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 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.

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 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or

 * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License

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 * accompanied this code).

 *

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package sun.security.util.math;

import java.math.BigInteger;

/**

 * An interface for the field of integers modulo a prime number. An

 * implementation of this interface can be used to get properties of the

 * field and to produce field elements of type ImmutableIntegerModuloP from

 * other objects and representations of field elements.

 */

public interface IntegerFieldModuloP {

    /**

     * Get the size of the field as a BigInteger. This size is equal to the

     * prime modulus used to construct the field.

     *

     * @return the size of the field.

     */

    BigInteger getSize();

    /**

     * Get the additive identity element 0

     *

     * @return the additive identity element

     */

    ImmutableIntegerModuloP get0();

    /**

     * Get the multiplicative identity element 1

     *

     * @return the multiplicative identity element

     */

    ImmutableIntegerModuloP get1();

    /**

     * Get the field element equivalent to the supplied BigInteger value. The

     * supplied value may be negative or larger than the modulus that defines

     * the field.

     *

     * @param v a BigInteger value

     * @return the field element corresponding to v

     */

    ImmutableIntegerModuloP getElement(BigInteger v);

    /**

     * Get a "small" value according to this implementation. This value may

     * be used in optimized forms of some operations to avoid unnecessary

     * calculations. For example, multiplication is much faster when it is

     * known that one of the numbers fits within a single limb.

     *

     * The definition of "small", and the range of accepted values, is

     * implementation-specific.

     *

     * @param v the small integer value

     * @throws IllegalArgumentException when the value is not small

     */

    SmallValue getSmallValue(int v);

    /**

     * Get a field element from a little-endian unsigned integer stored in an

     * array. The entire array will be used, and the supplied value may be

     * larger than the modulus that defines the field. The array will not be

     * modified.

     *

     * @param v an array containing a little-endian unsigned integer

     * @return the field element corresponding to v

     */

    default ImmutableIntegerModuloP getElement(byte[] v) {

        return getElement(v, 0, v.length, (byte) 0);

    }

    /**

     * Get a field element from a little-endian unsigned integer stored at the

     * specified position in an array. The supplied value may be

     * larger than the modulus that defines the field. This method also takes

     * a byte which is interpreted as an additional high-order byte of the

     * number. The array will not be modified.

     *

     * @param v an array containing a little-endian unsigned integer

     * @param offset the starting position of the integer

     * @param length the number of bytes to read

     * @param highByte the high-order byte of the number

     * @return the field element corresponding to the bytes at the specified

     *     position

     */

    ImmutableIntegerModuloP getElement(byte[] v, int offset, int length,

                                       byte highByte);

}