How to replace GDSADigestVerifier when upgrading from 4.1 to 5.0

[Yanmu Huang]

Hi,

When I am upgrading from 4.1 to 5.0, I found that GDSADigestVerifier is missing in 
5.0. So I need to replace it with something new in 5.0.

Here is my old code using v4.1:

        // convert signature from format DER to P1363
        DSAPublicKey pubkey(p, q, g, y);                        // I replaced this one 
with DSA::Verifier pubkey(p, q, g, y)
        // get P1363 signature length
        int new_siglen = pubkey.SignatureLength();
        byte new_sig[1024];
        try {
                DSAConvertSignatureFormat(new_sig, new_siglen, DSA_P1363,
                        m_signature, m_siglen, DSA_DER);
        }
        catch (...) {
                return false;   // invalid signature
        }

        // calculate digest
        byte digest[20];
        SHA sha1;
        sha1.CalculateDigest((byte*) digest, (byte*) m_body, strlen(m_body));

        // verify the signature
        GDSADigestVerifier verifier(p, q, g, y);                        // I don't 
know how to replace these two lines
        return verifier.VerifyDigest(digest, sizeof(digest), new_sig);

Anybody helps? Thanks in advance!

Yanmu Huang