I am looking for some feedback on the security of an encryption method I am working on. Overall, what I want to know is, with only the complied code and the output text, how easy would the method be to crack. I also appreishate any feedback as to how to improve the code.

Below is the code which I am using to generate the encryption table. This code is run every 1 to 5 characters, determined, semi-randomly, by the password. Each passVal is used for only one of these sets, after which the code is changed, using the default psuedo-random number generator.

VB Code:
  1. Private Sub GenerateKey(passVal)

  2.     Dim X&, Y&, Repeat As Boolean

  3.  
  4.     Rnd -1

  5.     Randomize passVal

  6.     

  7.     For X = 0 To 255

  8.         EncryptionOutput(X) = ""

  9.     Next X

  10.     For X = 0 To 15

  11.         EncryptionOutput(X) = String(17, Chr(1)) & Chr(X)

  12.     Next X

  13.     For X = 16 To 255

  14.         Do

  15.             Repeat = False

  16.             EncryptionOutput(X) = ""

  17.             For Y = 1 To 18

  18.                 EncryptionOutput(X) = EncryptionOutput(X) & Chr(Int((255 - 32 + 1) * Rnd + 32))

  19.             Next Y

  20.             For Y = 0 To 255

  21.                 If Y <> X Then

  22.                     If EncryptionOutput(X) = EncryptionOutput(Y) Then

  23.                         Repeat = True

  24.                         Exit For

  25.                     End If

  26.                     If Len(EncryptionOutput(Y)) = 0 Then

  27.                         Exit For

  28.                     End If

  29.                 End If

  30.             Next Y

  31.         Loop While Repeat

  32.     Next X

  33. End Sub

The passVal sent to the routine is gnerated with the code:
VB Code:
  1. (4294836225# - 0 + 1) * Rnd
and the number of characters to go without changing the passVal is:
VB Code:
  1. CLng(5 * Rnd + 1)
.


An example code generated is:
_|ýexA†^'ÒmqÊígºc

¾Z/Iwœvå*7ORnï*-4Q¾Z/Iwœvå*7ORnï*-4Q

L°k;tO£Ê™ÃXldD#?ê®L°k;tO£Ê™ÃXldD#?ê®L°k;tO£Ê™ÃXldD#?ê®

K3ŽTÕ]U‡æ$k€ˆ4öcáK3ŽTÕ]U‡æ$k€ˆ4öcáK3ŽTÕ]U‡æ$k€ˆ4öcá¸â°Uæ9«„2\;_ÛŽY¾e5

N8$¥ÐD@.@-Î|¢›@,¶N8$¥ÐD@.@-Î|¢›@,¶N8$¥ÐD@.@-Î|¢›@,¶N8$¥ÐD@.@-Î|¢›@,¶nà·AAgÿiƒLk*Я×%o÷

LRàÇæ’MrpnEdc‘þBÿðLRàÇæ’MrpnEdc‘þBÿðLRàÇæ’MrpnEdc‘þBÿðgKúqIK}ï0'¬t� �a{©’ÂgKúqIK}ï0'¬tÄa{©’ÂgKúqIK}ï0'¬tÄa{©’Â

'bëÔ7¸PÎËNn„ɉ;€Q'bëÔ7¸PÎËNn„ɉ;€Q'bëÔ7¸PÎËNn„ɉ;€Q'bëÔ7 ¸PÎËNn„ɉ;€QüQÝæJ„àþ½³M_3þ ÍüQÝæJ„àþ½³M_3þ ÍU©LTð䨯(Ö\ŽUL}u×ú

U©LTð䨯(Ö\ŽUL}u×úU©LTð䨯(Ö\ŽUL}u×úU©LTð䨯(Ö\ŽUL}u×ú²Íÿµ ÒVÊ-g!Ä«€ ڲ͏ÿµ ÒVÊ-g!Ä«€ ڲ͏ÿµ ÒVÊ-g!Ä«€ Ú0Åéè°*¸„ŸrH&ÛÒ†Ð+ì0Åéè°*¸„ŸrH&ÛÒ†Ð+ì

wwC‡í颢®ÈXC|C4ÁÁŽwwC‡í颢®ÈXC|C4ÁÁŽwwC‡í颢®ÈXC|C4ÁÁŽwwC‡íé¢� �®ÈXC|C4ÁÁŽ¦#ño!þ?ž? Å&R:óEÛ¦#ño!þ?ž? Å&R:óEÛ¦#ño!þ?ž? Å&R:óEÛ¤t}'GRiJ_{‘Ä´‘Êž³_¤t}'GRiJ_{‘Ä´‘Êž³_

ÃþŒ:0-TWËÿ¯ªE”;XZ’ÃþŒ:0-TWËÿ¯ªE”;XZ’ÃþŒ:0-TWËÿ¯ªE”;XZ’ÃþŒ:0-TWËÿ¯ªE”;XZ’ÃþŒ:0-TWËÿ¯ªE”;XZ’›pèl*O˜*YÞ6I¦Ñ¡4<Ä›pèl*O˜*YÞ6I¦Ñ¡4<Ä›pèl*O˜*YÞ6I¦Ñ¡4<� �›pèl*O˜*YÞ6I¦Ñ¡4<Ä›pèl*O˜*YÞ6I¦Ñ¡4<Ä

which was generated from the input of:
0
00
000
0000
00000
000000
0000000
00000000
000000000
0000000000

Thanks in advance for any feedback or suggested improvements.