This time i've included all info through comments in the code.
CODE
Private Sub Command1_Click()
Dim a As String
Dim B As String
a$ = Text1.text 'Text to encrypt
B$ = Text2.text 'Password
'encrypting text with a return to text1
Text1.text = Encrypt(a$, B$, True) 'true = Encrypt
End Sub
Explanation : Command1 is a Command Button used to Encrypt text
CODE
Private Sub Command2_Click()
Dim a As String
Dim B As String
a$ = Text1.text 'Text to decrypt
B$ = Text2.text 'Password
'decrypting text with a return to text1
Text1.text = Encrypt(a$, B$, False) 'false = decrypt
End Sub
Explanation : Command2 is a command button to decrypt.
==================Encrypt Function ===================
CODE
Function Encrypt(text As String, pw As String, type_of As Boolean) As String
'Declaring variables
Dim x As Integer
Dim i As Integer
Dim a As Integer
Dim text_chr As String
Dim text_asc As Integer
Dim pw_chr As String
Dim pw_asc As Integer
Dim fin As String
Dim fin_chr As String
Dim fin_asc As Integer
'if type_of = true then Encrypt
'if type_of = False then Decrypt
Call percent(Picture1, 0) 'clear percent
'making sure there is text to encrypt and a password
'to go with it
If Len(text$) = 0 Then Exit Function
If Len(pw$) = 0 Then Exit Function
x% = 1
'the X variable is the loop that goes through the password
'characters individually through the encrpytion processes
'X = 1 to set the loop at the first character
For i% = 1 To Len(text$) 'start of encrpyt loop
'taking out characters from text to encrypt
'the single character
text_chr$ = Mid(text$, i, 1)
'changing the character to its ASCII value to
'easily change the character for encrypting
text_asc% = Asc(text_chr$)
'doing the same process with the password
'using the X variable
pw_chr$ = Mid(pw$, x, 1)
pw_asc% = Asc(pw_chr$)
'adding up variable to continue loop through different
'characters within the password
x% = x% + 1
If x% > Len(pw$) Then x% = 1 'restarting password loop
'Case to check if the user is Encrypting or Decrypting the text
Select Case type_of
Case True: 'Encrypting
'adding the characters of both string and password
fin_asc% = text_asc% + pw_asc%
'making sure the final_asc will equal a valid ASCII character
If fin_asc% > 255 Then
'Character was an invalid character so we modify it
'to equal a valid character
a% = fin_asc% - 255
fin_chr$ = Chr$(a%)
Else
'character was valid;D
fin_chr$ = Chr$(fin_asc%)
End If
Case False: 'Decrypting
'here we subtract the characters...does the opposite of
'what encrypting does to put it back in its
'original state, which is why it's called Decrypting
fin_asc% = text_asc% - pw_asc% 'subtracting character values
If fin_asc% < 1 Then 'checking for invalid character
'invalid character..fixing problem =)
a% = fin_asc% + 255
fin_chr$ = Chr$(a%)
Else
'it was all good.
fin_chr$ = Chr$(fin_asc%)
End If
End Select 'End of case
'adding the final encrypted character to a string
'to be later shown in its final state at the end
fin$ = fin$ & fin_chr$
'thought i'd be mr. fancy pants by adding a little
'percentage bar =)
Call percent(Picture1, CInt((i / Len(text) * 100)))
Next 'continuing loop =)
'finalizing function to equal the final encrypted string
Encrypt$ = fin$
DoEvents
Call percent(Picture1, 0)
End Function
NOTE : For details, carefully go through the Comments.