Here is a pure AHK function, which computes the MD5 hash of binary data of size < 512MB. The result is a sequence of 32 hex digits.

; GLOBAL CONSTANTS r[64], k[64] r = 12, 17, 22, 7, 12, 17, 22, 7, 12, 17, 22, 7, 12, 17, 22 , 5, 9, 14, 20, 5, 9, 14, 20, 5, 9, 14, 20, 5, 9, 14, 20 , 4, 11, 16, 23, 4, 11, 16, 23, 4, 11, 16, 23, 4, 11, 16, 23 , 6, 10, 15, 21, 6, 10, 15, 21, 6, 10, 15, 21, 6, 10, 15, 21 StringSplit r, r, `, r0 := 7 Loop 64 i := A_Index-1, k%i% := floor(abs(sin(A_Index)) * 2**32) ; TEST CASES MsgBox % MD5(x:="", 0) ; d41d8cd98f00b204e9800998ecf8427e MsgBox % MD5(x:="a", StrLen(x)) ; 0cc175b9c0f1b6a831c399e269772661 MsgBox % MD5(x:="abc", StrLen(x)) ; 900150983cd24fb0d6963f7d28e17f72 MsgBox % MD5(x:="message digest", StrLen(x)) ; f96b697d7cb7938d525a2f31aaf161d0 MsgBox % MD5(x:="abcdefghijklmnopqrstuvwxyz", StrLen(x)) ; c3fcd3d76192e4007dfb496cca67e13b MsgBox % MD5(x:="ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789", StrLen(x)) ; d174ab98d277d9f5a5611c2c9f419d9f MsgBox % MD5(x:="12345678901234567890123456789012345678901234567890123456789012345678901234567890", StrLen(x)) ; 57edf4a22be3c955ac49da2e2107b67a MsgBox % MD5(x:="The quick brown fox jumps over the lazy dog", StrLen(x)) ; 9e107d9d372bb6826bd81d3542a419d6 MsgBox % MD5(x:="The quick brown fox jumps over the lazy cog", StrLen(x)) ; 1055d3e698d289f2af8663725127bd4b MD5(ByRef Buf, L) { ; Binary buffer, Length in bytes Static P, Q, N, i, a,b,c,d, t, h0,h1,h2,h3, y = 0xFFFFFFFF h0 := 0x67452301, h1 := 0xEFCDAB89, h2 := 0x98BADCFE, h3 := 0x10325476 N := ceil((L+9)/64)*64 ; padded length (100..separator, 8B length) VarSetCapacity(Q,N,0) ; room for padded data P := &Q ; pointer DllCall("RtlMoveMemory", UInt,P, UInt,&Buf, UInt,L) ; copy data DllCall("RtlFillMemory", UInt,P+L, UInt,1, UInt,0x80) ; pad separator DllCall("ntdll.dll\RtlFillMemoryUlong",UInt,P+N-8,UInt,4,UInt,8*L) ; at end: length in bits < 512 MB Loop % N//64 { Loop 16 i := A_Index-1, w%i% := *P | *(P+1)<<8 | *(P+2)<<16 | *(P+3)<<24, P += 4 a := h0, b := h1, c := h2, d := h3 Loop 64 { i := A_Index-1 If i < 16 f := (b & c) | (~b & d), g := i Else If i < 32 f := (d & b) | (~d & c), g := 5*i+1 & 15 Else If i < 48 f := b ^ c ^ d, g := 3*i+5 & 15 Else f := c ^ (b | ~d), g := 7*i & 15 t := d, d := c, c := b b += rotate(a + f + k%i% + w%g%, r%i%) ; reduced to 32 bits later a := t } h0 := h0+a & y, h1 := h1+b & y, h2 := h2+c & y, h3 := h3+d & y } Return hex(h0) . hex(h1) . hex(h2) . hex(h3) } rotate(a,b) { ; 32-bit rotate a to left by b bits, bit32..63 garbage Return a << b | (a & 0xFFFFFFFF) >> (32-b) } hex(x) { ; 32-bit little endian hex digits SetFormat Integer, HEX x += 0x100000000, x := SubStr(x,-1) . SubStr(x,8,2) . SubStr(x,6,2) . SubStr(x,4,2) SetFormat Integer, DECIMAL Return x }