Method sm4_crypt_cbc

src/com/autoDecoder/util/SM4.java:272–328

(SM4_Context ctx, byte[] iv, byte[] input)

    }

    public byte[] sm4_crypt_cbc(SM4_Context ctx, byte[] iv, byte[] input) throws Exception {
        if (iv == null || iv.length != 16) {
            throw new Exception("iv error!");
        }

        if (input == null) {
            throw new Exception("input is null!");
        }

        if (ctx.isPadding && ctx.mode == SM4_ENCRYPT) {
            input = padding(input, SM4_ENCRYPT);
        }

        int i = 0;
        int length = input.length;
        ByteArrayInputStream bins = new ByteArrayInputStream(input);
        ByteArrayOutputStream bous = new ByteArrayOutputStream();
        if (ctx.mode == SM4_ENCRYPT) {
            for (; length > 0; length -= 16) {
                byte[] in = new byte[16];
                byte[] out = new byte[16];
                byte[] out1 = new byte[16];

                bins.read(in);
                for (i = 0; i < 16; i++) {
                    out[i] = ((byte) (in[i] ^ iv[i]));
                }
                sm4_one_round(ctx.sk, out, out1);
                System.arraycopy(out1, 0, iv, 0, 16);
                bous.write(out1);
            }
        } else {
            byte[] temp = new byte[16];
            for (; length > 0; length -= 16) {
                byte[] in = new byte[16];
                byte[] out = new byte[16];
                byte[] out1 = new byte[16];

                bins.read(in);
                System.arraycopy(in, 0, temp, 0, 16);
                sm4_one_round(ctx.sk, in, out);
                for (i = 0; i < 16; i++) {
                    out1[i] = ((byte) (out[i] ^ iv[i]));
                }
                System.arraycopy(temp, 0, iv, 0, 16);
                bous.write(out1);
            }
        }

        byte[] output = bous.toByteArray();
        if (ctx.isPadding && ctx.mode == SM4_DECRYPT) {
            output = padding(output, SM4_DECRYPT);
        }
        bins.close();
        bous.close();
        return output;
    }
}