blob: 2851bcae18654ef389c28576ed859072ac6c4220 (
plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
|
package org.bouncycastle.asn1.x9;
import java.math.BigInteger;
import org.bouncycastle.math.ec.ECCurve;
import org.bouncycastle.math.ec.ECFieldElement;
/**
* A class which converts integers to byte arrays, allowing padding and calculations
* to be done according the the filed size of the curve or field element involved.
*/
public class X9IntegerConverter
{
/**
* Return the curve's field size in bytes.
*
* @param c the curve of interest.
* @return the field size in bytes (rounded up).
*/
public int getByteLength(
ECCurve c)
{
return (c.getFieldSize() + 7) / 8;
}
/**
* Return the field element's field size in bytes.
*
* @param fe the field element of interest.
* @return the field size in bytes (rounded up).
*/
public int getByteLength(
ECFieldElement fe)
{
return (fe.getFieldSize() + 7) / 8;
}
/**
* Convert an integer to a byte array, ensuring it is exactly qLength long.
*
* @param s the integer to be converted.
* @param qLength the length
* @return the resulting byte array.
*/
public byte[] integerToBytes(
BigInteger s,
int qLength)
{
byte[] bytes = s.toByteArray();
if (qLength < bytes.length)
{
byte[] tmp = new byte[qLength];
System.arraycopy(bytes, bytes.length - tmp.length, tmp, 0, tmp.length);
return tmp;
}
else if (qLength > bytes.length)
{
byte[] tmp = new byte[qLength];
System.arraycopy(bytes, 0, tmp, tmp.length - bytes.length, bytes.length);
return tmp;
}
return bytes;
}
}
|
