(Xojo Plugin) ECDSA Sign Data and Verify Signature

Demonstrates using the Elliptic Curve Digital Signature Algorithm to hash data and sign it. Also demonstrates how to verify the ECDSA signature.

Chilkat Xojo Plugin Download Xojo Plugin for Windows, Linux, Mac OS X, and ARM, ARM64

// This example requires the Chilkat API to have been previously unlocked.
// See Global Unlock Sample for sample code.

// To create an ECDSA signature, the data first needs to be hashed.  Then the hash
// is signed.

// Use Chilkat Crypt2 to generate a hash for any of the following
// hash algorithms: SHA256, SHA384, SHA512, SHA1, MD5, MD2, HAVAL, RIPEMD128/160/256/320

Dim crypt As New Chilkat.Crypt2
crypt.HashAlgorithm = "SHA256"
crypt.Charset = "utf-8"
crypt.EncodingMode = "base64"

// Hash a string.
Dim hash1 As String
hash1 = crypt.HashStringENC("The quick brown fox jumps over the lazy dog")
System.DebugLog("hash1 = " + hash1)

// Or hash a file..
Dim hash2 As String
hash2 = crypt.HashFileENC("qa_data/hamlet.xml")
System.DebugLog("hash2 = " + hash2)

// (The Crypt2 API provides many other ways to hash data..)

// -----------------------------------------------------------
// An ECDSA private key is used for signing.  The public key is for signature verification.
// Load our ECC private key.
// Our private key file contains this:

// 	// -----BEGIN PRIVATE KEY-----
// 	MIGHAgEAMBMGByqGSM49AgEGCCqGSM49AwEHBG0wawIBAQQg3J8q/24D1sEKGdP9
// 	72MGYElLGpw/a56Y3t6pfON3uhShRANCAATlSmoizyhAwoYZAOuFBATl07/1RR54
// 	a1Dzfm16grxJe666AGKR+bSs24hk7TEpaeCTvT8YOOM3l+xKFg7zq6Q9
// 	-----END PRIVATE KEY-----

Dim privKey As New Chilkat.PrivateKey
Dim success As Boolean
success = privKey.LoadPemFile("qa_data/ecc/secp256r1-key-pkcs8.pem")
If (success <> True) Then
    System.DebugLog(privKey.LastErrorText)
    Return
End If

// We'll need a PRNG source for random number generation.
// Use Chilkat's PRNG (for the Fortuna PRNG algorithm).
Dim prng As New Chilkat.Prng

// Sign the hash..
Dim ecdsa As New Chilkat.Ecc
Dim ecdsaSigBase64 As String
ecdsaSigBase64 = ecdsa.SignHashENC(hash1,"base64",privKey,prng)
If (ecdsa.LastMethodSuccess <> True) Then
    System.DebugLog(ecdsa.LastErrorText)
    Return
End If

System.DebugLog("ECDSA signature = " + ecdsaSigBase64)

// -----------------------------------------------------------
// Now let's verify the signature using the public key.

Dim pubKey As New Chilkat.PublicKey
success = pubKey.LoadFromFile("qa_data/ecc/secp256r1-pubkey.pem")
If (success <> True) Then
    System.DebugLog(pubKey.LastErrorText)
    Return
End If

Dim result As Int32
result = ecdsa.VerifyHashENC(hash1,ecdsaSigBase64,"base64",pubKey)
If (result = 1) Then
    System.DebugLog("Signature is valid.")
    Return
End If

If (result = 0) Then
    System.DebugLog("Signature is invalid.")
    Return
End If

If (result < 0) Then
    System.DebugLog(ecdsa.LastErrorText)
    System.DebugLog("The VerifyHashENC method call failed.")
    Return
End If