how can i sign a file in Qt using sha1 digest?

I need to sign a file using QCA and qca-ossl in Qt. the input is a private key 开发者_运维知识库and a zip file. in ruby this can be done like this

@sig = @key.sign(OpenSSL::Digest::SHA1.new, plain)

in Linux I can do this by with command:

openssl rsautl -sign -in file -inkey key.pem -out sig

Here the private key I got in qt by

QCA::PrivateKey seckey = QCA::KeyGenerator().createRSA(1024);

now I need to do the signing in qt

can anybody help me on this?

See QCA::PrivateKey::signMessage, QCA::SignatureAlgorithm and QCA::MemoryRegion

I guess something like:

QByteArray signResult = seckey.signMessage(QCA::MemoryRegion(plain),
                                                     QCA::EMSA1_SHA1);