diff options
Diffstat (limited to 'prov/src/main/java/org/spongycastle/jcajce/provider/asymmetric/dh/KeyAgreementSpi.java')
| -rw-r--r-- | prov/src/main/java/org/spongycastle/jcajce/provider/asymmetric/dh/KeyAgreementSpi.java | 227 |
1 files changed, 227 insertions, 0 deletions
diff --git a/prov/src/main/java/org/spongycastle/jcajce/provider/asymmetric/dh/KeyAgreementSpi.java b/prov/src/main/java/org/spongycastle/jcajce/provider/asymmetric/dh/KeyAgreementSpi.java new file mode 100644 index 00000000..63127236 --- /dev/null +++ b/prov/src/main/java/org/spongycastle/jcajce/provider/asymmetric/dh/KeyAgreementSpi.java @@ -0,0 +1,227 @@ +package org.spongycastle.jcajce.provider.asymmetric.dh; + +import java.math.BigInteger; +import java.security.InvalidAlgorithmParameterException; +import java.security.InvalidKeyException; +import java.security.Key; +import java.security.SecureRandom; +import java.security.spec.AlgorithmParameterSpec; +import java.util.Hashtable; + +import javax.crypto.SecretKey; +import javax.crypto.ShortBufferException; +import javax.crypto.interfaces.DHPrivateKey; +import javax.crypto.interfaces.DHPublicKey; +import javax.crypto.spec.DHParameterSpec; +import javax.crypto.spec.SecretKeySpec; + +import org.spongycastle.crypto.params.DESParameters; +import org.spongycastle.util.Integers; +import org.spongycastle.util.Strings; + +/** + * Diffie-Hellman key agreement. There's actually a better way of doing this + * if you are using long term public keys, see the light-weight version for + * details. + */ +public class KeyAgreementSpi + extends javax.crypto.KeyAgreementSpi +{ + private BigInteger x; + private BigInteger p; + private BigInteger g; + private BigInteger result; + + private static final Hashtable algorithms = new Hashtable(); + + static + { + Integer i64 = Integers.valueOf(64); + Integer i192 = Integers.valueOf(192); + Integer i128 = Integers.valueOf(128); + Integer i256 = Integers.valueOf(256); + + algorithms.put("DES", i64); + algorithms.put("DESEDE", i192); + algorithms.put("BLOWFISH", i128); + algorithms.put("AES", i256); + } + + private byte[] bigIntToBytes( + BigInteger r) + { + // + // RFC 2631 (2.1.2) specifies that the secret should be padded with leading zeros if necessary + // must be the same length as p + // + int expectedLength = (p.bitLength() + 7) / 8; + + byte[] tmp = r.toByteArray(); + + if (tmp.length == expectedLength) + { + return tmp; + } + + if (tmp[0] == 0 && tmp.length == expectedLength + 1) + { + byte[] rv = new byte[tmp.length - 1]; + + System.arraycopy(tmp, 1, rv, 0, rv.length); + return rv; + } + + // tmp must be shorter than expectedLength + // pad to the left with zeros. + byte[] rv = new byte[expectedLength]; + + System.arraycopy(tmp, 0, rv, rv.length - tmp.length, tmp.length); + + return rv; + } + + protected Key engineDoPhase( + Key key, + boolean lastPhase) + throws InvalidKeyException, IllegalStateException + { + if (x == null) + { + throw new IllegalStateException("Diffie-Hellman not initialised."); + } + + if (!(key instanceof DHPublicKey)) + { + throw new InvalidKeyException("DHKeyAgreement doPhase requires DHPublicKey"); + } + DHPublicKey pubKey = (DHPublicKey)key; + + if (!pubKey.getParams().getG().equals(g) || !pubKey.getParams().getP().equals(p)) + { + throw new InvalidKeyException("DHPublicKey not for this KeyAgreement!"); + } + + if (lastPhase) + { + result = ((DHPublicKey)key).getY().modPow(x, p); + return null; + } + else + { + result = ((DHPublicKey)key).getY().modPow(x, p); + } + + return new BCDHPublicKey(result, pubKey.getParams()); + } + + protected byte[] engineGenerateSecret() + throws IllegalStateException + { + if (x == null) + { + throw new IllegalStateException("Diffie-Hellman not initialised."); + } + + return bigIntToBytes(result); + } + + protected int engineGenerateSecret( + byte[] sharedSecret, + int offset) + throws IllegalStateException, ShortBufferException + { + if (x == null) + { + throw new IllegalStateException("Diffie-Hellman not initialised."); + } + + byte[] secret = bigIntToBytes(result); + + if (sharedSecret.length - offset < secret.length) + { + throw new ShortBufferException("DHKeyAgreement - buffer too short"); + } + + System.arraycopy(secret, 0, sharedSecret, offset, secret.length); + + return secret.length; + } + + protected SecretKey engineGenerateSecret( + String algorithm) + { + if (x == null) + { + throw new IllegalStateException("Diffie-Hellman not initialised."); + } + + String algKey = Strings.toUpperCase(algorithm); + byte[] res = bigIntToBytes(result); + + if (algorithms.containsKey(algKey)) + { + Integer length = (Integer)algorithms.get(algKey); + + byte[] key = new byte[length.intValue() / 8]; + System.arraycopy(res, 0, key, 0, key.length); + + if (algKey.startsWith("DES")) + { + DESParameters.setOddParity(key); + } + + return new SecretKeySpec(key, algorithm); + } + + return new SecretKeySpec(res, algorithm); + } + + protected void engineInit( + Key key, + AlgorithmParameterSpec params, + SecureRandom random) + throws InvalidKeyException, InvalidAlgorithmParameterException + { + if (!(key instanceof DHPrivateKey)) + { + throw new InvalidKeyException("DHKeyAgreement requires DHPrivateKey for initialisation"); + } + DHPrivateKey privKey = (DHPrivateKey)key; + + if (params != null) + { + if (!(params instanceof DHParameterSpec)) + { + throw new InvalidAlgorithmParameterException("DHKeyAgreement only accepts DHParameterSpec"); + } + DHParameterSpec p = (DHParameterSpec)params; + + this.p = p.getP(); + this.g = p.getG(); + } + else + { + this.p = privKey.getParams().getP(); + this.g = privKey.getParams().getG(); + } + + this.x = this.result = privKey.getX(); + } + + protected void engineInit( + Key key, + SecureRandom random) + throws InvalidKeyException + { + if (!(key instanceof DHPrivateKey)) + { + throw new InvalidKeyException("DHKeyAgreement requires DHPrivateKey"); + } + + DHPrivateKey privKey = (DHPrivateKey)key; + + this.p = privKey.getParams().getP(); + this.g = privKey.getParams().getG(); + this.x = this.result = privKey.getX(); + } +} |