PowerBuilder

Create ECSDA Signature using Raw r and s Format (not ASN.1)

See more ECC Examples

Demonstrates how to create an ECDSA signature using the raw r/s format.

ECDSA signatures have two equal sized parts, r and s. There are two common formats for encoding the signature:

(a) Concatenating the raw byte array of r and s
(b) Encoding both into a structured ASN.1 / DER sequence.

This example demonstrates how to create a signature that is a byte array of r and s concatenated.

Note: This example requires Chilkat v9.5.0.97 or greater.

PowerBuilder

integer li_rc
integer li_Success
oleobject loo_Sb
string ls_Hash
oleobject loo_PrivKey
oleobject loo_Prng
oleobject loo_Ecdsa
string ls_EcdsaSigBase64
oleobject loo_PubKey
integer li_Result

li_Success = 0

// 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.

loo_Sb = create oleobject
li_rc = loo_Sb.ConnectToNewObject("Chilkat.StringBuilder")
if li_rc < 0 then
    destroy loo_Sb
    MessageBox("Error","Connecting to COM object failed")
    return
end if
loo_Sb.Append("The quick brown fox jumps over the lazy dog")
ls_Hash = loo_Sb.GetHash("sha256","base64","utf-8")

// Load the ECDSA key to be used for signing.
loo_PrivKey = create oleobject
li_rc = loo_PrivKey.ConnectToNewObject("Chilkat.PrivateKey")

li_Success = loo_PrivKey.LoadPemFile("qa_data/ecc/secp256r1-key-pkcs8.pem")
if li_Success <> 1 then
    Write-Debug loo_PrivKey.LastErrorText
    destroy loo_Sb
    destroy loo_PrivKey
    return
end if

loo_Prng = create oleobject
li_rc = loo_Prng.ConnectToNewObject("Chilkat.Prng")

loo_Ecdsa = create oleobject
li_rc = loo_Ecdsa.ConnectToNewObject("Chilkat.Ecc")

// Produce a signature that is not ASN.1, but is instead the concatenation
// of the raw r and s signature parts.
// This feature was added in Chilkat v9.5.0.97
loo_Ecdsa.AsnFormat = 0

ls_EcdsaSigBase64 = loo_Ecdsa.SignHashENC(ls_Hash,"base64",loo_PrivKey,loo_Prng)
if loo_Ecdsa.LastMethodSuccess <> 1 then
    Write-Debug loo_Ecdsa.LastErrorText
    destroy loo_Sb
    destroy loo_PrivKey
    destroy loo_Prng
    destroy loo_Ecdsa
    return
end if

Write-Debug "ECDSA signature = " + ls_EcdsaSigBase64

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

loo_PubKey = create oleobject
li_rc = loo_PubKey.ConnectToNewObject("Chilkat.PublicKey")

li_Success = loo_PubKey.LoadFromFile("qa_data/ecc/secp256r1-pubkey.pem")
if li_Success <> 1 then
    Write-Debug loo_PubKey.LastErrorText
    destroy loo_Sb
    destroy loo_PrivKey
    destroy loo_Prng
    destroy loo_Ecdsa
    destroy loo_PubKey
    return
end if

// Note: When verifying, Chilkat will auto-detect the format for both kinds of ECDSA signatures (ASN.1 or binary r+s)
li_Result = loo_Ecdsa.VerifyHashENC(ls_Hash,ls_EcdsaSigBase64,"base64",loo_PubKey)
if li_Result = 1 then
    Write-Debug "Signature is valid."
    destroy loo_Sb
    destroy loo_PrivKey
    destroy loo_Prng
    destroy loo_Ecdsa
    destroy loo_PubKey
    return
end if

if li_Result = 0 then
    Write-Debug "Signature is invalid."
    destroy loo_Sb
    destroy loo_PrivKey
    destroy loo_Prng
    destroy loo_Ecdsa
    destroy loo_PubKey
    return
end if

if li_Result < 0 then
    Write-Debug loo_Ecdsa.LastErrorText
    Write-Debug "The VerifyHashENC method call failed."
    destroy loo_Sb
    destroy loo_PrivKey
    destroy loo_Prng
    destroy loo_Ecdsa
    destroy loo_PubKey
    return
end if



destroy loo_Sb
destroy loo_PrivKey
destroy loo_Prng
destroy loo_Ecdsa
destroy loo_PubKey