Go

Verify the RSA Signature of a SHA256 Hash

See more RSA Examples

Demonstrates how to verify an RSA signature of a SHA256 hash. Go

    success := false

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

    // Let's say you have a file containing the 32-bytes of a SHA256 hash,
    // and a file that is an RSA signature of those 32 bytes.
    // Here's how you verify using the RSA public key found in a PEM.

    pubKey := chilkat.NewPublicKey()
    success = pubKey.LoadFromFile("rsaPubKey.pem")
    if success == false {
        fmt.Println(pubKey.LastErrorText())
        pubKey.DisposePublicKey()
        return
    }

    rsa := chilkat.NewRsa()

    // Get the public key.
    success = rsa.UsePublicKey(pubKey)
    if success == false {
        fmt.Println(rsa.LastErrorText())
        pubKey.DisposePublicKey()
        rsa.DisposeRsa()
        return
    }

    // Get the 32-byte SHA256 hash.
    bdHash := chilkat.NewBinData()
    success = bdHash.LoadFile("myHash.sha256")
    if success == false {
        fmt.Println("Failed to load SHA256 hash.")
        pubKey.DisposePublicKey()
        rsa.DisposeRsa()
        bdHash.DisposeBinData()
        return
    }

    // Get the RSA signature to be validated.
    bdSig := chilkat.NewBinData()
    success = bdSig.LoadFile("mySig.sig")
    if success == false {
        fmt.Println("Failed to load RSA signature.")
        pubKey.DisposePublicKey()
        rsa.DisposeRsa()
        bdHash.DisposeBinData()
        bdSig.DisposeBinData()
        return
    }

    // Verify the signature against the SHA256 hash.
    enc := "base64"
    rsa.SetEncodingMode(enc)
    success = rsa.VerifyHashENC(*bdHash.GetEncoded(enc),"sha256",*bdSig.GetEncoded(enc))
    if success == false {
        fmt.Println(rsa.LastErrorText())
        pubKey.DisposePublicKey()
        rsa.DisposeRsa()
        bdHash.DisposeBinData()
        bdSig.DisposeBinData()
        return
    }

    fmt.Println("Signature validated.")

    pubKey.DisposePublicKey()
    rsa.DisposeRsa()
    bdHash.DisposeBinData()
    bdSig.DisposeBinData()