diff --git a/phpstan/baseline-8.3.neon b/phpstan/baseline-8.3.neon
index 4871d6cf6..cf5444103 100644
--- a/phpstan/baseline-8.3.neon
+++ b/phpstan/baseline-8.3.neon
@@ -65,6 +65,16 @@ parameters:
 			count: 1
 			path: ../src/Composer/Console/Input/InputOption.php
 
+		-
+			message: "#^Casting to string something that's already string\\.$#"
+			count: 1
+			path: ../src/Composer/DependencyResolver/GenericRule.php
+
+		-
+			message: "#^Casting to string something that's already string\\.$#"
+			count: 1
+			path: ../src/Composer/DependencyResolver/MultiConflictRule.php
+
 		-
 			message: "#^Parameter \\#2 \\$callback of function uksort expects callable\\(string, string\\)\\: int, 'version_compare' given\\.$#"
 			count: 2
@@ -260,6 +270,11 @@ parameters:
 			count: 2
 			path: ../tests/Composer/Test/ConfigTest.php
 
+		-
+			message: "#^Casting to string something that's already string\\.$#"
+			count: 1
+			path: ../tests/Composer/Test/DependencyResolver/RuleTest.php
+
 		-
 			message: "#^Call to function method_exists\\(\\) with Composer\\\\Console\\\\Application and 'setCatchErrors' will always evaluate to true\\.$#"
 			count: 1
diff --git a/phpstan/baseline.neon b/phpstan/baseline.neon
index 8bf450f15..9dd319027 100644
--- a/phpstan/baseline.neon
+++ b/phpstan/baseline.neon
@@ -85,11 +85,6 @@ parameters:
 			count: 1
 			path: ../src/Composer/Autoload/AutoloadGenerator.php
 
-		-
-			message: "#^Parameter \\#2 \\$subject of static method Composer\\\\Pcre\\\\Preg\\:\\:isMatch\\(\\) expects string, string\\|false given\\.$#"
-			count: 1
-			path: ../src/Composer/Autoload/AutoloadGenerator.php
-
 		-
 			message: "#^Parameter \\#2 \\$to of method Composer\\\\Util\\\\Filesystem\\:\\:findShortestPathCode\\(\\) expects string, string\\|false given\\.$#"
 			count: 1
@@ -1052,7 +1047,7 @@ parameters:
 
 		-
 			message: "#^Only booleans are allowed in \\|\\|, string\\|false given on the left side\\.$#"
-			count: 2
+			count: 1
 			path: ../src/Composer/Console/Application.php
 
 		-
@@ -4193,11 +4188,6 @@ parameters:
 			count: 1
 			path: ../src/Composer/Util/Perforce.php
 
-		-
-			message: "#^Only booleans are allowed in a negated boolean, string\\|false given\\.$#"
-			count: 1
-			path: ../src/Composer/Util/Platform.php
-
 		-
 			message: "#^Method Composer\\\\Util\\\\ProcessExecutor\\:\\:doExecute\\(\\) should return int but returns int\\|null\\.$#"
 			count: 1
diff --git a/src/Composer/Autoload/AutoloadGenerator.php b/src/Composer/Autoload/AutoloadGenerator.php
index e3dd15646..2296a7eb1 100644
--- a/src/Composer/Autoload/AutoloadGenerator.php
+++ b/src/Composer/Autoload/AutoloadGenerator.php
@@ -417,7 +417,7 @@ EOF;
             }
 
             if (null === $suffix) {
-                $suffix = $locker !== null && $locker->isLocked() ? $locker->getLockData()['content-hash'] : md5(uniqid('', true));
+                $suffix = $locker !== null && $locker->isLocked() ? $locker->getLockData()['content-hash'] : bin2hex(random_bytes(16));
             }
         }
 
@@ -1052,7 +1052,7 @@ CLASSMAPAUTHORITATIVE;
         }
 
         if ($this->apcu) {
-            $apcuPrefix = var_export(($this->apcuPrefix !== null ? $this->apcuPrefix : substr(base64_encode(md5(uniqid('', true), true)), 0, -3)), true);
+            $apcuPrefix = var_export(($this->apcuPrefix !== null ? $this->apcuPrefix : bin2hex(random_bytes(10))), true);
             $file .= <<<APCU
         \$loader->setApcuPrefix($apcuPrefix);
 
@@ -1312,7 +1312,8 @@ INITIALIZER;
      */
     protected function getFileIdentifier(PackageInterface $package, string $path)
     {
-        return md5($package->getName() . ':' . $path);
+        // TODO composer v3 change this to sha1 or xxh3? Possibly not worth the potential breakage though
+        return hash('md5', $package->getName() . ':' . $path);
     }
 
     /**
diff --git a/src/Composer/Cache.php b/src/Composer/Cache.php
index b1e008594..2e6f2edad 100644
--- a/src/Composer/Cache.php
+++ b/src/Composer/Cache.php
@@ -144,7 +144,7 @@ class Cache
 
             $this->io->writeError('Writing '.$this->root . $file.' into cache', true, IOInterface::DEBUG);
 
-            $tempFileName = $this->root . $file . uniqid('.', true) . '.tmp';
+            $tempFileName = $this->root . $file . bin2hex(random_bytes(5)) . '.tmp';
             try {
                 return file_put_contents($tempFileName, $contents) !== false && rename($tempFileName, $this->root . $file);
             } catch (\ErrorException $e) {
@@ -357,7 +357,7 @@ class Cache
         if ($this->isEnabled()) {
             $file = Preg::replace('{[^'.$this->allowlist.']}i', '-', $file);
             if (file_exists($this->root . $file)) {
-                return sha1_file($this->root . $file);
+                return hash_file('sha1', $this->root . $file);
             }
         }
 
diff --git a/src/Composer/Command/DiagnoseCommand.php b/src/Composer/Command/DiagnoseCommand.php
index 06a8a84af..e95ca8eaa 100644
--- a/src/Composer/Command/DiagnoseCommand.php
+++ b/src/Composer/Command/DiagnoseCommand.php
@@ -630,7 +630,7 @@ EOT
             $errors['ioncube'] = ioncube_loader_version();
         }
 
-        if (PHP_VERSION_ID < 70205) {
+        if (\PHP_VERSION_ID < 70205) {
             $errors['php'] = PHP_VERSION;
         }
 
diff --git a/src/Composer/Command/SelfUpdateCommand.php b/src/Composer/Command/SelfUpdateCommand.php
index bd006ea88..6ca01120c 100644
--- a/src/Composer/Command/SelfUpdateCommand.php
+++ b/src/Composer/Command/SelfUpdateCommand.php
@@ -328,7 +328,7 @@ TAGSPUBKEY
             $verified = 1 === openssl_verify((string) file_get_contents($tempFilename), $signatureSha384, $pubkeyid, $algo);
 
             // PHP 8 automatically frees the key instance and deprecates the function
-            if (PHP_VERSION_ID < 80000) {
+            if (\PHP_VERSION_ID < 80000) {
                 // @phpstan-ignore function.deprecated
                 openssl_free_key($pubkeyid);
             }
diff --git a/src/Composer/Console/Application.php b/src/Composer/Console/Application.php
index 217919bc0..64166a982 100644
--- a/src/Composer/Console/Application.php
+++ b/src/Composer/Console/Application.php
@@ -321,7 +321,7 @@ class Application extends BaseApplication
                 function_exists('php_uname') ? php_uname('s') . ' / ' . php_uname('r') : 'Unknown OS'
             ), true, IOInterface::DEBUG);
 
-            if (PHP_VERSION_ID < 70205) {
+            if (\PHP_VERSION_ID < 70205) {
                 $io->writeError('<warning>Composer supports PHP 7.2.5 and above, you will most likely encounter problems with your PHP '.PHP_VERSION.'. Upgrading is strongly recommended but you can use Composer 2.2.x LTS as a fallback.</warning>');
             }
 
@@ -348,7 +348,7 @@ class Application extends BaseApplication
             // Check system temp folder for usability as it can cause weird runtime issues otherwise
             Silencer::call(static function () use ($io): void {
                 $pid = function_exists('getmypid') ? getmypid() . '-' : '';
-                $tempfile = sys_get_temp_dir() . '/temp-' . $pid . md5(microtime());
+                $tempfile = sys_get_temp_dir() . '/temp-' . $pid . bin2hex(random_bytes(5));
                 if (!(file_put_contents($tempfile, __FILE__) && (file_get_contents($tempfile) === __FILE__) && unlink($tempfile) && !file_exists($tempfile))) {
                     $io->writeError(sprintf('<error>PHP temp directory (%s) does not exist or is not writable to Composer. Set sys_temp_dir in your php.ini</error>', sys_get_temp_dir()));
                 }
diff --git a/src/Composer/DependencyResolver/GenericRule.php b/src/Composer/DependencyResolver/GenericRule.php
index f7cf7f23c..c4b2f981a 100644
--- a/src/Composer/DependencyResolver/GenericRule.php
+++ b/src/Composer/DependencyResolver/GenericRule.php
@@ -46,7 +46,7 @@ class GenericRule extends Rule
      */
     public function getHash()
     {
-        $data = unpack('ihash', md5(implode(',', $this->literals), true));
+        $data = unpack('ihash', (string) hash(\PHP_VERSION_ID > 80100 ? 'xxh3' : 'sha1', implode(',', $this->literals), true));
 
         return $data['hash'];
     }
diff --git a/src/Composer/DependencyResolver/MultiConflictRule.php b/src/Composer/DependencyResolver/MultiConflictRule.php
index 4826489d2..05fedc207 100644
--- a/src/Composer/DependencyResolver/MultiConflictRule.php
+++ b/src/Composer/DependencyResolver/MultiConflictRule.php
@@ -52,7 +52,7 @@ class MultiConflictRule extends Rule
      */
     public function getHash()
     {
-        $data = unpack('ihash', md5('c:'.implode(',', $this->literals), true));
+        $data = unpack('ihash', (string) hash(\PHP_VERSION_ID > 80100 ? 'xxh3' : 'sha1', 'c:'.implode(',', $this->literals), true));
 
         return $data['hash'];
     }
diff --git a/src/Composer/Downloader/ArchiveDownloader.php b/src/Composer/Downloader/ArchiveDownloader.php
index 6de51ee58..ff132e28b 100644
--- a/src/Composer/Downloader/ArchiveDownloader.php
+++ b/src/Composer/Downloader/ArchiveDownloader.php
@@ -68,7 +68,7 @@ abstract class ArchiveDownloader extends FileDownloader
         }
 
         do {
-            $temporaryDir = $vendorDir.'/composer/'.substr(md5(uniqid('', true)), 0, 8);
+            $temporaryDir = $vendorDir.'/composer/'.bin2hex(random_bytes(4));
         } while (is_dir($temporaryDir));
 
         $this->addCleanupPath($package, $temporaryDir);
diff --git a/src/Composer/Downloader/FileDownloader.php b/src/Composer/Downloader/FileDownloader.php
index adf26785c..2e1207b55 100644
--- a/src/Composer/Downloader/FileDownloader.php
+++ b/src/Composer/Downloader/FileDownloader.php
@@ -126,7 +126,7 @@ class FileDownloader implements DownloaderInterface, ChangeReportInterface
         }
 
         $cacheKeyGenerator = static function (PackageInterface $package, $key): string {
-            $cacheKey = sha1($key);
+            $cacheKey = hash('sha1', $key);
 
             return $package->getName().'/'.$cacheKey.'.'.$package->getDistType();
         };
@@ -441,7 +441,7 @@ class FileDownloader implements DownloaderInterface, ChangeReportInterface
             $extension = $package->getDistType();
         }
 
-        return rtrim($this->config->get('vendor-dir') . '/composer/tmp-' . md5($package . spl_object_hash($package)) . '.' . $extension, '.');
+        return rtrim($this->config->get('vendor-dir') . '/composer/tmp-' . hash('md5', $package . spl_object_hash($package)) . '.' . $extension, '.');
     }
 
     /**
diff --git a/src/Composer/EventDispatcher/EventDispatcher.php b/src/Composer/EventDispatcher/EventDispatcher.php
index 0af571c39..d10ca53b2 100644
--- a/src/Composer/EventDispatcher/EventDispatcher.php
+++ b/src/Composer/EventDispatcher/EventDispatcher.php
@@ -299,7 +299,7 @@ class EventDispatcher
                         // it does not hurt to keep the same stream as the current Application
                         if ($this->io instanceof ConsoleIO) {
                             $reflProp = new \ReflectionProperty($this->io, 'output');
-                            if (PHP_VERSION_ID < 80100) {
+                            if (\PHP_VERSION_ID < 80100) {
                                 $reflProp->setAccessible(true);
                             }
                             $output = $reflProp->getValue($this->io);
diff --git a/src/Composer/Package/Archiver/ArchiveManager.php b/src/Composer/Package/Archiver/ArchiveManager.php
index 4b15fa844..77c3ebe3d 100644
--- a/src/Composer/Package/Archiver/ArchiveManager.php
+++ b/src/Composer/Package/Archiver/ArchiveManager.php
@@ -96,7 +96,7 @@ class ArchiveManager
 
         $sourceReference = $package->getSourceReference();
         if (null !== $sourceReference) {
-            $parts['source_reference'] = substr(sha1($sourceReference), 0, 6);
+            $parts['source_reference'] = substr(hash('sha1', $sourceReference), 0, 6);
         }
 
         $parts = array_filter($parts, function (?string $part) {
@@ -171,7 +171,7 @@ class ArchiveManager
             $sourcePath = realpath('.');
         } else {
             // Directory used to download the sources
-            $sourcePath = sys_get_temp_dir().'/composer_archive'.uniqid();
+            $sourcePath = sys_get_temp_dir().'/composer_archive'.bin2hex(random_bytes(5));
             $filesystem->ensureDirectoryExists($sourcePath);
 
             try {
@@ -216,7 +216,7 @@ class ArchiveManager
         }
 
         // Create the archive
-        $tempTarget = sys_get_temp_dir().'/composer_archive'.uniqid().'.'.$format;
+        $tempTarget = sys_get_temp_dir().'/composer_archive'.bin2hex(random_bytes(5)).'.'.$format;
         $filesystem->ensureDirectoryExists(dirname($tempTarget));
 
         $archivePath = $usableArchiver->archive(
diff --git a/src/Composer/Package/Comparer/Comparer.php b/src/Composer/Package/Comparer/Comparer.php
index 1fd79b8bb..70a7a28f8 100644
--- a/src/Composer/Package/Comparer/Comparer.php
+++ b/src/Composer/Package/Comparer/Comparer.php
@@ -136,7 +136,7 @@ class Comparer
                             return false;
                         }
                     } elseif (is_file($dir.'/'.$file) && filesize($dir.'/'.$file)) {
-                        $array[$dir][$file] = md5_file($dir.'/'.$file);
+                        $array[$dir][$file] = hash_file(\PHP_VERSION_ID > 80100 ? 'xxh3' : 'sha1', $dir.'/'.$file);
                     }
                 }
             }
diff --git a/src/Composer/Package/Locker.php b/src/Composer/Package/Locker.php
index da1e4bf5e..2c6ae087d 100644
--- a/src/Composer/Package/Locker.php
+++ b/src/Composer/Package/Locker.php
@@ -66,7 +66,7 @@ class Locker
     {
         $this->lockFile = $lockFile;
         $this->installationManager = $installationManager;
-        $this->hash = md5($composerFileContents);
+        $this->hash = hash('md5', $composerFileContents);
         $this->contentHash = self::getContentHash($composerFileContents);
         $this->loader = new ArrayLoader(null, true);
         $this->dumper = new ArrayDumper();
@@ -107,7 +107,7 @@ class Locker
 
         ksort($relevantContent);
 
-        return md5(JsonFile::encode($relevantContent, 0));
+        return hash('md5', JsonFile::encode($relevantContent, 0));
     }
 
     /**
diff --git a/src/Composer/Repository/ArtifactRepository.php b/src/Composer/Repository/ArtifactRepository.php
index f73f4e9e1..78176fad7 100644
--- a/src/Composer/Repository/ArtifactRepository.php
+++ b/src/Composer/Repository/ArtifactRepository.php
@@ -129,7 +129,7 @@ class ArtifactRepository extends ArrayRepository implements ConfigurableReposito
         $package['dist'] = [
             'type' => $fileType,
             'url' => strtr($file->getPathname(), '\\', '/'),
-            'shasum' => sha1_file($file->getRealPath()),
+            'shasum' => hash_file('sha1', $file->getRealPath()),
         ];
 
         try {
diff --git a/src/Composer/Repository/PathRepository.php b/src/Composer/Repository/PathRepository.php
index 06676e73e..7239b0d2d 100644
--- a/src/Composer/Repository/PathRepository.php
+++ b/src/Composer/Repository/PathRepository.php
@@ -181,7 +181,7 @@ class PathRepository extends ArrayRepository implements ConfigurableRepositoryIn
             if ('none' === $reference) {
                 $package['dist']['reference'] = null;
             } elseif ('config' === $reference || 'auto' === $reference) {
-                $package['dist']['reference'] = sha1($json . serialize($this->options));
+                $package['dist']['reference'] = hash('sha1', $json . serialize($this->options));
             }
 
             // copy symlink/relative options to transport options
diff --git a/src/Composer/SelfUpdate/Versions.php b/src/Composer/SelfUpdate/Versions.php
index 045fb22a7..8cc7d455c 100644
--- a/src/Composer/SelfUpdate/Versions.php
+++ b/src/Composer/SelfUpdate/Versions.php
@@ -89,7 +89,7 @@ class Versions
         $versions = $this->getVersionsData();
 
         foreach ($versions[$channel ?: $this->getChannel()] as $version) {
-            if ($version['min-php'] <= PHP_VERSION_ID) {
+            if ($version['min-php'] <= \PHP_VERSION_ID) {
                 return $version;
             }
         }
diff --git a/src/Composer/Util/ComposerMirror.php b/src/Composer/Util/ComposerMirror.php
index 106e76c41..6be539693 100644
--- a/src/Composer/Util/ComposerMirror.php
+++ b/src/Composer/Util/ComposerMirror.php
@@ -28,9 +28,9 @@ class ComposerMirror
     public static function processUrl(string $mirrorUrl, string $packageName, string $version, ?string $reference, ?string $type, ?string $prettyVersion = null): string
     {
         if ($reference) {
-            $reference = Preg::isMatch('{^([a-f0-9]*|%reference%)$}', $reference) ? $reference : md5($reference);
+            $reference = Preg::isMatch('{^([a-f0-9]*|%reference%)$}', $reference) ? $reference : hash('md5', $reference);
         }
-        $version = strpos($version, '/') === false ? $version : md5($version);
+        $version = strpos($version, '/') === false ? $version : hash('md5', $version);
 
         $from = ['%package%', '%version%', '%reference%', '%type%'];
         $to = [$packageName, $version, $reference, $type];
diff --git a/src/Composer/Util/Http/CurlDownloader.php b/src/Composer/Util/Http/CurlDownloader.php
index 8e755551a..0d14d1e7f 100644
--- a/src/Composer/Util/Http/CurlDownloader.php
+++ b/src/Composer/Util/Http/CurlDownloader.php
@@ -99,7 +99,7 @@ class CurlDownloader
 
         $this->multiHandle = $mh = curl_multi_init();
         if (function_exists('curl_multi_setopt')) {
-            curl_multi_setopt($mh, CURLMOPT_PIPELINING, PHP_VERSION_ID >= 70400 ? /* CURLPIPE_MULTIPLEX */ 2 : /*CURLPIPE_HTTP1 | CURLPIPE_MULTIPLEX*/ 3);
+            curl_multi_setopt($mh, CURLMOPT_PIPELINING, \PHP_VERSION_ID >= 70400 ? /* CURLPIPE_MULTIPLEX */ 2 : /*CURLPIPE_HTTP1 | CURLPIPE_MULTIPLEX*/ 3);
             if (defined('CURLMOPT_MAX_HOST_CONNECTIONS') && !defined('HHVM_VERSION')) {
                 curl_multi_setopt($mh, CURLMOPT_MAX_HOST_CONNECTIONS, 8);
             }
@@ -363,7 +363,7 @@ class CurlDownloader
                         continue;
                     }
 
-                    if ($errno === 28 /* CURLE_OPERATION_TIMEDOUT */ && PHP_VERSION_ID >= 70300 && $progress['namelookup_time'] === 0.0 && !$timeoutWarning) {
+                    if ($errno === 28 /* CURLE_OPERATION_TIMEDOUT */ && \PHP_VERSION_ID >= 70300 && $progress['namelookup_time'] === 0.0 && !$timeoutWarning) {
                         $timeoutWarning = true;
                         $this->io->writeError('<warning>A connection timeout was encountered. If you intend to run Composer without connecting to the internet, run the command again prefixed with COMPOSER_DISABLE_NETWORK=1 to make Composer run in offline mode.</warning>');
                     }
diff --git a/src/Composer/Util/RemoteFilesystem.php b/src/Composer/Util/RemoteFilesystem.php
index 7eeebc423..cafdee213 100644
--- a/src/Composer/Util/RemoteFilesystem.php
+++ b/src/Composer/Util/RemoteFilesystem.php
@@ -533,7 +533,7 @@ class RemoteFilesystem
         }
 
         // https://www.php.net/manual/en/reserved.variables.httpresponseheader.php
-        if (PHP_VERSION_ID >= 80400) {
+        if (\PHP_VERSION_ID >= 80400) {
             $responseHeaders = http_get_last_response_headers();
             http_clear_last_response_headers();
         } else {
diff --git a/src/Composer/Util/TlsHelper.php b/src/Composer/Util/TlsHelper.php
index 5ab2bf9c9..da0801a1a 100644
--- a/src/Composer/Util/TlsHelper.php
+++ b/src/Composer/Util/TlsHelper.php
@@ -150,7 +150,7 @@ final class TlsHelper
         $pemtrim = substr($pubkeypem, strpos($pubkeypem, $start) + strlen($start), (strlen($pubkeypem) - strpos($pubkeypem, $end)) * (-1));
         $der = base64_decode($pemtrim);
 
-        return sha1($der);
+        return hash('sha1', $der);
     }
 
     /**
diff --git a/tests/Composer/Test/DependencyResolver/RuleTest.php b/tests/Composer/Test/DependencyResolver/RuleTest.php
index fe13c2c6c..3742289b2 100644
--- a/tests/Composer/Test/DependencyResolver/RuleTest.php
+++ b/tests/Composer/Test/DependencyResolver/RuleTest.php
@@ -26,7 +26,7 @@ class RuleTest extends TestCase
     {
         $rule = new GenericRule([123], Rule::RULE_ROOT_REQUIRE, ['packageName' => '', 'constraint' => new MatchAllConstraint]);
 
-        $hash = unpack('ihash', md5('123', true));
+        $hash = unpack('ihash', (string) hash(\PHP_VERSION_ID > 80100 ? 'xxh3' : 'sha1', '123', true));
         self::assertEquals($hash['hash'], $rule->getHash());
     }
 
diff --git a/tests/Composer/Test/Downloader/FileDownloaderTest.php b/tests/Composer/Test/Downloader/FileDownloaderTest.php
index 967c726bb..cbb44b085 100644
--- a/tests/Composer/Test/Downloader/FileDownloaderTest.php
+++ b/tests/Composer/Test/Downloader/FileDownloaderTest.php
@@ -158,7 +158,7 @@ class FileDownloaderTest extends TestCase
         $composer->setConfig($config);
 
         $expectedUrl = 'foobar';
-        $expectedCacheKey = 'dummy/pkg/'.sha1($expectedUrl).'.';
+        $expectedCacheKey = 'dummy/pkg/'.hash('sha1', $expectedUrl).'.';
 
         $dispatcher = new EventDispatcher(
             $composer,
@@ -242,7 +242,7 @@ class FileDownloaderTest extends TestCase
 
         $expectedUrl = 'url';
         $customCacheKey = 'xyzzy';
-        $expectedCacheKey = 'dummy/pkg/'.sha1($customCacheKey).'.';
+        $expectedCacheKey = 'dummy/pkg/'.hash('sha1', $customCacheKey).'.';
 
         $dispatcher = new EventDispatcher(
             $composer,
diff --git a/tests/Composer/Test/Downloader/GitDownloaderTest.php b/tests/Composer/Test/Downloader/GitDownloaderTest.php
index 0abc0df59..50db7c73d 100644
--- a/tests/Composer/Test/Downloader/GitDownloaderTest.php
+++ b/tests/Composer/Test/Downloader/GitDownloaderTest.php
@@ -66,7 +66,7 @@ class GitDownloaderTest extends TestCase
             $config = new Config();
         }
         if (!$config->has('home')) {
-            $tmpDir = realpath(sys_get_temp_dir()).DIRECTORY_SEPARATOR.'cmptest-'.md5(uniqid('', true));
+            $tmpDir = realpath(sys_get_temp_dir()).DIRECTORY_SEPARATOR.'cmptest-'.bin2hex(random_bytes(5));
             $config->merge(['config' => ['home' => $tmpDir]]);
         }
 
diff --git a/tests/Composer/Test/Installer/BinaryInstallerTest.php b/tests/Composer/Test/Installer/BinaryInstallerTest.php
index 00f6ce618..e613ca7e1 100644
--- a/tests/Composer/Test/Installer/BinaryInstallerTest.php
+++ b/tests/Composer/Test/Installer/BinaryInstallerTest.php
@@ -121,7 +121,7 @@ EOL
     protected function createPackageMock()
     {
         return $this->getMockBuilder('Composer\Package\Package')
-            ->setConstructorArgs([md5((string) mt_rand()), '1.0.0.0', '1.0.0'])
+            ->setConstructorArgs([bin2hex(random_bytes(5)), '1.0.0.0', '1.0.0'])
             ->getMock();
     }
 }
diff --git a/tests/Composer/Test/Installer/MetapackageInstallerTest.php b/tests/Composer/Test/Installer/MetapackageInstallerTest.php
index 83bc2704f..6f083dd4b 100644
--- a/tests/Composer/Test/Installer/MetapackageInstallerTest.php
+++ b/tests/Composer/Test/Installer/MetapackageInstallerTest.php
@@ -113,7 +113,7 @@ class MetapackageInstallerTest extends TestCase
     private function createPackageMock()
     {
         return $this->getMockBuilder('Composer\Package\Package')
-            ->setConstructorArgs([md5((string) mt_rand()), '1.0.0.0', '1.0.0'])
+            ->setConstructorArgs([bin2hex(random_bytes(5)), '1.0.0.0', '1.0.0'])
             ->getMock();
     }
 }
diff --git a/tests/Composer/Test/Installer/SuggestedPackagesReporterTest.php b/tests/Composer/Test/Installer/SuggestedPackagesReporterTest.php
index 3f412c3d4..d2d5df994 100644
--- a/tests/Composer/Test/Installer/SuggestedPackagesReporterTest.php
+++ b/tests/Composer/Test/Installer/SuggestedPackagesReporterTest.php
@@ -272,7 +272,7 @@ class SuggestedPackagesReporterTest extends TestCase
     private function createPackageMock()
     {
         return $this->getMockBuilder('Composer\Package\Package')
-            ->setConstructorArgs([md5((string) mt_rand()), '1.0.0.0', '1.0.0'])
+            ->setConstructorArgs([bin2hex(random_bytes(5)), '1.0.0.0', '1.0.0'])
             ->getMock();
     }
 }
diff --git a/tests/Composer/Test/InstallerTest.php b/tests/Composer/Test/InstallerTest.php
index cecbdd942..c81257c22 100644
--- a/tests/Composer/Test/InstallerTest.php
+++ b/tests/Composer/Test/InstallerTest.php
@@ -533,7 +533,7 @@ class InstallerTest extends TestCase
                 if (!empty($testData['LOCK'])) {
                     $lock = JsonFile::parseJson($testData['LOCK']);
                     if (!isset($lock['hash'])) {
-                        $lock['hash'] = md5(JsonFile::encode($composer, 0));
+                        $lock['hash'] = hash('md5', JsonFile::encode($composer, 0));
                     }
                 }
                 if (!empty($testData['INSTALLED'])) {
diff --git a/tests/Composer/Test/Package/LockerTest.php b/tests/Composer/Test/Package/LockerTest.php
index fc0178cf2..fd52642ff 100644
--- a/tests/Composer/Test/Package/LockerTest.php
+++ b/tests/Composer/Test/Package/LockerTest.php
@@ -96,7 +96,7 @@ class LockerTest extends TestCase
         $package1 = self::getPackage('pkg1', '1.0.0-beta');
         $package2 = self::getPackage('pkg2', '0.1.10');
 
-        $contentHash = md5(trim($jsonContent));
+        $contentHash = hash('md5', trim($jsonContent));
 
         $json
             ->expects($this->once())
@@ -154,7 +154,7 @@ class LockerTest extends TestCase
         $json
             ->expects($this->once())
             ->method('read')
-            ->will($this->returnValue(['hash' => md5($jsonContent)]));
+            ->will($this->returnValue(['hash' => hash('md5', $jsonContent)]));
 
         self::assertTrue($locker->isFresh());
     }
@@ -185,7 +185,7 @@ class LockerTest extends TestCase
         $json
             ->expects($this->once())
             ->method('read')
-            ->will($this->returnValue(['hash' => md5($jsonContent . '  '), 'content-hash' => md5($jsonContent)]));
+            ->will($this->returnValue(['hash' => hash('md5', $jsonContent . '  '), 'content-hash' => hash('md5', $jsonContent)]));
 
         self::assertTrue($locker->isFresh());
     }
@@ -201,7 +201,7 @@ class LockerTest extends TestCase
         $json
             ->expects($this->once())
             ->method('read')
-            ->will($this->returnValue(['content-hash' => md5($jsonContent)]));
+            ->will($this->returnValue(['content-hash' => hash('md5', $jsonContent)]));
 
         self::assertTrue($locker->isFresh());
     }
@@ -213,7 +213,7 @@ class LockerTest extends TestCase
 
         $locker = new Locker(new NullIO, $json, $inst, $this->getJsonContent());
 
-        $differentHash = md5($this->getJsonContent(['name' => 'test2']));
+        $differentHash = hash('md5', $this->getJsonContent(['name' => 'test2']));
 
         $json
             ->expects($this->once())
diff --git a/tests/Composer/Test/Repository/PathRepositoryTest.php b/tests/Composer/Test/Repository/PathRepositoryTest.php
index f30aee388..d5deb664b 100644
--- a/tests/Composer/Test/Repository/PathRepositoryTest.php
+++ b/tests/Composer/Test/Repository/PathRepositoryTest.php
@@ -156,7 +156,7 @@ class PathRepositoryTest extends TestCase
         foreach ($packages as $package) {
             self::assertEquals(
                 $package->getDistReference(),
-                sha1(file_get_contents($package->getDistUrl() . '/composer.json') . serialize($options))
+                hash('sha1', file_get_contents($package->getDistUrl() . '/composer.json') . serialize($options))
             );
         }
     }
diff --git a/tests/Composer/Test/TestCase.php b/tests/Composer/Test/TestCase.php
index 233e1c3d1..0fc9a1acc 100644
--- a/tests/Composer/Test/TestCase.php
+++ b/tests/Composer/Test/TestCase.php
@@ -102,7 +102,7 @@ abstract class TestCase extends \PHPUnit\Framework\TestCase
         $root = sys_get_temp_dir();
 
         do {
-            $unique = $root . DIRECTORY_SEPARATOR . uniqid('composer-test-' . random_int(1000, 9000));
+            $unique = $root . DIRECTORY_SEPARATOR . 'composer-test-' . bin2hex(random_bytes(10));
 
             if (!file_exists($unique) && Silencer::call('mkdir', $unique, 0777)) {
                 return realpath($unique);
diff --git a/tests/Composer/Test/Util/ErrorHandlerTest.php b/tests/Composer/Test/Util/ErrorHandlerTest.php
index 29f10463f..ae89d83b2 100644
--- a/tests/Composer/Test/Util/ErrorHandlerTest.php
+++ b/tests/Composer/Test/Util/ErrorHandlerTest.php
@@ -36,7 +36,7 @@ class ErrorHandlerTest extends TestCase
      */
     public function testErrorHandlerCaptureNotice(): void
     {
-        if (PHP_VERSION_ID >= 80000) {
+        if (\PHP_VERSION_ID >= 80000) {
             self::expectException('\ErrorException');
             self::expectExceptionMessage('Undefined array key "baz"');
         } else {
@@ -54,7 +54,7 @@ class ErrorHandlerTest extends TestCase
      */
     public function testErrorHandlerCaptureWarning(): void
     {
-        if (PHP_VERSION_ID >= 80000) {
+        if (\PHP_VERSION_ID >= 80000) {
             self::expectException('TypeError');
             self::expectExceptionMessage('array_merge');
         } else {