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1 | /* |
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2 | * Blowfish mechanism for udp tunnel |
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3 | * |
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4 | * mechanisms: blowfish-cbc, blowfish-cbcmac |
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5 | * arguments: key size in bits (must be multiple of 8) |
6 | * |
7 | * key values: 8 byte random IV and n byte random key |
8 | * |
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9 | * restrictions: plaintext length must be multiple of block size (8 bytes) |
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10 | * encoding: do CBC encryption overwriting message |
11 | * encoding for MAC: do CBC and prepend last ciphertext block |
12 | */ |
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13 | /* |
14 | * Copyright (C) 2000 Ian Jackson |
15 | * |
16 | * This is free software; you can redistribute it and/or modify it |
17 | * under the terms of the GNU General Public License as published by |
18 | * the Free Software Foundation; either version 2 of the License, or |
19 | * (at your option) any later version. |
20 | * |
21 | * This program is distributed in the hope that it will be useful, but |
22 | * WITHOUT ANY WARRANTY; without even the implied warranty of |
23 | * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU |
24 | * General Public License for more details. |
25 | * |
26 | * You should have received a copy of the GNU General Public License |
27 | * along with userv-utils; if not, write to the Free Software |
28 | * Foundation, 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA. |
29 | */ |
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30 | |
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31 | #include "forwarder.h" |
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32 | #include "blowfish.h" |
33 | |
34 | struct mechdata { |
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35 | unsigned char iv[BLOWFISH_BLOCKBYTES]; |
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36 | struct blowfish_cbc_state cbc; |
37 | }; |
38 | |
39 | static void mds_blowfish(struct mechdata **md_r) { |
40 | struct mechdata *md; |
41 | unsigned long keysize; |
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42 | unsigned char key[BLOWFISH_MAXKEYBYTES]; |
43 | |
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44 | XMALLOC(md); |
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45 | |
46 | keysize= getarg_ulong(); |
47 | arg_assert(!(keysize & 7)); |
48 | keysize >>= 3; |
49 | arg_assert(keysize > 0 && keysize <= BLOWFISH_MAXKEYBYTES); |
50 | |
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51 | random_key(md->iv,sizeof(md->iv)); |
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52 | random_key(key,keysize); |
53 | |
54 | blowfish_loadkey(&md->cbc.ek, key,keysize); |
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55 | *md_r= md; |
56 | } |
57 | |
58 | static void mes_blowfish(struct mechdata **md_r, int *maxprefix_io, int *maxsuffix_io) { |
59 | mds_blowfish(md_r); |
60 | } |
61 | |
62 | static void mds_bfmac(struct mechdata **md_r) { |
63 | mds_blowfish(md_r); |
64 | } |
65 | |
66 | static void mes_bfmac(struct mechdata **md_r, int *maxprefix_io, int *maxsuffix_io) { |
67 | mds_blowfish(md_r); |
68 | *maxprefix_io += BLOWFISH_BLOCKBYTES; |
69 | } |
70 | |
71 | #define MSGSIZE_OUT \ |
72 | msgsize= buf->size; \ |
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73 | arg_assert(!(msgsize & (BLOWFISH_BLOCKBYTES-1))); |
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74 | |
75 | #define MSGSIZE_IN \ |
76 | msgsize= buf->size; \ |
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77 | if (msgsize & (BLOWFISH_BLOCKBYTES-1)) return "not multiple of block size" |
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78 | |
79 | #define FOREACH_BLOCK(func,inptr,outptr) \ |
80 | { \ |
81 | unsigned char *ptr; \ |
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82 | blowfish_cbc_setiv(&md->cbc, md->iv); \ |
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83 | for (ptr= buf->start; \ |
84 | ptr < buf->start + msgsize; \ |
85 | ptr += BLOWFISH_BLOCKBYTES) { \ |
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86 | func(&md->cbc,inptr,outptr); \ |
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87 | } \ |
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88 | } |
89 | |
90 | static void menc_blowfish(struct mechdata *md, struct buffer *buf) { |
91 | unsigned long msgsize; |
92 | MSGSIZE_OUT; |
93 | FOREACH_BLOCK(blowfish_cbc_encrypt,ptr,ptr); |
94 | } |
95 | |
96 | static const char *mdec_blowfish(struct mechdata *md, struct buffer *buf) { |
97 | unsigned long msgsize; |
98 | MSGSIZE_IN; |
99 | FOREACH_BLOCK(blowfish_cbc_decrypt,ptr,ptr); |
100 | return 0; |
101 | } |
102 | |
103 | static void menc_bfmac(struct mechdata *md, struct buffer *buf) { |
104 | unsigned long msgsize; |
105 | unsigned char outblock[BLOWFISH_BLOCKBYTES]; |
106 | |
107 | MSGSIZE_OUT; |
108 | FOREACH_BLOCK(blowfish_cbc_encrypt,ptr,outblock); |
109 | memcpy(buf_prepend(buf,BLOWFISH_BLOCKBYTES), outblock, BLOWFISH_BLOCKBYTES); |
110 | } |
111 | |
112 | static const char *mdec_bfmac(struct mechdata *md, struct buffer *buf) { |
113 | unsigned long msgsize; |
114 | unsigned char outblock[BLOWFISH_BLOCKBYTES]; |
115 | unsigned char *checkblock; |
116 | |
117 | BUF_UNPREPEND(checkblock,buf,BLOWFISH_BLOCKBYTES); |
118 | MSGSIZE_IN; |
119 | FOREACH_BLOCK(blowfish_cbc_encrypt,ptr,outblock); |
120 | if (memcmp(checkblock,outblock,BLOWFISH_BLOCKBYTES)) return "verify failed"; |
121 | return 0; |
122 | } |
123 | |
124 | const struct mechanism mechlist_blowfish[]= { |
125 | STANDARD_MECHANISM("blowfish-cbcmac", bfmac) |
126 | STANDARD_MECHANISM("blowfish-cbc", blowfish) |
127 | { 0 } |
128 | }; |