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749 | daniel-mar | 1 | unit WEID_Delphi; |
748 | daniel-mar | 2 | |
3 | (* |
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4 | * WEID<=>OID Converter for Delphi |
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5 | * (c) Webfan.de, ViaThinkSoft |
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6 | * Revision 2022-02-19 |
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7 | *) |
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8 | |||
9 | (* |
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10 | What is a WEID? |
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11 | A WEID (WEhowski IDentifier) is an alternative representation of an |
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12 | OID (Object IDentifier) defined by Till Wehowski. |
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13 | In OIDs, arcs are in decimal base 10. In WEIDs, the arcs are in base 36. |
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14 | Also, each WEID has a check digit at the end (called WeLohn Check Digit). |
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15 | |||
16 | Changes in the December 2021 definition by Daniel Marschall: |
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17 | - There are several classes of WEIDs which have different OID bases: |
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18 | "Class C" WEID: weid:EXAMPLE-3 (base .1.3.6.1.4.1.37553.8.) |
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19 | oid:1.3.6.1.4.1.37553.8.32488192274 |
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20 | "Class B" WEID: weid:pen:SX0-7PR-6 (base .1.3.6.1.4.1.) |
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21 | oid:1.3.6.1.4.1.37476.9999 |
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22 | "Class A" WEID: weid:root:2-RR-2 (base .) |
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23 | oid:2.999 |
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24 | - The namespace (weid:, weid:pen:, weid:root:) is now case insensitive. |
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25 | - Padding with '0' characters is valid (e.g. weid:000EXAMPLE-3) |
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26 | The paddings do not count into the WeLuhn check-digit. |
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27 | *) |
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28 | |||
29 | interface |
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30 | |||
31 | (* |
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32 | Translates a weid to an oid |
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33 | "weid:EXAMPLE-3" becomes "1.3.6.1.4.1.37553.8.32488192274" |
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34 | If it failed (e.g. wrong namespace, wrong checksum, etc.) then false is returned. |
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35 | If the weid ends with '?', then it will be replaced with the checksum, |
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36 | e.g. weid:EXAMPLE-? becomes weid:EXAMPLE-3 |
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37 | *) |
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38 | function WeidToOid(var weid: string): string; |
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39 | |||
40 | (* |
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41 | Converts an OID to WEID |
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42 | "1.3.6.1.4.1.37553.8.32488192274" becomes "weid:EXAMPLE-3" |
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43 | *) |
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44 | function OidToWeid(oid: string): string; |
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45 | |||
46 | implementation |
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47 | |||
48 | uses |
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49 | SysUtils; |
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50 | |||
51 | function LastCharPos(const S: string; const Chr: char): integer; |
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52 | var |
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53 | i: Integer; |
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54 | begin |
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55 | for i := length(S) downto 1 do |
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56 | begin |
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57 | if S[i] = Chr then |
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58 | begin |
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749 | daniel-mar | 59 | result := i; |
748 | daniel-mar | 60 | Exit; |
61 | end; |
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62 | end; |
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749 | daniel-mar | 63 | result := 0; |
748 | daniel-mar | 64 | Exit; |
65 | end; |
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66 | |||
67 | function base_convert_bigint(numstring: string; frombase, tobase: integer): string; |
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68 | var |
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69 | i: Integer; |
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70 | frombase_str: string; |
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71 | tobase_str: string; |
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72 | len: Integer; |
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73 | number: string; |
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74 | divide: Integer; |
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75 | newlen: Integer; |
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76 | res: string; |
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77 | begin |
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78 | frombase_str := ''; |
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79 | for i := 0 to frombase-1 do |
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80 | begin |
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81 | if i < 10 then |
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82 | frombase_str := frombase_str + IntToStr(i) |
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83 | else |
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84 | frombase_str := frombase_str + Chr(Ord('A') + (i-10)); |
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85 | end; |
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86 | |||
87 | tobase_str := ''; |
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88 | for i := 0 to tobase-1 do |
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89 | begin |
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90 | if i < 10 then |
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91 | tobase_str := tobase_str + IntToStr(i) |
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92 | else |
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93 | tobase_str := tobase_str + Chr(Ord('A') + (i-10)); |
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94 | end; |
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95 | |||
96 | len := Length(numstring); |
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749 | daniel-mar | 97 | result := ''; |
748 | daniel-mar | 98 | number := numstring; (* this is a fake "Int8" array (implemented with chars) *) |
99 | for i := 0 to len-1 do |
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100 | begin |
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101 | number[i+1] := Chr(Pos(UpCase(numstring[i+1]), frombase_str)-1); |
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102 | end; |
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103 | res := ''; |
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104 | repeat (* Loop until whole number is converted *) |
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105 | divide := 0; |
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106 | newlen := 0; |
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107 | for i := 0 to len-1 do (* Perform division manually (which is why this works with big numbers) *) |
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108 | begin |
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109 | divide := divide * frombase + Ord(number[i+1]); |
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110 | if (divide >= tobase) then |
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111 | begin |
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112 | number[newlen+1] := Chr(divide div tobase); |
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113 | Inc(newlen); |
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114 | divide := divide mod tobase; |
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115 | end |
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116 | else if newlen > 0 then |
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117 | begin |
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118 | number[newlen+1] := #0; |
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119 | Inc(newlen); |
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120 | end; |
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121 | end; |
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122 | len := newlen; |
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749 | daniel-mar | 123 | res := tobase_str[divide+1] + res; (* Divide is basically "numstring mod tobase" (i.e. the new character) *) |
748 | daniel-mar | 124 | until newlen = 0; |
749 | daniel-mar | 125 | result := res; |
748 | daniel-mar | 126 | end; |
127 | |||
128 | function weLuhnGetCheckDigit(s: string): integer; |
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129 | var |
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130 | p: integer; |
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131 | wrkstr: string; |
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132 | c: Char; |
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133 | i: Integer; |
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134 | sum: integer; |
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135 | nbdigits: Integer; |
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136 | parity: Integer; |
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137 | n: Integer; |
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138 | digit: Integer; |
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139 | begin |
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140 | (* Padding zeros don't count to the check digit (December 2021) *) |
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141 | s := '-' + s + '-'; |
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142 | while Pos('-0', s) > 0 do |
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143 | begin |
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144 | s := StringReplace(s, '-0-', #1, [rfReplaceAll]); |
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145 | s := StringReplace(s, '-0', '-', [rfReplaceAll]); |
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146 | end; |
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147 | s := StringReplace(s, #1, '-0-', [rfReplaceAll]); |
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148 | s := Copy(s, 2, Length(s)-2); |
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149 | |||
150 | (* remove separators of the WEID string *) |
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151 | wrkstr := StringReplace(s, '-', '', [rfReplaceAll]); |
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152 | |||
153 | (* Replace 'a' with '10', 'b' with '11', etc. *) |
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154 | for c := 'A' to 'Z' do |
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155 | begin |
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156 | wrkstr := StringReplace(wrkstr, c, IntToStr(Ord(c)-Ord('A')+10), [rfReplaceAll]); |
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157 | end; |
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158 | |||
749 | daniel-mar | 159 | (* At the end, wrkstr should only contain digits! Verify it! *) |
748 | daniel-mar | 160 | for i := 1 to Length(wrkstr) do |
161 | begin |
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162 | if not (wrkstr[i] in ['0'..'9']) then |
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163 | begin |
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749 | daniel-mar | 164 | result := -1; |
748 | daniel-mar | 165 | exit; |
166 | end; |
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167 | end; |
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168 | |||
169 | (* Now do the standard Luhn algorithm *) |
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170 | nbdigits := Length(wrkstr); |
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171 | parity := nbdigits and 1; (* mod 2 *) |
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172 | sum := 0; |
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173 | for n := nbdigits-1 downto 0 do |
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174 | begin |
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175 | digit := StrToInt(wrkstr[n+1]); |
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176 | if (n and 1) <> parity then digit := digit * 2; |
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177 | if digit > 9 then digit := digit - 9; |
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178 | sum := sum + digit; |
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179 | end; |
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180 | |||
181 | if sum mod 10 = 0 then |
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749 | daniel-mar | 182 | result := 0 |
748 | daniel-mar | 183 | else |
749 | daniel-mar | 184 | result := 10 - (sum mod 10); |
748 | daniel-mar | 185 | end; |
186 | |||
187 | function WeidToOid(var weid: string): string; |
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188 | var |
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189 | base: string; |
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190 | namespace: string; |
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191 | p: integer; |
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192 | rest: string; |
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193 | actual_checksum: string; |
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194 | expected_checksum: integer; |
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195 | complete: string; |
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196 | oidstr: string; |
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197 | arc: string; |
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198 | begin |
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199 | p := LastCharPos(weid,':'); |
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200 | namespace := Copy(weid, 1, p); |
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201 | rest := Copy(weid, p+1, Length(weid)-p); |
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202 | |||
203 | namespace := LowerCase(namespace); (* namespace is case insensitive *) |
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204 | if namespace = 'weid:' then |
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205 | begin |
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206 | (* Class C *) |
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207 | base := '1-3-6-1-4-1-SZ5-8'; |
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208 | end |
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209 | else if namespace = 'weid:pen:' then |
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210 | begin |
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211 | (* Class B *) |
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212 | base := '1-3-6-1-4-1'; |
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213 | end |
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214 | else if namespace = 'weid:root:' then |
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215 | begin |
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216 | (* Class A *) |
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217 | base := ''; |
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218 | end |
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219 | else |
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220 | begin |
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221 | (* Wrong namespace *) |
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749 | daniel-mar | 222 | result := ''; |
748 | daniel-mar | 223 | Exit; |
224 | end; |
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225 | |||
226 | weid := rest; |
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227 | |||
228 | if base <> '' then |
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229 | complete := base + '-' + weid |
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230 | else |
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231 | complete := weid; |
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232 | p := LastCharPos(complete, '-'); |
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233 | actual_checksum := Copy(complete, p+1, 1); |
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234 | complete := Copy(complete, 1, p-1); |
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235 | expected_checksum := weLuhnGetCheckDigit(complete); |
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236 | if (actual_checksum <> '?') then |
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237 | begin |
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238 | if actual_checksum <> IntToStr(expected_checksum) then |
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239 | begin |
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749 | daniel-mar | 240 | result := ''; (* wrong checksum *) |
748 | daniel-mar | 241 | Exit; |
242 | end; |
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243 | end |
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244 | else |
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245 | begin |
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246 | (* If checksum is '?', it will be replaced by the actual checksum, *) |
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247 | (* e.g. weid:EXAMPLE-? becomes weid:EXAMPLE-3 *) |
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248 | weid := StringReplace(weid, '?', IntToStr(expected_checksum), [rfReplaceAll]); |
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249 | end; |
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250 | |||
251 | oidstr := ''; |
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252 | while true do |
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253 | begin |
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254 | p := Pos('-', complete); |
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255 | if p = 0 then p := Length(complete)+1; |
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256 | arc := Copy(complete, 1, p-1); |
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257 | Delete(complete, 1, p); |
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258 | oidstr := oidstr + base_convert_bigint(arc, 36, 10) + '.'; |
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259 | if complete = '' then break; |
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260 | end; |
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261 | oidstr := Copy(oidstr, 1, Length(oidstr)-1); |
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262 | |||
263 | weid := namespace + weid; (* add namespace again *) |
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264 | |||
749 | daniel-mar | 265 | result := oidstr; |
748 | daniel-mar | 266 | end; |
267 | |||
268 | function OidToWeid(oid: string): string; |
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269 | var |
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270 | is_class_a: boolean; |
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271 | is_class_b: boolean; |
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272 | is_class_c: boolean; |
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273 | weidstr: string; |
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274 | checksum: string; |
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275 | namespace: string; |
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276 | p: Integer; |
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277 | cd: Integer; |
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278 | res: string; |
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279 | begin |
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280 | if Copy(oid,1,1) = '.' then |
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281 | Delete(oid,1,1); (* remove leading dot *) |
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282 | |||
283 | if oid <> '' then |
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284 | begin |
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285 | weidstr := ''; |
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286 | while true do |
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287 | begin |
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288 | p := Pos('.', oid); |
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289 | if p = 1 then |
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290 | begin |
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291 | Delete(oid, 1, 1); |
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292 | end |
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293 | else if p > 0 then |
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294 | begin |
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295 | weidstr := weidstr + base_convert_bigint(Copy(oid, 1, p-1),10,36) + '-'; |
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296 | Delete(oid, 1, p); |
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297 | end |
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298 | else |
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299 | begin |
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300 | weidstr := weidstr + base_convert_bigint(oid,10,36) + '-'; |
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301 | break; |
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302 | end; |
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303 | end; |
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304 | weidstr := Copy(weidstr, 1, Length(weidstr)-1); |
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305 | end |
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306 | else |
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307 | begin |
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308 | weidstr := ''; |
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309 | end; |
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310 | |||
311 | is_class_c := (Pos('1-3-6-1-4-1-SZ5-8-', weidstr) = 1) or |
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312 | (weidstr = '1-3-6-1-4-1-SZ5-8'); |
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313 | is_class_b := ((Pos('1-3-6-1-4-1-', weidstr) = 1) or |
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314 | (weidstr = '1-3-6-1-4-1')) |
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315 | and not is_class_c; |
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316 | is_class_a := not is_class_b and not is_class_c; |
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317 | |||
318 | cd := weLuhnGetCheckDigit(weidstr); |
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319 | if cd < 0 then |
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320 | begin |
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749 | daniel-mar | 321 | result := weidstr; |
748 | daniel-mar | 322 | exit; |
323 | end; |
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324 | checksum := IntToStr(cd); |
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325 | |||
326 | if is_class_c then |
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327 | begin |
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328 | Delete(weidstr, 1, Length('1-3-6-1-4-1-SZ5-8-')); |
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329 | namespace := 'weid:'; |
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330 | end |
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331 | else if is_class_b then |
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332 | begin |
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333 | Delete(weidstr, 1, Length('1-3-6-1-4-1-')); |
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334 | namespace := 'weid:pen:'; |
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335 | end |
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336 | else if is_class_a then |
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337 | begin |
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338 | (* weidstr stays *) |
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339 | namespace := 'weid:root:'; |
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340 | end |
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341 | else |
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342 | begin |
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343 | (* should not happen *) |
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749 | daniel-mar | 344 | result := ''; |
748 | daniel-mar | 345 | Exit; |
346 | end; |
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347 | |||
348 | res := namespace; |
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349 | if weidstr = '' then |
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350 | res := res + checksum |
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351 | else |
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352 | res := res + weidstr + '-' + checksum; |
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749 | daniel-mar | 353 | result := res; |
748 | daniel-mar | 354 | end; |
355 | |||
356 | end. |