dkey;
    int keyed_checksum;

    keyed_checksum = (ct->flags & F_KEYED) != 0;
    if(keyed_checksum && crypto == NULL)
	return KRB5_PROG_SUMTYPE_NOSUPP; /* XXX */
    if(keyed_checksum)
	ret = get_checksum_key(context, crypto, usage, ct, &dkey);
    else
	dkey = NULL;
    result->cksumtype = ct->type;
    krb5_data_alloc(&result->checksum, ct->checksumsize);
    (*ct->checksum)(context, dkey, data, len, result);
    return 0;
}

static krb5_error_code
create_checksum(krb5_context context,
		krb5_crypto crypto,
		unsigned usage, /* not krb5_key_usage */
		krb5_cksumtype type, /* if crypto == NULL */
		void *data,
		size_t len,
		Checksum *result)
{
    struct checksum_type *ct;

    if(crypto) {
	ct = crypto->et->keyed_checksum;
	if(ct == NULL)
	    ct = crypto->et->cksumtype;
    } else
	ct = _find_checksum(type);
    if(ct == NULL)
	return KRB5_PROG_SUMTYPE_NOSUPP;
    return do_checksum (context, ct, crypto, usage, data, len, result);
}

krb5_error_code
krb5_create_checksum(krb5_context context,
		     krb5_crypto crypto,
		     unsigned usage_or_type,
		     void *data,
		     size_t len,
		     Checksum *result)
{
    return create_checksum(context, crypto,
			   CHECKSUM_USAGE(usage_or_type),
			   usage_or_type, data, len, result);
}

static krb5_error_code
verify_checksum(krb5_context context,
		krb5_crypto crypto,
		unsigned usage, /* not krb5_key_usage */
		void *data,
		size_t len,
		Checksum *cksum)
{
    krb5_error_code ret;
    struct key_data *dkey;
    int keyed_checksum;
    Checksum c;
    struct checksum_type *ct;

    ct = _find_checksum(cksum->cksumtype);
    if(ct == NULL)
	return KRB5_PROG_SUMTYPE_NOSUPP;
    if(ct->checksumsize != cksum->checksum.length)
	return KRB5KRB_AP_ERR_BAD_INTEGRITY; /* XXX */
    keyed_checksum = (ct->flags & F_KEYED) != 0;
    if(keyed_checksum && crypto == NULL)
	return KRB5_PROG_SUMTYPE_NOSUPP; /* XXX */
    if(keyed_checksum)
	ret = get_checksum_key(context, crypto, usage, ct, &dkey);
    else
	dkey = NULL;
    if(ct->verify)
	return (*ct->verify)(context, dkey, data, len, cksum);

    ret = krb5_data_alloc (&c.checksum, ct->checksumsize);
    if (ret)
	return ret;

    (*ct->checksum)(context, dkey, data, len, &c);

    if(c.checksum.length != cksum->checksum.length ||
       memcmp(c.checksum.data, cksum->checksum.data, c.checksum.length))
	ret = KRB5KRB_AP_ERR_BAD_INTEGRITY;
    else
	ret = 0;
    krb5_data_free (&c.checksum);
    return ret;
}

krb5_error_code
krb5_verify_checksum(krb5_context context,
		     krb5_crypto crypto,
		     krb5_key_usage usage,
		     void *data,
		     size_t len,
		     Checksum *cksum)
{
    return verify_checksum(context, crypto,
			   CHECKSUM_USAGE(usage), data, len, cksum);
}

krb5_error_code
krb5_checksumsize(krb5_context context,
		  krb5_cksumtype type,
		  size_t *size)
{
    struct checksum_type *ct = _find_checksum(type);
    if(ct == NULL)
	return KRB5_PROG_SUMTYPE_NOSUPP;
    *size = ct->checksumsize;
    return 0;
}

krb5_boolean
krb5_checksum_is_keyed(krb5_context context,
		       krb5_cksumtype type)
{
    struct checksum_type *ct = _find_checksum(type);
    if(ct == NULL)
	return KRB5_PROG_SUMTYPE_NOSUPP;
    return ct->flags & F_KEYED;
}

krb5_boolean
krb5_checksum_is_collision_proof(krb5_context context,
				 krb5_cksumtype type)
{
    struct checksum_type *ct = _find_checksum(type);
    if(ct == NULL)
	return KRB5_PROG_SUMTYPE_NOSUPP;
    return ct->flags & F_CPROOF;
}

/************************************************************
 *                                                          *
 ************************************************************/

static void
NULL_encrypt(struct key_data *key,
	     void *data,
	     size_t len,
	     krb5_boolean encrypt)
{
}

static void
DES_CBC_encrypt_null_ivec(struct key_data *key,
			  void *data,
			  size_t len,
			  krb5_boolean encrypt)
{
    des_cblock ivec;
    des_key_schedule *s = key->schedule->data;
    memset(&ivec, 0, sizeof(ivec));
    des_cbc_encrypt(data, data, len, *s, &ivec, encrypt);
}

static void
DES_CBC_encrypt_key_ivec(struct key_data *key,
			 void *data,
			 size_t len,
			 krb5_boolean encrypt)
{
    des_cblock ivec;
    des_key_schedule *s = key->schedule->data;
    memcpy(&ivec, key->key->keyvalue.data, sizeof(ivec));
    des_cbc_encrypt(data, data, len, *s, &ivec, encrypt);
}

static void
DES3_CBC_encrypt(struct key_data *key,
		 void *data,
		 size_t len,
		 krb5_boolean encrypt)
{
    des_cblock ivec;
    des_key_schedule *s = key->schedule->data;
    memset(&ivec, 0, sizeof(ivec));
    des_ede3_cbc_encrypt(data, data, len, s[0], s[1], s[2], &ivec, encrypt);
}

static void
ARCFOUR_encrypt(struct key_data *key,
		void *data,
		size_t len,
		krb5_boolean encrypt)
{

}

/*
 * these should currently be in reverse preference order.
 */

static struct encryption_type etypes[] = {
    {
	ETYPE_NULL,
	"null",
	1,
	0,
	&keytype_null,
	&checksum_none,
	NULL,
	0,
	NULL_encrypt,
    },
    {
	ETYPE_DES_CBC_CRC,
	"des-cbc-crc",
	8,
	8,
	&keytype_des,
	&checksum_crc32,
	NULL,
	0,
	DES_CBC_encrypt_key_ivec,
    },
    {
	ETYPE_DES_CBC_MD4,
	"des-cbc-md4",
	8,
	8,
	&keytype_des,
	&checksum_rsa_md4,
	&checksum_rsa_md4_des,
	0,
	DES_CBC_encrypt_null_ivec,
    },
    {
	ETYPE_DES_CBC_MD5,
	"des-cbc-md5",
	8,
	8,
	&keytype_des,
	&checksum_rsa_md5,
	&checksum_rsa_md5_des,
	0,
	DES_CBC_encrypt_null_ivec,
    },
    {
	ETYPE_DES3_CBC_MD5,
	"des3-cbc-md5",
	8,
	8,
	&keytype_des3,
	&checksum_rsa_md5,
	&checksum_rsa_md5_des3,
	0,
 	DES3_CBC_encrypt,
    },
    {
	ETYPE_DES3_CBC_SHA1,
	"des3-cbc-sha1",
	8,
	8,
	&keytype_des3_derived,
	&checksum_sha1,
	&checksum_hmac_sha1_des3,
	F_DERIVED,
 	DES3_CBC_encrypt,
    },
    {
	ETYPE_OLD_DES3_CBC_SHA1,
	"old-des3-cbc-sha1",
	8,
	8,
	&keytype_des3,
	&checksum_sha1,
	&checksum_hmac_sha1_des3,
	0,
 	DES3_CBC_encrypt,
    },
    {
	ETYPE_DES_CBC_NONE,
	"des-cbc-none",
	8,
	0,
	&keytype_des,
	&checksum_none,
	NULL,
	F_PSEUDO,
	DES_CBC_encrypt_null_ivec,
    },
    {
	ETYPE_DES3_CBC_NONE,
	"des3-cbc-none",
	8,
	0,
	&keytype_des3_derived,
	&checksum_none,
	NULL,
	F_PSEUDO,
	DES_CBC_encrypt_null_ivec,
    },
};

static unsigned num_etypes = sizeof(etypes) / sizeof(etypes[0]);


static struct encryption_type *
_find_enctype(krb5_enctype type)
{
    int i;
    for(i = 0; i < num_etypes; i++)
	if(etypes[i].type == type)
	    return &etypes[i];
    return NULL;
}


krb5_error_code
krb5_enctype_to_string(krb5_context context,
		       krb5_enctype etype,
		       char **string)
{
    struct encryption_type *e;
    e = _find_enctype(etype);
    if(e == NULL)
	return KRB5_PROG_ETYPE_NOSUPP;
    *string = strdup(e->name);
    if(*string == NULL)
	return ENOMEM;
    return 0;
}

krb5_error_code
krb5_string_to_enctype(krb5_context context,
		       const char *string,
		       krb5_enctype *etype)
{
    int i;
    for(i = 0; i < num_etypes; i++)
	if(strcasecmp(etypes[i].name, string) == 0){
	    *etype = etypes[i].type;
	    return 0;
	}
    return KRB5_PROG_ETYPE_NOSUPP;
}

krb5_error_code
krb5_enctype_to_keytype(krb5_context context,
			krb5_enctype etype,
			krb5_keytype *keytype)
{
    struct encryption_type *e = _find_enctype(etype);
    if(e == NULL)
	return KRB5_PROG_ETYPE_NOSUPP;
    *keytype = e->keytype->type; /* XXX */
    return 0;
}

#if 0
krb5_error_code
krb5_keytype_to_enctype(krb5_context context,
			krb5_keytype keytype,
			krb5_enctype *etype)
{
    struct key_type *kt = _find_keytype(keytype);
    krb5_warnx(context, "krb5_keytype_to_enctype(%u)", keytype);
    if(kt == NULL)
	return KRB5_PROG_KEYTYPE_NOSUPP;
    *etype = kt->best_etype;
    return 0;
}
#endif

krb5_error_code
krb5_keytype_to_enctypes (krb5_context context,
			  krb5_keytype keytype,
			  unsigned *len,
			  int **val)
{
    int i;
    unsigned n = 0;
    int *ret;

    for (i = num_etypes - 1; i >= 0; --i) {
	if (etypes[i].keytype->type == keytype
	    && !(etypes[i].flags & F_PSEUDO))
	    ++n;
    }
    ret = malloc(n * sizeof(int));
    if (ret == NULL && n != 0)
	return ENOMEM;
    n = 0;
    for (i = num_etypes - 1; i >= 0; --i) {
	if (etypes[i].keytype->type == keytype
	    && !(etypes[i].flags & F_PSEUDO))
	    ret[n++] = etypes[i].type;
    }
    *len = n;
    *val = ret;
    return 0;
}

/*
 * First take the configured list of etypes for `keytype' if available,
 * else, do `krb5_keytype_to_enctypes'.
 */

krb5_error_code
krb5_keytype_to_enctypes_default (krb5_context context,
				  krb5_keytype keytype,
				  unsigned *len,
				  int **val)
{
    int i, n;
    int *ret;

    if (keytype != KEYTYPE_DES || context->etypes_des == NULL)
	return krb5_keytype_to_enctypes (context, keytype, len, val);

    for (n = 0; context->etypes_des[n]; ++n)
	;
    ret = malloc (n * sizeof(*ret));
    if (ret == NULL && n != 0)
	return ENOMEM;
    for (i = 0; i < n; ++i)
	ret[i] = context->etypes_des[i];
    *len = n;
    *val = ret;
    return 0;
}

krb5_error_code
krb5_enctype_valid(krb5_context context,
		 krb5_enctype etype)
{
    return _find_enctype(etype) != NULL;
}

/* if two enctypes have compatible keys */
krb5_boolean
krb5_enctypes_compatible_keys(krb5_context context,
			      krb5_enctype etype1,
			      krb5_enctype etype2)
{
    struct encryption_type *e1 = _find_enctype(etype1);
    struct encryption_type *e2 = _find_enctype(etype2);
    return e1 != NULL && e2 != NULL && e1->keytype == e2->keytype;
}

static krb5_boolean
derived_crypto(krb5_context context,
	       krb5_crypto crypto)
{
    return (crypto->et->flags & F_DERIVED) != 0;
}


#define CHECKSUMSIZE(C) ((C)->checksumsize)
#define CHECKSUMTYPE(C) ((C)->type)

static krb5_error_code
encrypt_internal_derived(krb5_context context,
			 krb5_crypto crypto,
			 unsigned usage,
			 void *data,
			 size_t len,
			 krb5_data *result)
{
    size_t sz, block_sz, checksum_sz;
    Checksum cksum;
    unsigned char *p, *q;
    krb5_error_code ret;
    struct key_data *dkey;
    struct encryption_type *et = crypto->et;

    checksum_sz = CHECKSUMSIZE(et->keyed_checksum);

    sz = et->confoundersize + /* 4 - length */ len;
    block_sz = (sz + et->blocksize - 1) &~ (et->blocksize - 1); /* pad */
    p = calloc(1, block_sz + checksum_sz);
    if(p == NULL)
	return ENOMEM;

    q = p;
    krb5_generate_random_block(q, et->confoundersize); /* XXX */
    q += et->confoundersize;
    memcpy(q, data, len);

    ret = create_checksum(context,
			  crypto,
			  INTEGRITY_USAGE(usage),
			  0,
			  p,
			  block_sz,
			  &cksum);
    if(ret == 0 && cksum.checksum.length != checksum_sz)
	ret =  KRB5_CRYPTO_INTERNAL;
    if(ret) {
	memset(p, 0, block_sz + checksum_sz);
	free(p);
	return ret;
    }
    memcpy(p + block_sz, cksum.checksum.data, cksum.checksum.length);
    ret = _get_derived_key(context, crypto, ENCRYPTION_USAGE(usage), &dkey);
    if(ret) {
	memset(p, 0, block_sz + checksum_sz);
	free(p);
	return ret;
    }
    ret = _key_schedule(context, dkey);
    if(ret) {
	memset(p, 0, block_sz);
	free(p);
	return ret;
    }
#ifdef CRYPTO_DEBUG
    krb5_crypto_debug(context, 1, block_sz, dkey->key);
#endif
    (*et->encrypt)(dkey, p, block_sz, 1);
    result->data = p;
    result->length = block_sz + checksum_sz;
    return 0;
}

static krb5_error_code
encrypt_internal(krb5_context context,
		 krb5_crypto crypto,
		 void *data,
		 size_t len,
		 krb5_data *result)
{
    size_t sz, block_sz, checksum_sz;
    Checksum cksum;
    unsigned char *p, *q;
    krb5_error_code ret;
    struct encryption_type *et = crypto->et;

    checksum_sz = CHECKSUMSIZE(et->cksumtype);

    sz = et->confoundersize + checksum_sz + len;
    block_sz = (sz + et->blocksize - 1) &~ (et->blocksize - 1); /* pad */
    p = calloc(1, block_sz);
    if(p == NULL)
	return ENOMEM;

    q = p;
    krb5_generate_random_block(q, et->confoundersize); /* XXX */
    q += et->confoundersize;
    memset(q, 0, checksum_sz);
    q += checksum_sz;
    memcpy(q, data, len);

    ret = create_checksum(context,
			  NULL,
			  0,
			  CHECKSUMTYPE(et->cksumtype),
			  p,
			  block_sz,
			  &cksum);
    if(ret == 0 && cksum.checksum.length != checksum_sz) {
	free_Checksum (&cksum);
	ret = KRB5_CRYPTO_INTERNAL;
    }
    if(ret) {
	memset(p, 0, block_sz);
	free(p);
	free_Checksum(&cksum);
	return ret;
    }
    memcpy(p + et->confoundersize, cksum.checksum.data, cksum.checksum.length);
    free_Checksum(&cksum);
    ret = _key_schedule(context, &crypto->key);
    if(ret) {
	memset(p, 0, block_sz);
	free(p);
	return ret;
    }
#ifdef CRYPTO_DEBUG
    krb5_crypto_debug(context, 1, block_sz, crypto->key.key);
#endif
    (*et->encrypt)(&crypto->key, p, block_sz, 1);
    result->data = p;
    result->length = block_sz;
    return 0;
}

static krb5_error_code
decrypt_internal_derived(krb5_context context,
			 krb5_crypto crypto,
			 unsigned usage,
			 void *data,
			 size_t len,
			 krb5_data *result)
{
    size_t checksum_sz;
    Checksum cksum;
    unsigned char *p;
    krb5_error_code ret;
    struct key_data *dkey;
    struct encryption_type *et = crypto->et;
    unsigned long l;

    p = malloc(len);
    if(len != 0 && p == NULL)
	return ENOMEM;
    memcpy(p, data, len);

    checksum_sz = CHECKSUMSIZE(et->keyed_checksum);
    len -= checksum_sz;

    ret = _get_derived_key(context, crypto, ENCRYPTION_USAGE(usage), &dkey);
    if(ret) {
	free(p);
	return ret;
    }
    ret = _key_schedule(context, dkey);
    if(ret) {
	free(p);
	return ret;
    }
#ifdef CRYPTO_DEBUG
    krb5_crypto_debug(context, 0, len, dkey->key);
#endif
    (*et->encrypt)(dkey, p, len, 0);

    cksum.checksum.data   = p + len;
    cksum.checksum.length = checksum_sz;
    cksum.cksumtype       = CHECKSUMTYPE(et->keyed_checksum);

    ret = verify_checksum(context,
			  crypto,
			  INTEGRITY_USAGE(usage),
			  p,
			  len,
			  &cksum);
    if(ret) {
	free(p);
	return ret;
    }
    l = len - et->confoundersize;
    memmove(p, p + et->confoundersize, l);
    result->data = realloc(p, l);
    if(p == NULL) {
	free(p);
	return ENOMEM;
    }
    result->length = l;
    return 0;
}

static krb5_error_code
decrypt_internal(krb5_context context,
		 krb5_crypto crypto,
		 void *data,
		 size_t len,
		 krb5_data *result)
{
    krb5_error_code ret;
    unsigned char *p;
    Checksum cksum;
    size_t checksum_sz, l;
    struct encryption_type *et = crypto->et;

    checksum_sz = CHECKSUMSIZE(et->cksumtype);
    p = malloc(len);
    if(len != 0 && p == NULL)
	return ENOMEM;
    memcpy(p, data, len);

    ret = _key_schedule(context, &crypto->key);
    if(ret) {
	free(p);
	return ret;
    }
#ifdef CRYPTO_DEBUG
    krb5_crypto_debug(context, 0, len, crypto->key.key);
#endif
    (*et->encrypt)(&crypto->key, p, len, 0);
    ret = krb5_data_copy(&cksum.checksum, p + et->confoundersize, checksum_sz);
    if(ret) {
	free(p);
	return ret;
    }
    memset(p + et->confoundersize, 0, checksum_sz);
    cksum.cksumtype = CHECKSUMTYPE(et->cksumtype);
    ret = verify_checksum(context, NULL, 0, p, len, &cksum);
    free_Checksum(&cksum);
    if(ret) {
	free(p);
	return ret;
    }
    l = len - et->confoundersize - checksum_sz;
    memmove(p, p + et->confoundersize + checksum_sz, l);
    result->data = realloc(p, l);
    if(result->data == NULL) {
	free(p);
	return ENOMEM;
    }
    result->length = l;
    return 0;
}

krb5_error_code
krb5_encrypt(krb5_context context,
	     krb5_crypto crypto,
	     unsigned usage,
	     void *data,
	     size_t len,
	     krb5_data *result)
{
    if(derived_crypto(context, crypto))
	return encrypt_internal_derived(context, crypto, usage,
					data, len, result);
    else
	return encrypt_internal(context, crypto, data, len, result);
}

krb5_error_code
krb5_encrypt_EncryptedData(krb5_context context,
			   krb5_crypto crypto,
			   unsigned usage,
			   void *data,
			   size_t len,
			   int kvno,
			   EncryptedData *result)
{
    result->etype = CRYPTO_ETYPE(crypto);
    if(kvno){
	ALLOC(result->kvno, 1);
	*result->kvno = kvno;
    }else
	result->kvno = NULL;
    return krb5_encrypt(context, crypto, usage, data, len, &result->cipher);
}

krb5_error_code
krb5_decrypt(krb5_context context,
	     krb5_crypto crypto,
	     unsigned usage,
	     void *data,
	     size_t len,
	     krb5_data *result)
{
    if(derived_crypto(context, crypto))
	return decrypt_internal_derived(context, crypto, usage,
					data, len, result);
    else
	return decrypt_internal(context, crypto, data, len, result);
}

krb5_error_code
krb5_decrypt_EncryptedData(krb5_context context,
			   krb5_crypto crypto,
			   unsigned usage,
			   EncryptedData *e,
			   krb5_data *result)
{
    return krb5_decrypt(context, crypto, usage,
			e->cipher.data, e->cipher.length, result);
}

/************************************************************
 *                                                          *
 ************************************************************/

void
krb5_generate_random_block(void *buf, size_t len)
{
    des_cblock key, out;
    static des_cblock counter;
    static des_key_schedule schedule;
    int i;
    static int initialized = 0;

    if(!initialized) {
	des_new_random_key(&key);
	des_set_key(&key, schedule);
	memset(&key, 0, sizeof(key));
	des_new_random_key(&counter);
    }
    while(len > 0) {
	des_ecb_encrypt(&counter, &out, schedule, DES_ENCRYPT);
	for(i = 7; i >=0; i--)
	    if(counter[i]++)
		break;
	memcpy(buf, out, min(len, sizeof(out)));
	len -= min(len, sizeof(out));
	buf = (char*)buf + sizeof(out);
    }
}

static void
DES3_postproc(krb5_context context,
	      unsigned char *k, size_t len, struct key_data *key)
{
    unsigned char x[24];
    int i, j;

    memset(x, 0, sizeof(x));
    for (i = 0; i < 3; ++i) {
	unsigned char foo;

	for (j = 0; j < 7; ++j) {
	    unsigned char b = k[7 * i + j];

	    x[8 * i + j] = b;
	}
	foo = 0;
	for (j = 6; j >= 0; --j) {
	    foo |= k[7 * i + j] & 1;
	    foo <<= 1;
	}
	x[8 * i + 7] = foo;
    }
    k = key->key->keyvalue.data;
    memcpy(k, x, 24);
    memset(x, 0, sizeof(x));
    if (key->schedule) {
	krb5_free_data(context, key->schedule);
	key->schedule = NULL;
    }
    des_set_odd_parity((des_cblock*)k);
    des_set_odd_parity((des_cblock*)(k + 8));
    des_set_odd_parity((des_cblock*)(k + 16));
}

static krb5_error_code
derive_key(krb5_context context,
	   struct encryption_type *et,
	   struct key_data *key,
	   void *constant,
	   size_t len)
{
    unsigned char *k;
    unsigned int nblocks = 0, i;
    krb5_error_code ret = 0;

    struct key_type *kt = et->keytype;
    ret = _key_schedule(context, key);
    if(ret)
	return ret;
    if(et->blocksize * 8 < kt->bits ||
       len != et->blocksize) {
	nblocks = (kt->bits + et->blocksize * 8 - 1) / (et->blocksize * 8);
	k = malloc(nblocks * et->blocksize);
	if(k == NULL)
	    return ENOMEM;
	_krb5_n_fold(constant, len, k, et->blocksize);
	for(i = 0; i < nblocks; i++) {
	    if(i > 0)
		memcpy(k + i * et->blocksize,
		       k + (i - 1) * et->blocksize,
		       et->blocksize);
	    (*et->encrypt)(key, k + i * et->blocksize, et->blocksize, 1);
	}
    } else {
	void *c = malloc(len);
	size_t res_len = (kt->bits + 7) / 8;

	if(len != 0 && c == NULL)
	    return ENOMEM;
	memcpy(c, constant, len);
	(*et->encrypt)(key, c, len, 1);
	k = malloc(res_len);
	if(res_len != 0 && k == NULL)
	    return ENOMEM;
	_krb5_n_fold(c, len, k, res_len);
	free(c);
    }

    /* XXX keytype dependent post-processing */
    switch(kt->type) {
    case KEYTYPE_DES3:
	DES3_postproc(context, k, nblocks * et->blocksize, key);
	break;
    default:
	krb5_warnx(context, "derive_key() called with unknown keytype (%u)",
		   kt->type);
	ret = KRB5_CRYPTO_INTERNAL;
	break;
    }
    memset(k, 0, nblocks * et->blocksize);
    free(k);
    return ret;
}

static struct key_data *
_new_derived_key(krb5_crypto crypto, unsigned usage)
{
    struct key_usage *d = crypto->key_usage;
    d = realloc(d, (crypto->num_key_usage + 1) * sizeof(*d));
    if(d == NULL)
	return NULL;
    crypto->key_usage = d;
    d += crypto->num_key_usage++;
    memset(d, 0, sizeof(*d));
    d->usage = usage;
    return &d->key;
}

static krb5_error_code
_get_derived_key(krb5_context context,
		 krb5_crypto crypto,
		 unsigned usage,
		 struct key_data **key)
{
    int i;
    struct key_data *d;
    unsigned char constant[5];

    for(i = 0; i < crypto->num_key_usage; i++)
	if(crypto->key_usage[i].usage == usage) {
	    *key = &crypto->key_usage[i].key;
	    return 0;
	}
    d = _new_derived_key(crypto, usage);
    if(d == NULL)
	return ENOMEM;
    krb5_copy_keyblock(context, crypto->key.key, &d->key);
    _krb5_put_int(constant, usage, 5);
    derive_key(context, crypto->et, d, constant, sizeof(constant));
    *key = d;
    return 0;
}


krb5_error_code
krb5_crypto_init(krb5_context context,
		 krb5_keyblock *key,
		 krb5_enctype etype,
		 krb5_crypto *crypto)
{
    krb5_error_code ret;
    ALLOC(*crypto, 1);
    if(*crypto == NULL)
	return ENOMEM;
    if(etype == ETYPE_NULL)
	etype = key->keytype;
    (*crypto)->et = _find_enctype(etype);
    if((*crypto)->et == NULL) {
	free(*crypto);
	return KRB5_PROG_ETYPE_NOSUPP;
    }
    ret = krb5_copy_keyblock(context, key, &(*crypto)->key.key);
    if(ret) {
	free(*crypto);
	return ret;
    }
    (*crypto)->key.schedule = NULL;
    (*crypto)->num_key_usage = 0;
    (*crypto)->key_usage = NULL;
    return 0;
}

static void
free_key_data(krb5_context context, struct key_data *key)
{
    krb5_free_keyblock(context, key->key);
    if(key->schedule) {
	memset(key->schedule->data, 0, key->schedule->length);
	krb5_free_data(context, key->schedule);
    }
}

static void
free_key_usage(krb5_context context, struct key_usage *ku)
{
    free_key_data(context, &ku->key);
}

krb5_error_code
krb5_crypto_destroy(krb5_context context,
		    krb5_crypto crypto)
{
    int i;

    for(i = 0; i < crypto->num_key_usage; i++)
	free_key_usage(context, &crypto->key_usage[i]);
    free(crypto->key_usage);
    free_key_data(context, &crypto->key);
    free (crypto);
    return 0;
}

krb5_error_code
krb5_string_to_key_derived(krb5_context context,
			   const void *str,
			   size_t len,
			   krb5_enctype etype,
			   krb5_keyblock *key)
{
    struct encryption_type *et = _find_enctype(etype);
    krb5_error_code ret;
    struct key_data kd;
    u_char *tmp;

    if(et == NULL)
	return KRB5_PROG_ETYPE_NOSUPP;
    ALLOC(kd.key, 1);
    kd.key->keytype = etype;
    tmp = malloc (et->keytype->bits / 8);
    _krb5_n_fold(str, len, tmp, et->keytype->bits / 8);
    krb5_data_alloc(&kd.key->keyvalue, et->keytype->size);
    kd.schedule = NULL;
    DES3_postproc (context, tmp, et->keytype->bits / 8, &kd); /* XXX */
    ret = derive_key(context,
		     et,
		     &kd,
		     "kerberos", /* XXX well known constant */
		     strlen("kerberos"));
    ret = krb5_copy_keyblock_contents(context, kd.key, key);
    free_key_data(context, &kd);
    return ret;
}

/*
 * Return the size of an encrypted packet of length `data_len'
 */

size_t
krb5_get_wrapped_length (krb5_context context,
			 krb5_crypto  crypto,
			 size_t       data_len)
{
    struct encryption_type *et = crypto->et;
    size_t blocksize = et->blocksize;
    size_t res;

    res = (data_len + blocksize - 1) / blocksize * blocksize;
    res = res + et->confoundersize + et->cksumtype->checksumsize;
    return res;
}

#ifdef CRYPTO_DEBUG

static krb5_error_code
krb5_get_keyid(krb5_context context,
	       krb5_keyblock *key,
	       u_int32_t *keyid)
{
    struct md5 md5;
    unsigned char tmp[16];
    md5_init(&md5);
    md5_update(&md5, key->keyvalue.data, key->keyvalue.length);
    md5_finito(&md5, tmp);
    *keyid = (tmp[12] << 24) | (tmp[13] << 16) | (tmp[14] << 8) | tmp[15];
    return 0;
}

static void
krb5_crypto_debug(krb5_context context,
		  int encrypt,
		  size_t len,
		  krb5_keyblock *key)
{
    u_int32_t keyid;
    char *kt;
    krb5_get_keyid(context, key, &keyid);
    krb5_enctype_to_string(context, key->keytype, &kt);
    krb5_warnx(context, "%s %lu bytes with key-id %#x (%s)",
	       encrypt ? "encrypting" : "decrypting",
	       (unsigned long)len,
	       keyid,
	       kt);
    free(kt);
}

#endif /* CRYPTO_DEBUG */