Revert of Add policies support to VerifyCertificateChain().

net/cert/internal/verify_certificate_chain.cc

 // Copyright 2015 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "net/cert/internal/verify_certificate_chain.h"
 
-#include <algorithm>
 #include <memory>
 
 #include "base/logging.h"
 #include "base/memory/ptr_util.h"
 #include "net/cert/internal/cert_error_params.h"
 #include "net/cert/internal/cert_errors.h"
 #include "net/cert/internal/extended_key_usage.h"
 #include "net/cert/internal/name_constraints.h"
 #include "net/cert/internal/parse_certificate.h"
 #include "net/cert/internal/signature_algorithm.h"
@@ skipping 39 matching lines @@
 DEFINE_CERT_ERROR_ID(kVerifySignedDataFailed, "VerifySignedData failed");
 DEFINE_CERT_ERROR_ID(kSignatureAlgorithmsDifferentEncoding,
                      "Certificate.signatureAlgorithm is encoded differently "
                      "than TBSCertificate.signature");
 DEFINE_CERT_ERROR_ID(kEkuLacksServerAuth,
                      "The extended key usage does not include server auth");
 DEFINE_CERT_ERROR_ID(kEkuLacksClientAuth,
                      "The extended key usage does not include client auth");
 DEFINE_CERT_ERROR_ID(kCertIsNotTrustAnchor,
                      "Certificate is not a trust anchor");
-DEFINE_CERT_ERROR_ID(kNoValidPolicy, "No valid policy");
-DEFINE_CERT_ERROR_ID(kPolicyMappingAnyPolicy,
-                     "PolicyMappings must not map anyPolicy");
 
 bool IsHandledCriticalExtensionOid(const der::Input& oid) {
   if (oid == BasicConstraintsOid())
     return true;
   // Key Usage is NOT processed for end-entity certificates (this is the
   // responsibility of callers), however it is considered "handled" here in
   // order to allow being marked as critical.
   if (oid == KeyUsageOid())
     return true;
   if (oid == ExtKeyUsageOid())
     return true;
   if (oid == NameConstraintsOid())
     return true;
   if (oid == SubjectAltNameOid())
     return true;
-  // TODO(eroman): The policy qualifiers are not processed (or in some cases
-  // even parsed). This is fine when the policies extension is non-critical,
-  // however if it is critical the code should also ensure that the policy
-  // qualifiers are only recognized ones (CPS and User Notice).
-  if (oid == CertificatePoliciesOid())
-    return true;
-  if (oid == PolicyMappingsOid())
-    return true;
-  if (oid == PolicyConstraintsOid())
-    return true;
-  if (oid == InhibitAnyPolicyOid())
-    return true;
 
+  // TODO(eroman): Make this more complete.
   return false;
 }
 
 // Adds errors to |errors| if the certificate contains unconsumed _critical_
 // extensions.
 void VerifyNoUnconsumedCriticalExtensions(const ParsedCertificate& cert,
                                           CertErrors* errors) {
   for (const auto& it : cert.extensions()) {
     const ParsedExtension& extension = it.second;
     if (extension.critical && !IsHandledCriticalExtensionOid(extension.oid)) {
@@ skipping 20 matching lines @@
 }
 
 // Adds errors to |errors| if |cert| is not valid at time |time|.
 //
 // The certificate's validity requirements are described by RFC 5280 section
 // 4.1.2.5:
 //
 //    The validity period for a certificate is the period of time from
 //    notBefore through notAfter, inclusive.
 void VerifyTimeValidity(const ParsedCertificate& cert,
-                        const der::GeneralizedTime& time,
+                        const der::GeneralizedTime time,
                         CertErrors* errors) {
   if (time < cert.tbs().validity_not_before)
     errors->AddError(kValidityFailedNotBefore);
 
   if (cert.tbs().validity_not_after < time)
     errors->AddError(kValidityFailedNotAfter);
 }
 
 // Adds errors to |errors| if |cert| has internally inconsistent signature
 // algorithms.
@@ skipping 75 matching lines @@
         if (key_purpose_oid == ClientAuth())
           return;
       }
 
       errors->AddError(kEkuLacksClientAuth);
       break;
     }
   }
 }
 
-// Returns |true| if |policies| contains the OID |search_oid|.
-bool SetContains(const std::set<der::Input>& policies,
-                 const der::Input& search_oid) {
-  return policies.count(search_oid) > 0;
-}
-
-// Representation of RFC 5280's "valid_policy_tree", used to keep track of the
-// valid policies and policy re-mappings.
-//
-// ValidPolicyTree differs slightly from RFC 5280's description in that:
-//
-//  (1) It does not track "qualifier_set". This is not needed as it is not
-//      output by this implementation.
-//
-//  (2) It only stores the most recent level of the policy tree rather than
-//      the full tree of nodes.
-class ValidPolicyTree {
- public:
-  ValidPolicyTree() {}
-
-  struct Node {
-    // |root_policy| is equivalent to |valid_policy|, but in the domain of the
-    // caller.
-    //
-    // The reason for this distinction is the Policy Mappings extension.
-    //
-    // So whereas |valid_policy| is in the remapped domain defined by the
-    // issuing certificate, |root_policy| is in the fixed domain of the caller.
-    //
-    // OIDs in "user_initial_policy_set" and "user_constrained_policy_set" are
-    // directly comparable to |root_policy| values, but not necessarily to
-    // |valid_policy|.
-    //
-    // In terms of the valid policy tree, |root_policy| can be found by
-    // starting at the node's root ancestor, and finding the first node with a
-    // valid_policy other than anyPolicy. This is effectively the same process
-    // as used during policy tree intersection in RFC 5280 6.1.5.g.iii.1
-    der::Input root_policy;
-
-    // The same as RFC 5280's "valid_policy" variable.
-    der::Input valid_policy;
-
-    // The same as RFC 5280s "expected_policy_set" variable.
-    std::set<der::Input> expected_policy_set;
-
-    // Note that RFC 5280's "qualifier_set" is omitted.
-  };
-
-  // Level represents all the nodes at depth "i" in the valid_policy_tree.
-  using Level = std::vector<Node>;
-
-  // Initializes the ValidPolicyTree for the given "user_initial_policy_set".
-  //
-  // In RFC 5280, the valid_policy_tree is initialized to a root node at depth
-  // 0 of "anyPolicy"; the intersection with the "user_initial_policy_set" is
-  // done at the end (Wrap Up) as described in section 6.1.5 step g.
-  //
-  // Whereas in this implementation, the restriction on policies is added here,
-  // and intersecting the valid policy tree during Wrap Up is no longer needed.
-  //
-  // The final "user_constrained_policy_set" obtained will be the same. The
-  // advantages of this approach is simpler code.
-  void Init(const std::set<der::Input>& user_initial_policy_set) {
-    Clear();
-    for (const der::Input& policy_oid : user_initial_policy_set)
-      AddRootNode(policy_oid);
-  }
-
-  // Returns the current level (i.e. all nodes at depth i in the valid
-  // policy tree).
-  const Level& current_level() const { return current_level_; }
-  Level& current_level() { return current_level_; }
-
-  // In RFC 5280 valid_policy_tree may be set to null. That is represented here
-  // by emptiness.
-  bool IsNull() const { return current_level_.empty(); }
-  void SetNull() { Clear(); }
-
-  // This implementation keeps only the last level of the valid policy
-  // tree. Calling StartLevel() returns the nodes for the previous
-  // level, and starts a new level.
-  Level StartLevel() {
-    Level prev_level;
-    std::swap(prev_level, current_level_);
-    return prev_level;
-  }
-
-  // Gets the set of policies (in terms of root authority's policy domain) that
-  // are valid at the curent level of the policy tree.
-  //
-  // For example:
-  //
-  //  * If the valid policy tree was initialized with anyPolicy, then this
-  //    function returns what X.509 calls "authorities-constrained-policy-set".
-  //
-  //  * If the valid policy tree was instead initialized with the
-  //    "user-initial-policy_set", then this function returns what X.509
-  //    calls "user-constrained-policy-set"
-  //    ("authorities-constrained-policy-set" intersected with the
-  //    "user-initial-policy-set").
-  void GetValidRootPolicySet(std::set<der::Input>* policy_set) {
-    policy_set->clear();
-    for (const Node& node : current_level_)
-      policy_set->insert(node.root_policy);
-
-    // If the result includes anyPolicy, simplify it to a set of size 1.
-    if (policy_set->size() > 1 && SetContains(*policy_set, AnyPolicy()))
-      *policy_set = {AnyPolicy()};
-  }
-
-  // Adds a node |n| to the current level which is a child of |parent|
-  // such that:
-  //   * n.valid_policy = policy_oid
-  //   * n.expected_policy_set = {policy_oid}
-  void AddNode(const Node& parent, const der::Input& policy_oid) {
-    AddNodeWithExpectedPolicySet(parent, policy_oid, {policy_oid});
-  }
-
-  // Adds a node |n| to the current level which is a child of |parent|
-  // such that:
-  //   * n.valid_policy = policy_oid
-  //   * n.expected_policy_set = expected_policy_set
-  void AddNodeWithExpectedPolicySet(
-      const Node& parent,
-      const der::Input& policy_oid,
-      const std::set<der::Input>& expected_policy_set) {
-    Node new_node;
-    new_node.valid_policy = policy_oid;
-    new_node.expected_policy_set = expected_policy_set;
-
-    // Consider the root policy as the first policy other than anyPolicy (or
-    // anyPolicy if it hasn't been restricted yet).
-    new_node.root_policy =
-        (parent.root_policy == AnyPolicy()) ? policy_oid : parent.root_policy;
-
-    current_level_.push_back(std::move(new_node));
-  }
-
-  // Returns the first node having valid_policy == anyPolicy in |level|, or
-  // nullptr if there is none.
-  static const Node* FindAnyPolicyNode(const Level& level) {
-    for (const Node& node : level) {
-      if (node.valid_policy == AnyPolicy())
-        return &node;
-    }
-    return nullptr;
-  }
-
-  // Deletes all nodes |n| in |level| where |n.valid_policy| matches the given
-  // |valid_policy|. This may re-order the nodes in |level|.
-  static void DeleteNodesMatchingValidPolicy(const der::Input& valid_policy,
-                                             Level* level) {
-    // This works by swapping nodes to the end of the vector, and then doing a
-    // single resize to delete them all.
-    auto cur = level->begin();
-    auto end = level->end();
-    while (cur != end) {
-      bool should_delete_node = cur->valid_policy == valid_policy;
-      if (should_delete_node) {
-        end = std::prev(end);
-        std::iter_swap(cur, end);
-      } else {
-        ++cur;
-      }
-    }
-    level->erase(end, level->end());
-  }
-
- private:
-  // Deletes all nodes in the valid policy tree.
-  void Clear() { current_level_.clear(); }
-
-  // Adds a node to the current level for OID |policy_oid|. The current level
-  // is assumed to be the root level.
-  void AddRootNode(const der::Input& policy_oid) {
-    Node new_node;
-    new_node.root_policy = policy_oid;
-    new_node.valid_policy = policy_oid;
-    new_node.expected_policy_set = {policy_oid};
-    current_level_.push_back(std::move(new_node));
-  }
-
-  Level current_level_;
-
-  DISALLOW_COPY_AND_ASSIGN(ValidPolicyTree);
-};
-
-// Class that encapsulates the state variables used by certificate path
-// validation.
-class PathVerifier {
- public:
-  // Same parameters and meaning as VerifyCertificateChain().
-  void Run(const ParsedCertificateList& certs,
-           const CertificateTrust& last_cert_trust,
-           const SignaturePolicy* signature_policy,
-           const der::GeneralizedTime& time,
-           KeyPurpose required_key_purpose,
-           InitialExplicitPolicy initial_explicit_policy,
-           const std::set<der::Input>& user_initial_policy_set,
-           InitialPolicyMappingInhibit initial_policy_mapping_inhibit,
-           InitialAnyPolicyInhibit initial_any_policy_inhibit,
-           std::set<der::Input>* user_constrained_policy_set,
-           CertPathErrors* errors);
-
- private:
-  // Verifies and updates the valid policies. This corresponds with RFC 5280
-  // section 6.1.3 steps d-f.
-  void VerifyPolicies(const ParsedCertificate& cert,
-                      bool is_target_cert,
-                      CertErrors* errors);
-
-  // Applies the policy mappings. This corresponds with RFC 5280 section 6.1.4
-  // steps a-b.
-  void VerifyPolicyMappings(const ParsedCertificate& cert, CertErrors* errors);
-
-  // This function corresponds to RFC 5280 section 6.1.3's "Basic Certificate
-  // Processing" procedure.
-  void BasicCertificateProcessing(const ParsedCertificate& cert,
-                                  bool is_target_cert,
-                                  const SignaturePolicy* signature_policy,
-                                  const der::GeneralizedTime& time,
-                                  KeyPurpose required_key_purpose,
-                                  CertErrors* errors);
-
-  // This function corresponds to RFC 5280 section 6.1.4's "Preparation for
-  // Certificate i+1" procedure. |cert| is expected to be an intermediate.
-  void PrepareForNextCertificate(const ParsedCertificate& cert,
-                                 CertErrors* errors);
-
-  // This function corresponds with RFC 5280 section 6.1.5's "Wrap-Up
-  // Procedure". It does processing for the final certificate (the target cert).
-  void WrapUp(const ParsedCertificate& cert, CertErrors* errors);
-
-  // Enforces trust anchor constraints compatibile with RFC 5937.
-  //
-  // Note that the anchor constraints are encoded via the attached certificate
-  // itself.
-  void ApplyTrustAnchorConstraints(const ParsedCertificate& cert,
-                                   KeyPurpose required_key_purpose,
-                                   CertErrors* errors);
-
-  // Initializes the path validation algorithm given anchor constraints. This
-  // follows the description in RFC 5937
-  void ProcessRootCertificate(const ParsedCertificate& cert,
-                              const CertificateTrust& trust,
-                              KeyPurpose required_key_purpose,
-                              CertErrors* errors);
-
-  ValidPolicyTree valid_policy_tree_;
-
-  // Will contain a NameConstraints for each previous cert in the chain which
-  // had nameConstraints. This corresponds to the permitted_subtrees and
-  // excluded_subtrees state variables from RFC 5280.
-  std::vector<const NameConstraints*> name_constraints_list_;
-
-  // |explicit_policy_| corresponds with the same named variable from RFC 5280
-  // section 6.1.2:
-  //
-  //   explicit_policy:  an integer that indicates if a non-NULL
-  //   valid_policy_tree is required.  The integer indicates the
-  //   number of non-self-issued certificates to be processed before
-  //   this requirement is imposed.  Once set, this variable may be
-  //   decreased, but may not be increased.  That is, if a certificate in the
-  //   path requires a non-NULL valid_policy_tree, a later certificate cannot
-  //   remove this requirement.  If initial-explicit-policy is set, then the
-  //   initial value is 0, otherwise the initial value is n+1.
-  size_t explicit_policy_;
-
-  // |inhibit_any_policy_| corresponds with the same named variable from RFC
-  // 5280 section 6.1.2:
-  //
-  //   inhibit_anyPolicy:  an integer that indicates whether the
-  //   anyPolicy policy identifier is considered a match.  The
-  //   integer indicates the number of non-self-issued certificates
-  //   to be processed before the anyPolicy OID, if asserted in a
-  //   certificate other than an intermediate self-issued
-  //   certificate, is ignored.  Once set, this variable may be
-  //   decreased, but may not be increased.  That is, if a
-  //   certificate in the path inhibits processing of anyPolicy, a
-  //   later certificate cannot permit it.  If initial-any-policy-
-  //   inhibit is set, then the initial value is 0, otherwise the
-  //   initial value is n+1.
-  size_t inhibit_any_policy_;
-
-  // |policy_mapping_| corresponds with the same named variable from RFC 5280
-  // section 6.1.2:
-  //
-  //   policy_mapping:  an integer that indicates if policy mapping
-  //   is permitted.  The integer indicates the number of non-self-
-  //   issued certificates to be processed before policy mapping is
-  //   inhibited.  Once set, this variable may be decreased, but may
-  //   not be increased.  That is, if a certificate in the path
-  //   specifies that policy mapping is not permitted, it cannot be
-  //   overridden by a later certificate.  If initial-policy-
-  //   mapping-inhibit is set, then the initial value is 0,
-  //   otherwise the initial value is n+1.
-  size_t policy_mapping_;
-
-  // |working_spki_| is an amalgamation of 3 separate variables from RFC 5280:
-  //    * working_public_key
-  //    * working_public_key_algorithm
-  //    * working_public_key_parameters
-  //
-  // They are combined for simplicity since the signature verification takes an
-  // SPKI, and the parameter inheritence is not applicable for the supported
-  // key types.
-  //
-  // An approximate explanation of |working_spki| is this description from RFC
-  // 5280 section 6.1.2:
-  //
-  //    working_public_key:  the public key used to verify the
-  //    signature of a certificate.
-  der::Input working_spki_;
-
-  // |working_normalized_issuer_name_| is the normalized value of the
-  // working_issuer_name variable in RFC 5280 section 6.1.2:
-  //
-  //    working_issuer_name:  the issuer distinguished name expected
-  //    in the next certificate in the chain.
-  der::Input working_normalized_issuer_name_;
-
-  // |max_path_length_| corresponds with the same named variable in RFC 5280
-  // section 6.1.2.
-  //
-  //    max_path_length:  this integer is initialized to n, is
-  //    decremented for each non-self-issued certificate in the path,
-  //    and may be reduced to the value in the path length constraint
-  //    field within the basic constraints extension of a CA
-  //    certificate.
-  size_t max_path_length_;
-};
-
-void PathVerifier::VerifyPolicies(const ParsedCertificate& cert,
-                                  bool is_target_cert,
-                                  CertErrors* errors) {
-  // From RFC 5280 section 6.1.3:
-  //
-  //  (d)  If the certificate policies extension is present in the
-  //       certificate and the valid_policy_tree is not NULL, process
-  //       the policy information by performing the following steps in
-  //       order:
-  if (cert.has_policy_oids() && !valid_policy_tree_.IsNull()) {
-    ValidPolicyTree::Level previous_level = valid_policy_tree_.StartLevel();
-
-    // Identify if there was a node with valid_policy == anyPolicy at depth i-1.
-    const ValidPolicyTree::Node* any_policy_node_prev_level =
-        ValidPolicyTree::FindAnyPolicyNode(previous_level);
-
-    //     (1)  For each policy P not equal to anyPolicy in the
-    //          certificate policies extension, let P-OID denote the OID
-    //          for policy P and P-Q denote the qualifier set for policy
-    //          P.  Perform the following steps in order:
-    bool cert_has_any_policy = false;
-    for (const der::Input& p_oid : cert.policy_oids()) {
-      if (p_oid == AnyPolicy()) {
-        cert_has_any_policy = true;
-        continue;
-      }
-
-      //        (i)   For each node of depth i-1 in the valid_policy_tree
-      //              where P-OID is in the expected_policy_set, create a
-      //              child node as follows: set the valid_policy to P-OID,
-      //              set the qualifier_set to P-Q, and set the
-      //              expected_policy_set to {P-OID}.
-      bool found_match = false;
-      for (const ValidPolicyTree::Node& prev_node : previous_level) {
-        if (SetContains(prev_node.expected_policy_set, p_oid)) {
-          valid_policy_tree_.AddNode(prev_node, p_oid);
-          found_match = true;
-        }
-      }
-
-      //        (ii)  If there was no match in step (i) and the
-      //              valid_policy_tree includes a node of depth i-1 with
-      //              the valid_policy anyPolicy, generate a child node with
-      //              the following values: set the valid_policy to P-OID,
-      //              set the qualifier_set to P-Q, and set the
-      //              expected_policy_set to  {P-OID}.
-      if (!found_match && any_policy_node_prev_level)
-        valid_policy_tree_.AddNode(*any_policy_node_prev_level, p_oid);
-    }
-
-    //     (2)  If the certificate policies extension includes the policy
-    //          anyPolicy with the qualifier set AP-Q and either (a)
-    //          inhibit_anyPolicy is greater than 0 or (b) i<n and the
-    //          certificate is self-issued, then:
-    //
-    //          For each node in the valid_policy_tree of depth i-1, for
-    //          each value in the expected_policy_set (including
-    //          anyPolicy) that does not appear in a child node, create a
-    //          child node with the following values: set the valid_policy
-    //          to the value from the expected_policy_set in the parent
-    //          node, set the qualifier_set to AP-Q, and set the
-    //          expected_policy_set to the value in the valid_policy from
-    //          this node.
-    if (cert_has_any_policy && ((inhibit_any_policy_ > 0) ||
-                                (!is_target_cert && IsSelfIssued(cert)))) {
-      // Keep track of the existing policies at depth i.
-      std::set<der::Input> child_node_policies;
-      for (const ValidPolicyTree::Node& node :
-           valid_policy_tree_.current_level())
-        child_node_policies.insert(node.valid_policy);
-
-      for (const ValidPolicyTree::Node& prev_node : previous_level) {
-        for (const der::Input& expected_policy :
-             prev_node.expected_policy_set) {
-          if (!SetContains(child_node_policies, expected_policy)) {
-            child_node_policies.insert(expected_policy);
-            valid_policy_tree_.AddNode(prev_node, expected_policy);
-          }
-        }
-      }
-    }
-
-    //     (3)  If there is a node in the valid_policy_tree of depth i-1
-    //          or less without any child nodes, delete that node.  Repeat
-    //          this step until there are no nodes of depth i-1 or less
-    //          without children.
-    //
-    // Nothing needs to be done for this step, since this implementation only
-    // stores the nodes at depth i, and the entire level has already been
-    // calculated.
-  }
-
-  //  (e)  If the certificate policies extension is not present, set the
-  //       valid_policy_tree to NULL.
-  if (!cert.has_policy_oids())
-    valid_policy_tree_.SetNull();
-
-  //  (f)  Verify that either explicit_policy is greater than 0 or the
-  //       valid_policy_tree is not equal to NULL;
-  if (!((explicit_policy_ > 0) || !valid_policy_tree_.IsNull()))
-    errors->AddError(kNoValidPolicy);
-}
-
-void PathVerifier::VerifyPolicyMappings(const ParsedCertificate& cert,
-                                        CertErrors* errors) {
-  if (!cert.has_policy_mappings())
-    return;
-
-  // From RFC 5280 section 6.1.4:
-  //
-  //  (a)  If a policy mappings extension is present, verify that the
-  //       special value anyPolicy does not appear as an
-  //       issuerDomainPolicy or a subjectDomainPolicy.
-  for (const ParsedPolicyMapping& mapping : cert.policy_mappings()) {
-    if (mapping.issuer_domain_policy == AnyPolicy() ||
-        mapping.subject_domain_policy == AnyPolicy()) {
-      // Because this implementation continues processing certificates after
-      // this error, clear the valid policy tree to ensure the
-      // "user_constrained_policy_set" output upon failure is empty.
-      valid_policy_tree_.SetNull();
-      errors->AddError(kPolicyMappingAnyPolicy);
-    }
-  }
-
-  //  (b)  If a policy mappings extension is present, then for each
-  //       issuerDomainPolicy ID-P in the policy mappings extension:
-  //
-  //     (1)  If the policy_mapping variable is greater than 0, for each
-  //          node in the valid_policy_tree of depth i where ID-P is the
-  //          valid_policy, set expected_policy_set to the set of
-  //          subjectDomainPolicy values that are specified as
-  //          equivalent to ID-P by the policy mappings extension.
-  //
-  //          If no node of depth i in the valid_policy_tree has a
-  //          valid_policy of ID-P but there is a node of depth i with a
-  //          valid_policy of anyPolicy, then generate a child node of
-  //          the node of depth i-1 that has a valid_policy of anyPolicy
-  //          as follows:
-  //
-  //        (i)    set the valid_policy to ID-P;
-  //
-  //        (ii)   set the qualifier_set to the qualifier set of the
-  //               policy anyPolicy in the certificate policies
-  //               extension of certificate i; and
-  //
-  //        (iii)  set the expected_policy_set to the set of
-  //               subjectDomainPolicy values that are specified as
-  //               equivalent to ID-P by the policy mappings extension.
-  //
-  if (policy_mapping_ > 0) {
-    const ValidPolicyTree::Node* any_policy_node =
-        ValidPolicyTree::FindAnyPolicyNode(valid_policy_tree_.current_level());
-
-    // Group mappings by issuer domain policy.
-    std::map<der::Input, std::set<der::Input>> mappings;
-    for (const ParsedPolicyMapping& mapping : cert.policy_mappings()) {
-      mappings[mapping.issuer_domain_policy].insert(
-          mapping.subject_domain_policy);
-    }
-
-    for (const auto& it : mappings) {
-      const der::Input& issuer_domain_policy = it.first;
-      const std::set<der::Input>& subject_domain_policies = it.second;
-      bool found_node = false;
-
-      for (ValidPolicyTree::Node& node : valid_policy_tree_.current_level()) {
-        if (node.valid_policy == issuer_domain_policy) {
-          node.expected_policy_set = subject_domain_policies;
-          found_node = true;
-        }
-      }
-
-      if (!found_node && any_policy_node) {
-        valid_policy_tree_.AddNodeWithExpectedPolicySet(
-            *any_policy_node, issuer_domain_policy, subject_domain_policies);
-      }
-    }
-  }
-
-  //  (b)  If a policy mappings extension is present, then for each
-  //       issuerDomainPolicy ID-P in the policy mappings extension:
-  //
-  //  ...
-  //
-  //     (2)  If the policy_mapping variable is equal to 0:
-  //
-  //        (i)    delete each node of depth i in the valid_policy_tree
-  //               where ID-P is the valid_policy.
-  //
-  //        (ii)   If there is a node in the valid_policy_tree of depth
-  //               i-1 or less without any child nodes, delete that
-  //               node.  Repeat this step until there are no nodes of
-  //               depth i-1 or less without children.
-  if (policy_mapping_ == 0) {
-    for (const ParsedPolicyMapping& mapping : cert.policy_mappings()) {
-      ValidPolicyTree::DeleteNodesMatchingValidPolicy(
-          mapping.issuer_domain_policy, &valid_policy_tree_.current_level());
-    }
-  }
-}
-
-void PathVerifier::BasicCertificateProcessing(
+// This function corresponds to RFC 5280 section 6.1.3's "Basic Certificate
+// Processing" procedure.
+void BasicCertificateProcessing(
     const ParsedCertificate& cert,
     bool is_target_cert,
     const SignaturePolicy* signature_policy,
     const der::GeneralizedTime& time,
-    KeyPurpose required_key_purpose,
+    const der::Input& working_spki,
+    const der::Input& working_normalized_issuer_name,
+    const std::vector<const NameConstraints*>& name_constraints_list,
     CertErrors* errors) {
   // Check that the signature algorithms in Certificate vs TBSCertificate
   // match. This isn't part of RFC 5280 section 6.1.3, but is mandated by
   // sections 4.1.1.2 and 4.1.2.3.
   VerifySignatureAlgorithmsMatch(cert, errors);
 
   // Verify the digital signature using the previous certificate's key (RFC
   // 5280 section 6.1.3 step a.1).
   if (!VerifySignedData(cert.signature_algorithm(), cert.tbs_certificate_tlv(),
-                        cert.signature_value(), working_spki_, signature_policy,
+                        cert.signature_value(), working_spki, signature_policy,
                         errors)) {
     errors->AddError(kVerifySignedDataFailed);
   }
 
   // Check the time range for the certificate's validity, ensuring it is valid
   // at |time|.
   // (RFC 5280 section 6.1.3 step a.2)
   VerifyTimeValidity(cert, time, errors);
 
   // TODO(eroman): Check revocation (RFC 5280 section 6.1.3 step a.3)
 
   // Verify the certificate's issuer name matches the issuing certificate's
   // subject name. (RFC 5280 section 6.1.3 step a.4)
-  if (cert.normalized_issuer() != working_normalized_issuer_name_)
+  if (cert.normalized_issuer() != working_normalized_issuer_name)
     errors->AddError(kSubjectDoesNotMatchIssuer);
 
   // Name constraints (RFC 5280 section 6.1.3 step b & c)
   // If certificate i is self-issued and it is not the final certificate in the
   // path, skip this step for certificate i.
-  if (!name_constraints_list_.empty() &&
+  if (!name_constraints_list.empty() &&
       (!IsSelfIssued(cert) || is_target_cert)) {
-    for (const NameConstraints* nc : name_constraints_list_) {
+    for (const NameConstraints* nc : name_constraints_list) {
       if (!nc->IsPermittedCert(cert.normalized_subject(),
                                cert.subject_alt_names())) {
         errors->AddError(kNotPermittedByNameConstraints);
       }
     }
   }
 
-  // RFC 5280 section 6.1.3 step d - f.
-  VerifyPolicies(cert, is_target_cert, errors);
-
-  // The key purpose is checked not just for the end-entity certificate, but
-  // also interpreted as a constraint when it appears in intermediates. This
-  // goes beyond what RFC 5280 describes, but is the de-facto standard. See
-  // https://wiki.mozilla.org/CA:CertificatePolicyV2.1#Frequently_Asked_Questions
-  VerifyExtendedKeyUsage(cert, required_key_purpose, errors);
+  // TODO(eroman): Steps d-f are omitted, as policy constraints are not yet
+  // implemented.
 }
 
-void PathVerifier::PrepareForNextCertificate(const ParsedCertificate& cert,
-                                             CertErrors* errors) {
-  // RFC 5280 section 6.1.4 step a-b
-  VerifyPolicyMappings(cert, errors);
+// This function corresponds to RFC 5280 section 6.1.4's "Preparation for
+// Certificate i+1" procedure. |cert| is expected to be an intermediate.
+void PrepareForNextCertificate(
+    const ParsedCertificate& cert,
+    size_t* max_path_length_ptr,
+    der::Input* working_spki,
+    der::Input* working_normalized_issuer_name,
+    std::vector<const NameConstraints*>* name_constraints_list,
+    CertErrors* errors) {
+  // TODO(crbug.com/634456): Steps a-b are omitted, as policy mappings are not
+  // yet implemented.
 
   // From RFC 5280 section 6.1.4 step c:
   //
   //    Assign the certificate subject name to working_normalized_issuer_name.
-  working_normalized_issuer_name_ = cert.normalized_subject();
+  *working_normalized_issuer_name = cert.normalized_subject();
 
   // From RFC 5280 section 6.1.4 step d:
   //
   //    Assign the certificate subjectPublicKey to working_public_key.
-  working_spki_ = cert.tbs().spki_tlv;
+  *working_spki = cert.tbs().spki_tlv;
 
   // Note that steps e and f are omitted as they are handled by
   // the assignment to |working_spki| above. See the definition
   // of |working_spki|.
 
   // From RFC 5280 section 6.1.4 step g:
   if (cert.has_name_constraints())
-    name_constraints_list_.push_back(&cert.name_constraints());
+    name_constraints_list->push_back(&cert.name_constraints());
 
-  //     (h)  If certificate i is not self-issued:
-  if (!IsSelfIssued(cert)) {
-    //         (1)  If explicit_policy is not 0, decrement explicit_policy by
-    //              1.
-    if (explicit_policy_ > 0)
-      explicit_policy_ -= 1;
-
-    //         (2)  If policy_mapping is not 0, decrement policy_mapping by 1.
-    if (policy_mapping_ > 0)
-      policy_mapping_ -= 1;
-
-    //         (3)  If inhibit_anyPolicy is not 0, decrement inhibit_anyPolicy
-    //              by 1.
-    if (inhibit_any_policy_ > 0)
-      inhibit_any_policy_ -= 1;
-  }
-
-  //      (i)  If a policy constraints extension is included in the
-  //           certificate, modify the explicit_policy and policy_mapping
-  //           state variables as follows:
-  if (cert.has_policy_constraints()) {
-    //         (1)  If requireExplicitPolicy is present and is less than
-    //              explicit_policy, set explicit_policy to the value of
-    //              requireExplicitPolicy.
-    if (cert.policy_constraints().has_require_explicit_policy &&
-        cert.policy_constraints().require_explicit_policy < explicit_policy_) {
-      explicit_policy_ = cert.policy_constraints().require_explicit_policy;
-    }
-
-    //         (2)  If inhibitPolicyMapping is present and is less than
-    //              policy_mapping, set policy_mapping to the value of
-    //              inhibitPolicyMapping.
-    if (cert.policy_constraints().has_inhibit_policy_mapping &&
-        cert.policy_constraints().inhibit_policy_mapping < policy_mapping_) {
-      policy_mapping_ = cert.policy_constraints().inhibit_policy_mapping;
-    }
-  }
-
-  //      (j)  If the inhibitAnyPolicy extension is included in the
-  //           certificate and is less than inhibit_anyPolicy, set
-  //           inhibit_anyPolicy to the value of inhibitAnyPolicy.
-  if (cert.has_inhibit_any_policy() &&
-      cert.inhibit_any_policy() < inhibit_any_policy_) {
-    inhibit_any_policy_ = cert.inhibit_any_policy();
-  }
+  // TODO(eroman): Steps h-j are omitted as policy
+  // constraints/mappings/inhibitAnyPolicy are not yet implemented.
 
   // From RFC 5280 section 6.1.4 step k:
   //
   //    If certificate i is a version 3 certificate, verify that the
   //    basicConstraints extension is present and that cA is set to
   //    TRUE.  (If certificate i is a version 1 or version 2
   //    certificate, then the application MUST either verify that
   //    certificate i is a CA certificate through out-of-band means
   //    or reject the certificate.  Conforming implementations may
   //    choose to reject all version 1 and version 2 intermediate
   //    certificates.)
   //
   // This code implicitly rejects non version 3 intermediates, since they
   // can't contain a BasicConstraints extension.
   if (!cert.has_basic_constraints()) {
     errors->AddError(kMissingBasicConstraints);
   } else if (!cert.basic_constraints().is_ca) {
     errors->AddError(kBasicConstraintsIndicatesNotCa);
   }
 
   // From RFC 5280 section 6.1.4 step l:
   //
   //    If the certificate was not self-issued, verify that
   //    max_path_length is greater than zero and decrement
   //    max_path_length by 1.
   if (!IsSelfIssued(cert)) {
-    if (max_path_length_ == 0) {
+    if (*max_path_length_ptr == 0) {
       errors->AddError(kMaxPathLengthViolated);
     } else {
-      --max_path_length_;
+      --(*max_path_length_ptr);
     }
   }
 
   // From RFC 5280 section 6.1.4 step m:
   //
   //    If pathLenConstraint is present in the certificate and is
   //    less than max_path_length, set max_path_length to the value
   //    of pathLenConstraint.
   if (cert.has_basic_constraints() && cert.basic_constraints().has_path_len &&
-      cert.basic_constraints().path_len < max_path_length_) {
-    max_path_length_ = cert.basic_constraints().path_len;
+      cert.basic_constraints().path_len < *max_path_length_ptr) {
+    *max_path_length_ptr = cert.basic_constraints().path_len;
   }
 
   // From RFC 5280 section 6.1.4 step n:
   //
   //    If a key usage extension is present, verify that the
   //    keyCertSign bit is set.
   if (cert.has_key_usage() &&
       !cert.key_usage().AssertsBit(KEY_USAGE_BIT_KEY_CERT_SIGN)) {
     errors->AddError(kKeyCertSignBitNotSet);
   }
@@ skipping 46 matching lines @@
                    cert.basic_constraints().is_ca &&
                    (!cert.has_key_usage() ||
                     cert.key_usage().AssertsBit(KEY_USAGE_BIT_KEY_CERT_SIGN));
     if (!success) {
       // TODO(eroman): Add DER for basic constraints and key usage.
       errors->AddError(kTargetCertInconsistentCaBits);
     }
   }
 }
 
-void PathVerifier::WrapUp(const ParsedCertificate& cert, CertErrors* errors) {
-  // From RFC 5280 section 6.1.5:
-  //      (a)  If explicit_policy is not 0, decrement explicit_policy by 1.
-  if (explicit_policy_ > 0)
-    explicit_policy_ -= 1;
+// This function corresponds with RFC 5280 section 6.1.5's "Wrap-Up Procedure".
+// It does processing for the final certificate (the target cert).
+void WrapUp(const ParsedCertificate& cert, CertErrors* errors) {
+  // TODO(crbug.com/634452): Steps a-b are omitted as policy constraints are not
+  // yet implemented.
 
-  //      (b)  If a policy constraints extension is included in the
-  //           certificate and requireExplicitPolicy is present and has a
-  //           value of 0, set the explicit_policy state variable to 0.
-  if (cert.has_policy_constraints() &&
-      cert.policy_constraints().has_require_explicit_policy &&
-      cert.policy_constraints().require_explicit_policy == 0) {
-    explicit_policy_ = 0;
-  }
-
-  // Note step c-e are omitted as the verification function does
+  // Note step c-e are omitted the verification function does
   // not output the working public key.
 
   // From RFC 5280 section 6.1.5 step f:
   //
   //    Recognize and process any other critical extension present in
   //    the certificate n.  Process any other recognized non-critical
   //    extension present in certificate n that is relevant to path
   //    processing.
   //
   // Note that this is duplicated by PrepareForNextCertificate() so as to
   // directly match the procedures in RFC 5280's section 6.1.
   VerifyNoUnconsumedCriticalExtensions(cert, errors);
 
-  // RFC 5280 section 6.1.5 step g is skipped, as the intersection of valid
-  // policies was computed during previous steps.
-  //
-  //    If either (1) the value of explicit_policy variable is greater than
-  //    zero or (2) the valid_policy_tree is not NULL, then path processing
-  //   has succeeded.
-  if (!(explicit_policy_ > 0 || !valid_policy_tree_.IsNull())) {
-    errors->AddError(kNoValidPolicy);
-  }
+  // TODO(eroman): Step g is omitted, as policy constraints are not yet
+  // implemented.
 
   // The following check is NOT part of RFC 5280 6.1.5's "Wrap-Up Procedure",
   // however is implied by RFC 5280 section 4.2.1.9.
   VerifyTargetCertHasConsistentCaBits(cert, errors);
 }
 
-void PathVerifier::ApplyTrustAnchorConstraints(const ParsedCertificate& cert,
-                                               KeyPurpose required_key_purpose,
-                                               CertErrors* errors) {
+// Enforces trust anchor constraints compatibile with RFC 5937.
+//
+// Note that the anchor constraints are encoded via the attached certificate
+// itself.
+void ApplyTrustAnchorConstraints(
+    const ParsedCertificate& cert,
+    KeyPurpose required_key_purpose,
+    size_t* max_path_length_ptr,
+    std::vector<const NameConstraints*>* name_constraints_list,
+    CertErrors* errors) {
   // This is not part of RFC 5937 nor RFC 5280, but matches the EKU handling
   // done for intermediates (described in Web PKI's Baseline Requirements).
   VerifyExtendedKeyUsage(cert, required_key_purpose, errors);
 
   // The following enforcements follow from RFC 5937 (primarily section 3.2):
 
   // Initialize name constraints initial-permitted/excluded-subtrees.
   if (cert.has_name_constraints())
-    name_constraints_list_.push_back(&cert.name_constraints());
+    name_constraints_list->push_back(&cert.name_constraints());
 
   // TODO(eroman): Initialize user-initial-policy-set based on anchor
   // constraints.
 
   // TODO(eroman): Initialize inhibit any policy based on anchor constraints.
 
   // TODO(eroman): Initialize require explicit policy based on anchor
   // constraints.
 
   // TODO(eroman): Initialize inhibit policy mapping based on anchor
   // constraints.
 
   // From RFC 5937 section 3.2:
   //
   //    If a basic constraints extension is associated with the trust
   //    anchor and contains a pathLenConstraint value, set the
   //    max_path_length state variable equal to the pathLenConstraint
   //    value from the basic constraints extension.
   //
   // NOTE: RFC 5937 does not say to enforce the CA=true part of basic
   // constraints.
   if (cert.has_basic_constraints() && cert.basic_constraints().has_path_len)
-    max_path_length_ = cert.basic_constraints().path_len;
+    *max_path_length_ptr = cert.basic_constraints().path_len;
 
   // From RFC 5937 section 2:
   //
   //    Extensions may be marked critical or not critical.  When trust anchor
   //    constraints are enforced, clients MUST reject certification paths
   //    containing a trust anchor with unrecognized critical extensions.
   VerifyNoUnconsumedCriticalExtensions(cert, errors);
 }
 
-void PathVerifier::ProcessRootCertificate(const ParsedCertificate& cert,
-                                          const CertificateTrust& trust,
-                                          KeyPurpose required_key_purpose,
-                                          CertErrors* errors) {
+// Initializes the path validation algorithm given anchor constraints. This
+// follows the description in RFC 5937
+void ProcessRootCertificate(
+    const ParsedCertificate& cert,
+    const CertificateTrust& trust,
+    KeyPurpose required_key_purpose,
+    size_t* max_path_length_ptr,
+    std::vector<const NameConstraints*>* name_constraints_list,
+    der::Input* working_spki,
+    der::Input* working_normalized_issuer_name,
+    CertErrors* errors) {
   // Use the certificate's SPKI and subject when verifying the next certificate.
   // Note this is initialized even in the case of untrusted roots (they already
   // emit an error for the distrust).
-  working_spki_ = cert.tbs().spki_tlv;
-  working_normalized_issuer_name_ = cert.normalized_subject();
+  *working_spki = cert.tbs().spki_tlv;
+  *working_normalized_issuer_name = cert.normalized_subject();
 
   switch (trust.type) {
     case CertificateTrustType::UNSPECIFIED:
       // Doesn't chain to a trust anchor - implicitly distrusted
       errors->AddError(kCertIsNotTrustAnchor);
       break;
     case CertificateTrustType::DISTRUSTED:
       // Chains to an actively distrusted certificate.
       errors->AddError(kCertIsDistrusted);
       break;
     case CertificateTrustType::TRUSTED_ANCHOR:
     case CertificateTrustType::TRUSTED_ANCHOR_WITH_CONSTRAINTS:
       // If the trust anchor has constraints, enforce them.
       if (trust.type == CertificateTrustType::TRUSTED_ANCHOR_WITH_CONSTRAINTS) {
-        ApplyTrustAnchorConstraints(cert, required_key_purpose, errors);
+        ApplyTrustAnchorConstraints(cert, required_key_purpose,
+                                    max_path_length_ptr, name_constraints_list,
+                                    errors);
       }
       break;
   }
 }
 
-void PathVerifier::Run(
-    const ParsedCertificateList& certs,
-    const CertificateTrust& last_cert_trust,
-    const SignaturePolicy* signature_policy,
-    const der::GeneralizedTime& time,
-    KeyPurpose required_key_purpose,
-    InitialExplicitPolicy initial_explicit_policy,
-    const std::set<der::Input>& user_initial_policy_set,
-    InitialPolicyMappingInhibit initial_policy_mapping_inhibit,
-    InitialAnyPolicyInhibit initial_any_policy_inhibit,
-    std::set<der::Input>* user_constrained_policy_set,
-    CertPathErrors* errors) {
-  // This implementation is structured to mimic the description of certificate
-  // path verification given by RFC 5280 section 6.1.
+}  // namespace
+
+// This implementation is structured to mimic the description of certificate
+// path verification given by RFC 5280 section 6.1.
+void VerifyCertificateChain(const ParsedCertificateList& certs,
+                            const CertificateTrust& last_cert_trust,
+                            const SignaturePolicy* signature_policy,
+                            const der::GeneralizedTime& time,
+                            KeyPurpose required_key_purpose,
+                            CertPathErrors* errors) {
   DCHECK(signature_policy);
   DCHECK(errors);
 
   // An empty chain is necessarily invalid.
   if (certs.empty()) {
     errors->GetOtherErrors()->AddError(kChainIsEmpty);
     return;
   }
 
   // TODO(eroman): Verifying a trusted leaf certificate is not currently
   // permitted.
   if (certs.size() == 1) {
     errors->GetOtherErrors()->AddError(kChainIsLength1);
     return;
   }
 
-  // RFC 5280's "n" variable is the length of the path, which does not count
-  // the trust anchor. (Although in practice it doesn't really change behaviors
-  // if n is used in place of n+1).
-  const size_t n = certs.size() - 1;
+  // Will contain a NameConstraints for each previous cert in the chain which
+  // had nameConstraints. This corresponds to the permitted_subtrees and
+  // excluded_subtrees state variables from RFC 5280.
+  std::vector<const NameConstraints*> name_constraints_list;
 
-  valid_policy_tree_.Init(user_initial_policy_set);
+  // |working_spki| is an amalgamation of 3 separate variables from RFC 5280:
+  //    * working_public_key
+  //    * working_public_key_algorithm
+  //    * working_public_key_parameters
+  //
+  // They are combined for simplicity since the signature verification takes an
+  // SPKI, and the parameter inheritence is not applicable for the supported
+  // key types.
+  //
+  // An approximate explanation of |working_spki| is this description from RFC
+  // 5280 section 6.1.2:
+  //
+  //    working_public_key:  the public key used to verify the
+  //    signature of a certificate.
+  der::Input working_spki;
 
-  // RFC 5280 section section 6.1.2:
+  // |working_normalized_issuer_name| is the normalized value of the
+  // working_issuer_name variable in RFC 5280 section 6.1.2:
   //
-  // If initial-explicit-policy is set, then the initial value
-  // [of explicit_policy] is 0, otherwise the initial value is n+1.
-  explicit_policy_ =
-      initial_explicit_policy == InitialExplicitPolicy::kTrue ? 0 : n + 1;
+  //    working_issuer_name:  the issuer distinguished name expected
+  //    in the next certificate in the chain.
+  der::Input working_normalized_issuer_name;
 
-  // RFC 5280 section section 6.1.2:
+  // |max_path_length| corresponds with the same named variable in RFC 5280
+  // section 6.1.2:
   //
-  // If initial-any-policy-inhibit is set, then the initial value
-  // [of inhibit_anyPolicy] is 0, otherwise the initial value is n+1.
-  inhibit_any_policy_ =
-      initial_any_policy_inhibit == InitialAnyPolicyInhibit::kTrue ? 0 : n + 1;
-
-  // RFC 5280 section section 6.1.2:
-  //
-  // If initial-policy-mapping-inhibit is set, then the initial value
-  // [of policy_mapping] is 0, otherwise the initial value is n+1.
-  policy_mapping_ =
-      initial_policy_mapping_inhibit == InitialPolicyMappingInhibit::kTrue
-          ? 0
-          : n + 1;
-
-  // RFC 5280 section section 6.1.2:
-  //
-  // max_path_length:  this integer is initialized to n, ...
-  max_path_length_ = n;
+  //    max_path_length:  this integer is initialized to n, is
+  //    decremented for each non-self-issued certificate in the path,
+  //    and may be reduced to the value in the path length constraint
+  //    field within the basic constraints extension of a CA
+  //    certificate.
+  size_t max_path_length = certs.size();
 
   // Iterate over all the certificates in the reverse direction: starting from
   // the root certificate and progressing towards the target certificate.
   //
-  //   * i=0  :  Root certificate (i.e. trust anchor)
-  //   * i=1  :  Certificate issued by root
-  //   * i=x  :  Certificate i=x is issued by certificate i=x-1
-  //   * i=n  :  Target certificate.
+  //   * i=0               :  Root certificate (i.e. trust anchor)
+  //   * i=1               :  Certificated signed by the root certificate
+  //   * i=certs.size()-1  :  Target certificate.
   for (size_t i = 0; i < certs.size(); ++i) {
     const size_t index_into_certs = certs.size() - i - 1;
 
     // |is_target_cert| is true if the current certificate is the target
     // certificate being verified. The target certificate isn't necessarily an
     // end-entity certificate.
     const bool is_target_cert = index_into_certs == 0;
     const bool is_root_cert = i == 0;
 
     const ParsedCertificate& cert = *certs[index_into_certs];
 
     // Output errors for the current certificate into an error bucket that is
     // associated with that certificate.
     CertErrors* cert_errors = errors->GetErrorsForCert(index_into_certs);
 
     if (is_root_cert) {
       ProcessRootCertificate(cert, last_cert_trust, required_key_purpose,
+                             &max_path_length, &name_constraints_list,
+                             &working_spki, &working_normalized_issuer_name,
                              cert_errors);
 
       // Don't do any other checks for root certificates.
       continue;
     }
 
     // Per RFC 5280 section 6.1:
     //  * Do basic processing for each certificate
     //  * If it is the last certificate in the path (target certificate)
     //     - Then run "Wrap up"
     //     - Otherwise run "Prepare for Next cert"
     BasicCertificateProcessing(cert, is_target_cert, signature_policy, time,
-                               required_key_purpose, cert_errors);
+                               working_spki, working_normalized_issuer_name,
+                               name_constraints_list, cert_errors);
+
+    // The key purpose is checked not just for the end-entity certificate, but
+    // also interpreted as a constraint when it appears in intermediates. This
+    // goes beyond what RFC 5280 describes, but is the de-facto standard. See
+    // https://wiki.mozilla.org/CA:CertificatePolicyV2.1#Frequently_Asked_Questions
+    VerifyExtendedKeyUsage(cert, required_key_purpose, cert_errors);
+
     if (!is_target_cert) {
-      PrepareForNextCertificate(cert, cert_errors);
+      PrepareForNextCertificate(cert, &max_path_length, &working_spki,
+                                &working_normalized_issuer_name,
+                                &name_constraints_list, cert_errors);
     } else {
       WrapUp(cert, cert_errors);
     }
   }
 
-  if (user_constrained_policy_set) {
-    // valid_policy_tree_ already contains the intersection of valid policies
-    // with user_initial_policy_set.
-    valid_policy_tree_.GetValidRootPolicySet(user_constrained_policy_set);
-  }
-
   // TODO(eroman): RFC 5280 forbids duplicate certificates per section 6.1:
   //
   //    A certificate MUST NOT appear more than once in a prospective
   //    certification path.
 }
 
-}  // namespace
-
-void VerifyCertificateChain(
-    const ParsedCertificateList& certs,
-    const CertificateTrust& last_cert_trust,
-    const SignaturePolicy* signature_policy,
-    const der::GeneralizedTime& time,
-    KeyPurpose required_key_purpose,
-    InitialExplicitPolicy initial_explicit_policy,
-    const std::set<der::Input>& user_initial_policy_set,
-    InitialPolicyMappingInhibit initial_policy_mapping_inhibit,
-    InitialAnyPolicyInhibit initial_any_policy_inhibit,
-    std::set<der::Input>* user_constrained_policy_set,
-    CertPathErrors* errors) {
-  PathVerifier verifier;
-  verifier.Run(certs, last_cert_trust, signature_policy, time,
-               required_key_purpose, initial_explicit_policy,
-               user_initial_policy_set, initial_policy_mapping_inhibit,
-               initial_any_policy_inhibit, user_constrained_policy_set, errors);
-}
-
 }  // namespace net