Codice:
Option Explicit
Private m_lOnBits(30)
Private m_l2Power(30)
Private K(63)
Private Const BITS_TO_A_BYTE = 8
Private Const BYTES_TO_A_WORD = 4
Private Const BITS_TO_A_WORD = 32
Public Sub Main()
	m_lOnBits(0) = CLng(1)
	m_lOnBits(1) = CLng(3)
	m_lOnBits(2) = CLng(7)
	m_lOnBits(3) = CLng(15)
	m_lOnBits(4) = CLng(31)
	m_lOnBits(5) = CLng(63)
	m_lOnBits(6) = CLng(127)
	m_lOnBits(7) = CLng(255)
	m_lOnBits(8) = CLng(511)
	m_lOnBits(9) = CLng(1023)
	m_lOnBits(10) = CLng(2047)
	m_lOnBits(11) = CLng(4095)
	m_lOnBits(12) = CLng(8191)
	m_lOnBits(13) = CLng(16383)
	m_lOnBits(14) = CLng(32767)
	m_lOnBits(15) = CLng(65535)
	m_lOnBits(16) = CLng(131071)
	m_lOnBits(17) = CLng(262143)
	m_lOnBits(18) = CLng(524287)
	m_lOnBits(19) = CLng(1048575)
	m_lOnBits(20) = CLng(2097151)
	m_lOnBits(21) = CLng(4194303)
	m_lOnBits(22) = CLng(8388607)
	m_lOnBits(23) = CLng(16777215)
	m_lOnBits(24) = CLng(33554431)
	m_lOnBits(25) = CLng(67108863)
	m_lOnBits(26) = CLng(134217727)
	m_lOnBits(27) = CLng(268435455)
	m_lOnBits(28) = CLng(536870911)
	m_lOnBits(29) = CLng(1073741823)
	m_lOnBits(30) = CLng(2147483647)
 
	m_l2Power(0) = CLng(1)
	m_l2Power(1) = CLng(2)
	m_l2Power(2) = CLng(4)
	m_l2Power(3) = CLng(8)
	m_l2Power(4) = CLng(16)
	m_l2Power(5) = CLng(32)
	m_l2Power(6) = CLng(64)
	m_l2Power(7) = CLng(128)
	m_l2Power(8) = CLng(256)
	m_l2Power(9) = CLng(512)
	m_l2Power(10) = CLng(1024)
	m_l2Power(11) = CLng(2048)
	m_l2Power(12) = CLng(4096)
	m_l2Power(13) = CLng(8192)
	m_l2Power(14) = CLng(16384)
	m_l2Power(15) = CLng(32768)
	m_l2Power(16) = CLng(65536)
	m_l2Power(17) = CLng(131072)
	m_l2Power(18) = CLng(262144)
	m_l2Power(19) = CLng(524288)
	m_l2Power(20) = CLng(1048576)
	m_l2Power(21) = CLng(2097152)
	m_l2Power(22) = CLng(4194304)
	m_l2Power(23) = CLng(8388608)
	m_l2Power(24) = CLng(16777216)
	m_l2Power(25) = CLng(33554432)
	m_l2Power(26) = CLng(67108864)
	m_l2Power(27) = CLng(134217728)
	m_l2Power(28) = CLng(268435456)
	m_l2Power(29) = CLng(536870912)
	m_l2Power(30) = CLng(1073741824)
 
	K(0) = &H428A2F98
	K(1) = &H71374491
	K(2) = &HB5C0FBCF
	K(3) = &HE9B5DBA5
	K(4) = &H3956C25B
	K(5) = &H59F111F1
	K(6) = &H923F82A4
	K(7) = &HAB1C5ED5
	K(8) = &HD807AA98
	K(9) = &H12835B01
	K(10) = &H243185BE
	K(11) = &H550C7DC3
	K(12) = &H72BE5D74
	K(13) = &H80DEB1FE
	K(14) = &H9BDC06A7
	K(15) = &HC19BF174
	K(16) = &HE49B69C1
	K(17) = &HEFBE4786
	K(18) = &HFC19DC6
	K(19) = &H240CA1CC
	K(20) = &H2DE92C6F
	K(21) = &H4A7484AA
	K(22) = &H5CB0A9DC
	K(23) = &H76F988DA
	K(24) = &H983E5152
	K(25) = &HA831C66D
	K(26) = &HB00327C8
	K(27) = &HBF597FC7
	K(28) = &HC6E00BF3
	K(29) = &HD5A79147
	K(30) = &H6CA6351
	K(31) = &H14292967
	K(32) = &H27B70A85
	K(33) = &H2E1B2138
	K(34) = &H4D2C6DFC
	K(35) = &H53380D13
	K(36) = &H650A7354
	K(37) = &H766A0ABB
	K(38) = &H81C2C92E
	K(39) = &H92722C85
	K(40) = &HA2BFE8A1
	K(41) = &HA81A664B
	K(42) = &HC24B8B70
	K(43) = &HC76C51A3
	K(44) = &HD192E819
	K(45) = &HD6990624
	K(46) = &HF40E3585
	K(47) = &H106AA070
	K(48) = &H19A4C116
	K(49) = &H1E376C08
	K(50) = &H2748774C
	K(51) = &H34B0BCB5
	K(52) = &H391C0CB3
	K(53) = &H4ED8AA4A
	K(54) = &H5B9CCA4F
	K(55) = &H682E6FF3
	K(56) = &H748F82EE
	K(57) = &H78A5636F
	K(58) = &H84C87814
	K(59) = &H8CC70208
	K(60) = &H90BEFFFA
	K(61) = &HA4506CEB
	K(62) = &HBEF9A3F7
	K(63) = &HC67178F2
	MsgBox SHA256("abc")
 
End Sub
Private Function LShift(lValue, iShiftBits)
	If iShiftBits = 0 Then
		LShift = lValue
		Exit Function
	ElseIf iShiftBits = 31 Then
		If lValue And 1 Then
			LShift = &H80000000
		Else
			LShift = 0
		End If
		Exit Function
	ElseIf iShiftBits < 0 Or iShiftBits > 31 Then
		Err.Raise 6
	End If
 
	If (lValue And m_l2Power(31 - iShiftBits)) Then
		LShift = ((lValue And m_lOnBits(31 - (iShiftBits + 1))) * m_l2Power(iShiftBits)) Or &H80000000
	Else
		LShift = ((lValue And m_lOnBits(31 - iShiftBits)) * m_l2Power(iShiftBits))
	End If
End Function
Private Function RShift(lValue, iShiftBits)
 
	If iShiftBits = 0 Then
		RShift = lValue
		Exit Function
	ElseIf iShiftBits = 31 Then
		If lValue And &H80000000 Then
			RShift = 1
		Else
			RShift = 0
		End If
		Exit Function
	ElseIf iShiftBits < 0 Or iShiftBits > 31 Then
		Err.Raise 6
	End If
 
	RShift = (lValue And &H7FFFFFFE) \ m_l2Power(iShiftBits)
 
	If (lValue And &H80000000) Then
		RShift = (RShift Or (&H40000000 \ m_l2Power(iShiftBits - 1)))
	End If
End Function
Private Function AddUnsigned(lX, lY)
 
	Dim lX4
	Dim lY4
	Dim lX8
	Dim lY8
	Dim lResult
 
	lX8 = lX And &H80000000
	lY8 = lY And &H80000000
	lX4 = lX And &H40000000
	lY4 = lY And &H40000000
 
	lResult = (lX And &H3FFFFFFF) + (lY And &H3FFFFFFF)
 
	If lX4 And lY4 Then
		lResult = lResult Xor &H80000000 Xor lX8 Xor lY8
	ElseIf lX4 Or lY4 Then
		If lResult And &H40000000 Then
			lResult = lResult Xor &HC0000000 Xor lX8 Xor lY8
		Else
			lResult = lResult Xor &H40000000 Xor lX8 Xor lY8
		End If
	Else
		lResult = lResult Xor lX8 Xor lY8
	End If
 
	AddUnsigned = lResult
End Function
Private Function Ch(x, y, z)
 
	Ch = ((x And y) Xor ((Not x) And z))
End Function
Private Function Maj(x, y, z)
 
	Maj = ((x And y) Xor (x And z) Xor (y And z))
End Function
Private Function S(x, n)
 
	S = (RShift(x, (n And m_lOnBits(4))) Or LShift(x, (32 - (n And m_lOnBits(4)))))
End Function
Private Function R(x, n)
 
	R = RShift(x, CLng(n And m_lOnBits(4)))
End Function
Private Function Sigma0(x)
 
	Sigma0 = (S(x, 2) Xor S(x, 13) Xor S(x, 22))
End Function
Private Function Sigma1(x)
 
	Sigma1 = (S(x, 6) Xor S(x, 11) Xor S(x, 25))
End Function
Private Function Gamma0(x)
 
	Gamma0 = (S(x, 7) Xor S(x, 18) Xor R(x, 3))
End Function
Private Function Gamma1(x)
 
	Gamma1 = (S(x, 17) Xor S(x, 19) Xor R(x, 10))
End Function
Private Function ConvertToWordArray(sMessage)
 
	Dim lMessageLength
	Dim lNumberOfWords
	Dim lWordArray()
	Dim lBytePosition
	Dim lByteCount
	Dim lWordCount
	Dim lByte
 
	Const MODULUS_BITS = 512
	Const CONGRUENT_BITS = 448
 
	lMessageLength = Len(sMessage)
 
	lNumberOfWords = (((lMessageLength + ((MODULUS_BITS - CONGRUENT_BITS) \ BITS_TO_A_BYTE)) \ (MODULUS_BITS \ BITS_TO_A_BYTE)) + 1) * (MODULUS_BITS \ BITS_TO_A_WORD)
	ReDim lWordArray(lNumberOfWords - 1)
 
	lBytePosition = 0
	lByteCount = 0
	Do Until lByteCount >= lMessageLength
		lWordCount = lByteCount \ BYTES_TO_A_WORD
 
		lBytePosition = (3 - (lByteCount Mod BYTES_TO_A_WORD)) * BITS_TO_A_BYTE
 
		lByte = AscB(Mid(sMessage, lByteCount + 1, 1))
 
		lWordArray(lWordCount) = lWordArray(lWordCount) Or LShift(lByte, lBytePosition)
		lByteCount = lByteCount + 1
	Loop
	lWordCount = lByteCount \ BYTES_TO_A_WORD
	lBytePosition = (3 - (lByteCount Mod BYTES_TO_A_WORD)) * BITS_TO_A_BYTE
	lWordArray(lWordCount) = lWordArray(lWordCount) Or LShift(&H80, lBytePosition)
	lWordArray(lNumberOfWords - 1) = LShift(lMessageLength, 3)
	lWordArray(lNumberOfWords - 2) = RShift(lMessageLength, 29)
 
	ConvertToWordArray = lWordArray
End Function
Public Function SHA256(sMessage)
	Dim HASH(7)
	Dim M
	Dim W(63)
	Dim a
	Dim b
	Dim c
	Dim d
	Dim e
	Dim f
	Dim g
	Dim h
	Dim i
	Dim j
	Dim T1
	Dim T2
 
	HASH(0) = &H6A09E667
	HASH(1) = &HBB67AE85
	HASH(2) = &H3C6EF372
	HASH(3) = &HA54FF53A
	HASH(4) = &H510E527F
	HASH(5) = &H9B05688C
	HASH(6) = &H1F83D9AB
	HASH(7) = &H5BE0CD19
 
	M = ConvertToWordArray(sMessage)
	For i = 0 To UBound(M) Step 16
		a = HASH(0)
		b = HASH(1)
		c = HASH(2)
		d = HASH(3)
		e = HASH(4)
		f = HASH(5)
		g = HASH(6)
		h = HASH(7)
 
		For j = 0 To 63
			If j < 16 Then
				W(j) = M(j + i)
			Else
				W(j) = AddUnsigned(AddUnsigned(AddUnsigned(Gamma1(W(j - 2)), W(j - 7)), Gamma0(W(j - 15))), W(j - 16))
			End If
 
			T1 = AddUnsigned(AddUnsigned(AddUnsigned(AddUnsigned(h, Sigma1(e)), Ch(e, f, g)), K(j)), W(j))
			T2 = AddUnsigned(Sigma0(a), Maj(a, b, c))
 
			h = g
			g = f
			f = e
			e = AddUnsigned(d, T1)
			d = c
			c = b
			b = a
			a = AddUnsigned(T1, T2)
		Next
 
		HASH(0) = AddUnsigned(a, HASH(0))
		HASH(1) = AddUnsigned(b, HASH(1))
		HASH(2) = AddUnsigned(c, HASH(2))
		HASH(3) = AddUnsigned(d, HASH(3))
		HASH(4) = AddUnsigned(e, HASH(4))
		HASH(5) = AddUnsigned(f, HASH(5))
		HASH(6) = AddUnsigned(g, HASH(6))
		HASH(7) = AddUnsigned(h, HASH(7))
	Next
 
	SHA256 = LCase(Right("00000000" & Hex(HASH(0)), 8) & Right("00000000" & Hex(HASH(1)), 8) & Right("00000000" & Hex(HASH(2)), 8) & Right("00000000" & Hex(HASH(3)), 8) & Right("00000000" & Hex(HASH(4)), 8) & Right("00000000" & Hex(HASH(5)), 8) & Right("00000000" & Hex(HASH(6)), 8) & Right("00000000" & Hex(HASH(7)), 8))
End Function