feat(common): add ChecksumUtils for MD5/SHA*/CRC32/Adler32 with Base64 and multi-algorithm support (#4261)

app/common/src/main/java/stirling/software/common/util/ChecksumUtils.java

@@ -0,0 +1,301 @@
+package stirling.software.common.util;
+
+import java.io.IOException;
+import java.io.InputStream;
+import java.nio.ByteBuffer;
+import java.nio.ByteOrder;
+import java.nio.file.Files;
+import java.nio.file.Path;
+import java.security.MessageDigest;
+import java.security.NoSuchAlgorithmException;
+import java.util.Base64;
+import java.util.LinkedHashMap;
+import java.util.Locale;
+import java.util.Map;
+import java.util.zip.Adler32;
+import java.util.zip.CRC32;
+import java.util.zip.Checksum;
+
+import lombok.experimental.UtilityClass;
+
+@UtilityClass
+public class ChecksumUtils {
+
+    /** Shared buffer size for streaming I/O. */
+    private static final int BUFFER_SIZE = 8192;
+
+    /** Mask to extract the lower 32 bits of a long value (unsigned int). */
+    private static final long UNSIGNED_32_BIT_MASK = 0xFFFFFFFFL;
+
+    /**
+     * Computes a checksum for the given file using the chosen algorithm and returns a lowercase hex
+     * string.
+     *
+     * <p>For digest algorithms (e.g., SHA-256, SHA-1, MD5), this returns the digest as hex. For
+     * 32-bit {@link Checksum} algorithms ("CRC32", "ADLER32"), this returns an 8-character
+     * lowercase hex string of the unsigned 32-bit value.
+     *
+     * @param path file to read
+     * @param algorithm algorithm name (case-insensitive). Special values: "CRC32", "ADLER32".
+     * @return hex string of the checksum
+     * @throws IOException if the file cannot be read
+     */
+    public static String checksum(Path path, String algorithm) throws IOException {
+        try (InputStream is = Files.newInputStream(path)) {
+            return checksum(is, algorithm);
+        }
+    }
+
+    /**
+     * Computes a checksum for the given stream using the chosen algorithm and returns a lowercase
+     * hex string.
+     *
+     * <p><strong>Note:</strong> This method does <em>not</em> close the provided stream.
+     *
+     * @param is input stream (not closed by this method)
+     * @param algorithm algorithm name (case-insensitive). Special values: "CRC32", "ADLER32".
+     * @return hex string of the checksum
+     * @throws IOException if reading from the stream fails
+     */
+    public static String checksum(InputStream is, String algorithm) throws IOException {
+        switch (algorithm.toUpperCase(Locale.ROOT)) {
+            case "CRC32":
+                return checksumChecksum(is, new CRC32());
+            case "ADLER32":
+                return checksumChecksum(is, new Adler32());
+            default:
+                return toHex(checksumBytes(is, algorithm));
+        }
+    }
+
+    /**
+     * Computes a checksum for the given file using the chosen algorithm and returns a Base64
+     * encoded string.
+     *
+     * <p>For digest algorithms this is the Base64 of the raw digest bytes. For 32-bit checksum
+     * algorithms ("CRC32", "ADLER32"), this is the Base64 of the 4-byte big-endian unsigned value.
+     *
+     * @param path file to read
+     * @param algorithm algorithm name (case-insensitive). Special values: "CRC32", "ADLER32".
+     * @return Base64-encoded checksum bytes
+     * @throws IOException if the file cannot be read
+     */
+    public static String checksumBase64(Path path, String algorithm) throws IOException {
+        try (InputStream is = Files.newInputStream(path)) {
+            return checksumBase64(is, algorithm);
+        }
+    }
+
+    /**
+     * Computes a checksum for the given stream using the chosen algorithm and returns a Base64
+     * encoded string.
+     *
+     * <p><strong>Note:</strong> This method does <em>not</em> close the provided stream.
+     *
+     * @param is input stream (not closed by this method)
+     * @param algorithm algorithm name (case-insensitive). Special values: "CRC32", "ADLER32".
+     * @return Base64-encoded checksum bytes
+     * @throws IOException if reading from the stream fails
+     */
+    public static String checksumBase64(InputStream is, String algorithm) throws IOException {
+        switch (algorithm.toUpperCase(Locale.ROOT)) {
+            case "CRC32":
+                return Base64.getEncoder().encodeToString(checksumChecksumBytes(is, new CRC32()));
+            case "ADLER32":
+                return Base64.getEncoder().encodeToString(checksumChecksumBytes(is, new Adler32()));
+            default:
+                return Base64.getEncoder().encodeToString(checksumBytes(is, algorithm));
+        }
+    }
+
+    /**
+     * Computes multiple checksums for the given file in a single pass over the data.
+     *
+     * <p>Returns a map from algorithm name to lowercase hex string. Order of results follows the
+     * order of the provided {@code algorithms}.
+     *
+     * @param path file to read
+     * @param algorithms algorithm names (case-insensitive). Special: "CRC32", "ADLER32".
+     * @return map of algorithm → hex string
+     * @throws IOException if the file cannot be read
+     */
+    public static Map<String, String> checksums(Path path, String... algorithms)
+            throws IOException {
+        try (InputStream is = Files.newInputStream(path)) {
+            return checksums(is, algorithms);
+        }
+    }
+
+    /**
+     * Computes multiple checksums for the given stream in a single pass over the data.
+     *
+     * <p><strong>Note:</strong> This method does <em>not</em> close the provided stream.
+     *
+     * @param is input stream (not closed by this method)
+     * @param algorithms algorithm names (case-insensitive). Special: "CRC32", "ADLER32".
+     * @return map of algorithm → hex string
+     * @throws IOException if reading from the stream fails
+     */
+    public static Map<String, String> checksums(InputStream is, String... algorithms)
+            throws IOException {
+        // Use LinkedHashMap to preserve the order of requested algorithms in the result.
+        Map<String, MessageDigest> digests = new LinkedHashMap<>();
+        Map<String, Checksum> checksums = new LinkedHashMap<>();
+
+        for (String algorithm : algorithms) {
+            String key = algorithm; // keep original key for output
+            switch (algorithm.toUpperCase(Locale.ROOT)) {
+                case "CRC32":
+                    checksums.put(key, new CRC32());
+                    break;
+                case "ADLER32":
+                    checksums.put(key, new Adler32());
+                    break;
+                default:
+                    try {
+                        // For MessageDigest, pass the original name (case-insensitive per JCA)
+                        digests.put(key, MessageDigest.getInstance(algorithm));
+                    } catch (NoSuchAlgorithmException e) {
+                        throw new IllegalStateException("Unsupported algorithm: " + algorithm, e);
+                    }
+            }
+        }
+
+        byte[] buffer = new byte[BUFFER_SIZE];
+        int read;
+        while ((read = is.read(buffer)) != -1) {
+            for (MessageDigest digest : digests.values()) {
+                digest.update(buffer, 0, read);
+            }
+            for (Checksum cs : checksums.values()) {
+                cs.update(buffer, 0, read);
+            }
+        }
+
+        Map<String, String> results = new LinkedHashMap<>();
+        for (Map.Entry<String, MessageDigest> entry : digests.entrySet()) {
+            results.put(entry.getKey(), toHex(entry.getValue().digest()));
+        }
+        for (Map.Entry<String, Checksum> entry : checksums.entrySet()) {
+            // Keep value as long and mask to ensure unsigned hex formatting.
+            long unsigned32 = entry.getValue().getValue() & UNSIGNED_32_BIT_MASK;
+            results.put(entry.getKey(), String.format("%08x", unsigned32));
+        }
+        return results;
+    }
+
+    /**
+     * Compares the checksum of a file with an expected hex string (case-insensitive).
+     *
+     * @param path file to read
+     * @param algorithm algorithm name (case-insensitive). Special: "CRC32", "ADLER32".
+     * @param expected expected hex string (case-insensitive)
+     * @return {@code true} if they match, otherwise {@code false}
+     * @throws IOException if the file cannot be read
+     */
+    public static boolean matches(Path path, String algorithm, String expected) throws IOException {
+        try (InputStream is = Files.newInputStream(path)) {
+            return matches(is, algorithm, expected);
+        }
+    }
+
+    /**
+     * Compares the checksum of a stream with an expected hex string (case-insensitive).
+     *
+     * <p><strong>Note:</strong> This method does <em>not</em> close the provided stream.
+     *
+     * @param is input stream (not closed by this method)
+     * @param algorithm algorithm name (case-insensitive). Special: "CRC32", "ADLER32".
+     * @param expected expected hex string (case-insensitive)
+     * @return {@code true} if they match, otherwise {@code false}
+     * @throws IOException if reading from the stream fails
+     */
+    public static boolean matches(InputStream is, String algorithm, String expected)
+            throws IOException {
+        return checksum(is, algorithm).equalsIgnoreCase(expected);
+    }
+
+    // ---------- Internal helpers ----------
+
+    /**
+     * Computes a MessageDigest over a stream and returns the raw digest bytes.
+     *
+     * @param is input stream (not closed)
+     * @param algorithm JCA MessageDigest algorithm (e.g., "SHA-256")
+     * @return raw digest bytes
+     * @throws IOException if reading fails
+     * @throws IllegalStateException if the algorithm is unsupported
+     */
+    private static byte[] checksumBytes(InputStream is, String algorithm) throws IOException {
+        try {
+            MessageDigest digest = MessageDigest.getInstance(algorithm);
+            byte[] buffer = new byte[BUFFER_SIZE];
+            int read;
+            while ((read = is.read(buffer)) != -1) {
+                digest.update(buffer, 0, read);
+            }
+            return digest.digest();
+        } catch (NoSuchAlgorithmException e) {
+            // Keep the message explicit to aid debugging
+            throw new IllegalStateException("Unsupported algorithm: " + algorithm, e);
+        }
+    }
+
+    /**
+     * Computes a 32-bit {@link Checksum} over a stream and returns the lowercase 8-char hex of the
+     * unsigned 32-bit value.
+     *
+     * @param is input stream (not closed)
+     * @param checksum checksum implementation (CRC32, Adler32, etc.)
+     * @return 8-character lowercase hex (big-endian representation)
+     * @throws IOException if reading fails
+     */
+    private static String checksumChecksum(InputStream is, Checksum checksum) throws IOException {
+        byte[] buffer = new byte[BUFFER_SIZE];
+        int read;
+        while ((read = is.read(buffer)) != -1) {
+            checksum.update(buffer, 0, read);
+        }
+        // Keep as long and mask to ensure correct unsigned representation.
+        long unsigned32 = checksum.getValue() & UNSIGNED_32_BIT_MASK;
+        return String.format("%08x", unsigned32);
+    }
+
+    /**
+     * Computes a 32-bit {@link Checksum} over a stream and returns the raw 4-byte big-endian
+     * representation of the unsigned 32-bit value.
+     *
+     * <p>Cast to int already truncates to the lower 32 bits; the sign is irrelevant because we
+     * serialize the bit pattern directly into 4 bytes.
+     *
+     * @param is input stream (not closed)
+     * @param checksum checksum implementation (CRC32, Adler32, etc.)
+     * @return 4 bytes (big-endian)
+     * @throws IOException if reading fails
+     */
+    private static byte[] checksumChecksumBytes(InputStream is, Checksum checksum)
+            throws IOException {
+        byte[] buffer = new byte[BUFFER_SIZE];
+        int read;
+        while ((read = is.read(buffer)) != -1) {
+            checksum.update(buffer, 0, read);
+        }
+        // Cast keeps only the lower 32 bits; mask is unnecessary here.
+        int v = (int) checksum.getValue();
+        return ByteBuffer.allocate(4).order(ByteOrder.BIG_ENDIAN).putInt(v).array();
+    }
+
+    /**
+     * Converts bytes to a lowercase hex string.
+     *
+     * @param hash the byte array to convert
+     * @return the lowercase hex string
+     */
+    private static String toHex(byte[] hash) {
+        StringBuilder sb = new StringBuilder(hash.length * 2);
+        for (byte b : hash) {
+            sb.append(String.format("%02x", b));
+        }
+        return sb.toString();
+    }
+}

app/common/src/test/java/stirling/software/common/util/ChecksumUtilsTest.java

@@ -0,0 +1,66 @@
+package stirling.software.common.util;
+
+import static org.junit.jupiter.api.Assertions.assertEquals;
+import static org.junit.jupiter.api.Assertions.assertTrue;
+
+import java.io.ByteArrayInputStream;
+import java.io.InputStream;
+import java.nio.charset.StandardCharsets;
+import java.util.Map;
+
+import org.junit.jupiter.api.Test;
+
+public class ChecksumUtilsTest {
+
+    @Test
+    void computeChecksums_basic() throws Exception {
+        byte[] data = "hello".getBytes(StandardCharsets.UTF_8);
+
+        // MD5 (hex)
+        try (InputStream is = new ByteArrayInputStream(data)) {
+            assertEquals("5d41402abc4b2a76b9719d911017c592", ChecksumUtils.checksum(is, "MD5"));
+        }
+
+        // MD5 (Base64)
+        try (InputStream is = new ByteArrayInputStream(data)) {
+            assertEquals("XUFAKrxLKna5cZ2REBfFkg==", ChecksumUtils.checksumBase64(is, "MD5"));
+        }
+
+        // MD5 + CRC32 (hex map)
+        try (InputStream is = new ByteArrayInputStream(data)) {
+            Map<String, String> map = ChecksumUtils.checksums(is, "MD5", "CRC32");
+            assertEquals("5d41402abc4b2a76b9719d911017c592", map.get("MD5"));
+            assertEquals("3610a686", map.get("CRC32"));
+        }
+    }
+
+    @Test
+    void crc32_base64_bigEndianBytes_forHello() throws Exception {
+        // CRC32("hello") = 0x3610A686 → bytes: 36 10 A6 86 → Base64: "NhCmhg=="
+        byte[] data = "hello".getBytes(StandardCharsets.UTF_8);
+        try (InputStream is = new ByteArrayInputStream(data)) {
+            assertEquals("NhCmhg==", ChecksumUtils.checksumBase64(is, "CRC32"));
+        }
+    }
+
+    @Test
+    void crc32_unsignedFormatting_highBitSet() throws Exception {
+        // CRC32 of single zero byte (0x00) is 0xD202EF8D (>= 0x8000_0000)
+        byte[] data = new byte[] {0x00};
+
+        // Hex (unsigned, 8 chars, lowercase)
+        try (InputStream is = new ByteArrayInputStream(data)) {
+            assertEquals("d202ef8d", ChecksumUtils.checksum(is, "CRC32"));
+        }
+
+        // Base64 of the 4-byte big-endian representation
+        try (InputStream is = new ByteArrayInputStream(data)) {
+            assertEquals("0gLvjQ==", ChecksumUtils.checksumBase64(is, "CRC32"));
+        }
+
+        // matches(..) must be case-insensitive for hex
+        try (InputStream is = new ByteArrayInputStream("hello".getBytes(StandardCharsets.UTF_8))) {
+            assertTrue(ChecksumUtils.matches(is, "CRC32", "3610A686")); // uppercase expected
+        }
+    }
+}