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

/* lib/crypto/krb/enc_raw.c */

/*

 * Copyright 2008 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.

 */

#include "crypto_int.h"

unsigned int

krb5int_raw_crypto_length(const struct krb5_keytypes *ktp,

                          krb5_cryptotype type)

{

    switch (type) {

    case KRB5_CRYPTO_TYPE_PADDING:

        return ktp->enc->block_size;

    default:

        return 0;

    }

}

krb5_error_code

krb5int_raw_encrypt(const struct krb5_keytypes *ktp, krb5_key key,

                    krb5_keyusage usage, const krb5_data *ivec,

                    krb5_crypto_iov *data, size_t num_data)

{

    krb5_crypto_iov *padding;

    size_t i;

    unsigned int blocksize, plainlen = 0, padsize = 0;

    blocksize = ktp->crypto_length(ktp, KRB5_CRYPTO_TYPE_PADDING);

    for (i = 0; i < num_data; i++) {

        krb5_crypto_iov *iov = &data[i];

        if (iov->flags == KRB5_CRYPTO_TYPE_DATA)

            plainlen += iov->data.length;

    }

    if (blocksize != 0) {

        /* Check that the input data is correctly padded */

        if (plainlen % blocksize)

            padsize = blocksize - (plainlen % blocksize);

    }

    padding = krb5int_c_locate_iov(data, num_data, KRB5_CRYPTO_TYPE_PADDING);

    if (padsize && (padding == NULL || padding->data.length < padsize))

        return KRB5_BAD_MSIZE;

    if (padding != NULL) {

        memset(padding->data.data, 0, padsize);

        padding->data.length = padsize;

    }

    return ktp->enc->encrypt(key, ivec, data, num_data);

}

krb5_error_code

krb5int_raw_decrypt(const struct krb5_keytypes *ktp, krb5_key key,

                    krb5_keyusage usage, const krb5_data *ivec,

                    krb5_crypto_iov *data, size_t num_data)

{

    size_t i;

    unsigned int blocksize = 0; /* enc block size, not confounder len */

    unsigned int cipherlen = 0;

    /* E(Confounder | Plaintext | Pad) | Checksum */

    blocksize = ktp->crypto_length(ktp, KRB5_CRYPTO_TYPE_PADDING);

    for (i = 0; i < num_data; i++) {

        const krb5_crypto_iov *iov = &data[i];

        if (ENCRYPT_DATA_IOV(iov))

            cipherlen += iov->data.length;

    }

    if (blocksize == 0) {

        /* Check for correct input length in CTS mode */

        if (ktp->enc->block_size != 0 && cipherlen < ktp->enc->block_size)

            return KRB5_BAD_MSIZE;

    } else {

        /* Check that the input data is correctly padded */

        if (cipherlen % blocksize != 0)

            return KRB5_BAD_MSIZE;

    }

    return ktp->enc->decrypt(key, ivec, data, num_data);

}