diff options
Diffstat (limited to 'src/main/java/org/uic/barcode/utils/ECKeyEncoder.java')
| -rw-r--r-- | src/main/java/org/uic/barcode/utils/ECKeyEncoder.java | 321 |
1 files changed, 321 insertions, 0 deletions
diff --git a/src/main/java/org/uic/barcode/utils/ECKeyEncoder.java b/src/main/java/org/uic/barcode/utils/ECKeyEncoder.java new file mode 100644 index 0000000..e1662a7 --- /dev/null +++ b/src/main/java/org/uic/barcode/utils/ECKeyEncoder.java @@ -0,0 +1,321 @@ +package org.uic.barcode.utils;
+
+import java.math.BigInteger;
+import java.security.AlgorithmParameters;
+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;
+import java.security.spec.ECPublicKeySpec;
+import java.security.spec.EllipticCurve;
+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;
+
+
+ String keyAlgName = null;
+ try {
+ keyAlgName = AlgorithmNameResolver.getName(AlgorithmNameResolver.TYPE_KEY_GENERATOR_ALG, oid,provider);
+ } catch (Exception e1) {
+ throw new IllegalArgumentException("algorithm unknown in: " + provider.getName());
+ }
+
+ if (keyAlgName == null || keyAlgName.length() == 0) {
+ throw new IllegalArgumentException("algorithm unknown in: " + provider.getName());
+ }
+
+ //try standard X.509 encoding first
+
+ try {
+
+ X509EncodedKeySpec keySpec = new X509EncodedKeySpec(keyBytes);
+
+ if (keyAlgName != null && keyAlgName.length() > 0) {
+
+ KeyFactory keyFactory = KeyFactory.getInstance(keyAlgName,provider);
+
+ key = keyFactory.generatePublic(keySpec);
+
+ }
+
+ } catch (Exception e) {
+
+ //try next option
+
+ }
+
+ if (key != null) return key;
+
+
+ //maybe a compressed X9.62 eliptic key
+ if (keyBytes[0] == X962_ODD || keyBytes[0] == X962_EVEN) {
+
+
+ try {
+
+ //we need to know the curve!
+ String curveName = EllipticCurveNames.getInstance().getName(oid);
+
+ AlgorithmParameters parameters = AlgorithmParameters.getInstance(keyAlgName, provider);
+ parameters.init(new ECGenParameterSpec(curveName));
+ ECParameterSpec ecParameters = parameters.getParameterSpec(ECParameterSpec.class);
+
+ //reconstruct the uncompressed version with the curve
+ byte[] uncompressed = decompressPubkey(keyBytes, ecParameters);
+
+ //decode the uncompressed key
+ return fromUncompressedPoint(uncompressed, ecParameters, provider);
+
+ } catch (Exception e) {
+ key = null;
+ // failed
+ }
+
+
+ }
+
+ //try X962 uncompressed
+ if (keyBytes[0] == X962_UNCOMPRESSED_POINT_INDICATOR) {
+
+ try {
+ //we need to know the curve!
+ String curveName = EllipticCurveNames.getInstance().getName(oid);
+
+ //get the curve parameters
+ AlgorithmParameters parameters = AlgorithmParameters.getInstance(keyAlgName, provider);
+ parameters.init(new ECGenParameterSpec(curveName));
+ ECParameterSpec ecParameters = parameters.getParameterSpec(ECParameterSpec.class);
+
+ //decode the uncompressed key
+ return fromUncompressedPoint(keyBytes, ecParameters, provider);
+
+ } catch(Exception e) {
+ //failed
+ }
+ }
+
+
+ throw new IllegalArgumentException("public key format unknown");
+ }
+
+
+
+ /**
+ * Gets the encoded.
+ *
+ * @param key the public key
+ * @param encoding the encoding ("X509","X962_UNCOMPRESSED","X962_COMPRESSED")
+ * @param provider
+ * @return the encoded key
+ */
+ public static byte[] getEncoded(PublicKey key, String encoding){
+
+ if (encoding.equals(ENCODING_X509)) {
+ return key.getEncoded();
+ } else if (encoding.equals(ENCODING_X962_UNCOMPESSED)) {
+
+ if (key instanceof ECPublicKey) {
+
+ return toUncompressedPoint((ECPublicKey) key);
+
+ }
+
+ } else if (encoding.equals(ENCODING_X962_COMPRESSED)) {
+
+ 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();
+
+
+ //compression indicator
+ if (y.testBit(0)) {
+ compressed[0] = 0x03;
+ } else {
+ compressed[0] = 0x02;
+ }
+ System.arraycopy(x, 0, compressed, 1 + fieldSize - x.length, x.length);
+
+ return compressed;
+ }
+ }
+
+ throw new IllegalArgumentException("unknown encoding");
+
+
+ }
+
+
+ /**
+ * 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, Provider provider)
+ throws Exception {
+
+ int offset = 0;
+ 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 (encoded.length != 1 + 2 * keySizeBytes) {
+ throw new IllegalArgumentException("Invalid uncompressedPoint encoding, not the correct size");
+ }
+
+ final BigInteger x = new BigInteger(1, Arrays.copyOfRange(encoded, offset, offset + keySizeBytes));
+ 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",provider);
+ return (ECPublicKey) keyFactory.generatePublic(ecPublicKeySpec);
+ }
+
+
+ /**
+ * 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;
+ }
+
+
+
+ /**
+ * 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[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);
+ boolean tempIsOdd = temp.testBit(0);
+ boolean yShouldBeOdd = compressedKey[0] == 3;
+ if (tempIsOdd != yShouldBeOdd) {
+ temp = temp.negate().mod(modulus);
+ }
+ final BigInteger yCoord = temp;
+
+ 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;
+
+ 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
+ if (b[0] == 0) {
+ b = Arrays.copyOfRange(b, 1, b.length);
+ }
+ return b;
+ }
+
+
+}
|