/* -*- mode: c; c-basic-offset: 4; indent-tabs-mode: nil -*- */

/* lib/crypto/openssl/enc_provider/des3.c */

/*

 * Copyright (C) 2009 by the Massachusetts Institute of Technology.

 * All rights reserved.

 *

 * Export of this software from the United States of America may

 *   require a specific license from the United States Government.

 *   It is the responsibility of any person or organization contemplating

 *   export to obtain such a license before exporting.

 *

 * WITHIN THAT CONSTRAINT, permission to use, copy, modify, and

 * distribute this software and its documentation for any purpose and

 * without fee is hereby granted, provided that the above copyright

 * notice appear in all copies and that both that copyright notice and

 * this permission notice appear in supporting documentation, and that

 * the name of M.I.T. not be used in advertising or publicity pertaining

 * to distribution of the software without specific, written prior

 * permission.  Furthermore if you modify this software you must label

 * your software as modified software and not distribute it in such a

 * fashion that it might be confused with the original M.I.T. software.

 * M.I.T. makes no representations about the suitability of

 * this software for any purpose.  It is provided "as is" without express

 * or implied warranty.

 */

/*

 * Copyright (C) 1998 by the FundsXpress, INC.

 *

 * All rights reserved.

 *

 * Export of this software from the United States of America may require

 * a specific license from the United States Government.  It is the

 * responsibility of any person or organization contemplating export to

 * obtain such a license before exporting.

 *

 * WITHIN THAT CONSTRAINT, permission to use, copy, modify, and

 * distribute this software and its documentation for any purpose and

 * without fee is hereby granted, provided that the above copyright

 * notice appear in all copies and that both that copyright notice and

 * this permission notice appear in supporting documentation, and that

 * the name of FundsXpress. not be used in advertising or publicity pertaining

 * to distribution of the software without specific, written prior

 * permission.  FundsXpress makes no representations about the suitability of

 * this software for any purpose.  It is provided "as is" without express

 * or implied warranty.

 *

 * THIS SOFTWARE IS PROVIDED ``AS IS'' AND WITHOUT ANY EXPRESS OR

 * IMPLIED WARRANTIES, INCLUDING, WITHOUT LIMITATION, THE IMPLIED

 * WARRANTIES OF MERCHANTIBILITY AND FITNESS FOR A PARTICULAR PURPOSE.

 */

#include "crypto_int.h"

#include <openssl/evp.h>

#define DES3_BLOCK_SIZE 8

#define DES3_KEY_SIZE 24

#define DES3_KEY_BYTES 21

static krb5_error_code

validate(krb5_key key, const krb5_data *ivec, const krb5_crypto_iov *data,

         size_t num_data, krb5_boolean *empty)

{

    size_t input_length = iov_total_length(data, num_data, FALSE);

    if (key->keyblock.length != DES3_KEY_SIZE)

        return(KRB5_BAD_KEYSIZE);

    if ((input_length%DES3_BLOCK_SIZE) != 0)

        return(KRB5_BAD_MSIZE);

    if (ivec && (ivec->length != 8))

        return(KRB5_BAD_MSIZE);

    *empty = (input_length == 0);

    return 0;

}

static krb5_error_code

k5_des3_encrypt(krb5_key key, const krb5_data *ivec, krb5_crypto_iov *data,

                size_t num_data)

{

    int ret, olen = DES3_BLOCK_SIZE;

    unsigned char iblock[DES3_BLOCK_SIZE], oblock[DES3_BLOCK_SIZE];

    struct iov_cursor cursor;

    EVP_CIPHER_CTX *ctx;

    krb5_boolean empty;

    ret = validate(key, ivec, data, num_data, &empty);

    if (ret != 0 || empty)

        return ret;

    ctx = EVP_CIPHER_CTX_new();

    if (ctx == NULL)

        return ENOMEM;

    ret = EVP_EncryptInit_ex(ctx, EVP_des_ede3_cbc(), NULL,

                             key->keyblock.contents,

                             (ivec) ? (unsigned char*)ivec->data : NULL);

    if (!ret) {

        EVP_CIPHER_CTX_free(ctx);

        return KRB5_CRYPTO_INTERNAL;

    }

    EVP_CIPHER_CTX_set_padding(ctx,0);

    k5_iov_cursor_init(&cursor, data, num_data, DES3_BLOCK_SIZE, FALSE);

    while (k5_iov_cursor_get(&cursor, iblock)) {

        ret = EVP_EncryptUpdate(ctx, oblock, &olen, iblock, DES3_BLOCK_SIZE);

        if (!ret)

            break;

        k5_iov_cursor_put(&cursor, oblock);

    }

    if (ivec != NULL)

        memcpy(ivec->data, oblock, DES3_BLOCK_SIZE);

    EVP_CIPHER_CTX_free(ctx);

    zap(iblock, sizeof(iblock));

    zap(oblock, sizeof(oblock));

    if (ret != 1)

        return KRB5_CRYPTO_INTERNAL;

    return 0;

}

static krb5_error_code

k5_des3_decrypt(krb5_key key, const krb5_data *ivec, krb5_crypto_iov *data,

                size_t num_data)

{

    int ret, olen = DES3_BLOCK_SIZE;

    unsigned char iblock[DES3_BLOCK_SIZE], oblock[DES3_BLOCK_SIZE];

    struct iov_cursor cursor;

    EVP_CIPHER_CTX *ctx;

    krb5_boolean empty;

    ret = validate(key, ivec, data, num_data, &empty);

    if (ret != 0 || empty)

        return ret;

    ctx = EVP_CIPHER_CTX_new();

    if (ctx == NULL)

        return ENOMEM;

    ret = EVP_DecryptInit_ex(ctx, EVP_des_ede3_cbc(), NULL,

                             key->keyblock.contents,

                             (ivec) ? (unsigned char*)ivec->data : NULL);

    if (!ret) {

        EVP_CIPHER_CTX_free(ctx);

        return KRB5_CRYPTO_INTERNAL;

    }

    EVP_CIPHER_CTX_set_padding(ctx,0);

    k5_iov_cursor_init(&cursor, data, num_data, DES3_BLOCK_SIZE, FALSE);

    while (k5_iov_cursor_get(&cursor, iblock)) {

        ret = EVP_DecryptUpdate(ctx, oblock, &olen,

                                (unsigned char *)iblock, DES3_BLOCK_SIZE);

        if (!ret)

            break;

        k5_iov_cursor_put(&cursor, oblock);

    }

    if (ivec != NULL)

        memcpy(ivec->data, iblock, DES3_BLOCK_SIZE);

    EVP_CIPHER_CTX_free(ctx);

    zap(iblock, sizeof(iblock));

    zap(oblock, sizeof(oblock));

    if (ret != 1)

        return KRB5_CRYPTO_INTERNAL;

    return 0;

}

const struct krb5_enc_provider krb5int_enc_des3 = {

    DES3_BLOCK_SIZE,

    DES3_KEY_BYTES, DES3_KEY_SIZE,

    k5_des3_encrypt,

    k5_des3_decrypt,

    NULL,

    krb5int_des_init_state,

    krb5int_default_free_state

};