How do I use my own key to encrypt data using ecdeffiehellmancng

Question

0.00/5 (No votes)

See more:

My task is to encrypt data using the Elliptic Curve Cryptography in .Net (specific from client), I tried using the sample from Microsoft but it seems to generate its own key everytime. I need to use my own key for this process, like creating a password "S3curEChaNNel_01?" and converting it to byte then use as a key, but i cant find a way to do this.

VB

Using alice As New ECDiffieHellmanCng()
                Dim abData() As Byte
                Dim Str = txtKey.Text 'custom password
                abData = System.Text.Encoding.Default.GetBytes(Str)
                Str = System.Text.Encoding.Default.GetString(abData)

                Dim bobPublicKey() As Byte
                Dim bobKey() As Byte
                Dim bob As New ECDiffieHellmanCng()

                bob.KeyDerivationFunction = ECDiffieHellmanKeyDerivationFunction.Hash
                bob.HashAlgorithm = CngAlgorithm.Sha256
                bobPublicKey = bob.PublicKey.ToByteArray()
                bob.HmacKey = abData

                bobKey = bob.DeriveKeyMaterial(CngKey.Create(CngAlgorithm.Sha256))
'at this line i get an exception, "The requested operation is not supported."

                'Dim aliceKey As Byte() = alice.DeriveKeyMaterial(CngKey.Create(CngAlgorithm.Sha256))
                Dim encryptedMessage As Byte() = Nothing
                Dim iv As Byte() = Nothing
                txtOutput.Text = ByteArrayToString(Encrypt(bobKey, txtPlainStr.Text, encryptedMessage, iv))
            End Using

Pls help me out, any working sample will be very much appreciated

What I have tried:

I have tried using the
bobKey = bob.DeriveKeyMaterial(CngKey.Import(abData, CngKeyBlobFormat.EccPrivateBlob))

and

bobKey = bob.DeriveKeyMaterial(CngKey.Import(abData, CngKeyBlobFormat.EccPublicBlob))

Posted 6-Sep-16 21:41pm

Ovie Prince Tegaton

Updated 4-Oct-16 12:45pm

Add a Solution

1 solution

Add a Solution

Add your solution here

Treat my content as plain text, not as HTML

Preview 0

…

Existing Members

Sign in to your account

...or Join us

Download, Vote, Comment, Publish.

Your Email
Password
Forgot your password?

Your Email
This email is in use. Do you need your password?
Optional Password

I have read and agree to the Terms of Service and Privacy Policy
Please subscribe me to the CodeProject newsletters

When answering a question please:

Read the question carefully.
Understand that English isn't everyone's first language so be lenient of bad spelling and grammar.
If a question is poorly phrased then either ask for clarification, ignore it, or edit the question and fix the problem. Insults are not welcome.
Don't tell someone to read the manual. Chances are they have and don't get it. Provide an answer or move on to the next question.

Let's work to help developers, not make them feel stupid.

This content, along with any associated source code and files, is licensed under The Code Project Open License (CPOL)

Daniel Fisher (lennybacon) · Answer 1 · 2016-10-04T12:45:00

You can't. You need an elliptic curve key. That is way more complex and secure that converting something like "S3curEChaNNel_01?" to a byte array.

An example for a ECC key would be an ECC certificate issued by an certificate authority.

If you don't want to go the PKI road. Create one and and import as follows:

C#

//Save
var key = CngKey.Create(CngAlgorithm.Sha256);
var bob = new ECDiffieHellmanCng(key);
var x = bob.Key.Export(CngKeyBlobFormat.EccPrivateBlob);

//Load
bob = new ECDiffieHellmanCng(CngKey.Import(x, CngKeyBlobFormat.EccPrivateBlob))