Visual FoxPro

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. Visual FoxPro

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

lnSuccess = 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

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-----

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

* Sign the hash..
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.

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