docs: public static byte[] changeC1C3C2ToC1C2C3(byte[] c1c3c2, ECDomainParameters ecDomainParameters) {
  		// sm2p256v1的这个固定65。可看GMNamedCurves、ECCurve代码。
  		final int c1Len = (ecDomainParameters.getCurve().getFieldSize() + 7) / 8 * 2 + 1;
  		final int c3Len = 32; // new SM3Digest().getDigestSize();
  		byte[] result = new byte[c1c3c2.length];
  		System.arraycopy(c1c3c2, 0, result, 0, c1Len); // c1: 0->65
  		System.arraycopy(c1c3c2, c1Len + c3Len, result, c1Len, c1c3c2.length - c1Len - c3Len); // c2
  		System.arraycopy(c1c3c2, c1Len, result, c1c3c2.length - c3Len, c3Len); // c3
  		return result;
  	}