|
|
 |
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In the remainder of this section, we present the specific functions used in DES.
The initial permutation IP is as follows:
| IP
|
| 58
| 50
| 42
| 34
| 26
| 18
| 10
| 2
|
| 60
| 52
| 44
| 36
| 28
| 20
| 12
| 4
|
| 62
| 54
| 46
| 38
| 30
| 22
| 14
| 6
|
| 64
| 56
| 48
| 40
| 32
| 24
| 16
| 8
|
| 57
| 49
| 41
| 33
| 25
| 17
| 9
| 1
|
| 59
| 51
| 43
| 35
| 27
| 19
| 11
| 3
|
| 61
| 53
| 45
| 37
| 29
| 21
| 13
| 5
|
| 63
| 55
| 47
| 39
| 31
| 23
| 15
| 7
|
This means that the 58th bit of x is the first bit of IP(x); the 50th bit of x is the second bit of IP(x), etc.
The inverse permutation IP-1 is:
| IP-1
|
| 40
| 8
| 48
| 16
| 56
| 24
| 64
| 32
|
| 39
| 7
| 47
| 15
| 55
| 23
| 63
| 31
|
| 38
| 6
| 46
| 14
| 54
| 22
| 62
| 30
|
| 37
| 5
| 45
| 13
| 53
| 21
| 61
| 29
|
| 36
| 4
| 44
| 12
| 52
| 20
| 60
| 28
|
| 35
| 3
| 43
| 11
| 51
| 19
| 59
| 27
|
| 34
| 2
| 42
| 10
| 50
| 18
| 58
| 26
|
| 33
| 1
| 41
| 9
| 49
| 17
| 57
| 25
|
The expansion function E is specified by the following table:
| E bit-selection table
|
| 32
| 1
| 2
| 3
| 4
| 5
|
| 4
| 5
| 6
| 7
| 8
| 9
|
| 8
| 9
| 10
| 11
| 12
| 13
|
| 12
| 13
| 14
| 15
| 16
| 17
|
| 16
| 17
| 18
| 19
| 20
| 21
|
| 20
| 21
| 22
| 23
| 24
| 25
|
| 24
| 25
| 26
| 27
| 28
| 29
|
| 28
| 29
| 30
| 31
| 32
| 1
|
|
