java.lang.Object
cryptix.openpgp.util.PGPMPI
- public class PGPMPI
- extends java.lang.Object
Read and write BigIntegers in a PGP compatible format.
From RFC 2440:
3.2. Multi-Precision Integers
Multi-Precision Integers (also called MPIs) are unsigned integers
used to hold large integers such as the ones used in cryptographic
calculations.
An MPI consists of two pieces: a two-octet scalar that is the length
of the MPI in bits followed by a string of octets that contain the
actual integer.
These octets form a big-endian number; a big-endian number can be
made into an MPI by prefixing it with the appropriate length.
Examples:
(all numbers are in hexadecimal)
The string of octets [00 01 01] forms an MPI with the value 1. The
string [00 09 01 FF] forms an MPI with the value of 511.
Additional rules:
The size of an MPI is ((MPI.length + 7) / 8) + 2 octets.
The length field of an MPI describes the length starting from its
most significant non-zero bit. Thus, the MPI [00 02 01] is not formed
correctly. It should be [00 01 01].
- Version:
- $Revision: 1.2 $
|
Constructor Summary |
private |
PGPMPI()
|
| Methods inherited from class java.lang.Object |
clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait |
PGPMPI
private PGPMPI()
decode
public static java.math.BigInteger decode(java.io.DataInput in)
throws java.io.IOException
- Read a BigInteger from a stream
encode
public static void encode(java.io.DataOutput out,
java.math.BigInteger x)
throws java.io.IOException
- Write a BigInteger to a stream
toFixedLenByteArray
public static byte[] toFixedLenByteArray(java.math.BigInteger x,
int resultByteLen)
- Fit (stretch or shrink) the given positive BigInteger into a
byte[] of resultByteLen bytes without losing precision.
JAVADOC | 
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