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25 package java.security.spec;
26 
27 import java.util.Objects;
28 
29 /**
30  * A class representing elliptic curve private keys as defined in RFC 7748,
31  * including the curve and other algorithm parameters. The private key is
32  * represented as an encoded scalar value. The decoding procedure defined in
33  * the RFC includes an operation that forces certain bits of the key to either
34  * 1 or 0. This operation is known as "pruning" or "clamping" the private key.
35  * All arrays in this spec are unpruned, and implementations will need to prune
36  * the array before using it in any numerical operations.
37  *
38  * @since 11
39  */
40 public class XECPrivateKeySpec implements KeySpec {
41 
42     private final AlgorithmParameterSpec params;
43     private final byte[] scalar;
44 
45     /**
46      * Construct a private key spec using the supplied parameters and
47      * encoded scalar value.
48      *
49      * @param params the algorithm parameters
50      * @param scalar the unpruned encoded scalar value. This array is copied
51      *               to protect against subsequent modification.
52      *
53      * @throws NullPointerException if {@code params} or {@code scalar}
54      *                              is null.
55      */
XECPrivateKeySpec(AlgorithmParameterSpec params, byte[] scalar)56     public XECPrivateKeySpec(AlgorithmParameterSpec params, byte[] scalar) {
57         Objects.requireNonNull(params, "params must not be null");
58         Objects.requireNonNull(scalar, "scalar must not be null");
59 
60         this.params = params;
61         this.scalar = scalar.clone();
62     }
63 
64     /**
65      * Get the algorithm parameters that define the curve and other settings.
66      *
67      * @return the algorithm parameters
68      */
getParams()69     public AlgorithmParameterSpec getParams() {
70         return params;
71     }
72 
73     /**
74      * Get the scalar value encoded as an unpruned byte array. A new copy of
75      * the array is returned each time this method is called.
76      *
77      * @return the unpruned encoded scalar value
78      */
getScalar()79     public byte[] getScalar() {
80         return scalar.clone();
81     }
82 }
83