com.google.crypto.tink.internal

Class BigIntegerEncoding

java.lang.Object

com.google.crypto.tink.internal.BigIntegerEncoding

public final class BigIntegerEncoding
extends Object

Helper class with functions that encode and decode non-negative BigInteger to and from byte[].

Method Summary

Modifier and Type	Method and Description
static BigInteger	fromUnsignedBigEndianBytes(byte[] bytes) Parses a BigInteger from a byte array using unsigned big-endian encoding.
static byte[]	toBigEndianBytes(BigInteger n) Encodes a non-negative BigInteger into the minimal two's-complement representation in big-endian byte-order.
static byte[]	toBigEndianBytesOfFixedLength(BigInteger n, int length) Encodes a non-negative BigInteger into a byte array of a specified length, using big-endian byte-order.

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Method Detail

toBigEndianBytes

public static byte[] toBigEndianBytes(BigInteger n)

Encodes a non-negative BigInteger into the minimal two's-complement representation in big-endian byte-order.

The most significant bit of the first byte is the sign bit, which is always 0 because the input number is non-negative. Because of that, the output is at the same time also an unsigned big-endian encoding that may have an additional zero byte at the beginning, and can be parsed with fromUnsignedBigEndianBytes(byte[]).

toBigEndianBytesOfFixedLength

public static byte[] toBigEndianBytesOfFixedLength(BigInteger n,
                                                   int length)
                                            throws GeneralSecurityException

Encodes a non-negative BigInteger into a byte array of a specified length, using big-endian byte-order.

See also RFC 8017, Sec. 4.2

throws a GeneralSecurityException if the number is negative or length is too short.

Throws:

GeneralSecurityException

fromUnsignedBigEndianBytes

public static BigInteger fromUnsignedBigEndianBytes(byte[] bytes)

Parses a BigInteger from a byte array using unsigned big-endian encoding.

See also RFC 8017, Sec. 4.2