| … | |
… | |
| 117 | |
117 | |
| 118 | ./configure --enable-hmac-length=4 --enable-rand-length=0 |
118 | ./configure --enable-hmac-length=4 --enable-rand-length=0 |
| 119 | |
119 | |
| 120 | Minimize the header overhead of VPN packets (the above will result in |
120 | Minimize the header overhead of VPN packets (the above will result in |
| 121 | only 4 bytes of overhead over the raw ethernet frame). This is a insecure |
121 | only 4 bytes of overhead over the raw ethernet frame). This is a insecure |
| 122 | configuration because a HMAC length of 4 makes collision attacks based on |
122 | configuration because a HMAC length of 4 makes collision attacks almost |
| 123 | the birthday paradox pretty easy. |
123 | trivial. |
| 124 | |
124 | |
| 125 | =head2 MINIMIZE CPU TIME REQUIRED |
125 | =head2 MINIMIZE CPU TIME REQUIRED |
| 126 | |
126 | |
| 127 | ./configure --enable-cipher=bf --enable-digest=md4 |
127 | ./configure --enable-cipher=bf --enable-digest=md4 |
| 128 | |
128 | |
| … | |
… | |
| 130 | gvpe. MD4 has been broken and is quite insecure, though, so using another |
130 | gvpe. MD4 has been broken and is quite insecure, though, so using another |
| 131 | digest algorithm is recommended. |
131 | digest algorithm is recommended. |
| 132 | |
132 | |
| 133 | =head2 MAXIMIZE SECURITY |
133 | =head2 MAXIMIZE SECURITY |
| 134 | |
134 | |
| 135 | ./configure --enable-hmac-length=16 --enable-rand-length=16 --enable-digest=sha384 |
135 | ./configure --enable-hmac-length=16 --enable-rand-length=12 --enable-digest=ripemd610 |
| 136 | |
136 | |
| 137 | This uses a 16 byte HMAC checksum to authenticate packets (I guess 8-12 |
137 | This uses a 16 byte HMAC checksum to authenticate packets (I guess 8-12 |
| 138 | would also be pretty secure ;) and will additionally prefix each packet |
138 | would also be pretty secure ;) and will additionally prefix each packet |
| 139 | with 16 bytes of random data. |
139 | with 12 bytes of random data. |
| 140 | |
140 | |
| 141 | In general, remember that AES-128 seems to be as secure but faster than |
141 | In general, remember that AES-128 seems to be as secure but faster than |
| 142 | AES-192 or AES-256, more randomness helps against sniffing and a longer |
142 | AES-192 or AES-256, more randomness helps against sniffing and a longer |
| 143 | HMAC helps against spoofing. MD4 is a fast digest, SHA1, RIPEMD160, SHA256 |
143 | HMAC helps against spoofing. MD4 is a fast digest, SHA1, RIPEMD160, SHA256 |
| 144 | are consecutively better, and Blowfish is a fast cipher (and also quite |
144 | are consecutively better, and Blowfish is a fast cipher (and also quite |
