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(.NET Core C#) Create ECSDA Signature using Raw r and s Format (not ASN.1)See more ECC ExamplesDemonstrates how to create an ECDSA signature using the raw r/s format. ECDSA signatures have two equal sized parts, r and s. There are two common formats for encoding the signature:
(a) Concatenating the raw byte array of r and s This example demonstrates how to create a signature that is a byte array of r and s concatenated. Note: This example requires Chilkat v9.5.0.97 or greater.
// 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. Chilkat.StringBuilder sb = new Chilkat.StringBuilder(); sb.Append("The quick brown fox jumps over the lazy dog"); string hash = sb.GetHash("sha256","base64","utf-8"); // Load the ECDSA key to be used for signing. Chilkat.PrivateKey privKey = new Chilkat.PrivateKey(); bool success = privKey.LoadPemFile("qa_data/ecc/secp256r1-key-pkcs8.pem"); if (success != true) { Debug.WriteLine(privKey.LastErrorText); return; } Chilkat.Prng prng = new Chilkat.Prng(); Chilkat.Ecc ecdsa = new Chilkat.Ecc(); // Produce a signature that is not ASN.1, but is instead the concatenation // of the raw r and s signature parts. // This feature was added in Chilkat v9.5.0.97 ecdsa.AsnFormat = false; string ecdsaSigBase64 = ecdsa.SignHashENC(hash,"base64",privKey,prng); if (ecdsa.LastMethodSuccess != true) { Debug.WriteLine(ecdsa.LastErrorText); return; } Debug.WriteLine("ECDSA signature = " + ecdsaSigBase64); // ----------------------------------------------------------- // Now let's verify the signature using the public key. Chilkat.PublicKey pubKey = new Chilkat.PublicKey(); success = pubKey.LoadFromFile("qa_data/ecc/secp256r1-pubkey.pem"); if (success != true) { Debug.WriteLine(pubKey.LastErrorText); return; } // Note: When verifying, Chilkat will auto-detect the format for both kinds of ECDSA signatures (ASN.1 or binary r+s) int result = ecdsa.VerifyHashENC(hash,ecdsaSigBase64,"base64",pubKey); if (result == 1) { Debug.WriteLine("Signature is valid."); return; } if (result == 0) { Debug.WriteLine("Signature is invalid."); return; } if (result < 0) { Debug.WriteLine(ecdsa.LastErrorText); Debug.WriteLine("The VerifyHashENC method call failed."); return; } |
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