Java byte array to ECCPrivateKey - InvalidKeySpecException: encoded key spec not recognised

Question

When I try to make ECC private key from byte array, I get exception mentioned below. I have public/private keys and out signed output from C library micro-ecc/uECC.h. C used secp192r1 curve. I am trying to verify data with C generated keys in Java. How to convert byte array to private/public key?

Security.addProvider(new org.bouncycastle.jce.provider.BouncyCastleProvider());
byte[] kb = new byte[]{(byte)0x24, (byte)0xF4, (byte)0x36, (byte)0x16, (byte)0xD0, (byte)0x96, (byte)0x12, (byte)0x63, (byte)0x90, (byte)0x2E, (byte)0x51, (byte)0xF6, (byte)0x87, (byte)0x55, (byte)0xAB, (byte)0xCB, (byte)0x5D, (byte)0xAC, (byte)0x56, (byte)0x1A, (byte)0xA5, (byte)0xFA, (byte)0x55, (byte)0xDB};
X509EncodedKeySpec ks = new X509EncodedKeySpec(kb);
KeyFactory kf = java.security.KeyFactory.getInstance("ECDH", "BC");
org.bouncycastle.jce.interfaces.ECPrivateKey remotePublicKey = (org.bouncycastle.jce.interfaces.ECPrivateKey)kf.generatePublic(ks);

java.security.spec.InvalidKeySpecException: encoded key spec not recognised
at org.bouncycastle.jcajce.provider.asymmetric.util.BaseKeyFactorySpi.engineGeneratePublic(Unknown Source)
at org.bouncycastle.jcajce.provider.asymmetric.ec.KeyFactorySpi.engineGeneratePublic(Unknown Source)
at java.security.KeyFactory.generatePublic(KeyFactory.java:328)

Also I have tried to use

KeyFactory.getInstance("ECDH", "BC");

but it throws the same exception above.

KeyFactory.getInstance("EC");

throws

java.security.InvalidKeyException: invalid key format

or

java.security.spec.InvalidKeySpecException: java.security.InvalidKeyException: IOException : DerInputStream.getLength(): lengthTag=116, too big.

I have public/private keys and out signed output in C librarary micro-ecc/uECC.h. I am trying to verify it in Java. — Justinas Jakavonis
– Justinas Jakavonis, Commented May 25, 2016 at 13:43
C used secp192r1 but I don't know if it necessary to provide it when loading public/private key in Java and how to do it. — Justinas Jakavonis
– Justinas Jakavonis, Commented May 25, 2016 at 13:51
When I generate key pair and create copies in Java, it works well. — Justinas Jakavonis
– Justinas Jakavonis, Commented May 26, 2016 at 14:54
@Justas If you generate correctly EC keypairs in Java using KeyPairGenerator.getInstance("EC") and then you can parse it using KeyFactory methods. Then probably your byte[] keys are wrong or has some specific format. Also note that there is an error in your code (not related directly with the exception): kf.generatePublic(ks) can not be cast to ECPrivateKey so change it to: (org.bouncycastle.jce.interfaces.ECPublicKey)kf.generatePublic(ks);. — albciff
– albciff, Commented May 26, 2016 at 21:29

Justinas Jakavonis · Accepted Answer · 2016-10-24 08:06:57Z

4

X509EncodedKeySpec(key) or PKCS8EncodedKeySpec(key) constructors take private/public keys in encoded format. Unencoded key bytes can be converted this way:

Security.addProvider(new org.bouncycastle.jce.provider.BouncyCastleProvider());
ECNamedCurveParameterSpec spec = ECNamedCurveTable.getParameterSpec("secp192r1");

ECPrivateKeySpec ecPrivateKeySpec = new ECPrivateKeySpec(new BigInteger(1, privateKeyBytes), spec); 

ECNamedCurveSpec params = new ECNamedCurveSpec("secp192r1", spec.getCurve(), spec.getG(), spec.getN());
java.security.spec.ECPoint w = new java.security.spec.ECPoint(new BigInteger(1, Arrays.copyOfRange(publicKeyBytes, 0, 24)), new BigInteger(1, Arrays.copyOfRange(publicKeyBytes, 24, 48)));
PublicKey publicKey = factory.generatePublic(new java.security.spec.ECPublicKeySpec(w, params));

edited Oct 24, 2016 at 8:06

answered Jun 10, 2016 at 10:17

Justinas Jakavonis

8,97812 gold badges82 silver badges118 bronze badges

Sign up to request clarification or add additional context in comments.

Collectives™ on Stack Overflow

Java byte array to ECCPrivateKey - InvalidKeySpecException: encoded key spec not recognised

1 Answer 1

Comments

Your Answer

Linked

Hot Network Questions

Collectives™ on Stack Overflow

1 Answer 1

Comments

Your Answer

Sign up or log in

Post as a guest

Linked

Related