diff --git a/phpstan/baseline.neon b/phpstan/baseline.neon
index 64828b622..801dd2336 100644
--- a/phpstan/baseline.neon
+++ b/phpstan/baseline.neon
@@ -4008,16 +4008,6 @@ parameters:
 			count: 1
 			path: ../src/Composer/Util/Http/CurlDownloader.php
 
-		-
-			message: "#^Constant CURLOPT_PROXY_CAINFO not found\\.$#"
-			count: 1
-			path: ../src/Composer/Util/Http/CurlDownloader.php
-
-		-
-			message: "#^Constant CURLOPT_PROXY_CAPATH not found\\.$#"
-			count: 1
-			path: ../src/Composer/Util/Http/CurlDownloader.php
-
 		-
 			message: "#^Construct empty\\(\\) is not allowed\\. Use more strict comparison\\.$#"
 			count: 3
@@ -4199,72 +4189,17 @@ parameters:
 			path: ../src/Composer/Util/Http/CurlDownloader.php
 
 		-
-			message: "#^Construct empty\\(\\) is not allowed\\. Use more strict comparison\\.$#"
-			count: 1
-			path: ../src/Composer/Util/Http/ProxyHelper.php
-
-		-
-			message: "#^Foreach overwrites \\$name with its value variable\\.$#"
-			count: 1
-			path: ../src/Composer/Util/Http/ProxyHelper.php
-
-		-
-			message: "#^Implicit array creation is not allowed \\- variable \\$options does not exist\\.$#"
-			count: 1
-			path: ../src/Composer/Util/Http/ProxyHelper.php
-
-		-
-			message: "#^Only booleans are allowed in a negated boolean, int\\<0, 65535\\>\\|false\\|null given\\.$#"
-			count: 1
-			path: ../src/Composer/Util/Http/ProxyHelper.php
-
-		-
-			message: "#^Only booleans are allowed in an if condition, string\\|null given\\.$#"
-			count: 3
-			path: ../src/Composer/Util/Http/ProxyHelper.php
-
-		-
-			message: "#^Parameter \\#1 \\$proxy of static method Composer\\\\Util\\\\Http\\\\ProxyHelper\\:\\:formatParsedUrl\\(\\) expects array\\{scheme\\?\\: string, host\\: string, port\\?\\: int, user\\?\\: string, pass\\?\\: string\\}, array\\{scheme\\?\\: string, host\\?\\: string, port\\?\\: int\\<0, 65535\\>, user\\?\\: string, pass\\?\\: string, path\\?\\: string, query\\?\\: string, fragment\\?\\: string\\}\\|false given\\.$#"
-			count: 1
-			path: ../src/Composer/Util/Http/ProxyHelper.php
-
-		-
-			message: "#^Only booleans are allowed in &&, Composer\\\\Util\\\\NoProxyPattern\\|null given on the left side\\.$#"
-			count: 1
-			path: ../src/Composer/Util/Http/ProxyManager.php
-
-		-
-			message: "#^Only booleans are allowed in &&, string\\|null given on the right side\\.$#"
-			count: 1
-			path: ../src/Composer/Util/Http/ProxyManager.php
-
-		-
-			message: "#^Only booleans are allowed in a negated boolean, Composer\\\\Util\\\\Http\\\\ProxyManager\\|null given\\.$#"
-			count: 1
-			path: ../src/Composer/Util/Http/ProxyManager.php
-
-		-
-			message: "#^Only booleans are allowed in an if condition, string\\|null given\\.$#"
-			count: 4
-			path: ../src/Composer/Util/Http/ProxyManager.php
-
-		-
-			message: "#^Parameter \\#3 \\$formattedUrl of class Composer\\\\Util\\\\Http\\\\RequestProxy constructor expects string, string\\|null given\\.$#"
-			count: 1
-			path: ../src/Composer/Util/Http/ProxyManager.php
-
-		-
-			message: "#^Short ternary operator is not allowed\\. Use null coalesce operator if applicable or consider using long ternary\\.$#"
-			count: 1
-			path: ../src/Composer/Util/Http/ProxyManager.php
-
-		-
-			message: "#^Only booleans are allowed in an if condition, string given\\.$#"
+			message: "#^Method Composer\\\\Util\\\\Http\\\\RequestProxy::getCurlOptions\\(\\) should return array\\<int, int\\|string\\> but returns array\\<int\\|string, int\\|string\\>.$#"
 			count: 1
 			path: ../src/Composer/Util/Http/RequestProxy.php
 
 		-
-			message: "#^Short ternary operator is not allowed\\. Use null coalesce operator if applicable or consider using long ternary\\.$#"
+			message: "#^Constant CURLOPT_PROXY_CAINFO not found\\.$#"
+			count: 1
+			path: ../src/Composer/Util/Http/RequestProxy.php
+
+		-
+			message: "#^Constant CURLOPT_PROXY_CAPATH not found\\.$#"
 			count: 1
 			path: ../src/Composer/Util/Http/RequestProxy.php
 
@@ -5281,26 +5216,6 @@ parameters:
 			count: 1
 			path: ../tests/Composer/Test/Util/GitTest.php
 
-		-
-			message: "#^Call to method PHPUnit\\\\Framework\\\\Assert\\:\\:assertInstanceOf\\(\\) with 'Composer\\\\\\\\Util\\\\\\\\Http…' and Composer\\\\Util\\\\Http\\\\ProxyManager will always evaluate to true\\.$#"
-			count: 1
-			path: ../tests/Composer/Test/Util/Http/ProxyManagerTest.php
-
-		-
-			message: "#^Call to method PHPUnit\\\\Framework\\\\Assert\\:\\:assertInstanceOf\\(\\) with 'Composer\\\\\\\\Util\\\\\\\\Http…' and Composer\\\\Util\\\\Http\\\\RequestProxy will always evaluate to true\\.$#"
-			count: 1
-			path: ../tests/Composer/Test/Util/Http/ProxyManagerTest.php
-
-		-
-			message: "#^Only booleans are allowed in an if condition, string given\\.$#"
-			count: 1
-			path: ../tests/Composer/Test/Util/Http/ProxyManagerTest.php
-
-		-
-			message: "#^Parameter \\#1 \\$haystack of function stripos expects string, string\\|null given\\.$#"
-			count: 1
-			path: ../tests/Composer/Test/Util/Http/ProxyManagerTest.php
-
 		-
 			message: "#^Only booleans are allowed in an if condition, string\\|false\\|null given\\.$#"
 			count: 1
diff --git a/src/Composer/Console/Application.php b/src/Composer/Console/Application.php
index fa7855331..d045bdf88 100644
--- a/src/Composer/Console/Application.php
+++ b/src/Composer/Console/Application.php
@@ -41,6 +41,7 @@ use Composer\EventDispatcher\ScriptExecutionException;
 use Composer\Exception\NoSslException;
 use Composer\XdebugHandler\XdebugHandler;
 use Symfony\Component\Process\Exception\ProcessTimedOutException;
+use Composer\Util\Http\ProxyManager;
 
 /**
  * The console application that handles the commands
@@ -398,6 +399,13 @@ class Application extends BaseApplication
                 $io->writeError('<info>Memory usage: '.round(memory_get_usage() / 1024 / 1024, 2).'MiB (peak: '.round(memory_get_peak_usage() / 1024 / 1024, 2).'MiB), time: '.round(microtime(true) - $startTime, 2).'s');
             }
 
+            if (ProxyManager::getInstance()->needsTransitionWarning()) {
+                $io->writeError('');
+                $io->writeError('<warning>Composer now requires separate proxy environment variables for HTTP and HTTPS requests.</warning>');
+                $io->writeError('<warning>Please set `https_proxy` in addition to your existing proxy environment variables.</warning>');
+                $io->writeError('<warning>This fallback (and warning) will be removed in Composer 2.8.0.</warning>');
+            }
+
             return $result;
         } catch (ScriptExecutionException $e) {
             if ($this->getDisablePluginsByDefault() && $this->isRunningAsRoot() && !$this->io->isInteractive()) {
diff --git a/src/Composer/Util/Http/CurlDownloader.php b/src/Composer/Util/Http/CurlDownloader.php
index e512f0824..4dd554065 100644
--- a/src/Composer/Util/Http/CurlDownloader.php
+++ b/src/Composer/Util/Http/CurlDownloader.php
@@ -52,10 +52,6 @@ class CurlDownloader
     private $maxRedirects = 20;
     /** @var int */
     private $maxRetries = 3;
-    /** @var ProxyManager */
-    private $proxyManager;
-    /** @var bool */
-    private $supportsSecureProxy;
     /** @var array<int, string[]> */
     protected $multiErrors = [
         CURLM_BAD_HANDLE => ['CURLM_BAD_HANDLE', 'The passed-in handle is not a valid CURLM handle.'],
@@ -117,11 +113,6 @@ class CurlDownloader
         }
 
         $this->authHelper = new AuthHelper($io, $config);
-        $this->proxyManager = ProxyManager::getInstance();
-
-        $version = curl_version();
-        $features = $version['features'];
-        $this->supportsSecureProxy = defined('CURL_VERSION_HTTPS_PROXY') && ($features & CURL_VERSION_HTTPS_PROXY);
     }
 
     /**
@@ -245,26 +236,8 @@ class CurlDownloader
             }
         }
 
-        // Always set CURLOPT_PROXY to enable/disable proxy handling
-        // Any proxy authorization is included in the proxy url
-        $proxy = $this->proxyManager->getProxyForRequest($url);
-        if ($proxy->getUrl() !== '') {
-            curl_setopt($curlHandle, CURLOPT_PROXY, $proxy->getUrl());
-        }
-
-        // Curl needs certificate locations for secure proxies.
-        // CURLOPT_PROXY_SSL_VERIFY_PEER/HOST are enabled by default
-        if ($proxy->isSecure()) {
-            if (!$this->supportsSecureProxy) {
-                throw new TransportException('Connecting to a secure proxy using curl is not supported on PHP versions below 7.3.0.');
-            }
-            if (!empty($options['ssl']['cafile'])) {
-                curl_setopt($curlHandle, CURLOPT_PROXY_CAINFO, $options['ssl']['cafile']);
-            }
-            if (!empty($options['ssl']['capath'])) {
-                curl_setopt($curlHandle, CURLOPT_PROXY_CAPATH, $options['ssl']['capath']);
-            }
-        }
+        $proxy = ProxyManager::getInstance()->getProxyForRequest($url);
+        curl_setopt_array($curlHandle, $proxy->getCurlOptions($options['ssl'] ?? []));
 
         $progress = array_diff_key(curl_getinfo($curlHandle), self::$timeInfo);
 
@@ -283,7 +256,7 @@ class CurlDownloader
             'primaryIp' => '',
         ];
 
-        $usingProxy = $proxy->getFormattedUrl(' using proxy (%s)');
+        $usingProxy = $proxy->getStatus(' using proxy (%s)');
         $ifModified = false !== stripos(implode(',', $options['http']['header']), 'if-modified-since:') ? ' if modified' : '';
         if ($attributes['redirects'] === 0 && $attributes['retries'] === 0) {
             $this->io->writeError('Downloading ' . Url::sanitize($url) . $usingProxy . $ifModified, true, IOInterface::DEBUG);
diff --git a/src/Composer/Util/Http/ProxyHelper.php b/src/Composer/Util/Http/ProxyHelper.php
deleted file mode 100644
index f2d864f29..000000000
--- a/src/Composer/Util/Http/ProxyHelper.php
+++ /dev/null
@@ -1,183 +0,0 @@
-<?php declare(strict_types=1);
-
-/*
- * This file is part of Composer.
- *
- * (c) Nils Adermann <naderman@naderman.de>
- *     Jordi Boggiano <j.boggiano@seld.be>
- *
- * For the full copyright and license information, please view the LICENSE
- * file that was distributed with this source code.
- */
-
-namespace Composer\Util\Http;
-
-/**
- * Proxy discovery and helper class
- *
- * @internal
- * @author John Stevenson <john-stevenson@blueyonder.co.uk>
- */
-class ProxyHelper
-{
-    /**
-     * Returns proxy environment values
-     *
-     * @return array{string|null, string|null, string|null} httpProxy, httpsProxy, noProxy values
-     *
-     * @throws \RuntimeException on malformed url
-     */
-    public static function getProxyData(): array
-    {
-        $httpProxy = null;
-        $httpsProxy = null;
-
-        // Handle http_proxy/HTTP_PROXY on CLI only for security reasons
-        if (PHP_SAPI === 'cli' || PHP_SAPI === 'phpdbg') {
-            if ($env = self::getProxyEnv(['http_proxy', 'HTTP_PROXY'], $name)) {
-                $httpProxy = self::checkProxy($env, $name);
-            }
-        }
-
-        // Prefer CGI_HTTP_PROXY if available
-        if ($env = self::getProxyEnv(['CGI_HTTP_PROXY'], $name)) {
-            $httpProxy = self::checkProxy($env, $name);
-        }
-
-        // Handle https_proxy/HTTPS_PROXY
-        if ($env = self::getProxyEnv(['https_proxy', 'HTTPS_PROXY'], $name)) {
-            $httpsProxy = self::checkProxy($env, $name);
-        } else {
-            $httpsProxy = $httpProxy;
-        }
-
-        // Handle no_proxy
-        $noProxy = self::getProxyEnv(['no_proxy', 'NO_PROXY'], $name);
-
-        return [$httpProxy, $httpsProxy, $noProxy];
-    }
-
-    /**
-     * Returns http context options for the proxy url
-     *
-     * @return array{http: array{proxy: string, header?: string}}
-     */
-    public static function getContextOptions(string $proxyUrl): array
-    {
-        $proxy = parse_url($proxyUrl);
-
-        // Remove any authorization
-        $proxyUrl = self::formatParsedUrl($proxy, false);
-        $proxyUrl = str_replace(['http://', 'https://'], ['tcp://', 'ssl://'], $proxyUrl);
-
-        $options['http']['proxy'] = $proxyUrl;
-
-        // Handle any authorization
-        if (isset($proxy['user'])) {
-            $auth = rawurldecode($proxy['user']);
-
-            if (isset($proxy['pass'])) {
-                $auth .= ':' . rawurldecode($proxy['pass']);
-            }
-            $auth = base64_encode($auth);
-            // Set header as a string
-            $options['http']['header'] = "Proxy-Authorization: Basic {$auth}";
-        }
-
-        return $options;
-    }
-
-    /**
-     * Sets/unsets request_fulluri value in http context options array
-     *
-     * @param mixed[] $options Set by method
-     */
-    public static function setRequestFullUri(string $requestUrl, array &$options): void
-    {
-        if ('http' === parse_url($requestUrl, PHP_URL_SCHEME)) {
-            $options['http']['request_fulluri'] = true;
-        } else {
-            unset($options['http']['request_fulluri']);
-        }
-    }
-
-    /**
-     * Searches $_SERVER for case-sensitive values
-     *
-     * @param non-empty-list<string> $names Names to search for
-     * @param string|null $name  Name of any found value, you should only rely on it if the function returned a non-null value
-     *
-     * @return string|null The found value
-     *
-     * @param-out string $name
-     */
-    private static function getProxyEnv(array $names, ?string &$name): ?string
-    {
-        foreach ($names as $name) {
-            if (!empty($_SERVER[$name])) {
-                return $_SERVER[$name];
-            }
-        }
-
-        return null;
-    }
-
-    /**
-     * Checks and formats a proxy url from the environment
-     *
-     * @throws \RuntimeException on malformed url
-     * @return string            The formatted proxy url
-     */
-    private static function checkProxy(string $proxyUrl, string $envName): string
-    {
-        $error = sprintf('malformed %s url', $envName);
-        $proxy = parse_url($proxyUrl);
-
-        // We need parse_url to have identified a host
-        if (!isset($proxy['host'])) {
-            throw new \RuntimeException($error);
-        }
-
-        $proxyUrl = self::formatParsedUrl($proxy, true);
-
-        // We need a port because streams and curl use different defaults
-        if (!parse_url($proxyUrl, PHP_URL_PORT)) {
-            throw new \RuntimeException($error);
-        }
-
-        return $proxyUrl;
-    }
-
-    /**
-     * Formats a url from its component parts
-     *
-     * @param  array{scheme?: string, host: string, port?: int, user?: string, pass?: string} $proxy
-     *
-     * @return string The formatted value
-     */
-    private static function formatParsedUrl(array $proxy, bool $includeAuth): string
-    {
-        $proxyUrl = isset($proxy['scheme']) ? strtolower($proxy['scheme']) . '://' : '';
-
-        if ($includeAuth && isset($proxy['user'])) {
-            $proxyUrl .= $proxy['user'];
-
-            if (isset($proxy['pass'])) {
-                $proxyUrl .= ':' . $proxy['pass'];
-            }
-            $proxyUrl .= '@';
-        }
-
-        $proxyUrl .= $proxy['host'];
-
-        if (isset($proxy['port'])) {
-            $proxyUrl .= ':' . $proxy['port'];
-        } elseif (strpos($proxyUrl, 'http://') === 0) {
-            $proxyUrl .= ':80';
-        } elseif (strpos($proxyUrl, 'https://') === 0) {
-            $proxyUrl .= ':443';
-        }
-
-        return $proxyUrl;
-    }
-}
diff --git a/src/Composer/Util/Http/ProxyItem.php b/src/Composer/Util/Http/ProxyItem.php
new file mode 100644
index 000000000..2839be923
--- /dev/null
+++ b/src/Composer/Util/Http/ProxyItem.php
@@ -0,0 +1,119 @@
+<?php declare(strict_types=1);
+
+/*
+ * This file is part of Composer.
+ *
+ * (c) Nils Adermann <naderman@naderman.de>
+ *     Jordi Boggiano <j.boggiano@seld.be>
+ *
+ * For the full copyright and license information, please view the LICENSE
+ * file that was distributed with this source code.
+ */
+
+namespace Composer\Util\Http;
+
+/**
+ * @internal
+ * @author John Stevenson <john-stevenson@blueyonder.co.uk>
+ */
+class ProxyItem
+{
+    /** @var non-empty-string */
+    private $url;
+    /** @var non-empty-string */
+    private $safeUrl;
+    /** @var ?non-empty-string */
+    private $curlAuth;
+    /** @var string */
+    private $optionsProxy;
+    /** @var ?non-empty-string */
+    private $optionsAuth;
+
+    /**
+     * @param string $proxyUrl The value from the environment
+     * @param string $envName The name of the environment variable
+     * @throws \RuntimeException If the proxy url is invalid
+     */
+    public function __construct(string $proxyUrl, string $envName)
+    {
+        $syntaxError = sprintf('unsupported `%s` syntax', $envName);
+
+        if (strpbrk($proxyUrl, "\r\n\t") !== false) {
+            throw new \RuntimeException($syntaxError);
+        }
+        if (false === ($proxy = parse_url($proxyUrl))) {
+            throw new \RuntimeException($syntaxError);
+        }
+        if (!isset($proxy['host'])) {
+            throw new \RuntimeException('unable to find proxy host in ' . $envName);
+        }
+
+        $scheme = isset($proxy['scheme']) ? strtolower($proxy['scheme']) . '://' : 'http://';
+        $safe = '';
+
+        if (isset($proxy['user'])) {
+            $safe = '***';
+            $user = $proxy['user'];
+            $auth = rawurldecode($proxy['user']);
+
+            if (isset($proxy['pass'])) {
+                $safe .= ':***';
+                $user .= ':' . $proxy['pass'];
+                $auth .= ':' . rawurldecode($proxy['pass']);
+            }
+
+            $safe .= '@';
+
+            if (strlen($user) > 0) {
+                $this->curlAuth = $user;
+                $this->optionsAuth = 'Proxy-Authorization: Basic ' . base64_encode($auth);
+            }
+        }
+
+        $host = $proxy['host'];
+        $port = null;
+
+        if (isset($proxy['port'])) {
+            $port = $proxy['port'];
+        } elseif ($scheme === 'http://') {
+            $port = 80;
+        } elseif ($scheme === 'https://') {
+            $port = 443;
+        }
+
+        // We need a port because curl uses 1080 for http. Port 0 is reserved,
+        // but is considered valid depending on the PHP or Curl version.
+        if ($port === null) {
+            throw new \RuntimeException('unable to find proxy port in ' . $envName);
+        }
+        if ($port === 0) {
+            throw new \RuntimeException('port 0 is reserved in ' . $envName);
+        }
+
+        $this->url = sprintf('%s%s:%d', $scheme, $host, $port);
+        $this->safeUrl = sprintf('%s%s%s:%d', $scheme, $safe, $host, $port);
+
+        $scheme = str_replace(['http://', 'https://'], ['tcp://', 'ssl://'], $scheme);
+        $this->optionsProxy = sprintf('%s%s:%d', $scheme, $host, $port);
+    }
+
+    /**
+     * Returns a RequestProxy instance for the scheme of the request url
+     *
+     * @param string $scheme The scheme of the request url
+     */
+    public function toRequestProxy(string $scheme): RequestProxy
+    {
+        $options = ['http' => ['proxy' => $this->optionsProxy]];
+
+        if ($this->optionsAuth !== null) {
+            $options['http']['header'] = $this->optionsAuth;
+        }
+
+        if ($scheme === 'http') {
+            $options['http']['request_fulluri'] = true;
+        }
+
+        return new RequestProxy($this->url, $this->curlAuth, $options, $this->safeUrl);
+    }
+}
diff --git a/src/Composer/Util/Http/ProxyManager.php b/src/Composer/Util/Http/ProxyManager.php
index 731638ab8..0571780fe 100644
--- a/src/Composer/Util/Http/ProxyManager.php
+++ b/src/Composer/Util/Http/ProxyManager.php
@@ -14,7 +14,6 @@ namespace Composer\Util\Http;
 
 use Composer\Downloader\TransportException;
 use Composer\Util\NoProxyPattern;
-use Composer\Util\Url;
 
 /**
  * @internal
@@ -24,40 +23,40 @@ class ProxyManager
 {
     /** @var ?string */
     private $error = null;
-    /** @var array{http: ?string, https: ?string} */
-    private $fullProxy;
-    /** @var array{http: ?string, https: ?string} */
-    private $safeProxy;
-    /** @var array{http: array{options: mixed[]|null}, https: array{options: mixed[]|null}} */
-    private $streams;
-    /** @var bool */
-    private $hasProxy;
-    /** @var ?string */
-    private $info = null;
+    /** @var ?ProxyItem */
+    private $httpProxy = null;
+    /** @var ?ProxyItem */
+    private $httpsProxy = null;
     /** @var ?NoProxyPattern */
     private $noProxyHandler = null;
 
-    /** @var ?ProxyManager */
+    /** @var ?self */
     private static $instance = null;
 
+    /** The following 3 properties can be removed after the transition period */
+
+    /** @var bool */
+    private $ignoreHttpsProxy = false;
+    /** @var bool */
+    private $isTransitional = false;
+    /** @var bool */
+    private $needsTransitionWarning = false;
+
     private function __construct()
     {
-        $this->fullProxy = $this->safeProxy = [
-            'http' => null,
-            'https' => null,
-        ];
+        // this can be removed after the transition period
+        $this->isTransitional = true;
 
-        $this->streams['http'] = $this->streams['https'] = [
-            'options' => null,
-        ];
-
-        $this->hasProxy = false;
-        $this->initProxyData();
+        try {
+            $this->getProxyData();
+        } catch (\RuntimeException $e) {
+            $this->error = $e->getMessage();
+        }
     }
 
     public static function getInstance(): ProxyManager
     {
-        if (!self::$instance) {
+        if (self::$instance === null) {
             self::$instance = new self();
         }
 
@@ -79,96 +78,116 @@ class ProxyManager
      */
     public function getProxyForRequest(string $requestUrl): RequestProxy
     {
-        if ($this->error) {
+        if ($this->error !== null) {
             throw new TransportException('Unable to use a proxy: '.$this->error);
         }
 
-        $scheme = parse_url($requestUrl, PHP_URL_SCHEME) ?: 'http';
-        $proxyUrl = '';
-        $options = [];
-        $formattedProxyUrl = '';
+        $scheme = (string) parse_url($requestUrl, PHP_URL_SCHEME);
+        $proxy = $this->getProxyForScheme($scheme);
 
-        if ($this->hasProxy && in_array($scheme, ['http', 'https'], true) && $this->fullProxy[$scheme]) {
-            if ($this->noProxy($requestUrl)) {
-                $formattedProxyUrl = 'excluded by no_proxy';
-            } else {
-                $proxyUrl = $this->fullProxy[$scheme];
-                $options = $this->streams[$scheme]['options'];
-                assert(is_array($options));
-                ProxyHelper::setRequestFullUri($requestUrl, $options);
-                $formattedProxyUrl = $this->safeProxy[$scheme];
+        if ($proxy === null) {
+            return RequestProxy::none();
+        }
+
+        if ($this->noProxy($requestUrl)) {
+            return RequestProxy::noProxy();
+        }
+
+        return $proxy->toRequestProxy($scheme);
+    }
+
+    /**
+     * Returns true if the user needs to set an https_proxy environment variable
+     *
+     * This method can be removed after the transition period
+     */
+    public function needsTransitionWarning(): bool
+    {
+        return $this->needsTransitionWarning;
+    }
+
+    /**
+     * Returns a ProxyItem if one is set for the scheme, otherwise null
+     */
+    private function getProxyForScheme(string $scheme): ?ProxyItem
+    {
+        if ($scheme === 'http') {
+            return $this->httpProxy;
+        }
+
+        if ($scheme === 'https') {
+            // this can be removed after the transition period
+            if ($this->isTransitional && $this->httpsProxy === null) {
+                if ($this->httpProxy !== null && !$this->ignoreHttpsProxy) {
+                    $this->needsTransitionWarning = true;
+
+                    return $this->httpProxy;
+                }
+            }
+
+            return $this->httpsProxy;
+        }
+
+        return null;
+    }
+
+    /**
+     * Finds proxy values from the environment and sets class properties
+     */
+    private function getProxyData(): void
+    {
+        // Handle http_proxy/HTTP_PROXY on CLI only for security reasons
+        if (PHP_SAPI === 'cli' || PHP_SAPI === 'phpdbg') {
+            [$env, $name] = $this->getProxyEnv('http_proxy');
+            if ($env !== null) {
+                $this->httpProxy = new ProxyItem($env, $name);
             }
         }
 
-        return new RequestProxy($proxyUrl, $options, $formattedProxyUrl);
-    }
-
-    /**
-     * Returns true if a proxy is being used
-     *
-     * @return bool If false any error will be in $message
-     */
-    public function isProxying(): bool
-    {
-        return $this->hasProxy;
-    }
-
-    /**
-     * Returns proxy configuration info which can be shown to the user
-     *
-     * @return string|null Safe proxy URL or an error message if setting up proxy failed or null if no proxy was configured
-     */
-    public function getFormattedProxy(): ?string
-    {
-        return $this->hasProxy ? $this->info : $this->error;
-    }
-
-    /**
-     * Initializes proxy values from the environment
-     */
-    private function initProxyData(): void
-    {
-        try {
-            [$httpProxy, $httpsProxy, $noProxy] = ProxyHelper::getProxyData();
-        } catch (\RuntimeException $e) {
-            $this->error = $e->getMessage();
-
-            return;
-        }
-
-        $info = [];
-
-        if ($httpProxy) {
-            $info[] = $this->setData($httpProxy, 'http');
-        }
-        if ($httpsProxy) {
-            $info[] = $this->setData($httpsProxy, 'https');
-        }
-        if ($this->hasProxy) {
-            $this->info = implode(', ', $info);
-            if ($noProxy) {
-                $this->noProxyHandler = new NoProxyPattern($noProxy);
+        // Handle cgi_http_proxy/CGI_HTTP_PROXY if needed
+        if ($this->httpProxy === null) {
+            [$env, $name] = $this->getProxyEnv('cgi_http_proxy');
+            if ($env !== null) {
+                $this->httpProxy = new ProxyItem($env, $name);
             }
         }
+
+        // Handle https_proxy/HTTPS_PROXY
+        [$env, $name] = $this->getProxyEnv('https_proxy');
+        if ($env !== null) {
+            $this->httpsProxy = new ProxyItem($env, $name);
+        }
+
+        // Handle no_proxy/NO_PROXY
+        [$env, $name] = $this->getProxyEnv('no_proxy');
+        if ($env !== null) {
+            $this->noProxyHandler = new NoProxyPattern($env);
+        }
     }
 
     /**
-     * Sets initial data
+     * Searches $_SERVER for case-sensitive values
      *
-     * @param non-empty-string $url    Proxy url
-     * @param 'http'|'https'   $scheme Environment variable scheme
-     *
-     * @return non-empty-string
+     * @return array{0: string|null, 1: string} value, name
      */
-    private function setData($url, $scheme): string
+    private function getProxyEnv(string $envName): array
     {
-        $safeProxy = Url::sanitize($url);
-        $this->fullProxy[$scheme] = $url;
-        $this->safeProxy[$scheme] = $safeProxy;
-        $this->streams[$scheme]['options'] = ProxyHelper::getContextOptions($url);
-        $this->hasProxy = true;
+        $names = [strtolower($envName), strtoupper($envName)];
 
-        return sprintf('%s=%s', $scheme, $safeProxy);
+        foreach ($names as $name) {
+            if (is_string($_SERVER[$name] ?? null)) {
+                if ($_SERVER[$name] !== '') {
+                    return [$_SERVER[$name], $name];
+                }
+                // this can be removed after the transition period
+                if ($this->isTransitional && strtolower($name) === 'https_proxy') {
+                    $this->ignoreHttpsProxy = true;
+                    break;
+                }
+            }
+        }
+
+        return [null, ''];
     }
 
     /**
@@ -176,6 +195,10 @@ class ProxyManager
      */
     private function noProxy(string $requestUrl): bool
     {
-        return $this->noProxyHandler && $this->noProxyHandler->test($requestUrl);
+        if ($this->noProxyHandler === null) {
+            return false;
+        }
+
+        return $this->noProxyHandler->test($requestUrl);
     }
 }
diff --git a/src/Composer/Util/Http/RequestProxy.php b/src/Composer/Util/Http/RequestProxy.php
index c80c8799e..d9df68861 100644
--- a/src/Composer/Util/Http/RequestProxy.php
+++ b/src/Composer/Util/Http/RequestProxy.php
@@ -12,78 +12,157 @@
 
 namespace Composer\Util\Http;
 
-use Composer\Util\Url;
+use Composer\Downloader\TransportException;
 
 /**
  * @internal
  * @author John Stevenson <john-stevenson@blueyonder.co.uk>
+ *
+ * @phpstan-type contextOptions array{http: array{proxy: string, header?: string, request_fulluri?: bool}}
  */
 class RequestProxy
 {
-    /** @var mixed[] */
+    /** @var ?contextOptions */
     private $contextOptions;
-    /** @var bool */
-    private $isSecure;
-    /** @var string */
-    private $formattedUrl;
-    /** @var string */
+    /** @var ?non-empty-string */
+    private $status;
+    /** @var ?non-empty-string */
     private $url;
+    /** @var ?non-empty-string */
+    private $auth;
 
     /**
-     * @param mixed[] $contextOptions
+     * @param ?non-empty-string $url The proxy url, without authorization
+     * @param ?non-empty-string $auth Authorization for curl
+     * @param ?contextOptions $contextOptions
+     * @param ?non-empty-string $status
      */
-    public function __construct(string $url, array $contextOptions, string $formattedUrl)
+    public function __construct(?string $url, ?string $auth, ?array $contextOptions, ?string $status)
     {
         $this->url = $url;
+        $this->auth = $auth;
         $this->contextOptions = $contextOptions;
-        $this->formattedUrl = $formattedUrl;
-        $this->isSecure = 0 === strpos($url, 'https://');
+        $this->status = $status;
+    }
+
+    public static function none(): RequestProxy
+    {
+        return new self(null, null, null, null);
+    }
+
+    public static function noProxy(): RequestProxy
+    {
+        return new self(null, null, null, 'excluded by no_proxy');
     }
 
     /**
-     * Returns an array of context options
+     * Returns the context options to use for this request, otherwise null
      *
-     * @return mixed[]
+     * @return ?contextOptions
      */
-    public function getContextOptions(): array
+    public function getContextOptions(): ?array
     {
         return $this->contextOptions;
     }
 
     /**
-     * Returns the safe proxy url from the last request
+     * Returns an array of curl proxy options
      *
-     * @param  string|null $format Output format specifier
-     * @return string      Safe proxy, no proxy or empty
+     * @param array<string, string|int> $sslOptions
+     * @return array<int, string|int>
      */
-    public function getFormattedUrl(?string $format = ''): string
+    public function getCurlOptions(array $sslOptions): array
     {
-        $result = '';
-        if ($this->formattedUrl) {
-            $format = $format ?: '%s';
-            $result = sprintf($format, $this->formattedUrl);
+        if ($this->isSecure() && !$this->supportsSecureProxy()) {
+            throw new TransportException('Cannot use an HTTPS proxy. PHP >= 7.3 and cUrl >= 7.52.0 are required.');
         }
 
-        return $result;
+        // Always set a proxy url, even an empty value, because it tells curl
+        // to ignore proxy environment variables
+        $options = [CURLOPT_PROXY => (string) $this->url];
+
+        // If using a proxy, tell curl to ignore no_proxy environment variables
+        if ($this->url !== null) {
+            $options[CURLOPT_NOPROXY] = '';
+        }
+
+        // Set any authorization
+        if ($this->auth !== null) {
+            $options[CURLOPT_PROXYAUTH] = CURLAUTH_BASIC;
+            $options[CURLOPT_PROXYUSERPWD] = $this->auth;
+        }
+
+        if ($this->isSecure()) {
+            if (isset($sslOptions['cafile'])) {
+                $options[CURLOPT_PROXY_CAINFO] = $sslOptions['cafile'];
+            }
+            if (isset($sslOptions['capath'])) {
+                $options[CURLOPT_PROXY_CAPATH] = $sslOptions['capath'];
+            }
+        }
+
+        return $options;
     }
 
     /**
-     * Returns the proxy url
+     * Returns proxy info associated with this request
      *
-     * @return string Proxy url or empty
+     * An empty return value means that the user has not set a proxy.
+     * A non-empty value will either be the sanitized proxy url if a proxy is
+     * required, or a message indicating that a no_proxy value has disabled the
+     * proxy.
+     *
+     * @param ?string $format Output format specifier
      */
-    public function getUrl(): string
+    public function getStatus(?string $format = null): string
     {
-        return $this->url;
+        if ($this->status === null) {
+            return '';
+        }
+
+        $format = $format ?? '%s';
+        if (strpos($format, '%s') !== false) {
+            return sprintf($format, $this->status);
+        }
+
+        throw new \InvalidArgumentException('String format specifier is missing');
     }
 
     /**
-     * Returns true if this is a secure-proxy
+     * Returns true if the request url has been excluded by a no_proxy value
      *
-     * @return bool False if not secure or there is no proxy
+     * A false value can also mean that the user has not set a proxy.
+     */
+    public function isExcludedByNoProxy(): bool
+    {
+        return $this->status !== null && $this->url === null;
+    }
+
+    /**
+     * Returns true if this is a secure (HTTPS) proxy
+     *
+     * A false value means that this is either an HTTP proxy, or that a proxy
+     * is not required for this request, or that the user has not set a proxy.
      */
     public function isSecure(): bool
     {
-        return $this->isSecure;
+        return 0 === strpos((string) $this->url, 'https://');
+    }
+
+    /**
+     * Returns true if an HTTPS proxy can be used.
+     *
+     * This depends on PHP7.3+ for CURL_VERSION_HTTPS_PROXY
+     * and curl including the feature (from version 7.52.0)
+     */
+    public function supportsSecureProxy(): bool
+    {
+        if (false === ($version = curl_version()) || !defined('CURL_VERSION_HTTPS_PROXY')) {
+            return false;
+        }
+
+        $features = $version['features'];
+
+        return (bool) ($features & CURL_VERSION_HTTPS_PROXY);
     }
 }
diff --git a/src/Composer/Util/RemoteFilesystem.php b/src/Composer/Util/RemoteFilesystem.php
index 6fa3437a3..560ef35db 100644
--- a/src/Composer/Util/RemoteFilesystem.php
+++ b/src/Composer/Util/RemoteFilesystem.php
@@ -64,8 +64,6 @@ class RemoteFilesystem
     private $redirects;
     /** @var int */
     private $maxRedirects = 20;
-    /** @var ProxyManager */
-    private $proxyManager;
 
     /**
      * Constructor.
@@ -91,7 +89,6 @@ class RemoteFilesystem
         $this->options = array_replace_recursive($this->options, $options);
         $this->config = $config;
         $this->authHelper = $authHelper ?? new AuthHelper($io, $config);
-        $this->proxyManager = ProxyManager::getInstance();
     }
 
     /**
@@ -276,8 +273,8 @@ class RemoteFilesystem
 
         $ctx = StreamContextFactory::getContext($fileUrl, $options, ['notification' => [$this, 'callbackGet']]);
 
-        $proxy = $this->proxyManager->getProxyForRequest($fileUrl);
-        $usingProxy = $proxy->getFormattedUrl(' using proxy (%s)');
+        $proxy = ProxyManager::getInstance()->getProxyForRequest($fileUrl);
+        $usingProxy = $proxy->getStatus(' using proxy (%s)');
         $this->io->writeError((strpos($origFileUrl, 'http') === 0 ? 'Downloading ' : 'Reading ') . Url::sanitize($origFileUrl) . $usingProxy, true, IOInterface::DEBUG);
         unset($origFileUrl, $proxy, $usingProxy);
 
diff --git a/src/Composer/Util/StreamContextFactory.php b/src/Composer/Util/StreamContextFactory.php
index 57fbe0f0e..be4c976a9 100644
--- a/src/Composer/Util/StreamContextFactory.php
+++ b/src/Composer/Util/StreamContextFactory.php
@@ -76,7 +76,8 @@ final class StreamContextFactory
         // Add stream proxy options if there is a proxy
         if (!$forCurl) {
             $proxy = ProxyManager::getInstance()->getProxyForRequest($url);
-            if ($proxyOptions = $proxy->getContextOptions()) {
+            $proxyOptions = $proxy->getContextOptions();
+            if ($proxyOptions !== null) {
                 $isHttpsRequest = 0 === strpos($url, 'https://');
 
                 if ($proxy->isSecure()) {
diff --git a/tests/Composer/Test/Util/Http/ProxyHelperTest.php b/tests/Composer/Test/Util/Http/ProxyHelperTest.php
deleted file mode 100644
index 8b9dfb1b1..000000000
--- a/tests/Composer/Test/Util/Http/ProxyHelperTest.php
+++ /dev/null
@@ -1,201 +0,0 @@
-<?php declare(strict_types=1);
-
-/*
- * This file is part of Composer.
- *
- * (c) Nils Adermann <naderman@naderman.de>
- *     Jordi Boggiano <j.boggiano@seld.be>
- *
- * For the full copyright and license information, please view the LICENSE
- * file that was distributed with this source code.
- */
-
-namespace Composer\Test\Util\Http;
-
-use Composer\Util\Http\ProxyHelper;
-use Composer\Test\TestCase;
-
-class ProxyHelperTest extends TestCase
-{
-    protected function setUp(): void
-    {
-        unset(
-            $_SERVER['HTTP_PROXY'],
-            $_SERVER['http_proxy'],
-            $_SERVER['HTTPS_PROXY'],
-            $_SERVER['https_proxy'],
-            $_SERVER['NO_PROXY'],
-            $_SERVER['no_proxy'],
-            $_SERVER['CGI_HTTP_PROXY']
-        );
-    }
-
-    protected function tearDown(): void
-    {
-        parent::tearDown();
-        unset(
-            $_SERVER['HTTP_PROXY'],
-            $_SERVER['http_proxy'],
-            $_SERVER['HTTPS_PROXY'],
-            $_SERVER['https_proxy'],
-            $_SERVER['NO_PROXY'],
-            $_SERVER['no_proxy'],
-            $_SERVER['CGI_HTTP_PROXY']
-        );
-    }
-
-    /**
-     * @dataProvider dataMalformed
-     */
-    public function testThrowsOnMalformedUrl(string $url): void
-    {
-        $_SERVER['http_proxy'] = $url;
-
-        self::expectException('RuntimeException');
-        ProxyHelper::getProxyData();
-    }
-
-    public static function dataMalformed(): array
-    {
-        return [
-            'no-host' => ['localhost'],
-            'no-port' => ['scheme://localhost'],
-        ];
-    }
-
-    /**
-     * @dataProvider dataFormatting
-     */
-    public function testUrlFormatting(string $url, string $expected): void
-    {
-        $_SERVER['http_proxy'] = $url;
-
-        [$httpProxy, $httpsProxy, $noProxy] = ProxyHelper::getProxyData();
-        $this->assertSame($expected, $httpProxy);
-    }
-
-    public static function dataFormatting(): array
-    {
-        // url, expected
-        return [
-            'lowercases-scheme' => ['HTTP://proxy.com:8888', 'http://proxy.com:8888'],
-            'adds-http-port' => ['http://proxy.com', 'http://proxy.com:80'],
-            'adds-https-port' => ['https://proxy.com', 'https://proxy.com:443'],
-        ];
-    }
-
-    /**
-     * @dataProvider dataCaseOverrides
-     *
-     * @param array<string, mixed> $server
-     */
-    public function testLowercaseOverridesUppercase(array $server, string $expected, int $index): void
-    {
-        $_SERVER = array_merge($_SERVER, $server);
-
-        $list = ProxyHelper::getProxyData();
-        $this->assertSame($expected, $list[$index]);
-    }
-
-    public static function dataCaseOverrides(): array
-    {
-        // server, expected, list index
-        return [
-            [['HTTP_PROXY' => 'http://upper.com', 'http_proxy' => 'http://lower.com'], 'http://lower.com:80', 0],
-            [['HTTPS_PROXY' => 'http://upper.com', 'https_proxy' => 'http://lower.com'], 'http://lower.com:80', 1],
-            [['NO_PROXY' => 'upper.com', 'no_proxy' => 'lower.com'], 'lower.com', 2],
-        ];
-    }
-
-    /**
-     * @dataProvider dataCGIOverrides
-     *
-     * @param array<string, mixed> $server
-     */
-    public function testCGIUpperCaseOverridesHttp(array $server, string $expected, int $index): void
-    {
-        $_SERVER = array_merge($_SERVER, $server);
-
-        $list = ProxyHelper::getProxyData();
-        $this->assertSame($expected, $list[$index]);
-    }
-
-    public static function dataCGIOverrides(): array
-    {
-        // server, expected, list index
-        return [
-            [['http_proxy' => 'http://http.com', 'CGI_HTTP_PROXY' => 'http://cgi.com'], 'http://cgi.com:80', 0],
-            [['http_proxy' => 'http://http.com', 'cgi_http_proxy' => 'http://cgi.com'], 'http://http.com:80', 0],
-        ];
-    }
-
-    public function testNoHttpsProxyUsesHttpProxy(): void
-    {
-        $_SERVER['http_proxy'] = 'http://http.com';
-
-        [$httpProxy, $httpsProxy, $noProxy] = ProxyHelper::getProxyData();
-        $this->assertSame('http://http.com:80', $httpsProxy);
-    }
-
-    public function testNoHttpProxyDoesNotUseHttpsProxy(): void
-    {
-        $_SERVER['https_proxy'] = 'http://https.com';
-
-        [$httpProxy, $httpsProxy, $noProxy] = ProxyHelper::getProxyData();
-        $this->assertSame(null, $httpProxy);
-    }
-
-    /**
-     * @dataProvider dataContextOptions
-     *
-     * @param array<string, string> $expected
-     *
-     * @phpstan-param array{http: array{proxy: string, header?: string}} $expected
-     */
-    public function testGetContextOptions(string $url, array $expected): void
-    {
-        $this->assertEquals($expected, ProxyHelper::getContextOptions($url));
-    }
-
-    public static function dataContextOptions(): array
-    {
-        // url, expected
-        return [
-            ['http://proxy.com', ['http' => [
-                'proxy' => 'tcp://proxy.com:80',
-            ]]],
-            ['https://proxy.com', ['http' => [
-                'proxy' => 'ssl://proxy.com:443',
-            ]]],
-            ['http://user:p%40ss@proxy.com', ['http' => [
-                'proxy' => 'tcp://proxy.com:80',
-                'header' => 'Proxy-Authorization: Basic dXNlcjpwQHNz',
-            ]]],
-        ];
-    }
-
-    /**
-     * @dataProvider dataRequestFullUri
-     *
-     * @param mixed[] $expected
-     */
-    public function testSetRequestFullUri(string $requestUrl, array $expected): void
-    {
-        $options = [];
-        ProxyHelper::setRequestFullUri($requestUrl, $options);
-
-        $this->assertEquals($expected, $options);
-    }
-
-    public static function dataRequestFullUri(): array
-    {
-        $options = ['http' => ['request_fulluri' => true]];
-
-        // $requestUrl, expected
-        return [
-            'http' => ['http://repo.org', $options],
-            'https' => ['https://repo.org', []],
-            'no-scheme' => ['repo.org', []],
-        ];
-    }
-}
diff --git a/tests/Composer/Test/Util/Http/ProxyItemTest.php b/tests/Composer/Test/Util/Http/ProxyItemTest.php
new file mode 100644
index 000000000..ccca76ec6
--- /dev/null
+++ b/tests/Composer/Test/Util/Http/ProxyItemTest.php
@@ -0,0 +1,72 @@
+<?php declare(strict_types=1);
+
+/*
+ * This file is part of Composer.
+ *
+ * (c) Nils Adermann <naderman@naderman.de>
+ *     Jordi Boggiano <j.boggiano@seld.be>
+ *
+ * For the full copyright and license information, please view the LICENSE
+ * file that was distributed with this source code.
+ */
+
+namespace Composer\Test\Util\Http;
+
+use Composer\Util\Http\ProxyItem;
+use Composer\Test\TestCase;
+
+class ProxyItemTest extends TestCase
+{
+    /**
+     * @dataProvider dataMalformed
+     */
+    public function testThrowsOnMalformedUrl(string $url): void
+    {
+        self::expectException('RuntimeException');
+        $proxyItem = new ProxyItem($url, 'http_proxy');
+    }
+
+    /**
+     * @return array<string, array<string>>
+     */
+    public static function dataMalformed(): array
+    {
+        return [
+            'ws-r' => ["http://user\rname@localhost:80"],
+            'ws-n' => ["http://user\nname@localhost:80"],
+            'ws-t' => ["http://user\tname@localhost:80"],
+            'no-host' => ['localhost'],
+            'no-port' => ['scheme://localhost'],
+            'port-0' => ['http://localhost:0'],
+            'port-big' => ['http://localhost:65536'],
+        ];
+    }
+
+    /**
+     * @dataProvider dataFormatting
+     */
+    public function testUrlFormatting(string $url, string $expected): void
+    {
+        $proxyItem = new ProxyItem($url, 'http_proxy');
+        $proxy = $proxyItem->toRequestProxy('http');
+
+        self::assertSame($expected, $proxy->getStatus());
+    }
+
+    /**
+     * @return array<string, array<string>>
+     */
+    public static function dataFormatting(): array
+    {
+        // url, expected
+        return [
+            'none' => ['http://proxy.com:8888', 'http://proxy.com:8888'],
+            'lowercases-scheme' => ['HTTP://proxy.com:8888', 'http://proxy.com:8888'],
+            'adds-http-scheme' => ['proxy.com:80', 'http://proxy.com:80'],
+            'adds-http-port' => ['http://proxy.com', 'http://proxy.com:80'],
+            'adds-https-port' => ['https://proxy.com', 'https://proxy.com:443'],
+            'removes-user' => ['http://user@proxy.com:6180', 'http://***@proxy.com:6180'],
+            'removes-user-pass' => ['http://user:p%40ss@proxy.com:6180', 'http://***:***@proxy.com:6180'],
+        ];
+    }
+}
diff --git a/tests/Composer/Test/Util/Http/ProxyManagerTest.php b/tests/Composer/Test/Util/Http/ProxyManagerTest.php
index 6321df6be..80c88a844 100644
--- a/tests/Composer/Test/Util/Http/ProxyManagerTest.php
+++ b/tests/Composer/Test/Util/Http/ProxyManagerTest.php
@@ -15,8 +15,16 @@ namespace Composer\Test\Util\Http;
 use Composer\Util\Http\ProxyManager;
 use Composer\Test\TestCase;
 
+/**
+ * @phpstan-import-type contextOptions from \Composer\Util\Http\RequestProxy
+ */
 class ProxyManagerTest extends TestCase
 {
+    // isTransitional can be removed after the transition period
+
+    /** @var bool */
+    private $isTransitional = true;
+
     protected function setUp(): void
     {
         unset(
@@ -26,7 +34,8 @@ class ProxyManagerTest extends TestCase
             $_SERVER['https_proxy'],
             $_SERVER['NO_PROXY'],
             $_SERVER['no_proxy'],
-            $_SERVER['CGI_HTTP_PROXY']
+            $_SERVER['CGI_HTTP_PROXY'],
+            $_SERVER['cgi_http_proxy']
         );
         ProxyManager::reset();
     }
@@ -41,7 +50,8 @@ class ProxyManagerTest extends TestCase
             $_SERVER['https_proxy'],
             $_SERVER['NO_PROXY'],
             $_SERVER['no_proxy'],
-            $_SERVER['CGI_HTTP_PROXY']
+            $_SERVER['CGI_HTTP_PROXY'],
+            $_SERVER['cgi_http_proxy']
         );
         ProxyManager::reset();
     }
@@ -49,54 +59,137 @@ class ProxyManagerTest extends TestCase
     public function testInstantiation(): void
     {
         $originalInstance = ProxyManager::getInstance();
-        $this->assertInstanceOf('Composer\Util\Http\ProxyManager', $originalInstance);
-
         $sameInstance = ProxyManager::getInstance();
-        $this->assertTrue($originalInstance === $sameInstance);
+        self::assertTrue($originalInstance === $sameInstance);
 
         ProxyManager::reset();
         $newInstance = ProxyManager::getInstance();
-        $this->assertFalse($sameInstance === $newInstance);
+        self::assertFalse($sameInstance === $newInstance);
     }
 
     public function testGetProxyForRequestThrowsOnBadProxyUrl(): void
     {
         $_SERVER['http_proxy'] = 'localhost';
         $proxyManager = ProxyManager::getInstance();
+
         self::expectException('Composer\Downloader\TransportException');
         $proxyManager->getProxyForRequest('http://example.com');
     }
 
     /**
-     * @dataProvider dataRequest
+     * @dataProvider dataCaseOverrides
      *
-     * @param array<string, mixed> $server
-     * @param mixed[]              $expectedOptions
-     * @param non-empty-string     $url
+     * @param array<string, string> $server
+     * @param non-empty-string      $url
      */
-    public function testGetProxyForRequest(array $server, string $url, string $expectedUrl, array $expectedOptions, bool $expectedSecure, string $expectedMessage): void
+    public function testLowercaseOverridesUppercase(array $server, string $url, string $expectedUrl): void
     {
         $_SERVER = array_merge($_SERVER, $server);
         $proxyManager = ProxyManager::getInstance();
 
         $proxy = $proxyManager->getProxyForRequest($url);
-        $this->assertInstanceOf('Composer\Util\Http\RequestProxy', $proxy);
-
-        $this->assertSame($expectedUrl, $proxy->getUrl());
-        $this->assertSame($expectedOptions, $proxy->getContextOptions());
-        $this->assertSame($expectedSecure, $proxy->isSecure());
-
-        $message = $proxy->getFormattedUrl();
-
-        if ($expectedMessage) {
-            $condition = stripos($message, $expectedMessage) !== false;
-        } else {
-            $condition = $expectedMessage === $message;
-        }
-
-        $this->assertTrue($condition, 'lastProxy check');
+        self::assertSame($expectedUrl, $proxy->getStatus());
     }
 
+    /**
+     * @return list<array{0: array<string, string>, 1: string, 2: string}>
+     */
+    public static function dataCaseOverrides(): array
+    {
+        // server, url, expectedUrl
+        return [
+            [['HTTP_PROXY' => 'http://upper.com', 'http_proxy' => 'http://lower.com'], 'http://repo.org', 'http://lower.com:80'],
+            [['CGI_HTTP_PROXY' => 'http://upper.com', 'cgi_http_proxy' => 'http://lower.com'], 'http://repo.org', 'http://lower.com:80'],
+            [['HTTPS_PROXY' => 'http://upper.com', 'https_proxy' => 'http://lower.com'], 'https://repo.org', 'http://lower.com:80'],
+        ];
+    }
+
+    /**
+     * @dataProvider dataCGIProxy
+     *
+     * @param array<string, string> $server
+     */
+    public function testCGIProxyIsOnlyUsedWhenNoHttpProxy(array $server, string $expectedUrl): void
+    {
+        $_SERVER = array_merge($_SERVER, $server);
+        $proxyManager = ProxyManager::getInstance();
+
+        $proxy = $proxyManager->getProxyForRequest('http://repo.org');
+        self::assertSame($expectedUrl, $proxy->getStatus());
+    }
+
+    /**
+     * @return list<array{0: array<string, string>, 1: string}>
+     */
+    public static function dataCGIProxy(): array
+    {
+        // server, expectedUrl
+        return [
+            [['CGI_HTTP_PROXY' => 'http://cgi.com:80'], 'http://cgi.com:80'],
+            [['http_proxy' => 'http://http.com:80', 'CGI_HTTP_PROXY' => 'http://cgi.com:80'], 'http://http.com:80'],
+        ];
+    }
+
+    public function testNoHttpProxyDoesNotUseHttpsProxy(): void
+    {
+        $_SERVER['https_proxy'] = 'https://proxy.com:443';
+        $proxyManager = ProxyManager::getInstance();
+
+        $proxy = $proxyManager->getProxyForRequest('http://repo.org');
+        self::assertSame('', $proxy->getStatus());
+    }
+
+    public function testNoHttpsProxyDoesNotUseHttpProxy(): void
+    {
+        $_SERVER['http_proxy'] = 'http://proxy.com:80';
+
+        // This can be removed after the transition period.
+        // An empty https_proxy value prevents using any http_proxy
+        if ($this->isTransitional) {
+            $_SERVER['https_proxy'] = '';
+        }
+
+        $proxyManager = ProxyManager::getInstance();
+        $proxy = $proxyManager->getProxyForRequest('https://repo.org');
+        self::assertSame('', $proxy->getStatus());
+    }
+
+    /**
+     * This test can be removed after the transition period
+     */
+    public function testTransitional(): void
+    {
+        $_SERVER['http_proxy'] = 'http://proxy.com:80';
+        $proxyManager = ProxyManager::getInstance();
+
+        $proxy = $proxyManager->getProxyForRequest('https://repo.org');
+        self::assertSame('http://proxy.com:80', $proxy->getStatus());
+        self::assertTrue($proxyManager->needsTransitionWarning());
+    }
+
+    /**
+     * @dataProvider dataRequest
+     *
+     * @param array<string, string> $server
+     * @param non-empty-string      $url
+     * @param ?contextOptions       $options
+     */
+    public function testGetProxyForRequest(array $server, string $url, ?array $options, string $status, bool $excluded): void
+    {
+        $_SERVER = array_merge($_SERVER, $server);
+        $proxyManager = ProxyManager::getInstance();
+
+        $proxy = $proxyManager->getProxyForRequest($url);
+        self::assertSame($options, $proxy->getContextOptions());
+        self::assertSame($status, $proxy->getStatus());
+        self::assertSame($excluded, $proxy->isExcludedByNoProxy());
+    }
+
+    /**
+     * Tests context options. curl options are tested in RequestProxyTest.php
+     *
+     * @return list<array{0: array<string, string>, 1: string, 2: ?contextOptions, 3: string, 4: bool}>
+     */
     public static function dataRequest(): array
     {
         $server = [
@@ -105,68 +198,26 @@ class ProxyManagerTest extends TestCase
             'no_proxy' => 'other.repo.org',
         ];
 
-        // server, url, expectedUrl, expectedOptions, expectedSecure, expectedMessage
+        // server, url, options, status, excluded
         return [
-            [[], 'http://repo.org', '', [], false, ''],
-            [$server, 'http://repo.org', 'http://user:p%40ss@proxy.com:80',
+            [[], 'http://repo.org', null, '', false],
+            [$server, 'http://repo.org',
                 ['http' => [
                     'proxy' => 'tcp://proxy.com:80',
                     'header' => 'Proxy-Authorization: Basic dXNlcjpwQHNz',
                     'request_fulluri' => true,
                 ]],
+                'http://***:***@proxy.com:80',
                 false,
-                'http://user:***@proxy.com:80',
             ],
-            [
-                $server, 'https://repo.org', 'https://proxy.com:443',
+            [$server, 'https://repo.org',
                 ['http' => [
                     'proxy' => 'ssl://proxy.com:443',
                 ]],
-                true,
                 'https://proxy.com:443',
+                false,
             ],
-            [$server, 'https://other.repo.org', '', [], false, 'no_proxy'],
-        ];
-    }
-
-    /**
-     * @dataProvider dataStatus
-     *
-     * @param array<string, mixed> $server
-     */
-    public function testGetStatus(array $server, bool $expectedStatus, ?string $expectedMessage): void
-    {
-        $_SERVER = array_merge($_SERVER, $server);
-        $proxyManager = ProxyManager::getInstance();
-        $status = $proxyManager->isProxying();
-        $message = $proxyManager->getFormattedProxy();
-
-        $this->assertSame($expectedStatus, $status);
-
-        if ($expectedMessage !== null) {
-            $condition = stripos($message, $expectedMessage) !== false;
-        } else {
-            $condition = $expectedMessage === $message;
-        }
-        $this->assertTrue($condition, 'message check');
-    }
-
-    public static function dataStatus(): array
-    {
-        // server, expectedStatus, expectedMessage
-        return [
-            [[], false, null],
-            [['http_proxy' => 'localhost'], false, 'malformed'],
-            [
-                ['http_proxy' => 'http://user:p%40ss@proxy.com:80'],
-                true,
-                'http=http://user:***@proxy.com:80',
-            ],
-            [
-                ['http_proxy' => 'proxy.com:80', 'https_proxy' => 'proxy.com:80'],
-                true,
-                'http=proxy.com:80, https=proxy.com:80',
-            ],
+            [$server, 'https://other.repo.org', null, 'excluded by no_proxy', true],
         ];
     }
 }
diff --git a/tests/Composer/Test/Util/Http/RequestProxyTest.php b/tests/Composer/Test/Util/Http/RequestProxyTest.php
index 66a03fccb..c01948598 100644
--- a/tests/Composer/Test/Util/Http/RequestProxyTest.php
+++ b/tests/Composer/Test/Util/Http/RequestProxyTest.php
@@ -17,45 +17,174 @@ use Composer\Test\TestCase;
 
 class RequestProxyTest extends TestCase
 {
-    /**
-     * @dataProvider dataSecure
-     */
-    public function testIsSecure(string $url, bool $expectedSecure): void
+    public function testFactoryNone(): void
     {
-        $proxy = new RequestProxy($url, [], '');
+        $proxy = RequestProxy::none();
 
-        $this->assertSame($expectedSecure, $proxy->isSecure());
+        $options = extension_loaded('curl') ? [CURLOPT_PROXY => ''] : [];
+        self::assertSame($options, $proxy->getCurlOptions([]));
+        self::assertNull($proxy->getContextOptions());
+        self::assertSame('', $proxy->getStatus());
     }
 
+    public function testFactoryNoProxy(): void
+    {
+        $proxy = RequestProxy::noProxy();
+
+        $options = extension_loaded('curl') ? [CURLOPT_PROXY => ''] : [];
+        self::assertSame($options, $proxy->getCurlOptions([]));
+        self::assertNull($proxy->getContextOptions());
+        self::assertSame('excluded by no_proxy', $proxy->getStatus());
+    }
+
+    /**
+     * @dataProvider dataSecure
+     *
+     * @param ?non-empty-string $url
+     */
+    public function testIsSecure(?string $url, bool $expected): void
+    {
+        $proxy = new RequestProxy($url, null, null, null);
+        self::assertSame($expected, $proxy->isSecure());
+    }
+
+    /**
+     * @return array<string, array{0: ?non-empty-string, 1: bool}>
+     */
     public static function dataSecure(): array
     {
-        // url, secure
+        // url, expected
         return [
             'basic' => ['http://proxy.com:80', false],
             'secure' => ['https://proxy.com:443', true],
-            'none' => ['', false],
+            'none' => [null, false],
         ];
     }
 
-    /**
-     * @dataProvider dataProxyUrl
-     */
-    public function testGetFormattedUrlFormat(string $url, string $format, string $expected): void
+    public function testGetStatusThrowsOnBadFormatSpecifier(): void
     {
-        $proxy = new RequestProxy($url, [], $url);
-
-        $message = $proxy->getFormattedUrl($format);
-        $this->assertSame($expected, $message);
+        $proxy = new RequestProxy('http://proxy.com:80', null, null, 'http://proxy.com:80');
+        self::expectException('InvalidArgumentException');
+        $proxy->getStatus('using proxy');
     }
 
-    public static function dataProxyUrl(): array
+    /**
+     * @dataProvider dataStatus
+     *
+     * @param ?non-empty-string $url
+     */
+    public function testGetStatus(?string $url, ?string $format, string $expected): void
+    {
+        $proxy = new RequestProxy($url, null, null, $url);
+
+        if ($format === null) {
+            // try with and without optional param
+            self::assertSame($expected, $proxy->getStatus());
+            self::assertSame($expected, $proxy->getStatus($format));
+        } else {
+            self::assertSame($expected, $proxy->getStatus($format));
+        }
+    }
+
+    /**
+     * @return array<string, array{0: ?non-empty-string, 1: ?string, 2: string}>
+     */
+    public static function dataStatus(): array
     {
         $format = 'proxy (%s)';
 
         // url, format, expected
         return [
-            ['', $format, ''],
-            ['http://proxy.com:80', $format, 'proxy (http://proxy.com:80)'],
+            'no-proxy' => [null, $format, ''],
+            'null-format' => ['http://proxy.com:80', null, 'http://proxy.com:80'],
+            'with-format' => ['http://proxy.com:80', $format, 'proxy (http://proxy.com:80)'],
+        ];
+    }
+
+    /**
+     * This test avoids HTTPS proxies so that it can be run on PHP < 7.3
+     *
+     * @requires extension curl
+     * @dataProvider dataCurlOptions
+     *
+     * @param ?non-empty-string $url
+     * @param ?non-empty-string $auth
+     * @param array<int, string|int> $expected
+     */
+    public function testGetCurlOptions(?string $url, ?string $auth, array $expected): void
+    {
+        $proxy = new RequestProxy($url, $auth, null, null);
+        self::assertSame($expected, $proxy->getCurlOptions([]));
+    }
+
+    /**
+     * @return list<array{0: ?string, 1: ?string, 2: array<int, string|int>}>
+     */
+    public static function dataCurlOptions(): array
+    {
+        // url, auth, expected
+        return [
+            [null, null, [CURLOPT_PROXY => '']],
+            ['http://proxy.com:80', null,
+                [
+                    CURLOPT_PROXY => 'http://proxy.com:80',
+                    CURLOPT_NOPROXY => '',
+                ],
+            ],
+            ['http://proxy.com:80', 'user:p%40ss',
+                [
+                    CURLOPT_PROXY => 'http://proxy.com:80',
+                    CURLOPT_NOPROXY => '',
+                    CURLOPT_PROXYAUTH => CURLAUTH_BASIC,
+                    CURLOPT_PROXYUSERPWD => 'user:p%40ss',
+                ],
+            ],
+        ];
+    }
+
+    /**
+     * @requires PHP >= 7.3.0
+     * @requires extension curl >= 7.52.0
+     * @dataProvider dataCurlSSLOptions
+     *
+     * @param non-empty-string $url
+     * @param ?non-empty-string $auth
+     * @param array<string, string> $sslOptions
+     * @param array<int, string|int> $expected
+     */
+    public function testGetCurlOptionsWithSSL(string $url, ?string $auth, array $sslOptions, array $expected): void
+    {
+        $proxy = new RequestProxy($url, $auth, null, null);
+        self::assertSame($expected, $proxy->getCurlOptions($sslOptions));
+    }
+
+    /**
+     * @return list<array{0: string, 1: ?string, 2: array<string, string>, 3: array<int, string|int>}>
+     */
+    public static function dataCurlSSLOptions(): array
+    {
+        // for PHPStan on PHP < 7.3
+        $caInfo = 10246; // CURLOPT_PROXY_CAINFO
+        $caPath = 10247; // CURLOPT_PROXY_CAPATH
+
+        // url, auth, sslOptions, expected
+        return [
+            ['https://proxy.com:443', null, ['cafile' => '/certs/bundle.pem'],
+                [
+                    CURLOPT_PROXY => 'https://proxy.com:443',
+                    CURLOPT_NOPROXY => '',
+                    $caInfo => '/certs/bundle.pem',
+                ],
+            ],
+            ['https://proxy.com:443', 'user:p%40ss', ['capath' => '/certs'],
+                [
+                    CURLOPT_PROXY => 'https://proxy.com:443',
+                    CURLOPT_NOPROXY => '',
+                    CURLOPT_PROXYAUTH => CURLAUTH_BASIC,
+                    CURLOPT_PROXYUSERPWD => 'user:p%40ss',
+                    $caPath => '/certs',
+                ],
+            ],
         ];
     }
 }