diff --git a/composer.json b/composer.json
index 1cc87a5..1ead76c 100644
--- a/composer.json
+++ b/composer.json
@@ -4,7 +4,8 @@
     "require": {
         "psr/clock": "1.0.0",
         "chillerlan/php-qrcode": "5.0.1",
-        "paragonie/constant_time_encoding": "2.6.3"
+        "paragonie/constant_time_encoding": "2.6.3",
+        "psr/log": "^3.0"
     },
     "require-dev": {
         "phpunit/phpunit": "^11"
diff --git a/devel.sh b/devel.sh
index db03ec4..0a6eb4c 100755
--- a/devel.sh
+++ b/devel.sh
@@ -1,8 +1,8 @@
 #!/bin/bash
 
 function tidy {
-    rm -vf {./,tests/,src/{./,AntiCSRF/,Clock/,Hash/,Request/,Required/,RFC/,Session/,URI/,Workflow/}}*~
-    rm -vf {./,tests/,src/{./,AntiCSRF/,Clock/,Hash/,Request/,Required/,RFC/,Session/,URI/,Workflow/}}#*#
+    rm -vf {./,tests/,src/{./,AntiCSRF/,Clock/,Hash/,Logger/,Request/,Required/,RFC/,Session/,URI/,Workflow/}}*~
+    rm -vf {./,tests/,src/{./,AntiCSRF/,Clock/,Hash/,Logger/,Request/,Required/,RFC/,Session/,URI/,Workflow/}}#*#
 }
 
 function clean {
diff --git a/src/Factory.php b/src/Factory.php
index e756011..428d8fa 100644
--- a/src/Factory.php
+++ b/src/Factory.php
@@ -2,20 +2,13 @@
 
 namespace BradyMcD\TAATP;
 
-use BradyMcD\TAATP\AntiCSRFInterface;
-use PSR\Clock\ClockInterface;
-use BradyMcD\TAATP\HashInterface;
 use BradyMcD\TAATP\Required\PersistenceInterface;
 use BradyMcD\TAATP\Required\RequestInterface;
-use BradyMcD\TAATP\SessionInterface;
 
-use BradyMcD\TAATP\AntiCSRF\Base as AntiCSRF;
-use BradyMcD\TAATP\Clock\Request as RequestClock;
-use BradyMcD\TAATP\Clock\Base as Clock;
-use BradyMcD\TAATP\Hash\HMAC_SHA1;
-use BradyMcD\TAATP\Session\Base as Session;
-use BradyMcD\TAATP\Workflow\UserManagement;
 use BradyMcD\TAATP\Workflow\Authenticate;
+use BradyMcD\TAATP\Workflow\UserManagement;
+use BradyMcD\TAATP\HashConfig;
+use BradyMcD\TAATP\ModuleConfig;
 
 /**
  * The primary entrypoint of the module.
@@ -26,21 +19,10 @@ class Factory
     public function __construct(
         private PersistenceInterface $db,
         private RequestInterface $request,
-        private ?SessionInterface $session,
-        private ?ClockInterface $csrfClock,
-        private ?AntiCSRFInterface $csrf,
-        private ?ClockInterface $totpClock,
-        private ?HashInterface $hash,
+        private ModuleConfig $moduleConfig = new moduleConfig,
+        private HashConfig $hashConfig = new HashConfig,
     )
     {
-        !is_null($this->session) ? : $this->session = new Session();
-        !is_null($this->csrfClock) ? : $this->csrfClock = new RequestClock();
-        !is_null($this->csrf) ? : $this->csrf = new AntiCSRF(
-            $this->session,
-            $this->csrfClock
-        );
-        !is_null($this->totpClock) ? : $this->totpClock = new Clock();
-        !is_null($this->hash) ? : $this->hash = new HMAC_SHA1();
     }
 
     public function userManagement(mixed $userIndex): UserManagement
@@ -48,10 +30,9 @@ class Factory
         return new UserManagement(
             $this->db,
             $this->request,
-            $this->csrf,
-            $this->session,
             $userIndex,
-            $this->hash
+            $this->moduleConfig,
+            $this->hashConfig
         );
     }
 
@@ -63,10 +44,9 @@ class Factory
             return new Authenticate(
                 $this->db,
                 $this->request,
-                $this->csrf,
-                $this->session,
                 $userIndex,
-                $this->hash
+                $this->moduleConfig,
+                $this->hashConfig
             );
     }
 }
diff --git a/src/Hash/HMAC_SHA1.php b/src/Hash/BuiltinHash.php
similarity index 61%
rename from src/Hash/HMAC_SHA1.php
rename to src/Hash/BuiltinHash.php
index d6d19ed..3dbd657 100644
--- a/src/Hash/HMAC_SHA1.php
+++ b/src/Hash/BuiltinHash.php
@@ -5,14 +5,22 @@ use BradyMcD\TAATP\HashInterface;
 use ParagonIE\ConstantTime\Base32;
 
 /** @SuppressWarnings(PHPMD.CamelCaseClassName)*/
-class HMAC_SHA1 implements HashInterface
+class BuiltinHash implements HashInterface
 {
+
     const DEFAULT_SECRET_SIZE = 32;
+
+    public function __construct(private readonly string $hashName)
+    {
+        (\array_search($this->hashName, \hash_hmac_algos())) ? : throw \ValueError(
+            $this->hashName . " is not the name of a built-in hash function");
+    }
+
     /** @SuppressWarnings(PHPMD.StaticAccess) */
     public function hash(string $key, string $val): string
     {
         $key = Base32::decode($key);
-        return \hash_hmac("sha1", \hex2bin($val), $key, true);
+        return \hash_hmac($this->hashName, \hex2bin($val), $key, true);
     }
 
     public function hashNumeric(string $key, int $val): string
@@ -20,9 +28,9 @@ class HMAC_SHA1 implements HashInterface
         return $this->hash($key, \dechex($val));
     }
 
-    public static function hashType(): string
+    public function hashType(): string
     {
-        return "SHA1";
+        return \strtoupper($this->hashName);
     }
 
     /** @SuppressWarnings(PHPMD.StaticAccess) */
diff --git a/src/HashConfig.php b/src/HashConfig.php
new file mode 100644
index 0000000..d2a1758
--- /dev/null
+++ b/src/HashConfig.php
@@ -0,0 +1,46 @@
+<?php declare(strict_types=1);
+
+namespace BradyMcD\TAATP;
+
+use Psr\Clock\ClockInterface;
+use BradyMcD\TAATP\HashInterface;
+
+use BradyMcD\TAATP\Clock\Base as Clock;
+use BradyMcD\TAATP\Hash\BuiltinHash;
+
+/**
+ * Configures the behaviour of the totp algorithm for newly enrolling users
+ */
+class HashConfig
+{
+    public function __construct(
+        public HashInterface|string $algorithm="SHA1",
+        public ClockInterface $clock=new Clock,
+        public int $period=30,
+        public int $digits=6
+    )
+    {
+        if (\is_string($this->hash))
+        {
+            $this->hash = new BuiltinHash($this->hash);
+        }
+    }
+
+    /**
+     * The Google Authenticator app does not handle customization to the hash function
+     * In testing as of February 2024 it would not accept otpauth URIs with any field beyond
+        the secret and issuer, failing with a generic error message
+     * Currently this is the same as the default constructor but is future proof.
+     */
+    public static function googleAuthenticator(): TotpConfig
+    {
+        return new Self(
+            "SHA1",
+            new Clock(),
+            30,
+            6,
+        );
+    }
+}
+
+?>
diff --git a/src/HashInterface.php b/src/HashInterface.php
index f765852..f2cf14f 100644
--- a/src/HashInterface.php
+++ b/src/HashInterface.php
@@ -6,7 +6,7 @@ interface HashInterface
 {
     public function hash(string $key, string $val): string;
     public function hashNumeric(string $key, int $val): string;
-    public static function hashType(): string;
+    public function hashType(): string;
     public static function keygen(): string;
 }
 
diff --git a/src/Logger/Base.php b/src/Logger/Base.php
new file mode 100644
index 0000000..a4d4a0e
--- /dev/null
+++ b/src/Logger/Base.php
@@ -0,0 +1,56 @@
+<?php declare(strict_types=1);
+
+use Psr\Log\LoggerInterface;
+
+/** @SuppressWarnings(PHPMD.DevelopmentCodeFragment)*/
+class Base implements LoggerInterface
+{
+    public function emergency(string $message, array $context = array())
+    {
+        \fwrite(STDERR, $message . \print_r($context, true) . PHP_EOL);
+    }
+
+    public function alert(string $message, array $context = array())
+    {
+        \fwrite(STDERR, $message . \print_r($context, true) . PHP_EOL);
+    }
+
+    public function critical(string $message, array $context = array())
+    {
+        \fwrite(STDERR, $message . \print_r($context, true) . PHP_EOL);
+    }
+
+    public function error(string $message, array $context = array())
+    {
+        \fwrite(STDERR, $message . \print_r($context, true) . PHP_EOL);
+    }
+
+    public function warning(string $message, array $context = array())
+    {
+        \fwrite(STDERR, $message . \print_r($context, true) . PHP_EOL);
+    }
+
+    public function notice(string $message, array $context = array())
+    {
+        \fwrite(STDOUT, $message . \print_r($context, true) . PHP_EOL);
+    }
+
+    public function info(string $message, array $context = array())
+    {
+        \fwrite(STDOUT, $message . \print_r($context, true) . PHP_EOL);
+    }
+
+    public function debug(string $message, array $context = array())
+    {
+        \fwrite(STDOUT, $message . \print_r($context, true) . PHP_EOL);
+    }
+
+    public function log(string $message, array $context = array())
+    {
+        \fwrite(STDOUT, $message . \print_r($context, true) . PHP_EOL);
+    }
+
+
+}
+
+?>
diff --git a/src/ModuleConfig.php b/src/ModuleConfig.php
new file mode 100644
index 0000000..63a7329
--- /dev/null
+++ b/src/ModuleConfig.php
@@ -0,0 +1,38 @@
+<?php declare(strict_types=1);
+
+namespace BradyMcD\TAATP;
+
+use BradyMcD\TAATP\AntiCSRFInterface;
+use Psr\Clock\ClockInterface;
+use BradyMcD\TAATP\HashInterface;
+use Psr\Log\LoggerInterface;
+use BradyMcD\TAATP\Required\PersistenceInterface;
+use BradyMcD\TAATP\Required\RequestInterface;
+use BradyMcD\TAATP\SessionInterface;
+
+use BradyMcD\TAATP\AntiCSRF\Base as AntiCSRF;
+use BradyMcD\TAATP\Clock\Request as RequestClock;
+use BradyMcD\TAATP\Clock\Base as Clock;
+use BradyMcD\TAATP\Hash\HMAC_SHA1;
+use BradyMcD\TAATP\Logger\Base as Logger;
+use BradyMcD\TAATP\Session\Base as Session;
+
+/**
+ * Configures the behaviour of the module overall
+ */
+class ModuleConfig
+{
+    public function __construct(
+        public LoggerInterface $logger=new Logger,
+        public SessionInterface $session=new Session,
+        public ?AntiCSRFInterface $csrf=null,
+    )
+    {
+        !\is_null($this->csrf) ? : $this->csrf = new AntiCSRF(
+            $this->session,
+            new RequestClock()
+        );
+    }
+}
+
+?>
diff --git a/src/Workflow/Authenticate.php b/src/Workflow/Authenticate.php
index 677fa40..5b23a71 100644
--- a/src/Workflow/Authenticate.php
+++ b/src/Workflow/Authenticate.php
@@ -2,11 +2,10 @@
 
 namespace BradyMcD\TAATP\Workflow;
 
-use BradyMcD\TAATP\AntiCSRFInterface;
-use BradyMcD\TAATP\HashInterface;
 use BradyMcD\TAATP\Required\PersistenceInterface;
 use BradyMcD\TAATP\Required\RequestInterface;
-use BradyMcD\TAATP\SessionInterface;
+use BradyMcD\TAATP\HashConfig;
+use BradyMcD\TAATP\ModuleConfig;
 use BradyMcD\TAATP\WorkflowInterface;
 
 use BradyMcD\TAATP\URI\Otpauth;
@@ -17,10 +16,9 @@ class Authenticate implements WorkflowInterface
     public function __construct(
         private PersistenceInterface $db,
         private RequestInterface $request,
-        private AntiCSRFInterface $csrf,
-        private SessionInterface $session,
         private mixed $userIndex,
-        private HashInterface $hash,
+        private ModuleConfig $taatp,
+        private HashConfig $totp,
     )
     {
     }
@@ -33,14 +31,14 @@ class Authenticate implements WorkflowInterface
     function emitStr(): string
     {
         $html  = "<div id=\"authenticate\"><form %frm>";
-        $html .= $this->csrf->emitStr();
+        $html .= $this->taatp.csrf->emitStr();
         $html .= "<p>Please enter the code showing on your authenticator</p>";
         $html .= "<intput name=\"totp_challenge\" id=\"totp_challenge\" type\"text\" />";
         $html .= "<input type=\"submit\" value=\"Submit\" />";
         $html .= "</form></div>";
 
         $values = [
-            "%frm" => $this->ri->formProps("authenticate"),
+            "%frm" => $this->request->formProps("authenticate"),
         ];
 
         return \str_replace(\array_keys($values), $values, $html);
@@ -48,21 +46,36 @@ class Authenticate implements WorkflowInterface
 
     function response(): bool
     {
-        if (!this->csrf->match())
+        if (!this->taatp.csrf->match())
         {
+            $this->taatp.logger->info("Anti-csrf token failure.");
             return false;
         }
 
         $pUri = $this->db->getSecret($this->userIndex);
 
+        try
+        {
+            $algorithm = new BuiltinHash($pUri.algorithm);
+        }
+        catch (\InvalidArgumentException $e)
+        {
+            $this->taatp.logger->alert(
+                "Unable to authenticate user:" .
+                    $db->userString($userIndex) .
+                    ". otp configuration on database refers to unsopported algorithm:" .
+                    $pUri.algorithm);
+            return false;
+        }
+
         $totp = _6238(
             $pUri.secret,
             $pUri.period,
             $this->db->getLastTime($this->userIndex),
             2,
             $pUri.digits,
-            $this->clock,
-            $this->hash
+            $this->totp.clock,
+            $algorithm
         );
         $flag = $totp.validate($this->ri->getResp("totp_challenge"));
 
diff --git a/src/Workflow/UserManagement.php b/src/Workflow/UserManagement.php
index 5bfa905..6c37a90 100644
--- a/src/Workflow/UserManagement.php
+++ b/src/Workflow/UserManagement.php
@@ -2,11 +2,10 @@
 
 namespace BradyMcD\TAATP\Workflow;
 
-use BradyMcD\TAATP\AntiCSRFInterface;
-use BradyMcD\TAATP\HashInterface;
 use BradyMcD\TAATP\Required\PersistenceInterface;
 use BradyMcD\TAATP\Required\RequestInterface;
-use BradyMcD\TAATP\SessionInterface;
+use BradyMcD\TAATP\HashConfig;
+use BradyMcD\TAATP\ModuleConfig;
 use BradyMcD\TAATP\WorkflowInterface;
 
 use BradyMcD\TAATP\URI\Otpauth;
@@ -20,10 +19,9 @@ class UserManagement implements WorkflowInterface
     public function __construct(
         private PersistenceInterface $db,
         private RequestInterface $request,
-        private AntiCSRFInterface $csrf,
-        private SessionInterface $session,
         private mixed $userIndex,
-        private HashInterface $hash,
+        private ModuleConfig $moduleConfig,
+        private HashConfig $hashConfig,
     )
     {
     }
@@ -36,7 +34,7 @@ class UserManagement implements WorkflowInterface
     private function viewEnrollForm(): string
     {
         $html  = "<div id=\"enroll\"><form %frm>";
-        $html .= $this->csrf->emitStr();
+        $html .= $this->moduleConfig.csrf->emitStr();
         $html .= "<p>To add an authenticator to your account, scan the QR code</p>";
         $html .= "<img src=%qr alt=\"qr-code\" height=256px width=256px/>";
         $html .= "<label for=\"totp_challenge\">Enter the authentication code:</label>";
@@ -46,15 +44,15 @@ class UserManagement implements WorkflowInterface
 
         $otpauthURI = new Otpauth(
             $this->db->userString($this->userIndex),
-            "taatp",
-            $this->hash->keygen(),
-            $this->hash->hashType(),
+            "taaatp",
+            $this->hashConfig.hash->keygen(),
+            $this->hashConfig.hash->hashType(),
             6,
             30
         );
         $provisioningUri = $otpauthURI->uriString();
         $persistentUri = $otpauthURI->uriStringExplicit();
-        $this->session->store("secret", $persistentUri);
+        $this->moduleConfig.session->store("secret", $persistentUri);
 
         $values = [
             "%frm" => $this->request->formProps("enroll"),
@@ -66,7 +64,7 @@ class UserManagement implements WorkflowInterface
     private function viewUnenrollForm(): string
     {
         $html  = "<div id=\"unenroll\"><form %frm>";
-        $html .= $this->csrf->emitStr();
+        $html .= $this->moduleConfig.csrf->emitStr();
         $html .= "<label for=\"totp_challenge\">To de-register your authenticator enter the current authentication code:</label>";
         $html .= "<intput name=\"totp_challenge\" id=\"totp_challenge\" type\"text\" />";
         $html .= "<input type=\"submit\" value=\"Submit\" />";
@@ -90,25 +88,26 @@ class UserManagement implements WorkflowInterface
 
     function response(): bool
     {
-        if (!$this->csrf->match())
+        if (!$this->moduleConfig.csrf->match())
         {
             return false;
         }
 
         $pUri = $this->db->getSecret($this->userIndex);
         $enrollFlag = \is_null($pUri);
-        $enrollFlag && $pUri = $this->session->get('secret');
+        $enrollFlag && $pUri = $this->moduleConfig.session->get('secret');
 
         echo "Recovered pURI for a " . ($enrollFlag)?"new user":"returning user";
 
+
         $totp = _6238(
             $pUri->getSecret(),
             $pUri.period,
             $enrollFlag? 0:$this->db->getLastTime($this->userIndex),
             2,
             $pUri.digits,
-            $this->clock,
-            $this->hash
+            $this->hashConfig.clock,
+            $this->hashConfig.algorithm
         );
         $flag = $totp.validate($this->request->getResp("totp_challenge"));