1 /* -*- mode: c; c-basic-offset: 4; indent-tabs-mode: nil -*- */
2 /*
3 * Copyright (C) 1998 by the FundsXpress, INC.
4 *
5 * All rights reserved.
6 *
7 * Export of this software from the United States of America may require
8 * a specific license from the United States Government. It is the
9 * responsibility of any person or organization contemplating export to
10 * obtain such a license before exporting.
11 *
12 * WITHIN THAT CONSTRAINT, permission to use, copy, modify, and
13 * distribute this software and its documentation for any purpose and
14 * without fee is hereby granted, provided that the above copyright
15 * notice appear in all copies and that both that copyright notice and
16 * this permission notice appear in supporting documentation, and that
17 * the name of FundsXpress. not be used in advertising or publicity pertaining
18 * to distribution of the software without specific, written prior
19 * permission. FundsXpress makes no representations about the suitability of
20 * this software for any purpose. It is provided "as is" without express
21 * or implied warranty.
22 *
23 * THIS SOFTWARE IS PROVIDED ``AS IS'' AND WITHOUT ANY EXPRESS OR
24 * IMPLIED WARRANTIES, INCLUDING, WITHOUT LIMITATION, THE IMPLIED
25 * WARRANTIES OF MERCHANTIBILITY AND FITNESS FOR A PARTICULAR PURPOSE.
26 */
27
28 #include "crypto_int.h"
29
30 krb5_error_code KRB5_CALLCONV
krb5_k_decrypt(krb5_context context,krb5_key key,krb5_keyusage usage,const krb5_data * cipher_state,const krb5_enc_data * input,krb5_data * output)31 krb5_k_decrypt(krb5_context context, krb5_key key,
32 krb5_keyusage usage, const krb5_data *cipher_state,
33 const krb5_enc_data *input, krb5_data *output)
34 {
35 const struct krb5_keytypes *ktp;
36 krb5_crypto_iov iov[4];
37 krb5_error_code ret;
38 unsigned int header_len, trailer_len, plain_len;
39 char *scratch = NULL;
40
41 ktp = find_enctype(key->keyblock.enctype);
42 if (ktp == NULL)
43 return KRB5_BAD_ENCTYPE;
44
45 if (input->enctype != ENCTYPE_UNKNOWN && ktp->etype != input->enctype)
46 return KRB5_BAD_ENCTYPE;
47
48 /* Verify the input and output lengths. */
49 header_len = ktp->crypto_length(ktp, KRB5_CRYPTO_TYPE_HEADER);
50 trailer_len = ktp->crypto_length(ktp, KRB5_CRYPTO_TYPE_TRAILER);
51 if (input->ciphertext.length < header_len + trailer_len)
52 return KRB5_BAD_MSIZE;
53 plain_len = input->ciphertext.length - header_len - trailer_len;
54 if (output->length < plain_len)
55 return KRB5_BAD_MSIZE;
56
57 scratch = k5alloc(header_len + trailer_len, &ret);
58 if (scratch == NULL)
59 return ret;
60
61 iov[0].flags = KRB5_CRYPTO_TYPE_HEADER;
62 iov[0].data = make_data(scratch, header_len);
63 memcpy(iov[0].data.data, input->ciphertext.data, header_len);
64
65 iov[1].flags = KRB5_CRYPTO_TYPE_DATA;
66 iov[1].data = make_data(output->data, plain_len);
67 memcpy(iov[1].data.data, input->ciphertext.data + header_len, plain_len);
68
69 /* Use empty padding since tokens don't indicate the padding length. */
70 iov[2].flags = KRB5_CRYPTO_TYPE_PADDING;
71 iov[2].data = empty_data();
72
73 iov[3].flags = KRB5_CRYPTO_TYPE_TRAILER;
74 iov[3].data = make_data(scratch + header_len, trailer_len);
75 memcpy(iov[3].data.data, input->ciphertext.data + header_len + plain_len,
76 trailer_len);
77
78 ret = ktp->decrypt(ktp, key, usage, cipher_state, iov, 4);
79 if (ret != 0)
80 zap(output->data, plain_len);
81 else
82 output->length = plain_len;
83 zapfree(scratch, header_len + trailer_len);
84 return ret;
85 }
86
87 krb5_error_code KRB5_CALLCONV
krb5_c_decrypt(krb5_context context,const krb5_keyblock * keyblock,krb5_keyusage usage,const krb5_data * cipher_state,const krb5_enc_data * input,krb5_data * output)88 krb5_c_decrypt(krb5_context context, const krb5_keyblock *keyblock,
89 krb5_keyusage usage, const krb5_data *cipher_state,
90 const krb5_enc_data *input, krb5_data *output)
91 {
92 krb5_key key;
93 krb5_error_code ret;
94
95 ret = krb5_k_create_key(context, keyblock, &key);
96 if (ret != 0)
97 return ret;
98 ret = krb5_k_decrypt(context, key, usage, cipher_state, input, output);
99 krb5_k_free_key(context, key);
100 return ret;
101 }
102