12 files changed, 147 insertions, 183 deletions

diff --git a/src/cert/x509/crl_ent.cpp b/src/cert/x509/crl_ent.cpp
index 42a742ebb..e7ce1a57a 100644
--- a/src/cert/x509/crl_ent.cpp
+++ b/src/cert/x509/crl_ent.cpp
@@ -11,7 +11,6 @@
 #include <botan/ber_dec.h>
 #include <botan/bigint.h>
 #include <botan/oids.h>
-#include <botan/time.h>
 
 namespace Botan {
 
@@ -31,7 +30,7 @@ CRL_Entry::CRL_Entry(const X509_Certificate& cert, CRL_Code why) :
    throw_on_unknown_critical(false)
    {
    serial = cert.serial_number();
-   time = X509_Time(system_time());
+   time = X509_Time(std::chrono::system_clock::now());
    reason = why;
    }
 
diff --git a/src/cert/x509/pkcs10.cpp b/src/cert/x509/pkcs10.cpp
index 81bb58555..e78439757 100644
--- a/src/cert/x509/pkcs10.cpp
+++ b/src/cert/x509/pkcs10.cpp
@@ -45,7 +45,7 @@ void PKCS10_Request::force_decode()
    cert_req_info.decode(version);
    if(version != 0)
       throw Decoding_Error("Unknown version code in PKCS #10 request: " +
-                           to_string(version));
+                           std::to_string(version));
 
    X509_DN dn_subject;
    cert_req_info.decode(dn_subject);
diff --git a/src/cert/x509/x509_ca.cpp b/src/cert/x509/x509_ca.cpp
index ea7f3a405..5af824946 100644
--- a/src/cert/x509/x509_ca.cpp
+++ b/src/cert/x509/x509_ca.cpp
@@ -14,10 +14,6 @@
 #include <botan/parsing.h>
 #include <botan/lookup.h>
 #include <botan/oids.h>
-#include <botan/time.h>
-#include <algorithm>
-#include <typeinfo>
-#include <iterator>
 #include <memory>
 #include <set>
 
@@ -57,7 +53,7 @@ X509_Certificate X509_CA::sign_request(const PKCS10_Request& req,
       constraints = Key_Constraints(KEY_CERT_SIGN | CRL_SIGN);
    else
       {
-      std::auto_ptr<Public_Key> key(req.subject_public_key());
+      std::unique_ptr<Public_Key> key(req.subject_public_key());
       constraints = X509::find_constraints(*key, req.constraints());
       }
 
@@ -171,8 +167,7 @@ X509_CRL X509_CA::update_crl(const X509_CRL& crl,
 
    for(u32bit j = 0; j != already_revoked.size(); ++j)
       {
-      std::set<SecureVector<byte> >::const_iterator i;
-      i = removed_from_crl.find(already_revoked[j].serial_number());
+      auto i = removed_from_crl.find(already_revoked[j].serial_number());
 
       if(i == removed_from_crl.end())
          all_revoked.push_back(already_revoked[j]);
@@ -199,7 +194,8 @@ X509_CRL X509_CA::make_crl(const std::vector<CRL_Entry>& revoked,
       next_update = timespec_to_u32bit("7d");
 
    // Totally stupid: ties encoding logic to the return of std::time!!
-   const u64bit current_time = system_time();
+   auto current_time = std::chrono::system_clock::now();
+   auto expire_time = current_time + std::chrono::seconds(next_update);
 
    Extensions extensions;
    extensions.add(
@@ -212,7 +208,7 @@ X509_CRL X509_CA::make_crl(const std::vector<CRL_Entry>& revoked,
             .encode(ca_sig_algo)
             .encode(cert.issuer_dn())
             .encode(X509_Time(current_time))
-            .encode(X509_Time(current_time + next_update))
+            .encode(X509_Time(expire_time))
             .encode_if(revoked.size() > 0,
                  DER_Encoder()
                     .start_cons(SEQUENCE)
diff --git a/src/cert/x509/x509_ca.h b/src/cert/x509/x509_ca.h
index 97be6a415..7aca26d03 100644
--- a/src/cert/x509/x509_ca.h
+++ b/src/cert/x509/x509_ca.h
@@ -99,11 +99,11 @@ class BOTAN_DLL X509_CA
               const Private_Key& key,
               const std::string& hash_fn);
 
+      X509_CA(const X509_CA&) = delete;
+      X509_CA& operator=(const X509_CA&) = delete;
+
       ~X509_CA();
    private:
-      X509_CA(const X509_CA&) {}
-      X509_CA& operator=(const X509_CA&) { return (*this); }
-
       X509_CRL make_crl(const std::vector<CRL_Entry>& entries,
                         u32bit crl_number, u32bit next_update,
                         RandomNumberGenerator& rng) const;
diff --git a/src/cert/x509/x509_crl.cpp b/src/cert/x509/x509_crl.cpp
index f6a344dba..3613c1a91 100644
--- a/src/cert/x509/x509_crl.cpp
+++ b/src/cert/x509/x509_crl.cpp
@@ -44,7 +44,7 @@ void X509_CRL::force_decode()
 
    if(version != 0 && version != 1)
       throw X509_CRL_Error("Unknown X.509 CRL version " +
-                           to_string(version+1));
+                           std::to_string(version+1));
 
    AlgorithmIdentifier sig_algo_inner;
    tbs_crl.decode(sig_algo_inner);
diff --git a/src/cert/x509/x509cert.cpp b/src/cert/x509/x509cert.cpp
index 05f23298b..e3844e8e9 100644
--- a/src/cert/x509/x509cert.cpp
+++ b/src/cert/x509/x509cert.cpp
@@ -27,12 +27,8 @@ std::vector<std::string> lookup_oids(const std::vector<std::string>& in)
    {
    std::vector<std::string> out;
 
-   std::vector<std::string>::const_iterator i = in.begin();
-   while(i != in.end())
-      {
+   for(auto i = in.begin(); i != in.end(); ++i)
       out.push_back(OIDS::lookup(OID(*i)));
-      ++i;
-      }
    return out;
    }
 
@@ -84,7 +80,7 @@ void X509_Certificate::force_decode()
       .decode(dn_subject);
 
    if(version > 2)
-      throw Decoding_Error("Unknown X.509 cert version " + to_string(version));
+      throw Decoding_Error("Unknown X.509 cert version " + std::to_string(version));
    if(sig_algo != sig_algo_inner)
       throw Decoding_Error("Algorithm identifier mismatch");
 
@@ -304,25 +300,16 @@ bool operator!=(const X509_Certificate& cert1, const X509_Certificate& cert2)
 */
 X509_DN create_dn(const Data_Store& info)
    {
-   class DN_Matcher : public Data_Store::Matcher
+   auto names = info.search_for(
+      [](const std::string& key, const std::string&)
       {
-      public:
-         bool operator()(const std::string& key, const std::string&) const
-            {
-            if(key.find("X520.") != std::string::npos)
-               return true;
-            return false;
-            }
-      };
-
-   std::multimap<std::string, std::string> names =
-      info.search_with(DN_Matcher());
+         return (key.find("X520.") != std::string::npos);
+      });
 
    X509_DN dn;
 
-   std::multimap<std::string, std::string>::iterator j;
-   for(j = names.begin(); j != names.end(); ++j)
-      dn.add_attribute(j->first, j->second);
+   for(auto i = names.begin(); i != names.end(); ++i)
+      dn.add_attribute(i->first, i->second);
 
    return dn;
    }
@@ -332,33 +319,19 @@ X509_DN create_dn(const Data_Store& info)
 */
 AlternativeName create_alt_name(const Data_Store& info)
    {
-   class AltName_Matcher : public Data_Store::Matcher
+   auto names = info.search_for(
+      [](const std::string& key, const std::string&)
       {
-      public:
-         bool operator()(const std::string& key, const std::string&) const
-            {
-            for(u32bit j = 0; j != matches.size(); ++j)
-               if(key.compare(matches[j]) == 0)
-                  return true;
-            return false;
-            }
-
-         AltName_Matcher(const std::string& match_any_of)
-            {
-            matches = split_on(match_any_of, '/');
-            }
-      private:
-         std::vector<std::string> matches;
-      };
-
-   std::multimap<std::string, std::string> names =
-      info.search_with(AltName_Matcher("RFC822/DNS/URI/IP"));
+         return (key == "RFC822" ||
+                 key == "DNS" ||
+                 key == "URI" ||
+                 key == "IP");
+      });
 
    AlternativeName alt_name;
 
-   std::multimap<std::string, std::string>::iterator j;
-   for(j = names.begin(); j != names.end(); ++j)
-      alt_name.add_attribute(j->first, j->second);
+   for(auto i = names.begin(); i != names.end(); ++i)
+      alt_name.add_attribute(i->first, i->second);
 
    return alt_name;
    }
diff --git a/src/cert/x509/x509find.cpp b/src/cert/x509/x509find.cpp
index 257367da9..41643a94a 100644
--- a/src/cert/x509/x509find.cpp
+++ b/src/cert/x509/x509find.cpp
@@ -11,6 +11,8 @@
 
 namespace Botan {
 
+namespace X509_Store_Search {
+
 namespace {
 
 /*
@@ -42,70 +44,65 @@ bool ignore_case(const std::string& searching_for, const std::string& found)
 /*
 * Search based on the contents of a DN entry
 */
-bool DN_Check::match(const X509_Certificate& cert) const
+std::function<bool (const X509_Certificate&)>
+by_dn(const std::string& dn_entry,
+      const std::string& to_find,
+      DN_Search_Type method)
    {
-   std::vector<std::string> info = cert.subject_info(dn_entry);
-
-   for(u32bit j = 0; j != info.size(); ++j)
-      if(compare(info[j], looking_for))
-         return true;
-   return false;
-   }
+   if(method == SUBSTRING_MATCHING)
+      return by_dn(dn_entry, to_find, substring_match);
+   else if(method == IGNORE_CASE)
+      return by_dn(dn_entry, to_find, ignore_case);
 
-/*
-* DN_Check Constructor
-*/
-DN_Check::DN_Check(const std::string& dn_entry, const std::string& looking_for,
-                   compare_fn func)
-   {
-   this->dn_entry = dn_entry;
-   this->looking_for = looking_for;
-   compare = func;
+   throw Invalid_Argument("Unknown method argument to by_dn");
    }
 
-/*
-* DN_Check Constructor
-*/
-DN_Check::DN_Check(const std::string& dn_entry, const std::string& looking_for,
-                   Search_Type method)
+std::function<bool (const X509_Certificate&)>
+by_dn(const std::string& dn_entry,
+      const std::string& to_find,
+      std::function<bool (std::string, std::string)> compare)
    {
-   this->dn_entry = dn_entry;
-   this->looking_for = looking_for;
+   return [&](const X509_Certificate& cert)
+      {
+      std::vector<std::string> info = cert.subject_info(dn_entry);
 
-   if(method == SUBSTRING_MATCHING)
-      compare = &substring_match;
-   else if(method == IGNORE_CASE)
-      compare = &ignore_case;
-   else
-      throw Invalid_Argument("Unknown method argument to DN_Check()");
+      for(u32bit i = 0; i != info.size(); ++i)
+         if(compare(info[i], to_find))
+            return true;
+      return false;
+      };
    }
 
-/*
-* Match by issuer and serial number
-*/
-bool IandS_Match::match(const X509_Certificate& cert) const
+std::function<bool (const X509_Certificate&)>
+by_issuer_and_serial(const X509_DN& issuer, const MemoryRegion<byte>& serial)
    {
-   if(cert.serial_number() != serial)
-      return false;
-   return (cert.issuer_dn() == issuer);
+   /* Serial number compare is much faster than X.509 DN, and unlikely
+   to collide even across issuers, so do that first to fail fast
+   */
+
+   return [&](const X509_Certificate& cert)
+      {
+      if(cert.serial_number() != serial)
+         return false;
+      return (cert.issuer_dn() == issuer);
+      };
    }
 
-/*
-* IandS_Match Constructor
-*/
-IandS_Match::IandS_Match(const X509_DN& issuer,
-                         const MemoryRegion<byte>& serial)
+std::function<bool (const X509_Certificate&)>
+by_issuer_and_serial(const X509_DN& issuer, const BigInt& serial)
    {
-   this->issuer = issuer;
-   this->serial = serial;
+   return by_issuer_and_serial(issuer, BigInt::encode(serial));
    }
 
-/*
-* Match by subject key identifier
-*/
-bool SKID_Match::match(const X509_Certificate& cert) const
+std::function<bool (const X509_Certificate&)>
+by_skid(const MemoryRegion<byte>& subject_key_id)
    {
-   return (cert.subject_key_id() == skid);
+   return [&](const X509_Certificate& cert)
+      {
+      return (cert.subject_key_id() == subject_key_id);
+      };
    }
 
 }
+
+}
diff --git a/src/cert/x509/x509find.h b/src/cert/x509/x509find.h
index 5624b717b..1bf29dfbc 100644
--- a/src/cert/x509/x509find.h
+++ b/src/cert/x509/x509find.h
@@ -9,51 +9,43 @@
 #define BOTAN_X509_CERT_STORE_SEARCH_H__
 
 #include <botan/x509stor.h>
+#include <botan/bigint.h>
 
 namespace Botan {
 
-/**
+namespace X509_Store_Search {
+
+/*
 * Search based on the contents of a DN entry
 */
-class BOTAN_DLL DN_Check : public X509_Store::Search_Func
-   {
-   public:
-      typedef bool (*compare_fn)(const std::string&, const std::string&);
-      enum Search_Type { SUBSTRING_MATCHING, IGNORE_CASE };
+enum DN_Search_Type { SUBSTRING_MATCHING, IGNORE_CASE };
 
-      bool match(const X509_Certificate& cert) const;
+std::function<bool (const X509_Certificate&)>
+by_dn(const std::string& dn_entry,
+          const std::string& to_find,
+          DN_Search_Type method);
 
-      DN_Check(const std::string&, const std::string&, compare_fn);
-      DN_Check(const std::string&, const std::string&, Search_Type);
-   private:
-      std::string dn_entry, looking_for;
-      compare_fn compare;
-   };
+std::function<bool (const X509_Certificate&)>
+by_dn(const std::string& dn_entry,
+          const std::string& to_find,
+          std::function<bool (std::string, std::string)> method);
 
 /**
-* Search for a certificate by issuer/serial
+* Search for certs by issuer + serial number
 */
-class BOTAN_DLL IandS_Match : public X509_Store::Search_Func
-   {
-   public:
-      bool match(const X509_Certificate& cert) const;
-      IandS_Match(const X509_DN&, const MemoryRegion<byte>&);
-   private:
-      X509_DN issuer;
-      MemoryVector<byte> serial;
-   };
+std::function<bool (const X509_Certificate&)>
+by_issuer_and_serial(const X509_DN& issuer, const MemoryRegion<byte>& serial);
+
+std::function<bool (const X509_Certificate&)>
+by_issuer_and_serial(const X509_DN& issuer, const BigInt& serial);
 
 /**
-* Search for a certificate by subject keyid
+* Search for certs by subject key identifier
 */
-class BOTAN_DLL SKID_Match : public X509_Store::Search_Func
-   {
-   public:
-      bool match(const X509_Certificate& cert) const;
-      SKID_Match(const MemoryRegion<byte>& s) : skid(s) {}
-   private:
-      MemoryVector<byte> skid;
-   };
+std::function<bool (const X509_Certificate&)>
+by_skid(const MemoryRegion<byte>& subject_key_id);
+
+}
 
 }
 
diff --git a/src/cert/x509/x509opt.cpp b/src/cert/x509/x509opt.cpp
index 0702ebf19..8d235ad5d 100644
--- a/src/cert/x509/x509opt.cpp
+++ b/src/cert/x509/x509opt.cpp
@@ -8,7 +8,7 @@
 #include <botan/x509self.h>
 #include <botan/oids.h>
 #include <botan/parsing.h>
-#include <botan/time.h>
+#include <chrono>
 
 namespace Botan {
 
@@ -78,16 +78,16 @@ void X509_Cert_Options::sanity_check() const
 * Initialize the certificate options
 */
 X509_Cert_Options::X509_Cert_Options(const std::string& initial_opts,
-                                     u32bit expiration_time_in_seconds)
+                                     u32bit expiration_time)
    {
    is_CA = false;
    path_limit = 0;
    constraints = NO_CONSTRAINTS;
 
-   const u64bit now = system_time();
+   auto now = std::chrono::system_clock::now();
 
    start = X509_Time(now);
-   end = X509_Time(now + expiration_time_in_seconds);
+   end = X509_Time(now + std::chrono::seconds(expiration_time));
 
    if(initial_opts == "")
       return;
diff --git a/src/cert/x509/x509self.cpp b/src/cert/x509/x509self.cpp
index e420ca503..6e570d3b6 100644
--- a/src/cert/x509/x509self.cpp
+++ b/src/cert/x509/x509self.cpp
@@ -54,7 +54,7 @@ X509_Certificate create_self_signed_cert(const X509_Cert_Options& opts,
    opts.sanity_check();
 
    MemoryVector<byte> pub_key = X509::BER_encode(key);
-   std::auto_ptr<PK_Signer> signer(choose_sig_format(key, hash_fn, sig_algo));
+   std::unique_ptr<PK_Signer> signer(choose_sig_format(key, hash_fn, sig_algo));
    load_info(opts, subject_dn, subject_alt);
 
    Key_Constraints constraints;
@@ -100,7 +100,7 @@ PKCS10_Request create_cert_req(const X509_Cert_Options& opts,
    opts.sanity_check();
 
    MemoryVector<byte> pub_key = X509::BER_encode(key);
-   std::auto_ptr<PK_Signer> signer(choose_sig_format(key, hash_fn, sig_algo));
+   std::unique_ptr<PK_Signer> signer(choose_sig_format(key, hash_fn, sig_algo));
    load_info(opts, subject_dn, subject_alt);
 
    const u32bit PKCS10_VERSION = 0;
diff --git a/src/cert/x509/x509stor.cpp b/src/cert/x509/x509stor.cpp
index a24d4a070..6b2c0eee0 100644
--- a/src/cert/x509/x509stor.cpp
+++ b/src/cert/x509/x509stor.cpp
@@ -9,8 +9,8 @@
 #include <botan/parsing.h>
 #include <botan/pubkey.h>
 #include <botan/oids.h>
-#include <botan/time.h>
 #include <algorithm>
+#include <chrono>
 #include <memory>
 
 namespace Botan {
@@ -21,13 +21,14 @@ namespace {
 * Do a validity check
 */
 s32bit validity_check(const X509_Time& start, const X509_Time& end,
-                      u64bit current_time, u32bit slack)
+                      const std::chrono::system_clock::time_point& now,
+                      std::chrono::seconds slack)
    {
    const s32bit NOT_YET_VALID = -1, VALID_TIME = 0, EXPIRED = 1;
 
-   if(start.cmp(current_time + slack) > 0)
+   if(start.cmp(now + slack) > 0)
       return NOT_YET_VALID;
-   if(end.cmp(current_time - slack) < 0)
+   if(end.cmp(now - slack) < 0)
       return EXPIRED;
    return VALID_TIME;
    }
@@ -168,7 +169,8 @@ bool X509_Store::CRL_Data::operator<(const X509_Store::CRL_Data& other) const
 /*
 * X509_Store Constructor
 */
-X509_Store::X509_Store(u32bit slack, u32bit cache_timeout)
+X509_Store::X509_Store(std::chrono::seconds slack,
+                       std::chrono::seconds cache_timeout)
    {
    revoked_info_valid = true;
 
@@ -211,10 +213,11 @@ X509_Code X509_Store::validate_cert(const X509_Certificate& cert,
    if(chaining_result != VERIFIED)
       return chaining_result;
 
-   const u64bit current_time = system_time();
+   auto current_time = std::chrono::system_clock::now();
 
    s32bit time_check = validity_check(cert.start_time(), cert.end_time(),
                                       current_time, time_slack);
+
    if(time_check < 0)      return CERT_NOT_YET_VALID;
    else if(time_check > 0) return CERT_HAS_EXPIRED;
 
@@ -379,7 +382,7 @@ X509_Code X509_Store::check_sig(const Cert_Info& cert_info,
 */
 X509_Code X509_Store::check_sig(const X509_Object& object, Public_Key* key)
    {
-   std::auto_ptr<Public_Key> pub_key(key);
+   std::unique_ptr<Public_Key> pub_key(key);
 
    try {
       std::vector<std::string> sig_info =
@@ -450,12 +453,12 @@ bool X509_Store::is_revoked(const X509_Certificate& cert) const
 * Retrieve all the certificates in the store
 */
 std::vector<X509_Certificate>
-X509_Store::get_certs(const Search_Func& search) const
+X509_Store::get_certs(std::function<bool (const X509_Certificate&)> pred) const
    {
    std::vector<X509_Certificate> found_certs;
    for(u32bit j = 0; j != certs.size(); ++j)
       {
-      if(search.match(certs[j].cert))
+      if(pred(certs[j].cert))
          found_certs.push_back(certs[j].cert);
       }
    return found_certs;
@@ -549,8 +552,10 @@ void X509_Store::add_trusted_certs(DataSource& source)
 */
 X509_Code X509_Store::add_crl(const X509_CRL& crl)
    {
+   auto current_time = std::chrono::system_clock::now();
+
    s32bit time_check = validity_check(crl.this_update(), crl.next_update(),
-                                      system_time(), time_slack);
+                                      current_time, time_slack);
 
    if(time_check < 0)      return CRL_NOT_YET_VALID;
    else if(time_check > 0) return CRL_HAS_EXPIRED;
@@ -589,8 +594,7 @@ X509_Code X509_Store::add_crl(const X509_CRL& crl)
       revoked_info.serial = revoked_certs[j].serial_number();
       revoked_info.auth_key_id = crl.authority_key_id();
 
-      std::vector<CRL_Data>::iterator p =
-         std::find(revoked.begin(), revoked.end(), revoked_info);
+      auto p = std::find(revoked.begin(), revoked.end(), revoked_info);
 
       if(revoked_certs[j].reason_code() == REMOVE_FROM_CRL)
          {
@@ -628,8 +632,8 @@ X509_Store::Cert_Info::Cert_Info(const X509_Certificate& c,
                                  bool t) : cert(c), trusted(t)
    {
    checked = false;
+   last_checked = std::chrono::system_clock::time_point::min();
    result = UNKNOWN_X509_ERROR;
-   last_checked = 0;
    }
 
 /*
@@ -647,9 +651,9 @@ X509_Code X509_Store::Cert_Info::verify_result() const
 */
 void X509_Store::Cert_Info::set_result(X509_Code code) const
    {
-   result = code;
-   last_checked = system_time();
    checked = true;
+   last_checked = std::chrono::system_clock::now();
+   result = code;
    }
 
 /*
@@ -663,16 +667,16 @@ bool X509_Store::Cert_Info::is_trusted() const
 /*
 * Check if this certificate has been verified
 */
-bool X509_Store::Cert_Info::is_verified(u32bit timeout) const
+bool X509_Store::Cert_Info::is_verified(std::chrono::seconds timeout) const
    {
    if(!checked)
       return false;
    if(result != VERIFIED && result != CERT_NOT_YET_VALID)
       return true;
 
-   const u64bit current_time = system_time();
+   auto now = std::chrono::system_clock::now();
 
-   if(current_time > last_checked + timeout)
+   if(now > last_checked + timeout)
       checked = false;
 
    return checked;
diff --git a/src/cert/x509/x509stor.h b/src/cert/x509/x509stor.h
index 7c3895635..8f2d5b405 100644
--- a/src/cert/x509/x509stor.h
+++ b/src/cert/x509/x509stor.h
@@ -11,6 +11,7 @@
 #include <botan/x509cert.h>
 #include <botan/x509_crl.h>
 #include <botan/certstor.h>
+#include <functional>
 
 namespace Botan {
 
@@ -48,16 +49,6 @@ enum X509_Code {
 class BOTAN_DLL X509_Store
    {
    public:
-      /**
-      * A callback for searching the store
-      */
-      class BOTAN_DLL Search_Func
-         {
-         public:
-            virtual bool match(const X509_Certificate&) const = 0;
-            virtual ~Search_Func() {}
-         };
-
       enum Cert_Usage {
          ANY              = 0x00,
          TLS_SERVER       = 0x01,
@@ -70,7 +61,13 @@ class BOTAN_DLL X509_Store
 
       X509_Code validate_cert(const X509_Certificate&, Cert_Usage = ANY);
 
-      std::vector<X509_Certificate> get_certs(const Search_Func&) const;
+      /**
+      * @param match the matching function
+      * @return list of certs for which match returns true
+      */
+      std::vector<X509_Certificate>
+         get_certs(std::function<bool (const X509_Certificate&)> match) const;
+
       std::vector<X509_Certificate> get_cert_chain(const X509_Certificate&);
       std::string PEM_encode() const;
 
@@ -83,14 +80,18 @@ class BOTAN_DLL X509_Store
 
       static X509_Code check_sig(const X509_Object&, Public_Key*);
 
-      X509_Store(u32bit time_slack = 24*60*60,
-                 u32bit cache_results = 30*60);
+      X509_Store& operator=(const X509_Store&) = delete;
+
+      /**
+      * @param slack the slack in checking validity times against current clock
+      * @param cache how long to cache validation results before rechecking
+      */
+      X509_Store(std::chrono::seconds slack = std::chrono::seconds(24*60*60),
+                 std::chrono::seconds cache = std::chrono::seconds(30*60));
 
       X509_Store(const X509_Store&);
       ~X509_Store();
    private:
-      X509_Store& operator=(const X509_Store&) { return (*this); }
-
       class BOTAN_DLL CRL_Data
          {
          public:
@@ -104,7 +105,7 @@ class BOTAN_DLL X509_Store
       class BOTAN_DLL Cert_Info
          {
          public:
-            bool is_verified(u32bit timeout) const;
+            bool is_verified(std::chrono::seconds cache_timeout) const;
             bool is_trusted() const;
             X509_Code verify_result() const;
             void set_result(X509_Code) const;
@@ -115,7 +116,7 @@ class BOTAN_DLL X509_Store
          private:
             mutable bool checked;
             mutable X509_Code result;
-            mutable u64bit last_checked;
+            mutable std::chrono::system_clock::time_point last_checked;
          };
 
       u32bit find_cert(const X509_DN&, const MemoryRegion<byte>&) const;
@@ -130,10 +131,12 @@ class BOTAN_DLL X509_Store
       bool is_revoked(const X509_Certificate&) const;
 
       static const u32bit NO_CERT_FOUND = 0xFFFFFFFF;
+
       std::vector<Cert_Info> certs;
       std::vector<CRL_Data> revoked;
       std::vector<Certificate_Store*> stores;
-      u32bit time_slack, validation_cache_timeout;
+
+      std::chrono::seconds time_slack, validation_cache_timeout;
       mutable bool revoked_info_valid;
    };