About signature authentication with java 1st

Signature and Authentication Example (Java)

1. 1. Required jar files: commons-codec-1.11.jar, bcprov-ext-jdk15on-158.jar

2. Sample source for signature

Data to be signed (character string (42 bytes) that combines "transaction date and time" (14 bytes), "terminal identification number" (13 bytes), "terminal processing serial number" (15 bytes)) String message = "20171201091011A004012345678012345678901234";

Reading the private key file Security.addProvider(new BouncyCastleProvider());

• When signing and authenticating together, you only have to do it once. PemReader pemPriReader = new PemReader(new FileReader("./file/private-key.pem"));
  PemObject objPri = pemPriReader.readPemObject();
  byte[] privateKeyByte = objPri.getContent();

Generate a private key target PKCS8EncodedKeySpec pkcs8 = new PKCS8EncodedKeySpec(privateKeyByte);
KeyFactory keyFactory = KeyFactory.getInstance("RSA");
RSAPrivateKey rsaPrivateKey = (RSAPrivateKey) keyFactory.generatePrivate(pkcs8);

Sign with the data to be signed and the private key target Signature signer = Signature.getInstance("SHA256withRSA");
signer.initSign(rsaPrivateKey);
signer.update(message.getBytes("UTF-8"));
byte[] signByte = signer.sign();

Convert to hexadecimal format based on the generated signature bytes Hex.encodeHexString(signByte);
↓
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

3. 3. Sample source for authentication

Read public key file PemReader pemPubReader = new PemReader(new FileReader("./file/public-key.pem"));
PemObject objPub = pemPubReader.readPemObject();
byte[] publicKeyByte = objPub.getContent();

Generate a public key target X509EncodedKeySpec x509 = new X509EncodedKeySpec(encodedByte);
KeyFactory keyFactory = KeyFactory.getInstance("RSA");
RSAPublicKey rsaPublicKey = (RSAPublicKey) keyFactory.generatePublic(x509);

Authenticate with public key target Signature verifier = Signature.getInstance("SHA256withRSA");
verifier.initVerify(rsaPublicKey);
verifier.update(message.getBytes("UTF-8"));
byte [] messageByte = Hex.decodeHex (Signed message above (hexadecimal format)); boolean result = verifier.verify(messageByte);