Go

ECDSA Sign and Verify Data using Different Hash Algorithms

See more ECC Examples

Demonstrates how to create ECDSA signatures on data using different hash algorithms.

Note: This example requires Chilkat v9.5.0.85 or greater because the SignBd and VerifyBd methods were added in v9.5.0.85.

Go

    success := false

    // This example assumes the Chilkat API to have been previously unlocked.
    // See Global Unlock Sample for sample code.

    // First load an ECDSA private key to be used for signing.
    privKey := chilkat.NewPrivateKey()
    success = privKey.LoadEncryptedPemFile("qa_data/ecc/secp256r1-key-pkcs8-secret.pem","secret")
    if success == false {
        fmt.Println(privKey.LastErrorText())
        privKey.DisposePrivateKey()
        return
    }

    // Load some data to be signed.
    bd := chilkat.NewBinData()
    success = bd.LoadFile("qa_data/hamlet.xml")
    if success == false {
        fmt.Println("Failed to load file to be hashed.")
        privKey.DisposePrivateKey()
        bd.DisposeBinData()
        return
    }

    ecdsa := chilkat.NewEcc()
    prng := chilkat.NewPrng()

    // Sign the sha256 hash of the data.  Return the ECDSA signature in the base64 encoding.
    fmt.Println("ECDSA signing the sha256 hash of the data...")
    sig := ecdsa.SignBd(bd,"sha256","base64",privKey,prng)
    fmt.Println("sig = ", *sig)

    // Verify the signature against the original data.
    // (We must use the same hash algorithm that was used when signing.)

    // Load the public key that corresponds to the private key used for signing.
    pubKey := chilkat.NewPublicKey()
    success = pubKey.LoadFromFile("qa_data/ecc/secp256r1-pub.pem")
    if success == false {
        fmt.Println(pubKey.LastErrorText())
        privKey.DisposePrivateKey()
        bd.DisposeBinData()
        ecdsa.DisposeEcc()
        prng.DisposePrng()
        pubKey.DisposePublicKey()
        return
    }

    ecc2 := chilkat.NewEcc()
    result := ecc2.VerifyBd(bd,"sha256",*sig,"base64",pubKey)
    if result != 1 {
        fmt.Println(ecc2.LastErrorText())
        privKey.DisposePrivateKey()
        bd.DisposeBinData()
        ecdsa.DisposeEcc()
        prng.DisposePrng()
        pubKey.DisposePublicKey()
        ecc2.DisposeEcc()
        return
    }

    fmt.Println("Verified!")

    // ----------------------------------------------------------------------------------------
    // Let's do the same thing, but with sha384 hashing...

    fmt.Println("--------------------------------------------")
    fmt.Println("ECDSA signing the sha384 hash of the data...")

    sig = ecdsa.SignBd(bd,"sha384","base64",privKey,prng)
    fmt.Println("sig = ", *sig)

    result = ecc2.VerifyBd(bd,"sha384",*sig,"base64",pubKey)
    if result != 1 {
        fmt.Println(ecc2.LastErrorText())
        privKey.DisposePrivateKey()
        bd.DisposeBinData()
        ecdsa.DisposeEcc()
        prng.DisposePrng()
        pubKey.DisposePublicKey()
        ecc2.DisposeEcc()
        return
    }

    fmt.Println("Verified!")

    privKey.DisposePrivateKey()
    bd.DisposeBinData()
    ecdsa.DisposeEcc()
    prng.DisposePrng()
    pubKey.DisposePublicKey()
    ecc2.DisposeEcc()