ecdsa

I have generated an ECDSA signature in Java and I would like to get the R and S values from it. It is my understanding that the signature I have generated is DER encoded. Can someone please provide me with some Java code (maybe using Bouncy Castle) to retrieve the R and S values as BigIntegers? Note: In case it helps, I generated the signature using a built in provider via the JCE's Signature class and the signature lengths for my P_256 EC key pair hover between 70 and 72 bytes usually. I was able to solve this myself. In case it helps anyone here is how I did it (most exception handling has

I want to make a ECDSA signature with this code : AsymmetricKeyAlgorithmProvider objAsymmAlgProv = AsymmetricKeyAlgorithmProvider.OpenAlgorithm(AsymmetricAlgorithmNames.EcdsaSha256); CryptographicKey keypair = objAsymmAlgProv.CreateKeyPairWithCurveName(EccCurveNames.SecP256r1); BinaryStringEncoding encoding = BinaryStringEncoding.Utf8; buffMsg = CryptographicBuffer.ConvertStringToBinary("Test Message", encoding); IBuffer buffSIG = CryptographicEngine.Sign(keypair, buffMsg); byte [] SignByteArray = buffSIG.ToArray(); bool res = CryptographicEngine.VerifySignature(keypair, buffMsg, buffSIG);

What will the signature length for 256 bit EC key in ECDSA algorithm? I wanted to validated signature length for the same. It will be great if some body can help me with one EC key set. It depends on how you encode the signature. This is the code segment from OpenSSL that measures the length of ECDSA signature in DER format. /** ECDSA_size * returns the maximum length of the DER encoded signature * \param eckey pointer to a EC_KEY object * \return numbers of bytes required for the DER encoded signature */ int ECDSA_size(const EC_KEY *r) { int ret,i; ASN1_INTEGER bs; BIGNUM *order=NULL;

Here is the Java code: public static String sign(String data) throws Exception { KeyPair keyPair = loadKeyPair(System.getProperty("user.dir"), "ECDSA"); Signature signature = Signature.getInstance("SHA256withECDSA", "BC"); signature.initSign(keyPair.getPrivate(), new SecureRandom()); byte[] message = data.getBytes(); signature.update(message); byte[] sigBytes = signature.sign(); String signatureStr = new BigInteger(1, sigBytes).toString(16); return signatureStr; } Then the C++ Code to verify signatures bool VerifyMessage( const ECDSA<ECP, SHA256>::PublicKey& key, const string& message, const

I'm trying to generate ECDSA self-signed certificate as described in generate certificate using ECDSA . Putting all pieces from bartonjs's answer together and using Net.Framework 4.7 (or Net.Core 2.0 ) following code seems to be working although there are some ambiguities (at least one) left: I'm not sure how to properly convert private key ('D' parameter) from BC-BigInteger to MS-byte[] . Using BigInteger.ToByteArray() throws exception: CryptographicException : The specified key parameters are not valid. Q.X and Q.Y are required fields. Q.X, Q.Y must be the same length. If D is specified it

I'm using the following example for signing + verifying in Node.js: https://github.com/nodejs/node-v0.x-archive/issues/6904 . The verification succeeds in Node.js but fails in WebCrypto. Similarly, a message signed using WebCrypto fails to verify in Node.js. Here's the code I used to verify a signature produced from the Node.js script using WebCrypto - https://jsfiddle.net/aj49e8sj/ . Tested in both Chrome 54.0.2840.27 and Firefox 48.0.2 // From https://github.com/nodejs/node-v0.x-archive/issues/6904 var keys = { priv: '-----BEGIN EC PRIVATE KEY-----\n' + 'MHcCAQEEIF+jnWY1D5kbVYDNvxxo/Y

I'm trying to generate (self-signed) certificate with private key using ECDSA. The goals is to get "the same" (pkcs12) certificate as when using openssl: openssl ecparam -genkey -name secp256r1 -out mykey.key openssl req -new -key mykey.key -out myreq.csr openssl req -x509 -days 7 -key mykey.key -in myreq.csr -out mycert.crt openssl pkcs12 -export -out mycert.pfx -inkey mykey.key -in mycert.crt I already use BouncyCastle to help me with creating RSA-based certificate(s), so next steps more or less follow the way I use to create RSA certs. (note that BC prefix is used for classes from

I have a task at hand that requires deriving key material using the key derivation function described in NIST SP 800-56A, section 5.8.1. I'm not an expert in Cryptography so please excuse me if the question is naive. Here's what I've done so far: I have the other party's public key and my private key Now I try to generate the shared secret using ECDH 1.3.132.1.12 using C# (.NET 4) ECDiffieHellmanCng class like so: // The GetCngKey method reads the private key from a certificate in my Personal certificate store CngKey cngPrivateKey = GetCngKey(); ECDiffieHellmanCng ecDiffieHellmanCng = new