PowerBuilder

ECDSA Sign Data and Get Raw R and S Values

See more ECC Examples

Demonstrates getting the raw R and S value of an ECDSA signature. PowerBuilder

integer li_rc
integer li_Success
oleobject loo_Crypt
string ls_Hash1
oleobject loo_PrivKey
oleobject loo_Prng
oleobject loo_Ecdsa
string ls_EcdsaSigBase64
oleobject loo_Asn
oleobject loo_Xml
oleobject loo_Bd
string r
string s

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_Crypt = create oleobject
li_rc = loo_Crypt.ConnectToNewObject("Chilkat.Crypt2")
if li_rc < 0 then
    destroy loo_Crypt
    MessageBox("Error","Connecting to COM object failed")
    return
end if
loo_Crypt.HashAlgorithm = "SHA256"
loo_Crypt.Charset = "utf-8"
loo_Crypt.EncodingMode = "base64"

// Hash a string.
ls_Hash1 = loo_Crypt.HashStringENC("The quick brown fox jumps over the lazy dog")
Write-Debug "hash1 = " + ls_Hash1

// -----------------------------------------------------------
// 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-----

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_Crypt
    destroy loo_PrivKey
    return
end if

// Sign the hash..
loo_Prng = create oleobject
li_rc = loo_Prng.ConnectToNewObject("Chilkat.Prng")

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

ls_EcdsaSigBase64 = loo_Ecdsa.SignHashENC(ls_Hash1,"base64",loo_PrivKey,loo_Prng)
if loo_Ecdsa.LastMethodSuccess <> 1 then
    Write-Debug loo_Ecdsa.LastErrorText
    destroy loo_Crypt
    destroy loo_PrivKey
    destroy loo_Prng
    destroy loo_Ecdsa
    return
end if

// The ECDSA signature is ASN.1 that contains a sequence of 2 large integers (r and s)
// For example:
// SEQUENCE (2 elem)
//   INTEGER (255 bit) 792134D9B4AD82D5431ED03835A88E2596EB35E5B13054BD9B05A0069281ACC9
//   INTEGER (255 bit) 481E758CC1E3CBF825537EC3D9A2CA627E5FAD1137BBEA65DF38658DCB0A9ED5

Write-Debug "Base64 ECDSA signature = " + ls_EcdsaSigBase64

// If the raw R and S values are needed, here's how to get them:
loo_Asn = create oleobject
li_rc = loo_Asn.ConnectToNewObject("Chilkat.Asn")

li_Success = loo_Asn.LoadEncoded(ls_EcdsaSigBase64,"base64")
if li_Success = 0 then
    Write-Debug loo_Asn.LastErrorText
    destroy loo_Crypt
    destroy loo_PrivKey
    destroy loo_Prng
    destroy loo_Ecdsa
    destroy loo_Asn
    return
end if

// The R and X will be in hexidecimal in the XML.
loo_Xml = create oleobject
li_rc = loo_Xml.ConnectToNewObject("Chilkat.Xml")

loo_Xml.LoadXml(loo_Asn.AsnToXml())
Write-Debug loo_Xml.GetXml()

// The XML looks like this:
// <sequence>
// <int>792134D9B4AD82D5431ED03835A88E2596EB35E5B13054BD9B05A0069281ACC9</int>
// <int>481E758CC1E3CBF825537EC3D9A2CA627E5FAD1137BBEA65DF38658DCB0A9ED5</int>
// </sequence>

// Copy raw R and S hex values into a Chilkat BinData object.
loo_Bd = create oleobject
li_rc = loo_Bd.ConnectToNewObject("Chilkat.BinData")

r = loo_Xml.GetChildContent("int[0]")
s = loo_Xml.GetChildContent("int[1]")
loo_Bd.AppendEncoded(r,"hex")
loo_Bd.AppendEncoded(s,"hex")

Write-Debug "Number of bytes in bd: " + string(loo_Bd.NumBytes)


destroy loo_Crypt
destroy loo_PrivKey
destroy loo_Prng
destroy loo_Ecdsa
destroy loo_Asn
destroy loo_Xml
destroy loo_Bd