(Visual FoxPro) 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

LOCAL loCrypt
LOCAL lcHash1
LOCAL lcHash2
LOCAL loPrivKey
LOCAL lnSuccess
LOCAL loPrng
LOCAL loEcdsa
LOCAL lcEcdsaSigBase64
LOCAL loPubKey
LOCAL lnResult

* 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')
loCrypt = CreateObject('Chilkat.Crypt2')
loCrypt.HashAlgorithm = "SHA256"
loCrypt.Charset = "utf-8"
loCrypt.EncodingMode = "base64"

* Hash a string.
lcHash1 = loCrypt.HashStringENC("The quick brown fox jumps over the lazy dog")
? "hash1 = " + lcHash1

* Or hash a file..
lcHash2 = loCrypt.HashFileENC("qa_data/hamlet.xml")
? "hash2 = " + lcHash2

* (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')
loPrivKey = CreateObject('Chilkat.PrivateKey')
lnSuccess = loPrivKey.LoadPemFile("qa_data/ecc/secp256r1-key-pkcs8.pem")
IF (lnSuccess <> 1) THEN
    ? loPrivKey.LastErrorText
    RELEASE loCrypt
    RELEASE loPrivKey
    CANCEL
ENDIF

* 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')
loPrng = CreateObject('Chilkat.Prng')

* Sign the hash..
* For versions of Chilkat < 10.0.0, use CreateObject('Chilkat_9_5_0.Ecc')
loEcdsa = CreateObject('Chilkat.Ecc')
lcEcdsaSigBase64 = loEcdsa.SignHashENC(lcHash1,"base64",loPrivKey,loPrng)
IF (loEcdsa.LastMethodSuccess <> 1) THEN
    ? loEcdsa.LastErrorText
    RELEASE loCrypt
    RELEASE loPrivKey
    RELEASE loPrng
    RELEASE loEcdsa
    CANCEL
ENDIF

? "ECDSA signature = " + lcEcdsaSigBase64

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

* For versions of Chilkat < 10.0.0, use CreateObject('Chilkat_9_5_0.PublicKey')
loPubKey = CreateObject('Chilkat.PublicKey')
lnSuccess = loPubKey.LoadFromFile("qa_data/ecc/secp256r1-pubkey.pem")
IF (lnSuccess <> 1) THEN
    ? loPubKey.LastErrorText
    RELEASE loCrypt
    RELEASE loPrivKey
    RELEASE loPrng
    RELEASE loEcdsa
    RELEASE loPubKey
    CANCEL
ENDIF

lnResult = loEcdsa.VerifyHashENC(lcHash1,lcEcdsaSigBase64,"base64",loPubKey)
IF (lnResult = 1) THEN
    ? "Signature is valid."
    RELEASE loCrypt
    RELEASE loPrivKey
    RELEASE loPrng
    RELEASE loEcdsa
    RELEASE loPubKey
    CANCEL
ENDIF

IF (lnResult = 0) THEN
    ? "Signature is invalid."
    RELEASE loCrypt
    RELEASE loPrivKey
    RELEASE loPrng
    RELEASE loEcdsa
    RELEASE loPubKey
    CANCEL
ENDIF

IF (lnResult < 0) THEN
    ? loEcdsa.LastErrorText
    ? "The VerifyHashENC method call failed."
    RELEASE loCrypt
    RELEASE loPrivKey
    RELEASE loPrng
    RELEASE loEcdsa
    RELEASE loPubKey
    CANCEL
ENDIF

RELEASE loCrypt
RELEASE loPrivKey
RELEASE loPrng
RELEASE loEcdsa
RELEASE loPubKey