fix getD

hutool-crypto/src/main/java/cn/hutool/crypto/asymmetric/SM2.java

@@ -19,7 +19,9 @@ import org.bouncycastle.crypto.signers.DSAEncoding;
 import org.bouncycastle.crypto.signers.PlainDSAEncoding;
 import org.bouncycastle.crypto.signers.SM2Signer;
 import org.bouncycastle.crypto.signers.StandardDSAEncoding;
+import org.bouncycastle.util.BigIntegers;
 
+import java.math.BigInteger;
 import java.security.PrivateKey;
 import java.security.PublicKey;
 
@@ -519,7 +521,27 @@ public class SM2 extends AbstractAsymmetricCrypto<SM2> {
 	 * @since 5.5.9
 	 */
 	public byte[] getD() {
-		return this.privateKeyParams.getD().toByteArray();
+		return BigIntegers.asUnsignedByteArray(getDBigInteger());
+	}
+
+	/**
+	 * 获得私钥D值（编码后的私钥）
+	 *
+	 * @return D值
+	 * @since 5.7.17
+	 */
+	public String getDHex() {
+		return getDBigInteger().toString(16);
+	}
+
+	/**
+	 * 获得私钥D值
+	 *
+	 * @return D值
+	 * @since 5.7.17
+	 */
+	public BigInteger getDBigInteger() {
+		return this.privateKeyParams.getD();
 	}
 
 	/**

hutool-crypto/src/test/java/cn/hutool/crypto/test/asymmetric/SM2Test.java

@@ -311,4 +311,14 @@ public class SM2Test {
 		byte[] dec =  sm2.decrypt(data, KeyType.PrivateKey);
 		Assert.assertArrayEquals(dec, src.getBytes(StandardCharsets.UTF_8));
 	}
+
+	@Test
+	public void dLengthTest(){
+		final SM2 sm2 = SmUtil.sm2();
+		Assert.assertEquals(64, sm2.getDHex().length());
+		Assert.assertEquals(32, sm2.getD().length);
+
+		// 04占位一个字节
+		Assert.assertEquals(65, sm2.getQ(false).length);
+	}
 }