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Bigint

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Zach S-B 2021-11-05 17:30:18 +11:00
parent a0ee0db03b
commit e5967e6e7a
1 changed files with 23 additions and 26 deletions
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49
Q2Tools.java
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@ -26,36 +26,33 @@ public class Q2Tools {
* @param B * @param B
* @param C * @param C
*/ */
public void fastModularExpon(int A, int B, int C) public BigInteger fastModularExpon(String base, String exponent, String modulus)
{ {
String bInBinary = Integer.toBinaryString(B); // BigInteger baseVal = new BigInteger(base);
// BigInteger exponentVal = new BigInteger(exponent);
double test = 1; // BigInteger modulusVal = new BigInteger(modulus);
{ //modulusVal.equals(BigInteger.valueOf(1));
int k = 0; if(modulusVal == 1)
//Loop through the Binary String, starting from the right {
for(int i = bInBinary.length()-1; i >= 0; i--) return BigInteger.valueOf(0);
{
if(bInBinary.charAt(i)=='1')
{
System.out.println("Loop: "+k);
double step1 = Math.pow(2, k);
System.out.println("STEP1: "+step1);
double step2 = Math.pow(A, step1)%C;
System.out.println("STEP2: "+step2);
test= test*step2;
}
k++;
}
} }
BigInteger temp = new BigInteger("1");
System.out.println(test);
System.out.println(Math.pow(5, 64)%19); while(exponentVal>0)
{
if((exponentVal & 1)==1)
{
// temp = (temp * baseVal) % modulusVal;
temp = temp.multiply(BigInteger.valueOf(baseVal));
temp = temp.mod(BigInteger.valueOf(modulusVal));
}
exponentVal = exponentVal >> 1;
baseVal = (baseVal*baseVal) % modulusVal;
}
return temp;
} }
} }