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Fix Base64.toIntegerBytes(BigInteger) for zero edge case. #441

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Merged
garydgregory merged 1 commit into from
Jul 9, 2026
+290 −18
Merged

Fix Base64.toIntegerBytes(BigInteger) for zero edge case. #441

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24 changes: 6 additions & 18 deletions src/main/java/org/apache/commons/codec/binary/Base64.java
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Original file line number Diff line number Diff line change
Expand Up @@ -794,25 +794,13 @@ public static boolean isBase64Url(final String base64) {
* @return a byte array representation of the BigInteger parameter.
*/
static byte[] toIntegerBytes(final BigInteger bigInt) {
int bitlen = bigInt.bitLength();
// round bitlen
bitlen = bitlen + 7 >> 3 << 3;
final byte[] bigBytes = bigInt.toByteArray();
if (bigInt.bitLength() % 8 != 0 && bigInt.bitLength() / 8 + 1 == bitlen / 8) {
return bigBytes;
byte[] unsigned = bigInt.toByteArray();
if (unsigned[0] == 0 && unsigned.length != 1) {
final byte[] tmp = new byte[unsigned.length - 1];
System.arraycopy(unsigned, 1, tmp, 0, tmp.length);
unsigned = tmp;
}
// set up params for copying everything but sign bit
int startSrc = 0;
int len = bigBytes.length;
// if bigInt is exactly byte-aligned, just skip signbit in copy
if (bigInt.bitLength() % 8 == 0) {
startSrc = 1;
len--;
}
final int startDst = bitlen / 8 - len; // to pad w/ nulls as per spec
final byte[] resizedBytes = new byte[bitlen / 8];
System.arraycopy(bigBytes, startSrc, resizedBytes, startDst, len);
return resizedBytes;
return unsigned;
}

static byte[] toUrlSafeEncodeTable(final boolean urlSafe) {
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284 changes: 284 additions & 0 deletions src/test/java/org/apache/commons/codec/binary/Base64ToIntegerBytesTest.java
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Original file line number Diff line number Diff line change
@@ -0,0 +1,284 @@
/*
* Licensed to the Apache Software Foundation (ASF) under one or more
* contributor license agreements. See the NOTICE file distributed with
* this work for additional information regarding copyright ownership.
* The ASF licenses this file to You under the Apache License, Version 2.0
* (the "License"); you may not use this file except in compliance with
* the License. You may obtain a copy of the License at
*
* https://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/

package org.apache.commons.codec.binary;

import static org.junit.jupiter.api.Assertions.assertArrayEquals;
import static org.junit.jupiter.api.Assertions.assertEquals;
import static org.junit.jupiter.api.Assertions.assertNotNull;
import static org.junit.jupiter.api.Assertions.assertThrows;
import static org.junit.jupiter.api.Assertions.assertTrue;

import java.math.BigInteger;

import org.junit.jupiter.api.Test;

class Base64ToIntegerBytesTest {

private static final byte[] ZERO_BYTE_ARRAY = new byte[] { 0 };

@Test
void testBigIntegerWithAllZeros() {
final BigInteger allZeros = new BigInteger("0");
final byte[] result = Base64.toIntegerBytes(allZeros);
assertArrayEquals(ZERO_BYTE_ARRAY, result);
}

@Test
void testBigIntegerWithBoundaryValues() {
// Test boundary values that might cause overflow or underflow issues
final BigInteger[] boundaries = { BigInteger.valueOf(Integer.MAX_VALUE), BigInteger.valueOf(Integer.MIN_VALUE), BigInteger.valueOf(Long.MAX_VALUE),
BigInteger.valueOf(Long.MIN_VALUE) };
for (final BigInteger boundary : boundaries) {
assertNotNull(Base64.toIntegerBytes(boundary), "Should handle boundary value: " + boundary);
}
}

@Test
void testBigIntegerWithByteBoundaryValues() {
// Test specific byte boundary values
final BigInteger[] boundaryValues = { BigInteger.valueOf(Byte.MAX_VALUE), // 127
BigInteger.valueOf(Byte.MIN_VALUE), // -128
BigInteger.valueOf(255), // 255 (unsigned byte max)
BigInteger.valueOf(-256) // -256
};
for (final BigInteger boundary : boundaryValues) {
assertNotNull(Base64.toIntegerBytes(boundary), "Should handle boundary value: " + boundary);
}
}

@Test
void testBigIntegerWithDecimalString() {
final BigInteger decimal = new BigInteger("100");
final byte[] result = Base64.toIntegerBytes(decimal);
assertNotNull(result);
assertTrue(result.length > 0);
}

@Test
void testBigIntegerWithHexValues() {
// Test with hex string representation
final BigInteger hexValue = new BigInteger("FF", 16); // 255
final byte[] result = Base64.toIntegerBytes(hexValue);
assertNotNull(result);
assertEquals(1, result.length);
assertEquals(-1, result[0]); // -1 in two's complement
}

@Test
void testBigIntegerWithLargeValues() {
// Test very large numbers that exceed typical integer ranges
final BigInteger huge = new BigInteger("9223372036854775807"); // Long.MAX_VALUE
final byte[] result = Base64.toIntegerBytes(huge);
assertNotNull(result);
assertTrue(result.length > 0);
}

@Test
void testBigIntegerWithLeadingZeros() {
// Create a BigInteger that would have leading zeros in byte representation
final BigInteger big = new BigInteger("00000000000000000000000000000001", 16);
final byte[] result = Base64.toIntegerBytes(big);
assertNotNull(result);
assertEquals(1, result.length);
assertEquals(1, result[0]);
}

@Test
void testBigIntegerWithMaxValue() {
final BigInteger max = BigInteger.valueOf(Long.MAX_VALUE);
final byte[] result = Base64.toIntegerBytes(max);
assertNotNull(result);
assertTrue(result.length > 0);
}

@Test
void testBigIntegerWithMinValue() {
final BigInteger min = BigInteger.valueOf(Long.MIN_VALUE);
final byte[] result = Base64.toIntegerBytes(min);
assertNotNull(result);
assertTrue(result.length > 0);
}

@Test
void testBigIntegerWithMixedSigns() {
// Test that the method correctly handles negative numbers
final BigInteger[] negativeValues = { BigInteger.valueOf(-1), BigInteger.valueOf(-256), BigInteger.valueOf(Integer.MIN_VALUE),
new BigInteger("-999999999999999999") };
for (final BigInteger negative : negativeValues) {
assertNotNull(Base64.toIntegerBytes(negative), "Should handle negative value: " + negative);
}
}

@Test
void testBigIntegerWithMultipleBytes() {
// Test a number that requires multiple bytes to represent
final BigInteger multiByte = new BigInteger("65536"); // 2^16
final byte[] result = Base64.toIntegerBytes(multiByte);
assertNotNull(result);
assertTrue(result.length >= 2);
// Should correctly represent the multi-byte value
}

@Test
void testBigIntegerWithNegativeHexValues() {
// Test with negative hex values
final BigInteger hexNeg = new BigInteger("80", 16); // -128 in two's complement
final byte[] result = Base64.toIntegerBytes(hexNeg);
assertNotNull(result);
assertEquals(1, result.length);
assertEquals(-128, result[0]);
}

@Test
void testBigIntegerWithNegativeLargeValues() {
final BigInteger hugeNeg = new BigInteger("-9223372036854775808"); // Long.MIN_VALUE
final byte[] result = Base64.toIntegerBytes(hugeNeg);
assertNotNull(result);
assertTrue(result.length > 0);
}

@Test
void testBigIntegerWithNegativeVeryLargeNumber() {
final String largeString = "-1234567890123456789012345678901234567890";
final BigInteger large = new BigInteger(largeString);
final byte[] result = Base64.toIntegerBytes(large);
assertNotNull(result);
assertTrue(result.length > 0);
}

@Test
void testBigIntegerWithOverflowProtection() {
// Test that the method handles overflow conditions gracefully
final BigInteger overflowTest = new BigInteger("12345678901234567890123456789012345678901234567890");
final byte[] result = Base64.toIntegerBytes(overflowTest);
assertNotNull(result);
assertTrue(result.length > 0);
}

@Test
void testBigIntegerWithSingleByteRange() {
// Test boundary values for single byte range
final BigInteger[] testValues = { BigInteger.valueOf(-128), // -128 (minimum byte value)
BigInteger.valueOf(-127), // -127
BigInteger.valueOf(-1), // -1
BigInteger.valueOf(0), // 0
BigInteger.valueOf(1), // 1
BigInteger.valueOf(126), // 126
BigInteger.valueOf(127) // 127 (maximum byte value)
};
for (final BigInteger value : testValues) {
final byte[] result = Base64.toIntegerBytes(value);
assertNotNull(result, "Should not return null for value: " + value);
}
}

@Test
void testBigIntegerWithVeryLargeNumber() {
// Test with numbers that have many digits
final String largeString = "1234567890123456789012345678901234567890";
final BigInteger large = new BigInteger(largeString);
final byte[] result = Base64.toIntegerBytes(large);
assertNotNull(result);
assertTrue(result.length > 0);
}

@Test
void testBigIntegerWithVeryLargePositiveValue() {
final BigInteger veryLarge = new BigInteger("123456789012345678901234567890");
final byte[] result = Base64.toIntegerBytes(veryLarge);
assertNotNull(result);
assertTrue(result.length > 0);
}

@Test
void testBigIntegerWithVerySmallNegativeValue() {
final BigInteger verySmall = new BigInteger("-256");
final byte[] result = Base64.toIntegerBytes(verySmall);
assertNotNull(result);
assertTrue(result.length > 0);
}

@Test
void testBigIntegerWithZeroInDifferentFormats() {
// Different ways to represent zero
final BigInteger zero1 = BigInteger.ZERO;
final BigInteger zero2 = new BigInteger("0");
final BigInteger zero3 = new BigInteger("0000000000000000");
final byte[] result1 = Base64.toIntegerBytes(zero1);
final byte[] result2 = Base64.toIntegerBytes(zero2);
final byte[] result3 = Base64.toIntegerBytes(zero3);
assertArrayEquals(ZERO_BYTE_ARRAY, result1);
assertArrayEquals(ZERO_BYTE_ARRAY, result2);
assertArrayEquals(ZERO_BYTE_ARRAY, result3);
}


@Test
void testLargeNegativeBigInteger() {
final BigInteger large = new BigInteger("-2147483648"); // Integer.MIN_VALUE
final byte[] result = Base64.toIntegerBytes(large);
assertNotNull(result);
// Should handle large negative numbers correctly
assertTrue(result.length > 0);
}

@Test
void testLargePositiveBigInteger() {
final BigInteger large = new BigInteger("2147483647"); // Integer.MAX_VALUE
final byte[] result = Base64.toIntegerBytes(large);
assertNotNull(result);
// Should handle large positive numbers correctly
assertTrue(result.length > 0);
}

@Test
void testNullBigInteger() {
assertThrows(NullPointerException.class, () -> {
Base64.toIntegerBytes(null);
});
}

@Test
void testOneBigInteger() {
final BigInteger one = BigInteger.ONE;
final byte[] result = Base64.toIntegerBytes(one);
assertNotNull(result);
// Should represent the integer value 1
assertEquals(1, result.length);
assertEquals(1, result[0]);
}

@Test
void testSmallNegativeBigInteger() {
final BigInteger small = new BigInteger("-128");
final byte[] result = Base64.toIntegerBytes(small);
assertNotNull(result);
assertEquals(1, result.length);
assertEquals(-128, result[0]);
}

@Test
void testSmallPositiveBigInteger() {
final BigInteger small = new BigInteger("127");
final byte[] result = Base64.toIntegerBytes(small);
assertNotNull(result);
assertEquals(1, result.length);
assertEquals(127, result[0]);
}

}
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