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 been stripped for readability):
import java.io.ByteArrayInputStream;
import java.math.BigInteger;
import java.security.KeyPair;
import java.security.KeyPairGenerator;
import java.security.Security;
import java.security.Signature;
import java.security.spec.ECGenParameterSpec;
import org.bouncycastle.asn1.ASN1Encodable;
import org.bouncycastle.asn1.ASN1InputStream;
import org.bouncycastle.asn1.ASN1Integer;
import org.bouncycastle.asn1.ASN1Primitive;
import org.bouncycastle.asn1.ASN1Sequence;
import org.bouncycastle.jce.provider.BouncyCastleProvider;
public class DecodeEcdsaSignature {
public static void main(String[] args) throws Exception {
Security.addProvider(new BouncyCastleProvider());
byte[] signature = getSignature();
ASN1Primitive asn1 = toAsn1Primitive(signature);
if (asn1 instanceof ASN1Sequence) {
ASN1Sequence asn1Sequence = (ASN1Sequence) asn1;
ASN1Encodable[] asn1Encodables = asn1Sequence.toArray();
for (ASN1Encodable asn1Encodable : asn1Encodables) {
ASN1Primitive asn1Primitive = asn1Encodable.toASN1Primitive();
if (asn1Primitive instanceof ASN1Integer) {
ASN1Integer asn1Integer = (ASN1Integer) asn1Primitive;
BigInteger integer = asn1Integer.getValue();
System.out.println(integer.toString());
}
}
}
}
private static ASN1Primitive toAsn1Primitive(byte[] data) throws Exception
{
try (ByteArrayInputStream inStream = new ByteArrayInputStream(data);
ASN1InputStream asnInputStream = new ASN1InputStream(inStream);)
{
return asnInputStream.readObject();
}
}
private static byte[] getSignature() throws Exception {
KeyPairGenerator keyPairGenerator = KeyPairGenerator.getInstance("ECDSA");
ECGenParameterSpec ecParameterSpec = new ECGenParameterSpec("P-256");
keyPairGenerator.initialize(ecParameterSpec);
KeyPair keyPair = keyPairGenerator.generateKeyPair();
Signature signature = Signature.getInstance("SHA256withECDSA");
signature.initSign(keyPair.getPrivate());
signature.update("message to sign".getBytes("UTF-8"));
return signature.sign();
}
}
Related
Here is the code, the second (message, signature and public key) works fine on Java, can verify the message. But when I am using python, it will failed.
If am signed the message and the code will verify the message correctly.
Would some one help me to check the problem? Thank you.
# -*- coding:utf-8 -*-
from Crypto.PublicKey import RSA
from Crypto.Hash import SHA256
from Crypto.Signature import PKCS1_v1_5
from base64 import b64decode, b64encode
public_key = 'MFwwDQYJKoZIhvcNAQEBBQADSwAwSAJBALyJy3rlD9EtWqVBzSIYxRRuFWRVn3juht2nupDCBSsWi7uKaRu3W0gn5y6aCacArtCkrf0EehwYRm0A4iHf8rkCAwEAAQ=='
private_key = 'MIIBVQIBADANBgkqhkiG9w0BAQEFAASCAT8wggE7AgEAAkEAvInLeuUP0S1apUHNIhjFFG4VZFWfeO6G3ae6kMIFKxaLu4ppG7dbSCfnLpoJpwCu0KSt/QR6HBhGbQDiId/yuQIDAQABAkEAqm/y15UtOE7Ey/HxLCqyNqbRhdN1h5AxsT0IhgYvP+PhWGc3hRElMwNCdiNaJBh04R1iK6wmKoi3DSjkdU6IAQIhAPRL9khAdPMxjy5tpswNWeaDjNJrlUKEnItQUkoHqve5AiEAxZIDz235HcUgLg9ApYK4spOpzLDGCCgfO3FxmrUEUwECIEaLjQIOQvdbT1p75Ze1H0nWoRq+YGrF+qKsPicMkc1ZAiARlNTR+K9afthGQQU3tVJKUemiVXjJ8QgWehnp8oHYAQIhANsC2fEVjWv94Oy2c8I9qhuX+yfNtvZ2m+Kmf2o4JFrR'
bank_response_data = """{"head":{"vernbr":"1.0","mchnbr":"BILL0003","mchtyp":"BILLTYP","trscod":"BILL001","msgidc":"201805011230500001","sigtim":"20190307115511","sigalg":"SHA256WithRSA","retcod":"F","retmsg":"GWB2B006 源IP地址不在商户IP白名单中；商户编号：BILL0003；IP地址：123.139.40.150"}}"""
bank_response_signature = """uZl0/5D694GnAd/G9OPRs9BSd9fb0fZGXSGThBtgLnKi+CDQAdasOX05mKazXZki0blXxApGYRAWa/kOrf+Wl0USfklx0G5w/eGERfMdRWpvtV3S2MBCH/H/0T81nKGgn8svkT/Trj7+Mc+e654Jn8IijGyV9m8Ak92hG2bLtbc="""
bank_public_key = """MIGfMA0GCSqGSIb3DQEBAQUAA4GNADCBiQKBgQDZs4l8Ez3F4MG0kF7RRSL+pn8MmxVE3nfdXzjx6d3rH8IfDbNvNRLS0X0b5iJnPyFO8sbbUo1Im4zX0M8XA0xnnviGyn5E6occiyUXJRgokphWb5BwaYdVhnLldctdimHoJTk3NFEQFav3guygR54i3tymrDc8lWtuG8EczVu8FwIDAQAB"""
def sign():
key_bytes = bytes(private_key, encoding="utf-8")
key_bytes = b64decode(key_bytes)
key = RSA.importKey(key_bytes)
hash_value = SHA256.new(bytes(bank_response_data, encoding="utf-8"))
signer = PKCS1_v1_5.new(key)
signature = signer.sign(hash_value)
return b64encode(signature)
def verify(data, signature, the_pub_key):
print(signature)
key_bytes = bytes(the_pub_key, encoding="utf-8")
key_bytes = b64decode(key_bytes)
key = RSA.importKey(key_bytes)
hash_value = SHA256.new(bytes(data, encoding="utf-8"))
verifier = PKCS1_v1_5.new(key)
if verifier.verify(hash_value, b64decode(signature)):
print("The signature is authentic.")
else:
print("The signature is not authentic.")
verify(bank_response_data, sign(), public_key)
verify(bank_response_data, bank_response_signature.encode('utf-8'),
bank_public_key)
# -*- coding:utf-8 -*-
from Cryptodome.Signature import PKCS1_v1_5 # pip install pycryptodomex
from Cryptodome.Hash import SHA256
from Cryptodome.PublicKey import RSA
from base64 import decodebytes, encodebytes
public_key = "MFwwDQYJKoZIhvcNAQEBBQADSwAwSAJBALyJy3rlD9EtWqVBzSIYxRRuFWRVn3juht2nupDCBSsWi7uKaRu3W0gn5y6aCacArtCkrf0EehwYRm0A4iHf8rkCAwEAAQ=="
private_key = "MIIBVQIBADANBgkqhkiG9w0BAQEFAASCAT8wggE7AgEAAkEAvInLeuUP0S1apUHNIhjFFG4VZFWfeO6G3ae6kMIFKxaLu4ppG7dbSCfnLpoJpwCu0KSt/QR6HBhGbQDiId/yuQIDAQABAkEAqm/y15UtOE7Ey/HxLCqyNqbRhdN1h5AxsT0IhgYvP+PhWGc3hRElMwNCdiNaJBh04R1iK6wmKoi3DSjkdU6IAQIhAPRL9khAdPMxjy5tpswNWeaDjNJrlUKEnItQUkoHqve5AiEAxZIDz235HcUgLg9ApYK4spOpzLDGCCgfO3FxmrUEUwECIEaLjQIOQvdbT1p75Ze1H0nWoRq+YGrF+qKsPicMkc1ZAiARlNTR+K9afthGQQU3tVJKUemiVXjJ8QgWehnp8oHYAQIhANsC2fEVjWv94Oy2c8I9qhuX+yfNtvZ2m+Kmf2o4JFrR"
bank_response_data = """{"head":{"vernbr":"1.0","mchnbr":"BILL0003","mchtyp":"BILLTYP","trscod":"BILL001","msgidc":"201805011230500001","sigtim":"20190307115511","sigalg":"SHA256WithRSA","retcod":"F","retmsg":"GWB2B006 源IP地址不在商户IP白名单中；商户编号：BILL0003；IP地址：123.139.40.150"}}"""
bank_response_signature = """uZl0/5D694GnAd/G9OPRs9BSd9fb0fZGXSGThBtgLnKi+CDQAdasOX05mKazXZki0blXxApGYRAWa/kOrf+Wl0USfklx0G5w/eGERfMdRWpvtV3S2MBCH/H/0T81nKGgn8svkT/Trj7+Mc+e654Jn8IijGyV9m8Ak92hG2bLtbc="""
bank_public_key = """MIGfMA0GCSqGSIb3DQEBAQUAA4GNADCBiQKBgQDZs4l8Ez3F4MG0kF7RRSL+pn8MmxVE3nfdXzjx6d3rH8IfDbNvNRLS0X0b5iJnPyFO8sbbUo1Im4zX0M8XA0xnnviGyn5E6occiyUXJRgokphWb5BwaYdVhnLldctdimHoJTk3NFEQFav3guygR54i3tymrDc8lWtuG8EczVu8FwIDAQAB"""
def sign(private_key=private_key, raw_string=bank_response_data):
private_key = RSA.importKey(decodebytes(private_key.encode()))
signer = PKCS1_v1_5.new(private_key)
signature = signer.sign(SHA256.new(raw_string.encode()))
return encodebytes(signature).decode().replace("\n", "")
def verify(data, signature, public_key):
print(signature)
key = RSA.importKey(decodebytes(public_key.encode()))
hash_value = SHA256.new(data.encode())
verifier = PKCS1_v1_5.new(key)
if verifier.verify(hash_value, decodebytes(signature.encode())):
print("The signature is authentic.")
else:
print("The signature is not authentic.")
verify(bank_response_data, sign(), public_key)
verify(bank_response_data, bank_response_signature, bank_public_key)
Below is the java code, it works fine with the same signature and public key.
import org.apache.commons.codec.digest.DigestUtils;
import java.security.KeyFactory;
import java.security.PrivateKey;
import java.security.PublicKey;
import java.security.Signature;
import java.security.spec.PKCS8EncodedKeySpec;
import java.security.spec.X509EncodedKeySpec;
import java.util.Base64;
public class MyTest {
public static final String KEY_ALGORITHM = "RSA";
public static final String SIGNATURE_ALGORITHM = "SHA256WithRSA";
public static void main(String[] args) {
String data = "{\"head\":{\"vernbr\":\"1.0\",\"mchnbr\":\"BILL0003\",\"mchtyp\":\"BILLTYP\",\"trscod\":\"BILL001\",\"msgidc\":\"201805011230500001\",\"sigtim\":\"20190307115511\",\"sigalg\":\"SHA256WithRSA\",\"retcod\":\"F\",\"retmsg\":\"GWB2B006 源IP地址不在商户IP白名单中；商户编号：BILL0003；IP地址：123.139.40.150\"}}";
String signature = "dnAFU2e5zFb8rJ1mXDNk5AG9UyujVIUArkBjb1Nonf7iMhZwHfHRO633eW5n7uELFnyJZk6Go2D6ovp4jEnIoA==";
String cmbcRespSignature = "uZl0/5D694GnAd/G9OPRs9BSd9fb0fZGXSGThBtgLnKi+CDQAdasOX05mKazXZki0blXxApGYRAWa/kOrf+Wl0USfklx0G5w/eGERfMdRWpvtV3S2MBCH/H/0T81nKGgn8svkT/Trj7+Mc+e654Jn8IijGyV9m8Ak92hG2bLtbc=";
String cmbcPublicKey = "MIGfMA0GCSqGSIb3DQEBAQUAA4GNADCBiQKBgQDZs4l8Ez3F4MG0kF7RRSL+pn8MmxVE3nfdXzjx6d3rH8IfDbNvNRLS0X0b5iJnPyFO8sbbUo1Im4zX0M8XA0xnnviGyn5E6occiyUXJRgokphWb5BwaYdVhnLldctdimHoJTk3NFEQFav3guygR54i3tymrDc8lWtuG8EczVu8FwIDAQAB";
try {
boolean verify = verify(DigestUtils.sha256(data), cmbcPublicKey, cmbcRespSignature);
if (verify) {
}
} catch (Exception e) {
}
}
public static boolean verify(byte[] data, String publicKey, String sign) throws Exception {
final Base64.Decoder decoder = Base64.getDecoder();
final byte[] keyBytes = publicKey.getBytes("UTF-8");
X509EncodedKeySpec keySpec = new X509EncodedKeySpec(decoder.decode(keyBytes));
KeyFactory keyFactory = KeyFactory.getInstance(KEY_ALGORITHM);
PublicKey pubKey = keyFactory.generatePublic(keySpec);
Signature signature = Signature.getInstance(SIGNATURE_ALGORITHM);
signature.initVerify(pubKey);
signature.update(data);
return signature.verify(decoder.decode(sign));
}
}
Finally, I get the answer.
In java
DigestUtils.sha256(data) did hash,
SHA256WithRSA algorithm will do hash
So what I should do is hash 2 times in my python code
The latest (beta) version of Bouncy Castle (bcprov-jdk15on-161b20.jar) supports ED25519 and ED448 EC cryptography for signing purposes. I setup this full working example and it works as expected.
My question: did I rebuild the private and public keys correctly as I didn't found any example in the bc-tests ? I expected that I have to use some Spec-functionality like "X509EncodedKeySpec pubKeySpec = new X509EncodedKeySpec(content)" for RSA-key rebuilding but my code is working.
package bc;
// original source: https://github.com/bcgit/bc-java/blob/master/core/src/test/java/org/bouncycastle/crypto/test/Ed25519Test.java
// needs bouncy castle beta: bcprov-jdk15on-161b20.jar (version 1.605)
// tested with Java 8 Build 191 x64
// this is a full working example for generating, signing, verififying with ed25519 keys
// code: https://github.com/java-crypto/Bouncy-Castle
import java.security.Provider;
import java.security.SecureRandom;
import java.security.Security;
import java.util.Arrays;
import java.io.UnsupportedEncodingException;
import javax.xml.bind.DatatypeConverter;
import org.bouncycastle.crypto.AsymmetricCipherKeyPair;
import org.bouncycastle.crypto.CryptoException;
import org.bouncycastle.crypto.DataLengthException;
import org.bouncycastle.crypto.Signer;
import org.bouncycastle.crypto.generators.Ed25519KeyPairGenerator;
import org.bouncycastle.crypto.params.Ed25519KeyGenerationParameters;
import org.bouncycastle.crypto.params.Ed25519PrivateKeyParameters;
import org.bouncycastle.crypto.params.Ed25519PublicKeyParameters;
import org.bouncycastle.crypto.signers.Ed25519Signer;
import org.bouncycastle.jce.provider.BouncyCastleProvider;
public class Ed25519Bc {
public static void main(String[] args) throws DataLengthException, CryptoException, UnsupportedEncodingException {
System.out.println("ED25519 with BC");
Security.addProvider(new BouncyCastleProvider());
Provider provider = Security.getProvider("BC");
System.out.println("Provider :" + provider.getName() + " Version: " + provider.getVersion());
// generate ed25519 keys
SecureRandom RANDOM = new SecureRandom();
Ed25519KeyPairGenerator keyPairGenerator = new Ed25519KeyPairGenerator();
keyPairGenerator.init(new Ed25519KeyGenerationParameters(RANDOM));
AsymmetricCipherKeyPair asymmetricCipherKeyPair = keyPairGenerator.generateKeyPair();
Ed25519PrivateKeyParameters privateKey = (Ed25519PrivateKeyParameters) asymmetricCipherKeyPair.getPrivate();
Ed25519PublicKeyParameters publicKey = (Ed25519PublicKeyParameters) asymmetricCipherKeyPair.getPublic();
// the message
byte[] message = "Message to sign".getBytes("utf-8");
// create the signature
Signer signer = new Ed25519Signer();
signer.init(true, privateKey);
signer.update(message, 0, message.length);
byte[] signature = signer.generateSignature();
// verify the signature
Signer verifier = new Ed25519Signer();
verifier.init(false, publicKey);
verifier.update(message, 0, message.length);
boolean shouldVerify = verifier.verifySignature(signature);
// output
byte[] privateKeyEncoded = privateKey.getEncoded();
byte[] publicKeyEncoded = publicKey.getEncoded();
System.out.println("privateKey Length :" + privateKeyEncoded.length + " Data:"
+ DatatypeConverter.printHexBinary(privateKeyEncoded));
System.out.println("publicKey Length :" + publicKeyEncoded.length + " Data:"
+ DatatypeConverter.printHexBinary(publicKeyEncoded));
System.out.println(
"signature Length :" + signature.length + " Data:" + DatatypeConverter.printHexBinary(signature));
System.out.println("signature correct :" + shouldVerify);
// rebuild the keys
System.out.println("Rebuild the keys and verify the signature with rebuild public key");
Ed25519PrivateKeyParameters privateKeyRebuild = new Ed25519PrivateKeyParameters(privateKeyEncoded, 0);
Ed25519PublicKeyParameters publicKeyRebuild = new Ed25519PublicKeyParameters(publicKeyEncoded, 0);
byte[] privateKeyRebuildEncoded = privateKeyRebuild.getEncoded();
System.out.println("privateKey Length :" + privateKeyRebuild.getEncoded().length + " Data:"
+ DatatypeConverter.printHexBinary(privateKeyRebuild.getEncoded()));
byte[] publicKeyRebuildEncoded = publicKeyRebuild.getEncoded();
System.out.println("publicKey Length :" + publicKeyRebuild.getEncoded().length + " Data:"
+ DatatypeConverter.printHexBinary(publicKeyRebuild.getEncoded()));
// compare the keys
System.out.println("private Keys Equal:" + Arrays.equals(privateKeyEncoded, privateKeyRebuildEncoded));
System.out.println("public Keys Equal :" + Arrays.equals(publicKeyEncoded, publicKeyRebuildEncoded));
// verify the signature with rebuild public key
Signer verifierRebuild = new Ed25519Signer();
verifierRebuild.init(false, publicKeyRebuild);
verifierRebuild.update(message, 0, message.length);
boolean shouldVerifyRebuild = verifierRebuild.verifySignature(signature);
System.out.println("signature correct :" + shouldVerifyRebuild + " with rebuild public key");
}
}
This is the console output that shows the properly rebuild keys:
ED25519 with BC
Provider :BC Version: 1.605
privateKey Length :32 Data:F6A1F3A0B8F44EE64ACE636AFCA262F656160A728C042E3F98F9A0FD45717DE7
publicKey Length :32 Data:858C2D6D5910B8AA7B52F7DF8E5806DAD3A7E43DC19C5A548F241BD8B82510FE
signature Length :64 Data:4D402B0095F6692742DCACB0C2C39BFB70A5687F162DFAB3721A660D2259C96B972DF41B97502347E534FAD8D59496811CDFFFA831264ECBB1429439CF350E08
signature correct :true
Rebuild the keys and verify the signature with rebuild public key
privateKey Length :32 Data:F6A1F3A0B8F44EE64ACE636AFCA262F656160A728C042E3F98F9A0FD45717DE7
publicKey Length :32 Data:858C2D6D5910B8AA7B52F7DF8E5806DAD3A7E43DC19C5A548F241BD8B82510FE
private Keys Equal:true
public Keys Equal :true
signature correct :true with rebuild public key
I'm also doing some research into Ed25519 so I've been looking at the BouncyCastle implementation along with Tink and libsodium; I certainly can't see anything wrong with how you're rebuilding the key pair, it seems be consistent with how BouncyCastle is using it in other places: OpenSSHPrivateKeyUtil and Ed25519Test.
Pure BouncyCastle
I re-wrote your test using the key pair and example signature from [RFC8037][3], which works fine as follows (Java 11):
import org.bouncycastle.crypto.CryptoException;
import org.bouncycastle.crypto.Signer;
import org.bouncycastle.crypto.params.Ed25519PrivateKeyParameters;
import org.bouncycastle.crypto.params.Ed25519PublicKeyParameters;
import org.bouncycastle.crypto.signers.Ed25519Signer;
import org.junit.Test;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import java.nio.charset.StandardCharsets;
import java.util.Base64;
import static org.junit.Assert.assertEquals;
public class BouncyCastleTest {
private static final Logger LOG = LoggerFactory.getLogger(BouncyCastleTest.class);
#Test
public void testBouncyCastle() throws CryptoException {
// Test case defined in https://www.rfc-editor.org/rfc/rfc8037
var msg = "eyJhbGciOiJFZERTQSJ9.RXhhbXBsZSBvZiBFZDI1NTE5IHNpZ25pbmc".getBytes(StandardCharsets.UTF_8);
var expectedSig = "hgyY0il_MGCjP0JzlnLWG1PPOt7-09PGcvMg3AIbQR6dWbhijcNR4ki4iylGjg5BhVsPt9g7sVvpAr_MuM0KAg";
var privateKeyBytes = Base64.getUrlDecoder().decode("nWGxne_9WmC6hEr0kuwsxERJxWl7MmkZcDusAxyuf2A");
var publicKeyBytes = Base64.getUrlDecoder().decode("11qYAYKxCrfVS_7TyWQHOg7hcvPapiMlrwIaaPcHURo");
var privateKey = new Ed25519PrivateKeyParameters(privateKeyBytes, 0);
var publicKey = new Ed25519PublicKeyParameters(publicKeyBytes, 0);
// Generate new signature
Signer signer = new Ed25519Signer();
signer.init(true, privateKey);
signer.update(msg, 0, msg.length);
byte[] signature = signer.generateSignature();
var actualSignature = Base64.getUrlEncoder().encodeToString(signature).replace("=", "");
LOG.info("Expected signature: {}", expectedSig);
LOG.info("Actual signature : {}", actualSignature);
assertEquals(expectedSig, actualSignature);
}
}
JCA
You can also achieve the same thing using JCA, in this example my keypair are in the 'raw' format (i.e. the X and D coordinates):
import org.bouncycastle.asn1.DEROctetString;
import org.bouncycastle.asn1.edec.EdECObjectIdentifiers;
import org.bouncycastle.asn1.pkcs.PrivateKeyInfo;
import org.bouncycastle.asn1.x509.AlgorithmIdentifier;
import org.bouncycastle.asn1.x509.SubjectPublicKeyInfo;
import org.bouncycastle.jce.provider.BouncyCastleProvider;
import org.junit.Test;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import java.nio.charset.StandardCharsets;
import java.security.KeyFactory;
import java.security.Security;
import java.security.Signature;
import java.security.spec.PKCS8EncodedKeySpec;
import java.security.spec.X509EncodedKeySpec;
import java.util.Base64;
import static org.junit.Assert.assertEquals;
public class Ed25519JCA {
private static final Logger LOG = LoggerFactory.getLogger(Ed25519JCA.class);
#Test
public void testEd25519WithJCA() throws Exception {
Security.addProvider(new BouncyCastleProvider());
// Test case defined in https://www.rfc-editor.org/rfc/rfc8037
var msg = "eyJhbGciOiJFZERTQSJ9.RXhhbXBsZSBvZiBFZDI1NTE5IHNpZ25pbmc".getBytes(StandardCharsets.UTF_8);
var expectedSig = "hgyY0il_MGCjP0JzlnLWG1PPOt7-09PGcvMg3AIbQR6dWbhijcNR4ki4iylGjg5BhVsPt9g7sVvpAr_MuM0KAg";
// Both formatted as 32bit raw key values (x and d)
var privateKeyBytes = Base64.getUrlDecoder().decode("nWGxne_9WmC6hEr0kuwsxERJxWl7MmkZcDusAxyuf2A");
var publicKeyBytes = Base64.getUrlDecoder().decode("11qYAYKxCrfVS_7TyWQHOg7hcvPapiMlrwIaaPcHURo");
var keyFactory = KeyFactory.getInstance("Ed25519");
// Wrap public key in ASN.1 format so we can use X509EncodedKeySpec to read it
var pubKeyInfo = new SubjectPublicKeyInfo(new AlgorithmIdentifier(EdECObjectIdentifiers.id_Ed25519), publicKeyBytes);
var x509KeySpec = new X509EncodedKeySpec(pubKeyInfo.getEncoded());
var jcaPublicKey = keyFactory.generatePublic(x509KeySpec);
// Wrap private key in ASN.1 format so we can use
var privKeyInfo = new PrivateKeyInfo(new AlgorithmIdentifier(EdECObjectIdentifiers.id_Ed25519), new DEROctetString(privateKeyBytes));
var pkcs8KeySpec = new PKCS8EncodedKeySpec(privKeyInfo.getEncoded());
var jcaPrivateKey = keyFactory.generatePrivate(pkcs8KeySpec);
// Generate new signature
var dsa = Signature.getInstance("EdDSA"); // Edwards digital signature algorithm
dsa.initSign(jcaPrivateKey);
dsa.update(msg, 0, msg.length);
byte[] signature = dsa.sign();
var actualSignature = Base64.getUrlEncoder().encodeToString(signature).replace("=", "");
LOG.info("Expected signature: {}", expectedSig);
LOG.info("Actual signature : {}", actualSignature);
assertEquals(expectedSig, actualSignature);
}
}
Just for completeness, you can also generate the keypair using JCA in the first place, this avoids lots of format conversion:
Security.addProvider(new BouncyCastleProvider());
var keyPair = KeyPairGenerator.getInstance("Ed25519").generateKeyPair();
I am totally new to security and signature verification and so far I couldn't find a place which explained the basics of signature verification. I need to verify the signature of a file by obtaining the public key from the appropriate certificate available from certificate store. the tutorial in Java (https://docs.oracle.com/javase/tutorial/security/apisign/versig.html) doesn't teach how to obtain a certificate from the trusted certificate store and verify using that. I went through Bouncy castle WIKI http://www.bouncycastle.org/wiki/display/JA1/BC+Version+2+APIs but its not really explanatory for a beginner. How do I do this? Given a signed file, how can I check for its public key from the certificate store and verify if its the right person who has sent the file? Please advice.
Because you did not provide what build management you use, I assume it will be Maven.
First, include BouncyCastle in your dependency
<dependency>
<groupId>org.bouncycastle</groupId>
<artifactId>bcprov-jdk15on</artifactId>
<version>1.53</version>
</dependency>
After that, you need to make a util class that you will be using for sign or verify the certificate. Something like this:
package your.pack.location;
import org.apache.logging.log4j.LogManager;
import org.apache.logging.log4j.Logger;
import org.bouncycastle.util.encoders.Base64;
import org.bouncycastle.util.io.pem.PemObject;
import org.bouncycastle.util.io.pem.PemReader;
import org.springframework.core.io.ClassPathResource;
import org.springframework.core.io.Resource;
import java.io.FileInputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.security.*;
import java.security.spec.InvalidKeySpecException;
import java.security.spec.KeySpec;
import java.security.spec.PKCS8EncodedKeySpec;
import java.security.spec.X509EncodedKeySpec;
/**
* Author: harunalfat
*/
public class SignatureUtils {
private static final Logger log = LogManager.getLogger(SignatureUtils.class);
public static String sign(String plainText, PrivateKey privateKey) throws Exception {
byte[] data = plainText.getBytes("ISO-8859-1");
Signature signature = Signature.getInstance("SHA1WithRSA", "BC");
signature.initSign(privateKey);
signature.update(data);
return Base64.toBase64String(signature.sign());
}
public static boolean verify(String plainText, String signString, PublicKey publicKey) throws Exception{
byte[] data = plainText.getBytes("ISO-8859-1");
Signature signature = Signature.getInstance("SHA1WithRSA", "BC");
signature.initVerify(publicKey);
signature.update(data);
byte[] signByte = Base64.decode(signString);
return signature.verify(signByte);
}
private static PemObject getPemObjectFromResource(String fileLocation) throws IOException {
Resource resource = new ClassPathResource(fileLocation);
InputStream is = resource.getInputStream();
PemObject pemObject = new PemReader(new InputStreamReader( is )).readPemObject();
return pemObject;
}
private static X509EncodedKeySpec getPubKeySpec(String fileLocation) throws IOException, NoSuchAlgorithmException {
PemObject pemObject = getPemObjectFromResource(fileLocation);
byte[] data = pemObject.getContent();
X509EncodedKeySpec keySpec = new X509EncodedKeySpec(data);
return keySpec;
}
private static PKCS8EncodedKeySpec getPriKeySpec(String fileLocation) throws IOException, NoSuchAlgorithmException {
PemObject pemObject = getPemObjectFromResource(fileLocation);
byte[] data = pemObject.getContent();
PKCS8EncodedKeySpec keySpec = new PKCS8EncodedKeySpec(data);
return keySpec;
}
public static PublicKey getPublicKey(String fileLocation) throws IOException, NoSuchAlgorithmException, InvalidKeySpecException {
KeyFactory kf = KeyFactory.getInstance("RSA");
KeySpec keySpec = getPubKeySpec(fileLocation);
return kf.generatePublic(keySpec);
}
public static PrivateKey getPrivateKey(String fileLocation) throws IOException, NoSuchAlgorithmException, InvalidKeySpecException {
KeyFactory kf = KeyFactory.getInstance("RSA");
KeySpec keySpec = getPriKeySpec(fileLocation);
return kf.generatePrivate(keySpec);
}
}
And then you will use it like this
package your.another.pack;
import org.apache.logging.log4j.LogManager;
import org.apache.logging.log4j.Logger;
import org.apache.tomcat.util.codec.binary.Base64;
import org.bouncycastle.jce.provider.BouncyCastleProvider;
import org.junit.Test;
import org.mockito.MockitoAnnotations;
import java.security.PrivateKey;
import java.security.PublicKey;
import java.security.Security;
import static org.junit.Assert.assertTrue;
/**
* Author: harunalfat
*/
public class SignatureUtilsTest {
private static final Logger log = LogManager.getLogger(SignatureUtilsTest.class);
private static final String PLAIN = "attack at dawn";
#Test
public void testSignAndVerify() throws Exception {
Security.addProvider(new BouncyCastleProvider()); // <-- IMPORTANT!!! This will add BouncyCastle as provider in Java Security
PrivateKey privateKey = SignatureUtils.getPrivateKey("key/private2.pem"); // This is located on src/main/resources/key/private2.pem
PublicKey publicKey = SignatureUtils.getPublicKey("key/public2.pem"); // This is located on src/main/resources/key/public2.pem
// In this example, I use junit test, so it will be on src/test/resources/...
log.info("Private Key : "+Base64.encodeBase64String(privateKey.getEncoded()));
log.info("Public Key : "+Base64.encodeBase64String(publicKey.getEncoded()));
String sign = SignatureUtils.sign(PLAIN, privateKey);
log.info("Plain String : "+PLAIN);
log.info("Sign : "+sign);
boolean result = SignatureUtils.verify(PLAIN,sign, publicKey);
log.info("Result : "+result);
assertTrue(result);
}
}
Of course, you can change the Signature instance with another Algorithm. In my case I use "SHA1WithRSA", but you get the point right?
With this, someone will encrypt their data using their private key, and send it to you. After that, you will verify the data using the public key they give.
In example, Bob send to you message about money amount he sent to you ($5000), and sign it using their private key, become encrypted. When the data arrived to you, you know Bob supposed to send $5000, then you verify the encrypted data with text $5000 and public key Bob share, but is it really $5000 OR does it comes from Bob?
If the data has been changed, OR when someday you ask for some Money to Bob, but the message tapped by someone else and s/he send you the amount message with private key other than Bob's, you will know.
Feel free to ask :)
I have a symmetric Key in my JKS (Java Key Store) file, I want to wrap my private key with a symmetric key.
Again I am using wrappedBytes to PrivateKey Object. And finally I want the KeyPair Object.
The below code gives the following error message:
java.security.spec.InvalidKeySpecException: java.security.InvalidKeyException: IOException : DerInputStream.getLength(): lengthTag=125, too big.**
public KeyPair wrapPrivateKeyWithSymmetricKey(KeyPair keyPair) {
try {
PrivateKey priv = keyPair.getPrivate();
SecretKey symmetricKey = "bjksabfkasdbgvkasbvkkj";//symmetricKey from jks file
//wrapping Private Key
Cipher cipher = Cipher.getInstance("AES/ECB/PKCS5Padding");
cipher.init(Cipher.WRAP_MODE, symmetricKey);
byte[] wrappedKey = cipher.wrap(priv);
//wrappedKey bytes to PrivateKey Object
KeyFactory keyFactory = KeyFactory.getInstance(priv.getAlgorithm());
EncodedKeySpec privateKeySpec = new PKCS8EncodedKeySpec(wrappedKey);
PrivateKey privateKey2 = keyFactory.generatePrivate(privateKeySpec); //above Error Throwing in this line
return new KeyPair(keyPair.getPublic(), privateKey2);;
}
How can I solve this?
In your example, wrappedBytes isn't in a PKCS #8 format. It's simply some AES encrypted blocks—essentially random data—with no encoded structure.
If you want to create an encrypted PKCS #8 (formally, EncryptedPrivateKeyInfo) you'll need a library that handles that. The built-in API you are trying to use only handles its clear-text payload, PrivateKeyInfo (as described in its documentation).
There isn't much to the wrapper, and you could write the necessary DER coding yourself, or use a library like BouncyCastle.
Here's code, using BouncyCastle to encoded and decode the EncryptyedPrivateKeyInfo structure. The useless class provided by the JCE doesn't work, because of poor handling of the key encryption algorithm identifier and its parameters.
import java.security.GeneralSecurityException;
import java.security.KeyFactory;
import java.security.KeyPair;
import java.security.KeyPairGenerator;
import java.security.PrivateKey;
import java.security.PublicKey;
import java.security.SecureRandom;
import java.security.interfaces.RSAPrivateCrtKey;
import java.security.interfaces.RSAPrivateKey;
import java.security.interfaces.RSAPublicKey;
import java.security.spec.RSAPublicKeySpec;
import javax.crypto.Cipher;
import javax.crypto.KeyGenerator;
import javax.crypto.SecretKey;
import javax.crypto.spec.IvParameterSpec;
import org.bouncycastle.asn1.ASN1Encodable;
import org.bouncycastle.asn1.ASN1ObjectIdentifier;
import org.bouncycastle.asn1.ASN1OctetString;
import org.bouncycastle.asn1.DEROctetString;
import org.bouncycastle.asn1.nist.NISTObjectIdentifiers;
import org.bouncycastle.asn1.pkcs.EncryptedPrivateKeyInfo;
import org.bouncycastle.asn1.x509.AlgorithmIdentifier;
import org.bouncycastle.pkcs.PKCS8EncryptedPrivateKeyInfo;
final class PKCS8
{
private static final ASN1ObjectIdentifier AES = ASN1ObjectIdentifier.getInstance(NISTObjectIdentifiers.id_aes128_CBC);
static RSAPublicKey toPublic(RSAPrivateCrtKey pvt)
throws GeneralSecurityException
{
RSAPublicKeySpec pub = new RSAPublicKeySpec(pvt.getModulus(), pvt.getPublicExponent());
KeyFactory f = KeyFactory.getInstance("RSA");
return (RSAPublicKey) f.generatePublic(pub);
}
static byte[] encrypt(SecretKey secret, PrivateKey pvt)
throws Exception
{
Cipher enc = Cipher.getInstance("AES/CBC/PKCS5Padding");
enc.init(Cipher.WRAP_MODE, secret);
ASN1Encodable params = new DEROctetString(enc.getIV());
AlgorithmIdentifier algId = new AlgorithmIdentifier(AES, params);
byte[] ciphertext = enc.wrap(pvt);
return new EncryptedPrivateKeyInfo(algId, ciphertext).getEncoded();
}
static PrivateKey decrypt(SecretKey secret, byte[] pkcs8)
throws Exception
{
EncryptedPrivateKeyInfo info = new PKCS8EncryptedPrivateKeyInfo(pkcs8).toASN1Structure();
AlgorithmIdentifier id = info.getEncryptionAlgorithm();
byte[] iv = ((ASN1OctetString) id.getParameters()).getOctets();
Cipher dec = Cipher.getInstance("AES/CBC/PKCS5Padding");
dec.init(Cipher.UNWRAP_MODE, secret, new IvParameterSpec(iv));
return (PrivateKey) dec.unwrap(info.getEncryptedData(), "RSA", Cipher.PRIVATE_KEY);
}
}
I want to sign a text file (may be a .exe file or something else in the future)
using PKCS#7 and verify the signature using Java.
What do I need to know?
Where will I find an API (.jar and documentation)?
What are the steps I need to follow in order to sign data and verify the data?
Please provide me code snippet if possible.
I reckon you need the following 2 Bouncy Castle jars to generate the PKCS7 digital signature:
bcprov-jdk15on-147.jar (for JDK 1.5 - JDK 1.7)
bcmail-jdk15on-147.jar (for JDK 1.5 - JDK 1.7)
You can download the Bouncy Castle jars from here.
You need to setup your keystore with the public & private key pair.
You need only the private key to generate the digital signature & the public key to verify it.
Here's how you'd pkcs7 sign content (Exception handling omitted for brevity) :
import java.io.FileInputStream;
import java.io.InputStream;
import java.security.KeyStore;
import java.security.PrivateKey;
import java.security.Security;
import java.security.cert.Certificate;
import java.security.cert.X509Certificate;
import java.util.ArrayList;
import java.util.List;
import org.bouncycastle.cert.jcajce.JcaCertStore;
import org.bouncycastle.cms.CMSProcessableByteArray;
import org.bouncycastle.cms.CMSSignedData;
import org.bouncycastle.cms.CMSSignedDataGenerator;
import org.bouncycastle.cms.CMSTypedData;
import org.bouncycastle.cms.jcajce.JcaSignerInfoGeneratorBuilder;
import org.bouncycastle.jce.provider.BouncyCastleProvider;
import org.bouncycastle.operator.ContentSigner;
import org.bouncycastle.operator.jcajce.JcaContentSignerBuilder;
import org.bouncycastle.operator.jcajce.JcaDigestCalculatorProviderBuilder;
import org.bouncycastle.util.Store;
import org.bouncycastle.util.encoders.Base64;
public final class PKCS7Signer {
private static final String PATH_TO_KEYSTORE = "/path/to/keyStore";
private static final String KEY_ALIAS_IN_KEYSTORE = "My_Private_Key";
private static final String KEYSTORE_PASSWORD = "MyPassword";
private static final String SIGNATUREALGO = "SHA1withRSA";
public PKCS7Signer() {
}
KeyStore loadKeyStore() throws Exception {
KeyStore keystore = KeyStore.getInstance("JKS");
InputStream is = new FileInputStream(PATH_TO_KEYSTORE);
keystore.load(is, KEYSTORE_PASSWORD.toCharArray());
return keystore;
}
CMSSignedDataGenerator setUpProvider(final KeyStore keystore) throws Exception {
Security.addProvider(new BouncyCastleProvider());
Certificate[] certchain = (Certificate[]) keystore.getCertificateChain(KEY_ALIAS_IN_KEYSTORE);
final List<Certificate> certlist = new ArrayList<Certificate>();
for (int i = 0, length = certchain == null ? 0 : certchain.length; i < length; i++) {
certlist.add(certchain[i]);
}
Store certstore = new JcaCertStore(certlist);
Certificate cert = keystore.getCertificate(KEY_ALIAS_IN_KEYSTORE);
ContentSigner signer = new JcaContentSignerBuilder(SIGNATUREALGO).setProvider("BC").
build((PrivateKey) (keystore.getKey(KEY_ALIAS_IN_KEYSTORE, KEYSTORE_PASSWORD.toCharArray())));
CMSSignedDataGenerator generator = new CMSSignedDataGenerator();
generator.addSignerInfoGenerator(new JcaSignerInfoGeneratorBuilder(new JcaDigestCalculatorProviderBuilder().setProvider("BC").
build()).build(signer, (X509Certificate) cert));
generator.addCertificates(certstore);
return generator;
}
byte[] signPkcs7(final byte[] content, final CMSSignedDataGenerator generator) throws Exception {
CMSTypedData cmsdata = new CMSProcessableByteArray(content);
CMSSignedData signeddata = generator.generate(cmsdata, true);
return signeddata.getEncoded();
}
public static void main(String[] args) throws Exception {
PKCS7Signer signer = new PKCS7Signer();
KeyStore keyStore = signer.loadKeyStore();
CMSSignedDataGenerator signatureGenerator = signer.setUpProvider(keyStore);
String content = "some bytes to be signed";
byte[] signedBytes = signer.signPkcs7(content.getBytes("UTF-8"), signatureGenerator);
System.out.println("Signed Encoded Bytes: " + new String(Base64.encode(signedBytes)));
}
}
PKCS#7 is known as CMS now (Cryptographic Message Syntax), and you will need the Bouncy Castle PKIX libraries to create one. It has ample documentation and a well established mailing list.
I won't supply code snippet, it is against house rules. Try yourself first.