?? bignum.java
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package rsa;import java.io.PrintStream;/** * <p>Title: </p> * <p>Description: </p> * <p>Copyright: Copyright (c) 2003</p> * <p>Company: </p> * @author not attributable * @version 1.0 */public class BigNum //implements myCloneable{ private static final String LIBRARY_NAME = "bignum"; private static boolean native_link_ok = false; private static boolean native_lib_loaded = false; private static String native_link_err = "Class not loaded"; private static BigNum staticZero; private static BigNum staticOne;/* static { // load the DLL or shared library that contains the native code try { System.loadLibrary( LIBRARY_NAME ); native_lib_loaded = true; try { // // Should really do a bit more testing than this ... // if (bignum_test() == 0) { // create a static BigNum that will be set to one. native_link_ok = true; native_link_err = null; staticOne = new BigNum(); staticOne.setToOne(); } else { native_link_err = "Self test failed"; } } catch ( UnsatisfiedLinkError ule ) { native_link_err = "Errors linking to " + LIBRARY_NAME + " native library"; } } catch ( UnsatisfiedLinkError ule ) { native_link_err = "The " + LIBRARY_NAME + " native library was not found"; } }*/ public final static boolean hasFileLibraryLoaded() { return native_lib_loaded; } public final static boolean isLibraryCorrect() { return native_link_ok; } public final static String getLinkErrorString() { return native_link_err; } // // Constants // // If LONG // static final int BITS = 62; // Not 63, since we dont have unsigned // static final long RADIX = (1L << BITS); // static final long MASK = RADIX-1; // static final int LBITS = BITS/2; // static final long LRADIX = (1L << LBITS); // static final long LMASK = LRADIX-1; // If not LONG static final int BITS = 30; static final int RADIX = (1 << BITS); static final int MASK = RADIX-1; static final int LBITS = BITS/2; static final int LRADIX = (1 << LBITS); static final int LMASK = LRADIX-1; // // Data members for Java implementation // // If LONG // private long n[]; // If not LONG private int n[]; private int len; private boolean negative; // // Data members for native implementation // private int pointer_; // N.B. may need to be long if running on a 64bit machine public int byteLength() { int r = ((len - 1) * BITS)/8; // If LONG // long i = n[0]; // If not LONG int i = n[0]; while (i != 0) { i >>>= 8; ++r; } return r; } public void check_state() { bitLength(this); } public static int bitLength(BigNum n) { int len = n.len; if (len == 0) return 0; int r = (len - 1) * BITS; // If LONG // long i = n.n[len-1]; // If not LONG int i = n.n[len-1]; // Could probably speed this up with a binary search while (i != 0) { i >>>= 1; ++r; }// For debugging onlyif (r == 0) throw new MathError("Invalid state"); return r; } public static boolean bit(BigNum n, int i) { int bit = i % BITS; i /= BITS; if (i >= n.len || ((n.n[i] & (1L << bit)) == 0)) return false; return true; } protected BigNum() { // If LONG // n = new long[8]; // 512 bits (nearly) // If not LONG n = new int[16]; // 512 bits (nearly) len = 0; negative = false; } public Object clone() { BigNum r = new BigNum(); copy(r, this); return r; } public void copy(Object src) { copy(this, (BigNum)src); } protected static void copy(BigNum dst, BigNum src) { if (dst == src) return; // throw new IllegalArgumentException(); // If LONG // dst.n = new long[src.n.length]; // If not LONG dst.n = new int[src.n.length]; dst.negative = src.negative; dst.len = src.len; if (src.len > 0) System.arraycopy(src.n, 0, dst.n, 0, src.len); } public static void grow(BigNum a, int i) { // If LONG // long an[] = a.n; // If not LONG int an[] = a.n; if (i <= an.length) return; i += 16; // Add 8 or 16 for efficiency // If LONG // long n[] = new long[i]; // If not LONG int n[] = new int[i]; System.arraycopy(an, 0, n, 0, an.length); a.n = n; } public int intoBinary(byte buffer[]) { int len = (bitLength(this)+7)/8; if (buffer.length < (len)) throw new MathError("into-binary buffer too small"); int pos = 0; int bitpos = 0; // Index in reverse to get LSB first for (int i = len-1; i >= 0; --i) { int b = (int)((n[pos] >>> bitpos) & 0xFFL); bitpos += 8; if (bitpos >= BITS) { bitpos -= BITS; pos++; if (bitpos > 0) b |= (n[pos] << (8-bitpos)) & 0xFFL; } buffer[i] = (byte)b; } return len; } protected void fromBinary(byte buffer[]) { negative = false; // Can't init negatives yet len = ((buffer.length)*8 + BITS-1) / BITS; grow(this, len); int pos = 0; n[pos] = 0; int bitpos = 0; // Index in reverse to get LSB first for (int i = buffer.length-1; i >= 0; --i) { // If LONG // long b = buffer[i] & 0xFF; // If not LONG int b = buffer[i] & 0xFF; n[pos] |= (b << bitpos) & MASK; bitpos += 8; if (bitpos >= BITS) { pos++; n[pos] = 0; bitpos -= BITS; if (bitpos > 0) n[pos] = b >>> (8-bitpos); } } while (len > 0 && n[len-1] == 0) len--; } public static void assign(BigNum r, int val) { if (val != 0) { r.len = 1; // If LONG // r.n[0] = val & 0x7FFFFFFFL; // If not LONG r.n[0] = val & 0x7FFFFFFF; r.negative = (val < 0); } else { r.len = 0; r.n[0] = 0; r.negative = false; } } public static void zero(BigNum a) { a.n[0] = 0; a.negative = false; a.len = 0; } public static void one(BigNum a) { a.n[0] = 1; a.negative = false; a.len = 1; } public static boolean isOne(BigNum a) { return (a.len == 1 && a.n[0] == 1); } public static boolean even(BigNum a) { return !(a.len > 0 && (a.n[0] & 1) == 1); } public static boolean odd(BigNum a) { return (a.len > 0 && (a.n[0] & 1) == 1); } public static boolean isZero(BigNum a) { if (a.len == 0) return true;a.check_state(); // if (a.len > 1) return false; // return (a.n[0] == 0); return false; } public static void inc(BigNum a) { add(a, 1); } public static void dec(BigNum a) { sub(a, 1); } public static void add( BigNum r, int a ) { if (a == 0) return; if (a < 0) { if (r.negative) { r.negative = false; add_unsigned(r, -a); r.negative = true; } else { sub_unsigned(r, -a); } } else { if (r.negative) {?? 快捷鍵說明
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