(Classic ASP) 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 ActiveX Downloads

ActiveX for 32-bit and 64-bit Windows

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' 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

' For versions of Chilkat < 10.0.0, use CreateObject("Chilkat_9_5_0.Crypt2")
set crypt = Server.CreateObject("Chilkat.Crypt2")
crypt.HashAlgorithm = "SHA256"
crypt.Charset = "utf-8"
crypt.EncodingMode = "base64"

' Hash a string.
hash1 = crypt.HashStringENC("The quick brown fox jumps over the lazy dog")
Response.Write "<pre>" & Server.HTMLEncode( "hash1 = " & hash1) & "</pre>"

' Or hash a file..
hash2 = crypt.HashFileENC("qa_data/hamlet.xml")
Response.Write "<pre>" & Server.HTMLEncode( "hash2 = " & hash2) & "</pre>"

' (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-----

' For versions of Chilkat < 10.0.0, use CreateObject("Chilkat_9_5_0.PrivateKey")
set privKey = Server.CreateObject("Chilkat.PrivateKey")
success = privKey.LoadPemFile("qa_data/ecc/secp256r1-key-pkcs8.pem")
If (success <> 1) Then
    Response.Write "<pre>" & Server.HTMLEncode( privKey.LastErrorText) & "</pre>"
    Response.End
End If

' We'll need a PRNG source for random number generation.
' Use Chilkat's PRNG (for the Fortuna PRNG algorithm).
' For versions of Chilkat < 10.0.0, use CreateObject("Chilkat_9_5_0.Prng")
set prng = Server.CreateObject("Chilkat.Prng")

' Sign the hash..
' For versions of Chilkat < 10.0.0, use CreateObject("Chilkat_9_5_0.Ecc")
set ecdsa = Server.CreateObject("Chilkat.Ecc")
ecdsaSigBase64 = ecdsa.SignHashENC(hash1,"base64",privKey,prng)
If (ecdsa.LastMethodSuccess <> 1) Then
    Response.Write "<pre>" & Server.HTMLEncode( ecdsa.LastErrorText) & "</pre>"
    Response.End
End If

Response.Write "<pre>" & Server.HTMLEncode( "ECDSA signature = " & ecdsaSigBase64) & "</pre>"

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

' For versions of Chilkat < 10.0.0, use CreateObject("Chilkat_9_5_0.PublicKey")
set pubKey = Server.CreateObject("Chilkat.PublicKey")
success = pubKey.LoadFromFile("qa_data/ecc/secp256r1-pubkey.pem")
If (success <> 1) Then
    Response.Write "<pre>" & Server.HTMLEncode( pubKey.LastErrorText) & "</pre>"
    Response.End
End If

result = ecdsa.VerifyHashENC(hash1,ecdsaSigBase64,"base64",pubKey)
If (result = 1) Then
    Response.Write "<pre>" & Server.HTMLEncode( "Signature is valid.") & "</pre>"
    Response.End
End If

If (result = 0) Then
    Response.Write "<pre>" & Server.HTMLEncode( "Signature is invalid.") & "</pre>"
    Response.End
End If

If (result < 0) Then
    Response.Write "<pre>" & Server.HTMLEncode( ecdsa.LastErrorText) & "</pre>"
    Response.Write "<pre>" & Server.HTMLEncode( "The VerifyHashENC method call failed.") & "</pre>"
    Response.End
End If


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