2010年计算机二级VB辅导：VBBase64编码类代码

Option Explicit

Public key(1 To 3) As Long

Private Const base64 = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/"

Public Sub GenKey()Sub GenKey()

Dim d As Long， phi As Long， e As Long

Dim m As Long， x As Long， q As Long

Dim p As Long

Randomize

On Error GoTo top

top:

p = Rnd * 1000 1

If IsPrime(p) = False Then GoTo top

Sel_q:

q = Rnd * 1000 1

If IsPrime(q) = False Then GoTo Sel_q

n = p * q 1

phi = (p - 1) * (q - 1) 1

d = Rnd * n 1

If d = 0 Or n = 0 Or d = 1 Then GoTo top

e = Euler(phi， d)

If e = 0 Or e = 1 Then GoTo top

x = Mult(255， e， n)

If Not Mult(x， d， n) = 255 Then

DoEvents

GoTo top

ElseIf Mult(x， d， n) = 255 Then

key(1) = e

key(2) = d

key(3) = n

End If

End Sub

Public Function Euler()Function Euler(ByVal a As Long， ByVal b As Long) As Long

On Error GoTo error2

r1 = a: r = b

p1 = 0: p = 1

q1 = 2: q = 0

n = -1

Do Until r = 0

r2 = r1: r1 = r

p2 = p1: p1 = p

q2 = q1: q1 = q

n = n + 1

r = r2 Mod r1

c = r2 r1

p = (c * p1) + p2

q = (c * q1) + q2

Loop

s = (b * p1) - (a * q1)

If s 0 Then

x = p1

Else

x = (0 - p1) + a

End If

Euler = x

Exit Function

error2:

Euler = 0

End Function

Public Function Mult()Function Mult(ByVal x As Long， ByVal p As Long， ByVal m As Long) As Long

y = 1

On Error GoTo error1

Do While p 0

Do While (p / 2) = (p 2)

x = (x * x) Mod m

p = p / 2

Loop

y = (x * y) Mod m

p = p - 1

Loop

Mult = y

Exit Function

error1:

y = 0

End Function