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reduce object churn in ElG decrypt

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zzz
2014-09-21 22:20:37 +00:00
parent 7639c24bfe
commit 3fae6f06dd
1 changed files with 22 additions and 18 deletions
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40
core/java/src/net/i2p/crypto/ElGamalEngine.java
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@@ -56,6 +56,9 @@ public class ElGamalEngine {
private final Log _log;
private final I2PAppContext _context;
private final YKGenerator _ykgen;
private static final BigInteger ELGPM1 = CryptoConstants.elgp.subtract(BigInteger.ONE);
/**
* The ElGamal engine should only be constructed and accessed through the
@@ -171,10 +174,11 @@ public class ElGamalEngine {
if (_log.shouldLog(Log.WARN)) _log.warn("Took too long to encrypt ElGamal block (" + diff + "ms)");
}
_context.statManager().addRateData("crypto.elGamal.encrypt", diff, 0);
_context.statManager().addRateData("crypto.elGamal.encrypt", diff);
return out;
}
/** Decrypt the data
* @param encrypted encrypted data, must be exactly 514 bytes
* Contains the two-part encrypted data starting at bytes 0 and 257.
@@ -184,26 +188,26 @@ public class ElGamalEngine {
* @return unencrypted data or null on failure
*/
public byte[] decrypt(byte encrypted[], PrivateKey privateKey) {
// actually it must be exactly 514 bytes or the arraycopy below will AIOOBE
if ((encrypted == null) || (encrypted.length > 514))
throw new IllegalArgumentException("Data to decrypt must be <= 514 bytes at the moment");
if ((encrypted == null) || (encrypted.length != 514))
throw new IllegalArgumentException("Data to decrypt must be exactly 514 bytes");
long start = _context.clock().now();
byte[] ybytes = new byte[257];
byte[] dbytes = new byte[257];
System.arraycopy(encrypted, 0, ybytes, 0, 257);
System.arraycopy(encrypted, 257, dbytes, 0, 257);
BigInteger y = new NativeBigInteger(1, ybytes);
BigInteger d = new NativeBigInteger(1, dbytes);
BigInteger a = new NativeBigInteger(1, privateKey.getData());
BigInteger y1p = CryptoConstants.elgp.subtract(BigInteger.ONE).subtract(a);
BigInteger y1p = ELGPM1.subtract(a);
// we use this buf first for Y, then for D, then for the hash
byte[] buf = SimpleByteCache.acquire(257);
System.arraycopy(encrypted, 0, buf, 0, 257);
BigInteger y = new NativeBigInteger(1, buf);
BigInteger ya = y.modPow(y1p, CryptoConstants.elgp);
System.arraycopy(encrypted, 257, buf, 0, 257);
BigInteger d = new NativeBigInteger(1, buf);
BigInteger m = ya.multiply(d);
m = m.mod(CryptoConstants.elgp);
byte val[] = m.toByteArray();
int i = 0;
for (i = 0; i < val.length; i++)
int i;
for (i = 0; i < val.length; i++) {
if (val[i] != (byte) 0x00) break;
}
int payloadLen = val.length - i - 1 - Hash.HASH_LENGTH;
if (payloadLen < 0) {
@@ -220,10 +224,10 @@ public class ElGamalEngine {
byte rv[] = new byte[payloadLen];
System.arraycopy(val, i + 1 + Hash.HASH_LENGTH, rv, 0, rv.length);
byte[] calcHash = SimpleByteCache.acquire(Hash.HASH_LENGTH);
_context.sha().calculateHash(rv, 0, payloadLen, calcHash, 0);
boolean ok = DataHelper.eq(calcHash, 0, val, i + 1, Hash.HASH_LENGTH);
SimpleByteCache.release(calcHash);
// we reuse buf here for the calculated hash
_context.sha().calculateHash(rv, 0, payloadLen, buf, 0);
boolean ok = DataHelper.eq(buf, 0, val, i + 1, Hash.HASH_LENGTH);
SimpleByteCache.release(buf);
long end = _context.clock().now();
@@ -233,7 +237,7 @@ public class ElGamalEngine {
_log.warn("Took too long to decrypt and verify ElGamal block (" + diff + "ms)");
}
_context.statManager().addRateData("crypto.elGamal.decrypt", diff, 0);
_context.statManager().addRateData("crypto.elGamal.decrypt", diff);
if (ok) {
//_log.debug("Hash matches: " + DataHelper.toString(hash.getData(), hash.getData().length));