Xbase++

ECDSA Sign Data and Verify Signature

See more ECC Examples

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

LOCAL nSuccess
LOCAL oCrypt
LOCAL cHash1
LOCAL cHash2
LOCAL oPrivKey
LOCAL oPrng
LOCAL oEcdsa
LOCAL cEcdsaSigBase64
LOCAL oPubKey
LOCAL nResult

nSuccess := 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.

//  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

oCrypt := CreateObject("Chilkat.Crypt2")
oCrypt:HashAlgorithm := "SHA256"
oCrypt:Charset := "utf-8"
oCrypt:EncodingMode := "base64"

//  Hash a string.
cHash1 := oCrypt:HashStringENC("The quick brown fox jumps over the lazy dog")
? "hash1 = " + cHash1

//  Or hash a file..
cHash2 := oCrypt:HashFileENC("qa_data/hamlet.xml")
? "hash2 = " + cHash2

//  (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-----

oPrivKey := CreateObject("Chilkat.PrivateKey")
nSuccess := oPrivKey:LoadPemFile("qa_data/ecc/secp256r1-key-pkcs8.pem")
IF (nSuccess != 1)
    ? oPrivKey:LastErrorText
    oCrypt:destroy()
    oPrivKey:destroy()
    RETURN
ENDIF

//  We'll need a PRNG source for random number generation.
//  Use Chilkat's PRNG (for the Fortuna PRNG algorithm).
oPrng := CreateObject("Chilkat.Prng")

//  Sign the hash..
oEcdsa := CreateObject("Chilkat.Ecc")
cEcdsaSigBase64 := oEcdsa:SignHashENC(cHash1, "base64", oPrivKey, oPrng)
IF (oEcdsa:LastMethodSuccess != 1)
    ? oEcdsa:LastErrorText
    oCrypt:destroy()
    oPrivKey:destroy()
    oPrng:destroy()
    oEcdsa:destroy()
    RETURN
ENDIF

? "ECDSA signature = " + cEcdsaSigBase64

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

oPubKey := CreateObject("Chilkat.PublicKey")
nSuccess := oPubKey:LoadFromFile("qa_data/ecc/secp256r1-pubkey.pem")
IF (nSuccess != 1)
    ? oPubKey:LastErrorText
    oCrypt:destroy()
    oPrivKey:destroy()
    oPrng:destroy()
    oEcdsa:destroy()
    oPubKey:destroy()
    RETURN
ENDIF

nResult := oEcdsa:VerifyHashENC(cHash1, cEcdsaSigBase64, "base64", oPubKey)
IF (nResult == 1)
    ? "Signature is valid."
    oCrypt:destroy()
    oPrivKey:destroy()
    oPrng:destroy()
    oEcdsa:destroy()
    oPubKey:destroy()
    RETURN
ENDIF

IF (nResult == 0)
    ? "Signature is invalid."
    oCrypt:destroy()
    oPrivKey:destroy()
    oPrng:destroy()
    oEcdsa:destroy()
    oPubKey:destroy()
    RETURN
ENDIF

IF (nResult < 0)
    ? oEcdsa:LastErrorText
    ? "The VerifyHashENC method call failed."
    oCrypt:destroy()
    oPrivKey:destroy()
    oPrng:destroy()
    oEcdsa:destroy()
    oPubKey:destroy()
    RETURN
ENDIF

oCrypt:destroy()
oPrivKey:destroy()
oPrng:destroy()
oEcdsa:destroy()
oPubKey:destroy()