diff options
Diffstat (limited to 'src/main/java/org/uic/barcode')
| -rw-r--r-- | src/main/java/org/uic/barcode/utils/ECKeyEncoder.java | 187 |
1 files changed, 112 insertions, 75 deletions
diff --git a/src/main/java/org/uic/barcode/utils/ECKeyEncoder.java b/src/main/java/org/uic/barcode/utils/ECKeyEncoder.java index 96038d3..705b178 100644 --- a/src/main/java/org/uic/barcode/utils/ECKeyEncoder.java +++ b/src/main/java/org/uic/barcode/utils/ECKeyEncoder.java @@ -6,6 +6,7 @@ import java.security.KeyFactory; import java.security.Provider;
import java.security.PublicKey;
import java.security.interfaces.ECPublicKey;
+import java.security.spec.ECFieldFp;
import java.security.spec.ECGenParameterSpec;
import java.security.spec.ECParameterSpec;
import java.security.spec.ECPoint;
@@ -15,17 +16,40 @@ import java.security.spec.X509EncodedKeySpec; import java.util.Arrays;
+// TODO: Auto-generated Javadoc
+/**
+ * The Class ECKeyEncoder.
+ */
public class ECKeyEncoder {
+ /** The Constant X962_UNCOMPRESSED_POINT_INDICATOR. */
private static final byte X962_UNCOMPRESSED_POINT_INDICATOR = 0x04;
+
+ /** The Constant X962_ODD. */
private static final byte X962_ODD = 0x02;
+
+ /** The Constant X962_EVEN. */
private static final byte X962_EVEN = 0x03;
+ /** The Constant ENCODING_X509. */
public static final String ENCODING_X509 = "X509";
+
+ /** The Constant ENCODING_X962_UNCOMPESSED. */
public static final String ENCODING_X962_UNCOMPESSED = "X962_UNCOMPRESSED";
+
+ /** The Constant ENCODING_X962_COMPRESSED. */
public static final String ENCODING_X962_COMPRESSED = "X962_COMPRESSED";
+
+ /**
+ * From encoded.
+ *
+ * @param keyBytes the encoded key
+ * @param oid the algorithm OID of the key algorithm
+ * @param provider the provider of the security implementation
+ * @return the public key
+ */
public static PublicKey fromEncoded (byte[] keyBytes, String oid, Provider provider) {
PublicKey key = null;
@@ -64,12 +88,7 @@ public class ECKeyEncoder { if (key != null) return key;
- if (keyBytes[0] == X962_UNCOMPRESSED_POINT_INDICATOR) {
-
-
-
- }
-
+
//maybe a compressed X9.62 eliptic key
if (keyBytes[0] == X962_ODD || keyBytes[0] == X962_EVEN) {
@@ -82,11 +101,10 @@ public class ECKeyEncoder { //get the curve parameters
AlgorithmParameters parameters = AlgorithmParameters.getInstance(keyAlgName, provider);
parameters.init(new ECGenParameterSpec(curveName));
- ECParameterSpec ecParameters = parameters.getParameterSpec(ECParameterSpec.class);
- EllipticCurve curve = ecParameters.getCurve();
+ ECParameterSpec ecParameters = parameters.getParameterSpec(ECParameterSpec.class);
//reconstruct the uncompressed version with the curve
- byte[] uncompressed = decompressPubkey(keyBytes, curve);
+ byte[] uncompressed = decompressPubkey(keyBytes, ecParameters);
//decode the uncompressed key
return fromUncompressedPoint(uncompressed, ecParameters);
@@ -125,7 +143,14 @@ public class ECKeyEncoder { - public static byte[] getEncoded(PublicKey key, String encoding){
+ /**
+ * Gets the encoded.
+ *
+ * @param key the public key
+ * @param encoding the encoding ("X509","X962_UNCOMPRESSED","X962_COMPRESSED")
+ * @return the encoded key
+ */
+ public static byte[] getEncoded(PublicKey key, String encoding){
if (encoding.equals(ENCODING_X509)) {
return key.getEncoded();
@@ -142,12 +167,17 @@ public class ECKeyEncoder { if (key instanceof ECPublicKey) {
ECPoint point = ((ECPublicKey) key).getW();
+
+ int fieldSize = (((ECPublicKey)key).getParams().getCurve().getField().getFieldSize() + 7) / 8;
+ int keySizeBytes = fieldSize + 1;
+ final byte[] compressed = new byte[keySizeBytes];
+
+
byte[] x = toUnsignedBytes(point.getAffineX());
BigInteger y = point.getAffineY();
- byte[] compressed = new byte[x.length + 1];
//compression indicator
if (y.testBit(0)) {
@@ -155,7 +185,7 @@ public class ECKeyEncoder { } else {
compressed[0] = 0x02;
}
- System.arraycopy(x, 0, compressed, 1, x.length);
+ System.arraycopy(x, 0, compressed, 1 + fieldSize - x.length, x.length);
return compressed;
}
@@ -167,110 +197,117 @@ public class ECKeyEncoder { }
- private static ECPublicKey fromUncompressedPoint(
- final byte[] uncompressedPoint, final ECParameterSpec params)
+ /**
+ * From uncompressed point.
+ *
+ * @param encoded the public key in uncompressed encoding
+ * @param params the elliptic curve parameters
+ * @return the EC public key
+ * @throws Exception the exception
+ */
+ private static ECPublicKey fromUncompressedPoint(
+ final byte[] encoded, final ECParameterSpec params)
throws Exception {
int offset = 0;
- if (uncompressedPoint[offset++] != X962_UNCOMPRESSED_POINT_INDICATOR) {
- throw new IllegalArgumentException(
- "Invalid uncompressedPoint encoding, no uncompressed point indicator");
+ if (encoded[offset++] != X962_UNCOMPRESSED_POINT_INDICATOR) {
+ throw new IllegalArgumentException("Invalid uncompressedPoint encoding, no uncompressed point indicator");
}
int keySizeBytes = (params.getOrder().bitLength() + Byte.SIZE - 1)
/ Byte.SIZE;
- if (uncompressedPoint.length != 1 + 2 * keySizeBytes) {
- throw new IllegalArgumentException(
- "Invalid uncompressedPoint encoding, not the correct size");
+ if (encoded.length != 1 + 2 * keySizeBytes) {
+ throw new IllegalArgumentException("Invalid uncompressedPoint encoding, not the correct size");
}
- final BigInteger x = new BigInteger(1, Arrays.copyOfRange(
- uncompressedPoint, offset, offset + keySizeBytes));
+ final BigInteger x = new BigInteger(1, Arrays.copyOfRange(encoded, offset, offset + keySizeBytes));
offset += keySizeBytes;
- final BigInteger y = new BigInteger(1, Arrays.copyOfRange(
- uncompressedPoint, offset, offset + keySizeBytes));
+ final BigInteger y = new BigInteger(1, Arrays.copyOfRange(encoded, offset, offset + keySizeBytes));
final ECPoint w = new ECPoint(x, y);
final ECPublicKeySpec ecPublicKeySpec = new ECPublicKeySpec(w, params);
final KeyFactory keyFactory = KeyFactory.getInstance("EC");
return (ECPublicKey) keyFactory.generatePublic(ecPublicKeySpec);
}
- private static byte[] toUncompressedPoint(final ECPublicKey publicKey) {
-
- int keySizeBytes = (publicKey.getParams().getOrder().bitLength() + Byte.SIZE - 1)
- / Byte.SIZE;
-
- final byte[] uncompressedPoint = new byte[1 + 2 * keySizeBytes];
- int offset = 0;
- uncompressedPoint[offset++] = 0x04;
-
- final byte[] x = publicKey.getW().getAffineX().toByteArray();
- if (x.length <= keySizeBytes) {
- System.arraycopy(x, 0, uncompressedPoint, offset + keySizeBytes
- - x.length, x.length);
- } else if (x.length == keySizeBytes + 1 && x[0] == 0) {
- System.arraycopy(x, 1, uncompressedPoint, offset, keySizeBytes);
- } else {
- throw new IllegalStateException("x value is too large");
- }
- offset += keySizeBytes;
-
- final byte[] y = publicKey.getW().getAffineY().toByteArray();
- if (y.length <= keySizeBytes) {
- System.arraycopy(y, 0, uncompressedPoint, offset + keySizeBytes
- - y.length, y.length);
- } else if (y.length == keySizeBytes + 1 && y[0] == 0) {
- System.arraycopy(y, 1, uncompressedPoint, offset, keySizeBytes);
- } else {
- throw new IllegalStateException("y value is too large");
- }
+
+ /**
+ * To uncompressed point.
+ *
+ * @param publicKey the public key
+ * @return the encoded public key
+ */
+ private static byte[] toUncompressedPoint(final ECPublicKey publicKey) {
+
+ final byte[] xCoordBytes = toUnsignedBytes(publicKey.getW().getAffineX());
+ final byte[] yCoordBytes = toUnsignedBytes(publicKey.getW().getAffineY());
+
+ int fieldSize = (publicKey.getParams().getCurve().getField().getFieldSize() + 7) / 8;
+ int keySizeBytes = 2 * fieldSize + 1;
+ final byte[] uncompressedPoint = new byte[keySizeBytes];
+
+ System.arraycopy(xCoordBytes, 0, uncompressedPoint, 1 + fieldSize - xCoordBytes.length, xCoordBytes.length);
+ System.arraycopy(yCoordBytes, 0, uncompressedPoint, 1 + 2 * fieldSize - yCoordBytes.length, yCoordBytes.length);
+ uncompressedPoint[0] = 0x04;
return uncompressedPoint;
}
- static final BigInteger MODULUS =
- new BigInteger("FFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFEFFFFFC2F", 16);
-
- static final BigInteger POW = MODULUS.add(BigInteger.ONE).shiftRight(2);
- // Given a 33-byte compressed public key, this returns a 65-byte uncompressed key.
- private static byte[] decompressPubkey(byte[] compressedKey, EllipticCurve curve ) {
+
+ /**
+ * Decompress public key.
+ *
+ * @param compressedKey the compressed public key
+ * @param ecParameters the elliptic curve parameters
+ * @return uncompressed encoded public key
+ */
+ private static byte[] decompressPubkey(byte[] compressedKey, ECParameterSpec ecParameters ) {
+ EllipticCurve curve = ecParameters.getCurve();
+
// Check array length and type indicator byte
- if (compressedKey.length != 33 || compressedKey[0] != 2 && compressedKey[0] != 3)
+ if (compressedKey[0] != 2 && compressedKey[0] != 3) {
throw new IllegalArgumentException();
+ }
final byte[] xCoordBytes = Arrays.copyOfRange(compressedKey, 1, compressedKey.length);
final BigInteger xCoord = new BigInteger(1, xCoordBytes); // Range [0, 2^256)
+ ECFieldFp ecf = (ECFieldFp) curve.getField();
+ BigInteger modulus = ecf.getP();
+ BigInteger pow = modulus.add(BigInteger.ONE).shiftRight(2);
+
BigInteger temp = xCoord.pow(2).add(curve.getA());
temp = temp.multiply(xCoord);
temp = temp.add(curve.getB());
- temp = temp.modPow(POW, MODULUS);
-
- //temp = sqrtMod(temp.add(curveParamB));
-
+ temp = temp.modPow(pow, modulus);
boolean tempIsOdd = temp.testBit(0);
boolean yShouldBeOdd = compressedKey[0] == 3;
- if (tempIsOdd != yShouldBeOdd)
- temp = temp.negate().mod(MODULUS);
+ if (tempIsOdd != yShouldBeOdd) {
+ temp = temp.negate().mod(modulus);
+ }
final BigInteger yCoord = temp;
-
- // Copy the x coordinate into the new
- // uncompressed key, and change the type byte
- byte[] result = Arrays.copyOf(compressedKey, 65);
+
+ final byte[] yCoordBytes = toUnsignedBytes(yCoord);
+
+ int fieldSize = (curve.getField().getFieldSize() + 7) / 8;
+ byte[] result = new byte[2 * fieldSize + 1];
+ System.arraycopy(compressedKey, 0,result, 1 + fieldSize - compressedKey.length, compressedKey.length);
+ System.arraycopy(yCoordBytes, 0,result, 1 + 2 * fieldSize - yCoordBytes.length, yCoordBytes.length);
+ // set uncompressed key indicator
result[0] = 0x04;
- // Carefully copy the y coordinate into uncompressed key
- final byte[] yCoordBytes = yCoord.toByteArray();
- for (int i = 0; i < 32 && i < yCoordBytes.length; i++)
- result[result.length - 1 - i] = yCoordBytes[yCoordBytes.length - 1 - i];
-
return result;
}
+ /**
+ * To unsigned bytes.
+ *
+ * @param i the i
+ * @return the unsigned bytes of the integer
+ */
private static byte[] toUnsignedBytes(BigInteger i) {
byte[] b = i.abs().toByteArray();
//remove top sign bit
|