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Edit to show you how I'm using SHA256 code.

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edited Oct 26, 2019 at 13:12

'------ Edit to write how I'm using SHA256 code. A lot of info I'm reading to learn is form https://docs.microsoft.com

Public Function FxSHA256(ByVal textHashed As String) As String
        If textHashed.Length <= 0 Then
            MsgBox("No text to hash.")
            Return 0
            Exit Function
        End If
        Dim hash As String = String.Empty
        Using mySHA256 As SHA256 = SHA256.Create()
            hash = ModuleConvert.GetHASH(mySHA256, textHashed)
        End Using
        myHash256 = hash
        Return hash
    End Function

In other module I have this:

'HashAlgorythm
Public Function GetHASH(ByVal hashAlgorithm As HashAlgorithm, ByVal textHashed As String) As String
    Dim data As Byte() = hashAlgorithm.ComputeHash(Encoding.UTF8.GetBytes(textHashed))
    Dim sBuilder As New StringBuilder()
    For i As Integer = 0 To data.Length - 1
        sBuilder.Append(data(i).ToString("x2"))
    Next
    Return sBuilder.ToString()
End Function

'------ Edit to write how I'm using SHA256 code. A lot of info I'm reading to learn is form https://docs.microsoft.com

Public Function FxSHA256(ByVal textHashed As String) As String
        If textHashed.Length <= 0 Then
            MsgBox("No text to hash.")
            Return 0
            Exit Function
        End If
        Dim hash As String = String.Empty
        Using mySHA256 As SHA256 = SHA256.Create()
            hash = ModuleConvert.GetHASH(mySHA256, textHashed)
        End Using
        myHash256 = hash
        Return hash
    End Function

In other module I have this:

'HashAlgorythm
Public Function GetHASH(ByVal hashAlgorithm As HashAlgorithm, ByVal textHashed As String) As String
    Dim data As Byte() = hashAlgorithm.ComputeHash(Encoding.UTF8.GetBytes(textHashed))
    Dim sBuilder As New StringBuilder()
    For i As Integer = 0 To data.Length - 1
        sBuilder.Append(data(i).ToString("x2"))
    Next
    Return sBuilder.ToString()
End Function

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asked Oct 25, 2019 at 15:33

B221D9

Get a correct SHA256 of a PublicKey as bytes

I’m new in code develop and I’m studying it by myself (books, tutorials, official help of sites…) since a year VB.NET. A lot of information I read is in C# that I rewrite in VB.NET. I’ve started four months ago to read and write some code about SHA256, Aes, ECDsa… and there are some things those I understand with time and practice, but there are other things that I can’t understand (or find) until read a lot of information. Well in this case, I think I can understand but I don’t know how write the code or understand how SHA256 works. I’m following these instructions:

http://gobittest.appspot.com/Address

ripemd160(sha256(publickey)) - Where am I going wrong? << I think I have the same problem.

I’ll try to be specific and write all necessary code for other people that it could be for their interest. Thank you for advance for all help, links, information that you can give me to follow the right path. Well, this is my situation: I’ve created a Public key (x coord and y coord) and a private key by ECDsa with SecP256k1 curve. This is the code:

Private Sub GetKeys()
Using myECDsa As New System.Security.Cryptography.ECDsaCng(vCurve)
myECDsa.HashAlgorithm = CngAlgorithm.Sha256
Dim PrivateKey() As Byte = myECDsa.Key.Export(CngKeyBlobFormat.EccPrivateBlob)
Dim PublicKey() As Byte = myECDsa.Key.Export(CngKeyBlobFormat.EccPublicBlob)

Console.WriteLine(Convert.ToBase64String(PrivateKey))
Console.WriteLine(Convert.ToBase64String(PublicKey))
End Using
End Sub

*vCurve is a var that contains the string “SecP256k1”

Output maybe this:

Private Key: RUNEViAAAADvJ2dk9gUnYF2XDIr5dNITLUXnXJRgXD8A3WHeDe6YkBBTJAlNizJCp5rMG0163U2JfNWEnBKEE7AjU2guVar63+jTifUg8/UrjTfoLkoIgdk8VLnTz1HYDxEvR2GtE70=
Public Key: RUNEUCAAAADvJ2dk9gUnYF2XDIr5dNITLUXnXJRgXD8A3WHeDe6YkBBTJAlNizJCp5rMG0163U2JfNWEnBKEE7AjU2guVar6

I can convert to string and clean data if I write this code into Using

'Private Key
Dim StrPrivateKey As String = String.Empty
For Each bt As Byte In PrivateKey
StrPrivateKey &= bt.ToString("X2")
Next
'Public Key
Dim StrPublicKey As String = String.Empty
For Each bt As Byte In PublicKey
StrPublicKey &= bt.ToString("X2")
Next
Dim StrDigits As String = StrPrivateKey.Substring(0, 16)
'Clean data
StrPrivateKey = StrPrivateKey.Substring(StrPublicKey.Length)
StrPublicKey = StrPublicKey.Substring(16)
Dim StrXCoord As String = StrPublicKey.Substring(0, 64)
Dim StrYCoord As String = StrPublicKey.Substring(64)

Output is:

Private Key: 6624B7D42BA98F09B4782B755DEE4A050A3E5F15D1DFB152E5A0571ABD045797
Public Key: C400BED535B984BADCB6DA96D4167709314085B6E5405C7CE1A3D2CF76FA991DC34F2FAA9533FEFD80E6EAA20ED0BD2D7A30F2696A08570B053159FA7068CE90
Digits: 4543445620000000
Xcoord: C400BED535B984BADCB6DA96D4167709314085B6E5405C7CE1A3D2CF76FA991D
YCoord: C34F2FAA9533FEFD80E6EAA20ED0BD2D7A30F2696A08570B053159FA7068CE90

First Question: I saw that every Private/Public key has a similar number or 8 bytes. In this example is: 4543445620000000

What is this number? Is it a version of something?

Second Question: I’ve found a little information about how to get a SHA256 of Public Key. If I get the SHA256 of this example, the result is:

Public Key: 04C400BED535B984BADCB6DA96D4167709314085B6E5405C7CE1A3D2CF76FA991DC34F2FAA9533FEFD80E6EAA20ED0BD2D7A30F2696A08570B053159FA7068CE90
SHA256: f7beda57bd9e0c9838dd4e1336aaa363c2bfa88eca25407b472a620fcaa1626f

Sha256 is correct if I take Public Key as a string (yes, I write “04” at the start and I know that is not a byte). But I’ve read that Public Key must be in bytes, and this is the part where I lost the way. I have PublicKey() as byte, but I don’t know how work with it to get a SHA256. All sha256 tutorials and help about it, hash a single string or files, and as you can see, I need some information that I don’t know how to search.

Thanks a lot.

sha256