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Password Scrambling Algorithm#

The pserver authentication protocol, as described in Connection and Authentication, trivially encodes the passwords. This is only to prevent inadvertent compromise; it provides no protection against even a relatively unsophisticated attacker. For comparison, HTTP Basic Authentication (as described in RFC2068) uses BASE64 for a similar purpose. CVS uses its own algorithm, described here.

The scrambled password starts with A, which serves to identify the scrambling algorithm in use. After that follows a single octet for each character in the password, according to a fixed encoding. The values are shown here, with the encoded values in decimal. Control characters, space, and characters outside the invariant ISO 646 character set are not shown; such characters are not recommended for use in passwords. There is a long discussion of character set issues in Protocol Notes.

IN OUT
DEC HEX CHAR → DEC HEX CHAR
33 21 ! → 120 78 x
34 22 " → 53 35 5
37 25 % → 109 6D m
38 26 & → 72 48 H
39 27 ' → 108 6C l
40 28 ( → 70 46 F
41 29 ) → 64 40 @
42 2A * → 76 4C L
43 2B + → 67 43 C
44 2C , → 116 74 t
45 2D - → 74 4A J
46 2E . → 68 44 D
47 2F / → 87 57 W
48 30 0 → 111 6F o
49 31 1 → 52 34 4
50 32 2 → 75 4B K
51 33 3 → 119 77 w
52 34 4 → 49 31 1
53 35 5 → 34 22 "
54 36 6 → 82 52 R
55 37 7 → 81 51 Q
56 38 8 → 95 5F _
57 39 9 → 65 41 A
58 3A : → 112 70 p
59 3B ; → 86 56 V
60 3C < → 118 76 v
61 3D = → 110 6E n
62 3E > → 122 7A z
63 3F ? → 105 69 i
65 41 A → 57 39 9
66 42 B → 83 53 S
67 43 C → 43 2B +
68 44 D → 46 2E .
69 45 E → 102 66 f
70 46 F → 40 28 (
71 47 G → 89 59 Y
72 48 H → 38 26 &
73 49 I → 103 67 g
74 4A J → 45 2D -
75 4B K → 50 32 2
76 4C L → 42 2A *
77 4D M → 123 7B {
78 4E N → 91 5B [
79 4F O → 35 23 #
80 50 P → 125 7D }
81 51 Q → 55 37 7
82 52 R → 54 36 6
83 53 S → 66 42 B
84 54 T → 124 7C
85 55 U → 126 7E ~
86 56 V → 59 3B ;
87 57 W → 47 2F /
88 58 X → 92 5C \
89 59 Y → 71 47 G
90 5A Z → 115 73 s
95 5F _ → 56 38 8
97 61 a → 121 79 y
98 62 b → 117 75 u
99 63 c → 104 68 h
100 64 d → 101 65 e
101 65 e → 100 64 d
102 66 f → 69 45 E
103 67 g → 73 49 I
104 68 h → 99 63 c
105 69 i → 63 3F ?
106 6A j → 94 5E ^
107 6B k → 93 5D ]
108 6C l → 39 27 '
109 6D m → 37 25 %
110 6E n → 61 3D =
111 6F o → 48 30 0
112 70 p → 58 3A :
113 71 q → 113 71 q
114 72 r → 32 20
115 73 s → 90 5A Z
116 74 t → 44 2C ,
117 75 u → 98 62 b
118 76 v → 60 3C <
119 77 w → 51 33 3
120 78 x → 33 21 !
121 79 y → 97 61 a
122 7A z → 62 3E >