[rubygems/rubygems] Add CHECKSUMS for each gem in lockfile

We lock the checksum for each resolved spec under a new CHECKSUMS
section in the lockfile.

If the locked spec does not resolve for the local platform, we preserve
the locked checksum, similar to how we preserve specs.

Checksum locking only makes sense on install. The compact index
information is only available then.

https://github.com/rubygems/rubygems/commit/bde37ca6bf

31 files changed, 760 insertions, 21 deletions

diff --git a/lib/bundler.rb b/lib/bundler.rb
index ee08a2dab8..cc6c2c075c 100644
--- a/lib/bundler.rb
+++ b/lib/bundler.rb
@@ -39,6 +39,7 @@ module Bundler
   environment_preserver.replace_with_backup
   SUDO_MUTEX = Thread::Mutex.new
 
+  autoload :Checksum,               File.expand_path("bundler/checksum", __dir__)
   autoload :Definition,             File.expand_path("bundler/definition", __dir__)
   autoload :Dependency,             File.expand_path("bundler/dependency", __dir__)
   autoload :Deprecate,              File.expand_path("bundler/deprecate", __dir__)
diff --git a/lib/bundler/checksum.rb b/lib/bundler/checksum.rb
new file mode 100644
index 0000000000..2e0a80cac2
--- /dev/null
+++ b/lib/bundler/checksum.rb
@@ -0,0 +1,42 @@
+# frozen_string_literal: true
+
+module Bundler
+  class Checksum
+    attr_reader :name, :version, :platform
+    attr_accessor :checksum
+
+    SHA256 = /\Asha256-([a-z0-9]{64}|[A-Za-z0-9+\/=]{44})\z/.freeze
+
+    def initialize(name, version, platform, checksum = nil)
+      @name     = name
+      @version  = version
+      @platform = platform || Gem::Platform::RUBY
+      @checksum = checksum
+
+      if @checksum && @checksum !~ SHA256
+        raise ArgumentError, "invalid checksum (#{@checksum})"
+      end
+    end
+
+    def match_spec?(spec)
+      name == spec.name &&
+        version == spec.version &&
+        platform.to_s == spec.platform.to_s
+    end
+
+    def to_lock
+      out = String.new
+
+      if platform == Gem::Platform::RUBY
+        out << "  #{name} (#{version})"
+      else
+        out << "  #{name} (#{version}-#{platform})"
+      end
+
+      out << " #{checksum}" if checksum
+      out << "\n"
+
+      out
+    end
+  end
+end
diff --git a/lib/bundler/definition.rb b/lib/bundler/definition.rb
index d9c2670d6d..6b066051d8 100644
--- a/lib/bundler/definition.rb
+++ b/lib/bundler/definition.rb
@@ -15,6 +15,7 @@ module Bundler
       :dependencies,
       :locked_deps,
       :locked_gems,
+      :locked_checksums,
       :platforms,
       :ruby_version,
       :lockfile,
@@ -92,6 +93,7 @@ module Bundler
         @locked_bundler_version = @locked_gems.bundler_version
         @locked_ruby_version = @locked_gems.ruby_version
         @originally_locked_specs = SpecSet.new(@locked_gems.specs)
+        @locked_checksums = @locked_gems.checksums
 
         if unlock != true
           @locked_deps    = @locked_gems.dependencies
@@ -112,6 +114,7 @@ module Bundler
         @originally_locked_specs = @locked_specs
         @locked_sources = []
         @locked_platforms = []
+        @locked_checksums = []
       end
 
       locked_gem_sources = @locked_sources.select {|s| s.is_a?(Source::Rubygems) }
diff --git a/lib/bundler/endpoint_specification.rb b/lib/bundler/endpoint_specification.rb
index 863544b1f9..4c41285043 100644
--- a/lib/bundler/endpoint_specification.rb
+++ b/lib/bundler/endpoint_specification.rb
@@ -104,6 +104,11 @@ module Bundler
       @remote_specification = spec
     end
 
+    def to_checksum
+      digest = "sha256-#{checksum}" if checksum
+      Bundler::Checksum.new(name, version, platform, digest)
+    end
+
     private
 
     def _remote_specification
diff --git a/lib/bundler/lazy_specification.rb b/lib/bundler/lazy_specification.rb
index c9b161dc0e..b4aadb0b5c 100644
--- a/lib/bundler/lazy_specification.rb
+++ b/lib/bundler/lazy_specification.rb
@@ -76,6 +76,18 @@ module Bundler
       out
     end
 
+    #def materialize_for_checksum
+      #if @specification
+        #yield
+      #else
+        #materialize_for_installation
+
+        #yield
+
+        #@specification = nil
+      #end
+    #end
+
     def materialize_for_installation
       source.local!
 
@@ -134,6 +146,20 @@ module Bundler
       " #{source.revision[0..6]}"
     end
 
+    def to_checksum
+      return nil unless @specification
+
+      #
+      # See comment about #ruby_platform_materializes_to_ruby_platform?
+      # If the old lockfile format is present where there is no specific
+      # platform, then we should skip locking checksums as it is not
+      # deterministic which platform variant is locked.
+      #
+      return nil unless ruby_platform_materializes_to_ruby_platform?
+
+      @specification.to_checksum
+    end
+
     private
 
     def use_exact_resolved_specifications?
diff --git a/lib/bundler/lockfile_generator.rb b/lib/bundler/lockfile_generator.rb
index f7ba51b3e6..11e8e3f103 100644
--- a/lib/bundler/lockfile_generator.rb
+++ b/lib/bundler/lockfile_generator.rb
@@ -19,6 +19,7 @@ module Bundler
       add_sources
       add_platforms
       add_dependencies
+      add_checksums
       add_locked_ruby_version
       add_bundled_with
 
@@ -65,6 +66,24 @@ module Bundler
       end
     end
 
+    def add_checksums
+      out << "\nCHECKSUMS\n"
+
+      definition.resolve.sort_by(&:full_name).each do |spec|
+        checksum = spec.to_checksum if spec.respond_to?(:to_checksum)
+
+        #if spec.is_a?(LazySpecification)
+          #spec.materialize_for_checksum do
+            #checksum ||= spec.to_checksum if spec.respond_to?(:to_checksum)
+          #end
+        #end
+
+        checksum ||= definition.locked_checksums.find {|c| c.match_spec?(spec) }
+
+        out << checksum.to_lock if checksum
+      end
+    end
+
     def add_locked_ruby_version
       return unless locked_ruby_version = definition.locked_ruby_version
       add_section("RUBY VERSION", locked_ruby_version.to_s)
diff --git a/lib/bundler/lockfile_parser.rb b/lib/bundler/lockfile_parser.rb
index 31f57f14e8..fc331a928c 100644
--- a/lib/bundler/lockfile_parser.rb
+++ b/lib/bundler/lockfile_parser.rb
@@ -2,10 +2,11 @@
 
 module Bundler
   class LockfileParser
-    attr_reader :sources, :dependencies, :specs, :platforms, :bundler_version, :ruby_version
+    attr_reader :sources, :dependencies, :specs, :platforms, :bundler_version, :ruby_version, :checksums
 
     BUNDLED      = "BUNDLED WITH"
     DEPENDENCIES = "DEPENDENCIES"
+    CHECKSUMS    = "CHECKSUMS"
     PLATFORMS    = "PLATFORMS"
     RUBY         = "RUBY VERSION"
     GIT          = "GIT"
@@ -21,6 +22,7 @@ module Bundler
       Gem::Version.create("1.10") => [BUNDLED].freeze,
       Gem::Version.create("1.12") => [RUBY].freeze,
       Gem::Version.create("1.13") => [PLUGIN].freeze,
+      Gem::Version.create("2.4.0") => [CHECKSUMS].freeze,
     }.freeze
 
     KNOWN_SECTIONS = SECTIONS_BY_VERSION_INTRODUCED.values.flatten!.freeze
@@ -64,6 +66,7 @@ module Bundler
       @sources      = []
       @dependencies = {}
       @parse_method = nil
+      @checksums    = []
       @specs        = {}
 
       if lockfile.match?(/<<<<<<<|=======|>>>>>>>|\|\|\|\|\|\|\|/)
@@ -77,6 +80,8 @@ module Bundler
           parse_source(line)
         elsif line == DEPENDENCIES
           @parse_method = :parse_dependency
+        elsif line == CHECKSUMS
+          @parse_method = :parse_checksum
         elsif line == PLATFORMS
           @parse_method = :parse_platform
         elsif line == RUBY
@@ -144,6 +149,7 @@ module Bundler
       (?:#{space}\(([^-]*)                               # Space, followed by version
       (?:-(.*))?\))?                                     # Optional platform
       (!)?                                               # Optional pinned marker
+      (?:#{space}(.*))?                                  # Optional checksum
       $                                                  # Line end
     /xo.freeze
 
@@ -176,6 +182,21 @@ module Bundler
       @dependencies[dep.name] = dep
     end
 
+    def parse_checksum(line)
+      if line =~ NAME_VERSION
+        spaces = $1
+        return unless spaces.size == 2
+        name = $2
+        version = $3
+        platform = $4
+        checksum = $6
+
+        version = Gem::Version.new(version)
+        platform = platform ? Gem::Platform.new(platform) : Gem::Platform::RUBY
+        @checksums << Bundler::Checksum.new(name, version, platform, checksum)
+      end
+    end
+
     def parse_spec(line)
       return unless line =~ NAME_VERSION
       spaces = $1
diff --git a/spec/bundler/bundler/definition_spec.rb b/spec/bundler/bundler/definition_spec.rb
index 59b958ae42..a5d244d3aa 100644
--- a/spec/bundler/bundler/definition_spec.rb
+++ b/spec/bundler/bundler/definition_spec.rb
@@ -77,6 +77,10 @@ RSpec.describe Bundler::Definition do
         DEPENDENCIES
           foo!
 
+        CHECKSUMS
+          foo (1.0)
+          #{checksum_for_repo_gem gem_repo1, "rack", "1.0.0"}
+
         BUNDLED WITH
            #{Bundler::VERSION}
       G
@@ -132,6 +136,10 @@ RSpec.describe Bundler::Definition do
         DEPENDENCIES
           foo!
 
+        CHECKSUMS
+          foo (1.0)
+          #{checksum_for_repo_gem gem_repo1, "rack", "1.0.0"}
+
         BUNDLED WITH
            #{Bundler::VERSION}
       G
@@ -159,6 +167,8 @@ RSpec.describe Bundler::Definition do
         DEPENDENCIES
           only_java
 
+        CHECKSUMS
+
         BUNDLED WITH
            #{Bundler::VERSION}
       G
@@ -185,6 +195,9 @@ RSpec.describe Bundler::Definition do
         DEPENDENCIES
           foo
 
+        CHECKSUMS
+          #{checksum_for_repo_gem gem_repo1, "foo", "1.0"}
+
         BUNDLED WITH
            #{Bundler::VERSION}
       G
diff --git a/spec/bundler/bundler/lockfile_parser_spec.rb b/spec/bundler/bundler/lockfile_parser_spec.rb
index 30fbeac71a..0b8db36324 100644
--- a/spec/bundler/bundler/lockfile_parser_spec.rb
+++ b/spec/bundler/bundler/lockfile_parser_spec.rb
@@ -60,7 +60,7 @@ RSpec.describe Bundler::LockfileParser do
 
       it "returns the same as > 1.0" do
         expect(subject).to contain_exactly(
-          described_class::BUNDLED, described_class::RUBY, described_class::PLUGIN
+          described_class::BUNDLED, described_class::CHECKSUMS, described_class::RUBY, described_class::PLUGIN
         )
       end
     end
@@ -70,7 +70,7 @@ RSpec.describe Bundler::LockfileParser do
 
       it "returns the same as for the release version" do
         expect(subject).to contain_exactly(
-          described_class::RUBY, described_class::PLUGIN
+          described_class::CHECKSUMS, described_class::RUBY, described_class::PLUGIN
         )
       end
     end
diff --git a/spec/bundler/commands/check_spec.rb b/spec/bundler/commands/check_spec.rb
index 99a858e9e9..7832a9d877 100644
--- a/spec/bundler/commands/check_spec.rb
+++ b/spec/bundler/commands/check_spec.rb
@@ -425,6 +425,10 @@ RSpec.describe "bundle check" do
         DEPENDENCIES
           depends_on_rack!
 
+        CHECKSUMS
+          #{checksum_for_repo_gem gem_repo4, "depends_on_rack", "1.0"}
+          #{checksum_for_repo_gem gem_repo4, "rack", "1.0"}
+
         BUNDLED WITH
            #{Bundler::VERSION}
       L
@@ -488,6 +492,11 @@ RSpec.describe "bundle check" do
           bundle-check-issue!
           dex-dispatch-engine!
 
+        CHECKSUMS
+          #{checksum_for_repo_gem gem_repo4, "awesome_print", "1.0"}
+          bundle-check-issue (9999)
+          #{checksum_for_repo_gem gem_repo2, "dex-dispatch-engine", "1.0"}
+
         BUNDLED WITH
            #{Bundler::VERSION}
       L
diff --git a/spec/bundler/commands/install_spec.rb b/spec/bundler/commands/install_spec.rb
index 92415bd9d5..d6ce92b6d5 100644
--- a/spec/bundler/commands/install_spec.rb
+++ b/spec/bundler/commands/install_spec.rb
@@ -543,6 +543,8 @@ RSpec.describe "bundle install with gem sources" do
 
          DEPENDENCIES
 
+         CHECKSUMS
+
          RUBY VERSION
             #{Bundler::RubyVersion.system}
 
@@ -567,6 +569,8 @@ RSpec.describe "bundle install with gem sources" do
 
          DEPENDENCIES
 
+         CHECKSUMS
+
          RUBY VERSION
             #{Bundler::RubyVersion.system}
 
@@ -888,16 +892,16 @@ RSpec.describe "bundle install with gem sources" do
   context "with missing platform specific gems in lockfile" do
     before do
       build_repo4 do
-        build_gem "racc", "1.5.2"
+        build_gem "racca", "1.5.2"
 
         build_gem "nokogiri", "1.12.4" do |s|
           s.platform = "x86_64-darwin"
-          s.add_runtime_dependency "racc", "~> 1.4"
+          s.add_runtime_dependency "racca", "~> 1.4"
         end
 
         build_gem "nokogiri", "1.12.4" do |s|
           s.platform = "x86_64-linux"
-          s.add_runtime_dependency "racc", "~> 1.4"
+          s.add_runtime_dependency "racca", "~> 1.4"
         end
 
         build_gem "crass", "1.0.6"
@@ -916,6 +920,13 @@ RSpec.describe "bundle install with gem sources" do
         gem "loofah", "~> 2.12.0"
       G
 
+      checksums = construct_checksum_section do |c|
+        c.repo_gem gem_repo4, "crass", "1.0.6"
+        c.repo_gem gem_repo4, "loofah", "2.12.0"
+        c.repo_gem gem_repo4, "nokogiri", "1.12.4", "x86_64-darwin"
+        c.repo_gem gem_repo4, "racca", "1.5.2"
+      end
+
       lockfile <<-L
         GEM
           remote: https://gem.repo4/
@@ -925,8 +936,8 @@ RSpec.describe "bundle install with gem sources" do
               crass (~> 1.0.2)
               nokogiri (>= 1.5.9)
             nokogiri (1.12.4-x86_64-darwin)
-              racc (~> 1.4)
-            racc (1.5.2)
+              racca (~> 1.4)
+            racca (1.5.2)
 
         PLATFORMS
           x86_64-darwin-20
@@ -935,6 +946,9 @@ RSpec.describe "bundle install with gem sources" do
         DEPENDENCIES
           loofah (~> 2.12.0)
 
+        CHECKSUMS
+          #{checksums}
+
         RUBY VERSION
            #{Bundler::RubyVersion.system}
 
@@ -950,6 +964,14 @@ RSpec.describe "bundle install with gem sources" do
         bundle "install", :artifice => "compact_index"
       end
 
+      expected_checksums = construct_checksum_section do |c|
+        c.repo_gem gem_repo4, "crass", "1.0.6"
+        c.repo_gem gem_repo4, "loofah", "2.12.0"
+        c.repo_gem gem_repo4, "nokogiri", "1.12.4", "x86_64-darwin"
+        c.repo_gem gem_repo4, "nokogiri", "1.12.4", "x86_64-linux"
+        c.repo_gem gem_repo4, "racca", "1.5.2"
+      end
+
       expect(lockfile).to eq <<~L
         GEM
           remote: https://gem.repo4/
@@ -959,10 +981,10 @@ RSpec.describe "bundle install with gem sources" do
               crass (~> 1.0.2)
               nokogiri (>= 1.5.9)
             nokogiri (1.12.4-x86_64-darwin)
-              racc (~> 1.4)
+              racca (~> 1.4)
             nokogiri (1.12.4-x86_64-linux)
-              racc (~> 1.4)
-            racc (1.5.2)
+              racca (~> 1.4)
+            racca (1.5.2)
 
         PLATFORMS
           x86_64-darwin-20
@@ -971,6 +993,9 @@ RSpec.describe "bundle install with gem sources" do
         DEPENDENCIES
           loofah (~> 2.12.0)
 
+        CHECKSUMS
+          #{expected_checksums}
+
         RUBY VERSION
            #{Bundler::RubyVersion.system}
 
diff --git a/spec/bundler/commands/lock_spec.rb b/spec/bundler/commands/lock_spec.rb
index 7f2e24c086..ff387a5990 100644
--- a/spec/bundler/commands/lock_spec.rb
+++ b/spec/bundler/commands/lock_spec.rb
@@ -42,6 +42,8 @@ RSpec.describe "bundle lock" do
         rails
         weakling
 
+      CHECKSUMS
+
       BUNDLED WITH
          #{Bundler::VERSION}
     L
@@ -104,6 +106,8 @@ RSpec.describe "bundle lock" do
       DEPENDENCIES
         foo
 
+      CHECKSUMS
+
       BUNDLED WITH
          #{Bundler::VERSION}
     L
@@ -126,8 +130,58 @@ RSpec.describe "bundle lock" do
     bundle "install"
     bundle "lock --lockfile=lock"
 
+    expected_checksums = construct_checksum_section do |c|
+      c.repo_gem repo, "actionmailer", "2.3.2"
+      c.repo_gem repo, "actionpack", "2.3.2"
+      c.repo_gem repo, "activerecord", "2.3.2"
+      c.repo_gem repo, "activeresource", "2.3.2"
+      c.repo_gem repo, "activesupport", "2.3.2"
+      c.repo_gem repo, "foo", "1.0"
+      c.repo_gem repo, "rails", "2.3.2"
+      c.repo_gem repo, "rake", "13.0.1"
+      c.repo_gem repo, "weakling", "0.0.3"
+    end
+
+    lockfile = strip_lockfile(<<-L)
+      GEM
+        remote: #{file_uri_for(repo)}/
+        specs:
+          actionmailer (2.3.2)
+            activesupport (= 2.3.2)
+          actionpack (2.3.2)
+            activesupport (= 2.3.2)
+          activerecord (2.3.2)
+            activesupport (= 2.3.2)
+          activeresource (2.3.2)
+            activesupport (= 2.3.2)
+          activesupport (2.3.2)
+          foo (1.0)
+          rails (2.3.2)
+            actionmailer (= 2.3.2)
+            actionpack (= 2.3.2)
+            activerecord (= 2.3.2)
+            activeresource (= 2.3.2)
+            rake (= 13.0.1)
+          rake (13.0.1)
+          weakling (0.0.3)
+
+      PLATFORMS
+        #{lockfile_platforms}
+
+      DEPENDENCIES
+        foo
+        rails
+        weakling
+
+      CHECKSUMS
+        #{expected_checksums}
+
+      BUNDLED WITH
+         #{Bundler::VERSION}
+    L
+
     expect(out).to match(/Writing lockfile to.+lock/)
-    expect(read_lockfile("lock")).to eq(@lockfile)
+    expect(read_lockfile("lock")).to eq(lockfile)
   end
 
   it "update specific gems using --update" do
@@ -535,6 +589,8 @@ RSpec.describe "bundle lock" do
         gssapi
         mixlib-shellout
 
+      CHECKSUMS
+
       BUNDLED WITH
          #{Bundler::VERSION}
     G
@@ -564,6 +620,8 @@ RSpec.describe "bundle lock" do
         gssapi
         mixlib-shellout
 
+      CHECKSUMS
+
       BUNDLED WITH
          #{Bundler::VERSION}
     G
@@ -642,6 +700,8 @@ RSpec.describe "bundle lock" do
       DEPENDENCIES
         libv8
 
+      CHECKSUMS
+
       BUNDLED WITH
          #{Bundler::VERSION}
     G
@@ -677,6 +737,10 @@ RSpec.describe "bundle lock" do
       DEPENDENCIES
         libv8
 
+      CHECKSUMS
+        #{checksum_for_repo_gem gem_repo4, "libv8", "8.4.255.0", "x86_64-darwin-19"}
+        #{checksum_for_repo_gem gem_repo4, "libv8", "8.4.255.0", "x86_64-darwin-20"}
+
       BUNDLED WITH
          #{Bundler::VERSION}
     G
@@ -895,6 +959,8 @@ RSpec.describe "bundle lock" do
         DEPENDENCIES
           debug
 
+        CHECKSUMS
+
         BUNDLED WITH
            #{Bundler::VERSION}
       L
@@ -918,6 +984,8 @@ RSpec.describe "bundle lock" do
         DEPENDENCIES
           debug
 
+        CHECKSUMS
+
         BUNDLED WITH
            #{Bundler::VERSION}
       L
diff --git a/spec/bundler/commands/update_spec.rb b/spec/bundler/commands/update_spec.rb
index 84042709bf..eb578d4dff 100644
--- a/spec/bundler/commands/update_spec.rb
+++ b/spec/bundler/commands/update_spec.rb
@@ -290,6 +290,8 @@ RSpec.describe "bundle update" do
           countries
           country_select
 
+        CHECKSUMS
+
         BUNDLED WITH
            #{Bundler::VERSION}
       L
@@ -505,6 +507,11 @@ RSpec.describe "bundle update" do
 
       original_lockfile = lockfile
 
+      expected_checksums = construct_checksum_section do |c|
+        c.repo_gem gem_repo4, "activesupport", "6.0.4.1"
+        c.repo_gem gem_repo4, "tzinfo", "1.2.9"
+      end
+
       expected_lockfile = <<~L
         GEM
           remote: #{file_uri_for(gem_repo4)}/
@@ -519,6 +526,9 @@ RSpec.describe "bundle update" do
         DEPENDENCIES
           activesupport (~> 6.0.0)
 
+        CHECKSUMS
+          #{expected_checksums}
+
         BUNDLED WITH
            #{Bundler::VERSION}
       L
@@ -535,7 +545,25 @@ RSpec.describe "bundle update" do
       lockfile original_lockfile
       bundle "lock --update"
       expect(the_bundle).to include_gems("activesupport 6.0.4.1", "tzinfo 1.2.9")
-      expect(lockfile).to eq(expected_lockfile)
+      expect(lockfile).to eq <<~L
+        GEM
+          remote: #{file_uri_for(gem_repo4)}/
+          specs:
+            activesupport (6.0.4.1)
+              tzinfo (~> 1.1)
+            tzinfo (1.2.9)
+
+        PLATFORMS
+          #{lockfile_platforms}
+
+        DEPENDENCIES
+          activesupport (~> 6.0.0)
+
+        CHECKSUMS
+
+        BUNDLED WITH
+           #{Bundler::VERSION}
+      L
     end
   end
 
@@ -1128,6 +1156,8 @@ RSpec.describe "bundle update --ruby" do
 
        DEPENDENCIES
 
+       CHECKSUMS
+
        BUNDLED WITH
           #{Bundler::VERSION}
       L
@@ -1159,6 +1189,8 @@ RSpec.describe "bundle update --ruby" do
 
        DEPENDENCIES
 
+       CHECKSUMS
+
        RUBY VERSION
           #{Bundler::RubyVersion.system}
 
@@ -1199,6 +1231,8 @@ RSpec.describe "bundle update --ruby" do
 
        DEPENDENCIES
 
+       CHECKSUMS
+
        RUBY VERSION
           ruby 2.1.4p222
 
@@ -1224,6 +1258,8 @@ RSpec.describe "bundle update --ruby" do
 
        DEPENDENCIES
 
+       CHECKSUMS
+
        RUBY VERSION
           #{Bundler::RubyVersion.system}
 
@@ -1246,6 +1282,10 @@ RSpec.describe "bundle update --bundler" do
     G
     lockfile lockfile.sub(/(^\s*)#{Bundler::VERSION}($)/, '\11.0.0\2')
 
+    excepted_checksum = checksum_for_repo_gem(gem_repo4, "rack", "1.0")
+
+    FileUtils.rm_r gem_repo4
+
     bundle :update, :bundler => true, :artifice => "compact_index", :verbose => true
     expect(out).to include("Using bundler #{Bundler::VERSION}")
 
@@ -1261,6 +1301,9 @@ RSpec.describe "bundle update --bundler" do
       DEPENDENCIES
         rack
 
+      CHECKSUMS
+        #{excepted_checksum}
+
       BUNDLED WITH
          #{Bundler::VERSION}
     L
@@ -1296,6 +1339,9 @@ RSpec.describe "bundle update --bundler" do
       DEPENDENCIES
         rack
 
+      CHECKSUMS
+        #{checksum_for_repo_gem(gem_repo4, "rack", "1.0")}
+
       BUNDLED WITH
          #{Bundler::VERSION}
     L
@@ -1399,6 +1445,9 @@ RSpec.describe "bundle update --bundler" do
         DEPENDENCIES
           rack
 
+        CHECKSUMS
+          #{checksum_for_repo_gem(gem_repo4, "rack", "1.0")}
+
         BUNDLED WITH
            2.3.0.dev
       L
@@ -1438,6 +1487,9 @@ RSpec.describe "bundle update --bundler" do
         DEPENDENCIES
           rack
 
+        CHECKSUMS
+          #{checksum_for_repo_gem(gem_repo4, "rack", "1.0")}
+
         BUNDLED WITH
            2.3.9
       L
@@ -1628,6 +1680,8 @@ RSpec.describe "bundle update conservative" do
           shared_owner_a
           shared_owner_b
 
+        CHECKSUMS
+
         BUNDLED WITH
            #{Bundler::VERSION}
       L
@@ -1681,6 +1735,8 @@ RSpec.describe "bundle update conservative" do
           shared_owner_a
           shared_owner_b
 
+        CHECKSUMS
+
         BUNDLED WITH
            #{Bundler::VERSION}
       L
diff --git a/spec/bundler/install/gemfile/gemspec_spec.rb b/spec/bundler/install/gemfile/gemspec_spec.rb
index bed1d7fe04..23f1a05c10 100644
--- a/spec/bundler/install/gemfile/gemspec_spec.rb
+++ b/spec/bundler/install/gemfile/gemspec_spec.rb
@@ -448,6 +448,12 @@ RSpec.describe "bundle install from an existing gemspec" do
         context "as a runtime dependency" do
           it "keeps all platform dependencies in the lockfile" do
             expect(the_bundle).to include_gems "foo 1.0", "platform_specific 1.0 RUBY"
+
+            expected_checksums = construct_checksum_section do |c|
+              c.repo_gem gem_repo2, "platform_specific", "1.0"
+              c.repo_gem gem_repo2, "platform_specific", "1.0", x64_mingw32
+            end
+
             expect(lockfile).to eq <<~L
               PATH
                 remote: .
@@ -470,6 +476,10 @@ RSpec.describe "bundle install from an existing gemspec" do
               DEPENDENCIES
                 foo!
 
+              CHECKSUMS
+                foo (1.0)
+                #{expected_checksums}
+
               BUNDLED WITH
                  #{Bundler::VERSION}
             L
@@ -481,6 +491,12 @@ RSpec.describe "bundle install from an existing gemspec" do
 
           it "keeps all platform dependencies in the lockfile" do
             expect(the_bundle).to include_gems "foo 1.0", "platform_specific 1.0 RUBY"
+
+            expected_checksums = construct_checksum_section do |c|
+              c.repo_gem gem_repo2, "platform_specific", "1.0"
+              c.repo_gem gem_repo2, "platform_specific", "1.0", x64_mingw32
+            end
+
             expect(lockfile).to eq <<~L
               PATH
                 remote: .
@@ -503,6 +519,10 @@ RSpec.describe "bundle install from an existing gemspec" do
                 foo!
                 platform_specific
 
+              CHECKSUMS
+                foo (1.0)
+                #{expected_checksums}
+
               BUNDLED WITH
                  #{Bundler::VERSION}
             L
@@ -515,6 +535,13 @@ RSpec.describe "bundle install from an existing gemspec" do
 
           it "keeps all platform dependencies in the lockfile" do
             expect(the_bundle).to include_gems "foo 1.0", "indirect_platform_specific 1.0", "platform_specific 1.0 RUBY"
+
+            expected_checksums = construct_checksum_section do |c|
+              c.repo_gem gem_repo2, "indirect_platform_specific", "1.0"
+              c.repo_gem gem_repo2, "platform_specific", "1.0"
+              c.repo_gem gem_repo2, "platform_specific", "1.0", x64_mingw32
+            end
+
             expect(lockfile).to eq <<~L
               PATH
                 remote: .
@@ -539,6 +566,10 @@ RSpec.describe "bundle install from an existing gemspec" do
                 foo!
                 indirect_platform_specific
 
+              CHECKSUMS
+                foo (1.0)
+                #{expected_checksums}
+
               BUNDLED WITH
                  #{Bundler::VERSION}
             L
@@ -623,6 +654,11 @@ RSpec.describe "bundle install from an existing gemspec" do
         DEPENDENCIES
           chef!
 
+        CHECKSUMS
+          chef (17.1.17)
+          chef (17.1.17-universal-mingw32)
+          #{checksum_for_repo_gem gem_repo4, "win32-api", "1.5.3", "universal-mingw32"}
+
         BUNDLED WITH
            #{Bundler::VERSION}
       L
@@ -680,6 +716,10 @@ RSpec.describe "bundle install from an existing gemspec" do
           activeadmin!
           jruby-openssl
 
+        CHECKSUMS
+          activeadmin (2.9.0)
+          #{checksum_for_repo_gem gem_repo4, "railties", "6.1.4"}
+
         BUNDLED WITH
            #{Bundler::VERSION}
       L
diff --git a/spec/bundler/install/gemfile/install_if_spec.rb b/spec/bundler/install/gemfile/install_if_spec.rb
index 3d2d15a698..441b309afe 100644
--- a/spec/bundler/install/gemfile/install_if_spec.rb
+++ b/spec/bundler/install/gemfile/install_if_spec.rb
@@ -37,6 +37,10 @@ RSpec.describe "bundle install with install_if conditionals" do
         rack
         thin
 
+      CHECKSUMS
+        #{checksum_for_repo_gem gem_repo1, "activesupport", "2.3.5"}
+        #{checksum_for_repo_gem gem_repo1, "rack", "1.0.0"}
+
       BUNDLED WITH
          #{Bundler::VERSION}
     L
diff --git a/spec/bundler/install/gemfile/path_spec.rb b/spec/bundler/install/gemfile/path_spec.rb
index a5207036c3..086d6c3ed1 100644
--- a/spec/bundler/install/gemfile/path_spec.rb
+++ b/spec/bundler/install/gemfile/path_spec.rb
@@ -120,6 +120,10 @@ RSpec.describe "bundle install with explicit source paths" do
         aaa!
         demo!
 
+      CHECKSUMS
+        aaa (1.0)
+        demo (1.0)
+
       BUNDLED WITH
          #{Bundler::VERSION}
     L
@@ -359,6 +363,10 @@ RSpec.describe "bundle install with explicit source paths" do
       DEPENDENCIES
         foo!
 
+      CHECKSUMS
+        foo (0.1.0)
+        #{checksum_for_repo_gem gem_repo4, "graphql", "2.0.15"}
+
       BUNDLED WITH
          #{Bundler::VERSION}
     L
@@ -683,6 +691,10 @@ RSpec.describe "bundle install with explicit source paths" do
         DEPENDENCIES
           foo!
 
+        CHECKSUMS
+          foo (1.0)
+          #{checksum_for_repo_gem gem_repo1, "rack", "0.9.1"}
+
         BUNDLED WITH
            #{Bundler::VERSION}
       G
@@ -711,6 +723,10 @@ RSpec.describe "bundle install with explicit source paths" do
         DEPENDENCIES
           foo!
 
+        CHECKSUMS
+          foo (1.0)
+          #{checksum_for_repo_gem gem_repo1, "rack", "0.9.1"}
+
         BUNDLED WITH
            #{Bundler::VERSION}
       G
@@ -745,6 +761,10 @@ RSpec.describe "bundle install with explicit source paths" do
         DEPENDENCIES
           foo!
 
+        CHECKSUMS
+          foo (1.0)
+          #{checksum_for_repo_gem gem_repo1, "rack", "0.9.1"}
+
         BUNDLED WITH
            #{Bundler::VERSION}
       G
@@ -776,6 +796,11 @@ RSpec.describe "bundle install with explicit source paths" do
         DEPENDENCIES
           foo!
 
+        CHECKSUMS
+          foo (1.0)
+          #{checksum_for_repo_gem gem_repo1, "rack", "0.9.1"}
+          #{checksum_for_repo_gem gem_repo1, "rake", "13.0.1"}
+
         BUNDLED WITH
            #{Bundler::VERSION}
       G
diff --git a/spec/bundler/install/gemfile/platform_spec.rb b/spec/bundler/install/gemfile/platform_spec.rb
index d28c7b781f..3992d11458 100644
--- a/spec/bundler/install/gemfile/platform_spec.rb
+++ b/spec/bundler/install/gemfile/platform_spec.rb
@@ -225,6 +225,8 @@ RSpec.describe "bundle install across platforms" do
         empyrean (= 0.1.0)
         pry
 
+      CHECKSUMS
+
       BUNDLED WITH
          #{Bundler::VERSION}
     L
@@ -257,6 +259,8 @@ RSpec.describe "bundle install across platforms" do
         empyrean (= 0.1.0)
         pry
 
+      CHECKSUMS
+
       BUNDLED WITH
          #{Bundler::VERSION}
     L
@@ -290,6 +294,8 @@ RSpec.describe "bundle install across platforms" do
         empyrean (= 0.1.0)
         pry
 
+      CHECKSUMS
+
       BUNDLED WITH
          1.16.1
     L
@@ -399,6 +405,9 @@ RSpec.describe "bundle install across platforms" do
       DEPENDENCIES
         platform_specific
 
+      CHECKSUMS
+        #{checksum_for_repo_gem(gem_repo1, "platform_specific", "1.0")}
+
       BUNDLED WITH
          #{Bundler::VERSION}
     G
@@ -568,6 +577,8 @@ RSpec.describe "bundle install with platform conditionals" do
       DEPENDENCIES
         rack
 
+      CHECKSUMS
+
       BUNDLED WITH
          #{Bundler::VERSION}
     L
diff --git a/spec/bundler/install/gemfile/sources_spec.rb b/spec/bundler/install/gemfile/sources_spec.rb
index 8cb0476821..40c4bebdd3 100644
--- a/spec/bundler/install/gemfile/sources_spec.rb
+++ b/spec/bundler/install/gemfile/sources_spec.rb
@@ -284,6 +284,11 @@ RSpec.describe "bundle install with gems on multiple sources" do
           expect(err).to include("Warning: the gem 'rack' was found in multiple sources.")
           expect(err).to include("Installed from: https://gem.repo2")
 
+          expected_checksums = construct_checksum_section do |c|
+            c.repo_gem gem_repo3, "depends_on_rack", "1.0.1"
+            c.repo_gem gem_repo2, "rack", "1.0.0"
+          end
+
           expect(lockfile).to eq <<~L
             GEM
               remote: https://gem.repo1/
@@ -303,6 +308,9 @@ RSpec.describe "bundle install with gems on multiple sources" do
             DEPENDENCIES
               depends_on_rack!
 
+            CHECKSUMS
+              #{expected_checksums}
+
             BUNDLED WITH
                #{Bundler::VERSION}
           L
@@ -698,6 +706,21 @@ RSpec.describe "bundle install with gems on multiple sources" do
         expect(the_bundle).to include_gems("concurrent-ruby 1.1.8")
         expect(the_bundle).not_to include_gems("concurrent-ruby 1.1.9")
 
+        expected_checksums = construct_checksum_section do |c|
+          c.repo_gem gem_repo2, "activesupport", "6.0.3.4"
+          c.repo_gem gem_repo2, "concurrent-ruby", "1.1.8"
+          c.repo_gem gem_repo2, "connection_pool", "2.2.3"
+          c.repo_gem gem_repo2, "i18n", "1.8.9"
+          c.repo_gem gem_repo2, "minitest", "5.14.3"
+          c.repo_gem gem_repo2, "rack", "2.2.3"
+          c.repo_gem gem_repo2, "redis", "4.2.5"
+          c.repo_gem gem_repo2, "sidekiq", "6.1.3"
+          c.repo_gem gem_repo3, "sidekiq-pro", "5.2.1"
+          c.repo_gem gem_repo2, "thread_safe", "0.3.6"
+          c.repo_gem gem_repo2, "tzinfo", "1.2.9"
+          c.repo_gem gem_repo2, "zeitwerk", "2.4.2"
+        end
+
         expect(lockfile).to eq <<~L
           GEM
             remote: https://gem.repo2/
@@ -738,6 +761,9 @@ RSpec.describe "bundle install with gems on multiple sources" do
             activesupport
             sidekiq-pro!
 
+          CHECKSUMS
+            #{expected_checksums}
+
           BUNDLED WITH
              #{Bundler::VERSION}
         L
@@ -783,6 +809,20 @@ RSpec.describe "bundle install with gems on multiple sources" do
         expect(the_bundle).not_to include_gems("concurrent-ruby 1.1.8")
         expect(the_bundle).to include_gems("concurrent-ruby 1.1.9")
 
+        expected_checksums = construct_checksum_section do |c|
+          c.repo_gem gem_repo2, "activesupport", "6.1.2.1"
+          c.repo_gem gem_repo2, "concurrent-ruby", "1.1.9"
+          c.repo_gem gem_repo2, "connection_pool", "2.2.3"
+          c.repo_gem gem_repo2, "i18n", "1.8.9"
+          c.repo_gem gem_repo2, "minitest", "5.14.3"
+          c.repo_gem gem_repo2, "rack", "2.2.3"
+          c.repo_gem gem_repo2, "redis", "4.2.5"
+          c.repo_gem gem_repo2, "sidekiq", "6.1.3"
+          c.repo_gem gem_repo3, "sidekiq-pro", "5.2.1"
+          c.repo_gem gem_repo2, "tzinfo", "2.0.4"
+          c.repo_gem gem_repo2, "zeitwerk", "2.4.2"
+        end
+
         expect(lockfile).to eq <<~L
           GEM
             remote: https://gem.repo2/
@@ -822,6 +862,9 @@ RSpec.describe "bundle install with gems on multiple sources" do
             activesupport
             sidekiq-pro!
 
+          CHECKSUMS
+            #{expected_checksums}
+
           BUNDLED WITH
              #{Bundler::VERSION}
         L
@@ -838,6 +881,21 @@ RSpec.describe "bundle install with gems on multiple sources" do
         expect(the_bundle).to include_gems("concurrent-ruby 1.1.9")
         expect(the_bundle).not_to include_gems("concurrent-ruby 1.1.8")
 
+        expected_checksums = construct_checksum_section do |c|
+          c.repo_gem gem_repo2, "activesupport", "6.0.3.4"
+          c.repo_gem gem_repo2, "concurrent-ruby", "1.1.9"
+          c.repo_gem gem_repo2, "connection_pool", "2.2.3"
+          c.repo_gem gem_repo2, "i18n", "1.8.9"
+          c.repo_gem gem_repo2, "minitest", "5.14.3"
+          c.repo_gem gem_repo2, "rack", "2.2.3"
+          c.repo_gem gem_repo2, "redis", "4.2.5"
+          c.repo_gem gem_repo2, "sidekiq", "6.1.3"
+          c.repo_gem gem_repo3, "sidekiq-pro", "5.2.1"
+          c.repo_gem gem_repo2, "thread_safe", "0.3.6"
+          c.repo_gem gem_repo2, "tzinfo", "1.2.9"
+          c.repo_gem gem_repo2, "zeitwerk", "2.4.2"
+        end
+
         expect(lockfile).to eq <<~L
           GEM
             remote: https://gem.repo2/
@@ -878,6 +936,9 @@ RSpec.describe "bundle install with gems on multiple sources" do
             activesupport
             sidekiq-pro!
 
+          CHECKSUMS
+            #{expected_checksums}
+
           BUNDLED WITH
              #{Bundler::VERSION}
         L
@@ -945,6 +1006,12 @@ RSpec.describe "bundle install with gems on multiple sources" do
       end
 
       it "installs from the default source without any warnings or errors and generates a proper lockfile" do
+        expected_checksums = construct_checksum_section do |c|
+          c.repo_gem gem_repo3, "handsoap", "0.2.5.5"
+          c.repo_gem gem_repo2, "nokogiri", "1.11.1"
+          c.repo_gem gem_repo2, "racca", "1.5.2"
+        end
+
         expected_lockfile = <<~L
           GEM
             remote: https://gem.repo2/
@@ -966,6 +1033,9 @@ RSpec.describe "bundle install with gems on multiple sources" do
             handsoap!
             nokogiri
 
+          CHECKSUMS
+            #{expected_checksums}
+
           BUNDLED WITH
              #{Bundler::VERSION}
         L
@@ -1489,6 +1559,8 @@ RSpec.describe "bundle install with gems on multiple sources" do
         DEPENDENCIES
           capybara (~> 2.5.0)
           mime-types (~> 3.0)!
+
+        CHECKSUMS
       L
     end
 
@@ -1514,6 +1586,8 @@ RSpec.describe "bundle install with gems on multiple sources" do
           capybara (~> 2.5.0)
           mime-types (~> 3.0)!
 
+        CHECKSUMS
+
         BUNDLED WITH
            #{Bundler::VERSION}
       L
@@ -1567,6 +1641,10 @@ RSpec.describe "bundle install with gems on multiple sources" do
         DEPENDENCIES
           ruport (= 1.7.0.3)!
 
+        CHECKSUMS
+          #{checksum_for_repo_gem gem_repo4, "pdf-writer", "1.1.8"}
+          #{checksum_for_repo_gem gem_repo2, "ruport", "1.7.0.3"}
+
         BUNDLED WITH
            #{Bundler::VERSION}
       L
@@ -1602,6 +1680,11 @@ RSpec.describe "bundle install with gems on multiple sources" do
     it "handles that fine" do
       bundle "install", :artifice => "compact_index_extra", :env => { "BUNDLER_SPEC_GEM_REPO" => gem_repo4.to_s }
 
+      expected_checksums = construct_checksum_section do |c|
+        c.repo_gem gem_repo4, "pdf-writer", "1.1.8"
+        c.repo_gem gem_repo2, "ruport", "1.7.0.3"
+      end
+
       expect(lockfile).to eq <<~L
         GEM
           remote: https://localgemserver.test/
@@ -1620,6 +1703,9 @@ RSpec.describe "bundle install with gems on multiple sources" do
         DEPENDENCIES
           ruport (= 1.7.0.3)!
 
+        CHECKSUMS
+          #{expected_checksums}
+
         BUNDLED WITH
            #{Bundler::VERSION}
       L
@@ -1649,6 +1735,10 @@ RSpec.describe "bundle install with gems on multiple sources" do
     it "handles that fine" do
       bundle "install --verbose", :artifice => "endpoint", :env => { "BUNDLER_SPEC_GEM_REPO" => gem_repo4.to_s }
 
+      expected_checksums = construct_checksum_section do |c|
+        c.repo_gem gem_repo4, "pdf-writer", "1.1.8"
+      end
+
       expect(lockfile).to eq <<~L
         GEM
           remote: https://localgemserver.test/
@@ -1661,6 +1751,9 @@ RSpec.describe "bundle install with gems on multiple sources" do
         DEPENDENCIES
           pdf-writer (= 1.1.8)
 
+        CHECKSUMS
+          #{expected_checksums}
+
         BUNDLED WITH
            #{Bundler::VERSION}
       L
diff --git a/spec/bundler/install/gemfile/specific_platform_spec.rb b/spec/bundler/install/gemfile/specific_platform_spec.rb
index 30bf50c48e..6938507dd5 100644
--- a/spec/bundler/install/gemfile/specific_platform_spec.rb
+++ b/spec/bundler/install/gemfile/specific_platform_spec.rb
@@ -101,6 +101,8 @@ RSpec.describe "bundle install with specific platforms" do
         DEPENDENCIES
           google-protobuf
 
+        CHECKSUMS
+
         BUNDLED WITH
            #{Bundler::VERSION}
       L
@@ -522,6 +524,13 @@ RSpec.describe "bundle install with specific platforms" do
 
     bundle "update"
 
+    expected_checksums = construct_checksum_section do |c|
+      c.repo_gem gem_repo4, "sorbet", "0.5.10160"
+      c.repo_gem gem_repo4, "sorbet-runtime", "0.5.10160"
+      c.repo_gem gem_repo4, "sorbet-static", "0.5.10160", Gem::Platform.local
+      c.repo_gem gem_repo4, "sorbet-static-and-runtime", "0.5.10160"
+    end
+
     expect(lockfile).to eq <<~L
       GEM
         remote: #{file_uri_for(gem_repo4)}/
@@ -540,6 +549,9 @@ RSpec.describe "bundle install with specific platforms" do
       DEPENDENCIES
         sorbet-static-and-runtime
 
+      CHECKSUMS
+        #{expected_checksums}
+
       BUNDLED WITH
          #{Bundler::VERSION}
     L
@@ -662,6 +674,13 @@ RSpec.describe "bundle install with specific platforms" do
 
     bundle "update"
 
+    expected_checksums = construct_checksum_section do |c|
+      c.repo_gem gem_repo4, "sorbet", "0.5.10160"
+      c.repo_gem gem_repo4, "sorbet-runtime", "0.5.10160"
+      c.repo_gem gem_repo4, "sorbet-static", "0.5.10160", Gem::Platform.local
+      c.repo_gem gem_repo4, "sorbet-static-and-runtime", "0.5.10160"
+    end
+
     expect(lockfile).to eq <<~L
       GEM
         remote: #{file_uri_for(gem_repo4)}/
@@ -680,6 +699,9 @@ RSpec.describe "bundle install with specific platforms" do
       DEPENDENCIES
         sorbet-static-and-runtime
 
+      CHECKSUMS
+        #{expected_checksums}
+
       BUNDLED WITH
          #{Bundler::VERSION}
     L
@@ -836,6 +858,8 @@ RSpec.describe "bundle install with specific platforms" do
         nokogiri
         tzinfo (~> 1.2)
 
+      CHECKSUMS
+
       BUNDLED WITH
          #{Bundler::VERSION}
     L
diff --git a/spec/bundler/install/gems/compact_index_spec.rb b/spec/bundler/install/gems/compact_index_spec.rb
index 1d193a0f20..20e3d93175 100644
--- a/spec/bundler/install/gems/compact_index_spec.rb
+++ b/spec/bundler/install/gems/compact_index_spec.rb
@@ -949,6 +949,6 @@ Running `bundle update rails` should fix the problem.
     G
     gem_command "uninstall activemerchant"
     bundle "update rails", :artifice => "compact_index"
-    expect(lockfile.scan(/activemerchant \(/).size).to eq(1)
+    expect(lockfile.scan(/activemerchant \(/).size).to eq(2) # Once in the specs, and once in CHECKSUMS
   end
 end
diff --git a/spec/bundler/install/gems/flex_spec.rb b/spec/bundler/install/gems/flex_spec.rb
index ddb9480343..484ec1f839 100644
--- a/spec/bundler/install/gems/flex_spec.rb
+++ b/spec/bundler/install/gems/flex_spec.rb
@@ -283,6 +283,10 @@ RSpec.describe "bundle flex_install" do
           rack (= 0.9.1)
           rack-obama
 
+        CHECKSUMS
+          #{checksum_for_repo_gem gem_repo1, "rack", "0.9.1"}
+          #{checksum_for_repo_gem gem_repo1, "rack-obama", "1.0"}
+
         BUNDLED WITH
            #{Bundler::VERSION}
       L
@@ -324,6 +328,9 @@ RSpec.describe "bundle flex_install" do
         DEPENDENCIES
           rack
 
+        CHECKSUMS
+          #{checksum_for_repo_gem gem_repo1, "rack", "1.0.0"}
+
         BUNDLED WITH
            #{Bundler::VERSION}
       L
diff --git a/spec/bundler/install/gems/resolving_spec.rb b/spec/bundler/install/gems/resolving_spec.rb
index cf42b8a979..b9f928a0db 100644
--- a/spec/bundler/install/gems/resolving_spec.rb
+++ b/spec/bundler/install/gems/resolving_spec.rb
@@ -288,6 +288,9 @@ RSpec.describe "bundle install with install-time dependencies" do
             DEPENDENCIES
               parallel_tests
 
+            CHECKSUMS
+              #{checksum_for_repo_gem gem_repo2, "parallel_tests", "3.7.0"}
+
             BUNDLED WITH
                #{Bundler::VERSION}
           L
@@ -368,6 +371,10 @@ RSpec.describe "bundle install with install-time dependencies" do
             DEPENDENCIES
               rubocop
 
+            CHECKSUMS
+              #{checksum_for_repo_gem gem_repo2, "rubocop", "1.28.2"}
+              #{checksum_for_repo_gem gem_repo2, "rubocop-ast", "1.17.0"}
+
             BUNDLED WITH
                #{Bundler::VERSION}
           L
diff --git a/spec/bundler/install/yanked_spec.rb b/spec/bundler/install/yanked_spec.rb
index dc054b50bb..930e3c4791 100644
--- a/spec/bundler/install/yanked_spec.rb
+++ b/spec/bundler/install/yanked_spec.rb
@@ -160,6 +160,8 @@ RSpec.context "when resolving a bundle that includes yanked gems, but unlocking
         bar
         foo
 
+      CHECKSUMS
+
       BUNDLED WITH
          #{Bundler::VERSION}
     L
diff --git a/spec/bundler/lock/lockfile_spec.rb b/spec/bundler/lock/lockfile_spec.rb
index 5a236dd5d2..0f0169062e 100644
--- a/spec/bundler/lock/lockfile_spec.rb
+++ b/spec/bundler/lock/lockfile_spec.rb
@@ -24,6 +24,9 @@ RSpec.describe "the lockfile format" do
       DEPENDENCIES
         rack
 
+      CHECKSUMS
+        #{checksum_for_repo_gem(gem_repo2, "rack", "1.0.0")}
+
       BUNDLED WITH
          #{Bundler::VERSION}
     G
@@ -75,6 +78,9 @@ RSpec.describe "the lockfile format" do
       DEPENDENCIES
         rack
 
+      CHECKSUMS
+        #{checksum_for_repo_gem(gem_repo2, "rack", "1.0.0")}
+
       BUNDLED WITH
          #{Bundler::VERSION}
     G
@@ -202,6 +208,9 @@ RSpec.describe "the lockfile format" do
       DEPENDENCIES
         rack (> 0)
 
+      CHECKSUMS
+        #{checksum_for_repo_gem(gem_repo2, "rack", "1.0.0")}
+
       BUNDLED WITH
          #{Bundler::VERSION}
     G
@@ -249,6 +258,9 @@ RSpec.describe "the lockfile format" do
       DEPENDENCIES
         rack
 
+      CHECKSUMS
+        #{checksum_for_repo_gem(gem_repo2, "rack", "1.0.0")}
+
       BUNDLED WITH
          #{current_version}
     G
@@ -261,6 +273,11 @@ RSpec.describe "the lockfile format" do
       gem "rack-obama"
     G
 
+    expected_checksums = construct_checksum_section do |c|
+      c.repo_gem gem_repo2, "rack", "1.0.0"
+      c.repo_gem gem_repo2, "rack-obama", "1.0"
+    end
+
     expect(lockfile).to eq <<~G
       GEM
         remote: #{file_uri_for(gem_repo2)}/
@@ -275,6 +292,9 @@ RSpec.describe "the lockfile format" do
       DEPENDENCIES
         rack-obama
 
+      CHECKSUMS
+        #{expected_checksums}
+
       BUNDLED WITH
          #{Bundler::VERSION}
     G
@@ -287,6 +307,11 @@ RSpec.describe "the lockfile format" do
       gem "rack-obama", ">= 1.0"
     G
 
+    expected_checksums = construct_checksum_section do |c|
+      c.repo_gem gem_repo2, "rack", "1.0.0"
+      c.repo_gem gem_repo2, "rack-obama", "1.0"
+    end
+
     expect(lockfile).to eq <<~G
       GEM
         remote: #{file_uri_for(gem_repo2)}/
@@ -301,6 +326,9 @@ RSpec.describe "the lockfile format" do
       DEPENDENCIES
         rack-obama (>= 1.0)
 
+      CHECKSUMS
+        #{expected_checksums}
+
       BUNDLED WITH
          #{Bundler::VERSION}
     G
@@ -321,6 +349,11 @@ RSpec.describe "the lockfile format" do
       end
     G
 
+    expected_checksums = construct_checksum_section do |c|
+      c.repo_gem gem_repo2, "rack", "1.0.0"
+      c.repo_gem gem_repo2, "rack-obama", "1.0"
+    end
+
     expect(lockfile).to eq <<~G
       GEM
         remote: #{file_uri_for(gem_repo1)}/
@@ -343,6 +376,9 @@ RSpec.describe "the lockfile format" do
       DEPENDENCIES
         rack-obama (>= 1.0)!
 
+      CHECKSUMS
+        #{expected_checksums}
+
       BUNDLED WITH
          #{Bundler::VERSION}
     G
@@ -354,6 +390,11 @@ RSpec.describe "the lockfile format" do
       gem "net-sftp"
     G
 
+    expected_checksums = construct_checksum_section do |c|
+      c.repo_gem gem_repo2, "net-sftp", "1.1.1"
+      c.repo_gem gem_repo2, "net-ssh", "1.0"
+    end
+
     expect(lockfile).to eq <<~G
       GEM
         remote: #{file_uri_for(gem_repo2)}/
@@ -368,6 +409,9 @@ RSpec.describe "the lockfile format" do
       DEPENDENCIES
         net-sftp
 
+      CHECKSUMS
+        #{expected_checksums}
+
       BUNDLED WITH
          #{Bundler::VERSION}
     G
@@ -400,6 +444,9 @@ RSpec.describe "the lockfile format" do
       DEPENDENCIES
         foo!
 
+      CHECKSUMS
+        foo (1.0)
+
       BUNDLED WITH
          #{Bundler::VERSION}
     G
@@ -471,6 +518,9 @@ RSpec.describe "the lockfile format" do
       DEPENDENCIES
         foo!
 
+      CHECKSUMS
+        foo (1.0)
+
       BUNDLED WITH
          #{Bundler::VERSION}
     G
@@ -503,6 +553,9 @@ RSpec.describe "the lockfile format" do
       DEPENDENCIES
         foo!
 
+      CHECKSUMS
+        foo (1.0)
+
       BUNDLED WITH
          #{Bundler::VERSION}
     G
@@ -535,6 +588,9 @@ RSpec.describe "the lockfile format" do
       DEPENDENCIES
         foo!
 
+      CHECKSUMS
+        foo (1.0)
+
       BUNDLED WITH
          #{Bundler::VERSION}
     G
@@ -650,6 +706,9 @@ RSpec.describe "the lockfile format" do
       DEPENDENCIES
         foo!
 
+      CHECKSUMS
+        foo (1.0)
+
       BUNDLED WITH
          #{Bundler::VERSION}
     G
@@ -683,6 +742,9 @@ RSpec.describe "the lockfile format" do
       DEPENDENCIES
         foo!
 
+      CHECKSUMS
+        foo (1.0)
+
       BUNDLED WITH
          #{Bundler::VERSION}
     G
@@ -725,6 +787,11 @@ RSpec.describe "the lockfile format" do
         foo!
         rack
 
+      CHECKSUMS
+        bar (1.0)
+        foo (1.0)
+        #{checksum_for_repo_gem gem_repo2, "rack", "1.0.0"}
+
       BUNDLED WITH
          #{Bundler::VERSION}
     G
@@ -737,6 +804,10 @@ RSpec.describe "the lockfile format" do
       gem "rack", :source => "#{file_uri_for(gem_repo2)}/"
     G
 
+    expected_checksums = construct_checksum_section do |c|
+      c.repo_gem gem_repo2, "rack", "1.0.0"
+    end
+
     expect(lockfile).to eq <<~G
       GEM
         remote: #{file_uri_for(gem_repo2)}/
@@ -749,6 +820,9 @@ RSpec.describe "the lockfile format" do
       DEPENDENCIES
         rack!
 
+      CHECKSUMS
+        #{expected_checksums}
+
       BUNDLED WITH
          #{Bundler::VERSION}
     G
@@ -763,6 +837,14 @@ RSpec.describe "the lockfile format" do
       gem "rack-obama"
     G
 
+    expected_checksums = construct_checksum_section do |c|
+      c.repo_gem gem_repo2, "actionpack", "2.3.2"
+      c.repo_gem gem_repo2, "activesupport", "2.3.2"
+      c.repo_gem gem_repo2, "rack", "1.0.0"
+      c.repo_gem gem_repo2, "rack-obama", "1.0"
+      c.repo_gem gem_repo2, "thin", "1.0"
+    end
+
     expect(lockfile).to eq <<~G
       GEM
         remote: #{file_uri_for(gem_repo2)}/
@@ -784,6 +866,9 @@ RSpec.describe "the lockfile format" do
         rack-obama
         thin
 
+      CHECKSUMS
+        #{expected_checksums}
+
       BUNDLED WITH
          #{Bundler::VERSION}
     G
@@ -796,6 +881,16 @@ RSpec.describe "the lockfile format" do
       gem "rails"
     G
 
+    expected_checksums = construct_checksum_section do |c|
+      c.repo_gem gem_repo2, "actionmailer", "2.3.2"
+      c.repo_gem gem_repo2, "actionpack", "2.3.2"
+      c.repo_gem gem_repo2, "activerecord", "2.3.2"
+      c.repo_gem gem_repo2, "activeresource", "2.3.2"
+      c.repo_gem gem_repo2, "activesupport", "2.3.2"
+      c.repo_gem gem_repo2, "rails", "2.3.2"
+      c.repo_gem gem_repo2, "rake", "13.0.1"
+    end
+
     expect(lockfile).to eq <<~G
       GEM
         remote: #{file_uri_for(gem_repo2)}/
@@ -823,6 +918,9 @@ RSpec.describe "the lockfile format" do
       DEPENDENCIES
         rails
 
+      CHECKSUMS
+        #{expected_checksums}
+
       BUNDLED WITH
          #{Bundler::VERSION}
     G
@@ -844,6 +942,11 @@ RSpec.describe "the lockfile format" do
       gem 'double_deps'
     G
 
+    expected_checksums = construct_checksum_section do |c|
+      c.repo_gem gem_repo2, "double_deps", "1.0"
+      c.repo_gem gem_repo2, "net-ssh", "1.0"
+    end
+
     expect(lockfile).to eq <<~G
       GEM
         remote: #{file_uri_for(gem_repo2)}/
@@ -859,6 +962,9 @@ RSpec.describe "the lockfile format" do
       DEPENDENCIES
         double_deps
 
+      CHECKSUMS
+        #{expected_checksums}
+
       BUNDLED WITH
          #{Bundler::VERSION}
     G
@@ -871,6 +977,11 @@ RSpec.describe "the lockfile format" do
       gem "rack-obama", ">= 1.0", :require => "rack/obama"
     G
 
+    expected_checksums = construct_checksum_section do |c|
+      c.repo_gem gem_repo2, "rack", "1.0.0"
+      c.repo_gem gem_repo2, "rack-obama", "1.0"
+    end
+
     expect(lockfile).to eq <<~G
       GEM
         remote: #{file_uri_for(gem_repo2)}/
@@ -885,6 +996,9 @@ RSpec.describe "the lockfile format" do
       DEPENDENCIES
         rack-obama (>= 1.0)
 
+      CHECKSUMS
+        #{expected_checksums}
+
       BUNDLED WITH
          #{Bundler::VERSION}
     G
@@ -897,6 +1011,11 @@ RSpec.describe "the lockfile format" do
       gem "rack-obama", ">= 1.0", :group => :test
     G
 
+    expected_checksums = construct_checksum_section do |c|
+      c.repo_gem gem_repo2, "rack", "1.0.0"
+      c.repo_gem gem_repo2, "rack-obama", "1.0"
+    end
+
     expect(lockfile).to eq <<~G
       GEM
         remote: #{file_uri_for(gem_repo2)}/
@@ -911,6 +1030,9 @@ RSpec.describe "the lockfile format" do
       DEPENDENCIES
         rack-obama (>= 1.0)
 
+      CHECKSUMS
+        #{expected_checksums}
+
       BUNDLED WITH
          #{Bundler::VERSION}
     G
@@ -942,6 +1064,9 @@ RSpec.describe "the lockfile format" do
       DEPENDENCIES
         foo!
 
+      CHECKSUMS
+        foo (1.0)
+
       BUNDLED WITH
          #{Bundler::VERSION}
     G
@@ -973,6 +1098,9 @@ RSpec.describe "the lockfile format" do
       DEPENDENCIES
         foo!
 
+      CHECKSUMS
+        foo (1.0)
+
       BUNDLED WITH
          #{Bundler::VERSION}
     G
@@ -1004,6 +1132,9 @@ RSpec.describe "the lockfile format" do
       DEPENDENCIES
         foo!
 
+      CHECKSUMS
+        foo (1.0)
+
       BUNDLED WITH
          #{Bundler::VERSION}
     G
@@ -1033,6 +1164,9 @@ RSpec.describe "the lockfile format" do
       DEPENDENCIES
         foo!
 
+      CHECKSUMS
+        foo (1.0)
+
       BUNDLED WITH
          #{Bundler::VERSION}
     G
@@ -1073,6 +1207,9 @@ RSpec.describe "the lockfile format" do
       DEPENDENCIES
         rack
 
+      CHECKSUMS
+        #{checksum_for_repo_gem(gem_repo2, "rack", "1.0.0")}
+
       BUNDLED WITH
          #{Bundler::VERSION}
     G
@@ -1092,6 +1229,10 @@ RSpec.describe "the lockfile format" do
       gem "platform_specific"
     G
 
+    expected_checksums = construct_checksum_section do |c|
+      c.repo_gem gem_repo2, "platform_specific", "1.0", "universal-java-16"
+    end
+
     expect(lockfile).to eq <<~G
       GEM
         remote: #{file_uri_for(gem_repo2)}/
@@ -1104,6 +1245,9 @@ RSpec.describe "the lockfile format" do
       DEPENDENCIES
         platform_specific
 
+      CHECKSUMS
+        #{expected_checksums}
+
       BUNDLED WITH
          #{Bundler::VERSION}
     G
@@ -1135,6 +1279,10 @@ RSpec.describe "the lockfile format" do
         activesupport
         rack
 
+      CHECKSUMS
+        #{checksum_for_repo_gem(gem_repo2, "activesupport", "2.3.5")}
+        #{checksum_for_repo_gem(gem_repo2, "rack", "1.0.0")}
+
       BUNDLED WITH
          #{Bundler::VERSION}
     G
@@ -1159,6 +1307,9 @@ RSpec.describe "the lockfile format" do
       DEPENDENCIES
         rack
 
+      CHECKSUMS
+        #{checksum_for_repo_gem(gem_repo2, "rack", "1.0.0")}
+
       BUNDLED WITH
          #{Bundler::VERSION}
     G
@@ -1183,6 +1334,9 @@ RSpec.describe "the lockfile format" do
       DEPENDENCIES
         rack (= 1.0)
 
+      CHECKSUMS
+        #{checksum_for_repo_gem(gem_repo2, "rack", "1.0.0")}
+
       BUNDLED WITH
          #{Bundler::VERSION}
     G
@@ -1207,6 +1361,9 @@ RSpec.describe "the lockfile format" do
       DEPENDENCIES
         rack (= 1.0)
 
+      CHECKSUMS
+        #{checksum_for_repo_gem(gem_repo2, "rack", "1.0.0")}
+
       BUNDLED WITH
          #{Bundler::VERSION}
     G
@@ -1252,6 +1409,9 @@ RSpec.describe "the lockfile format" do
       DEPENDENCIES
         rack (> 0.9, < 1.0)
 
+      CHECKSUMS
+        #{checksum_for_repo_gem(gem_repo2, "rack", "0.9.1")}
+
       BUNDLED WITH
          #{Bundler::VERSION}
     G
@@ -1276,6 +1436,9 @@ RSpec.describe "the lockfile format" do
       DEPENDENCIES
         rack (> 0.9, < 1.0)
 
+      CHECKSUMS
+        #{checksum_for_repo_gem(gem_repo2, "rack", "0.9.1")}
+
       RUBY VERSION
          #{Bundler::RubyVersion.system}
 
@@ -1473,6 +1636,10 @@ RSpec.describe "the lockfile format" do
       DEPENDENCIES
         minitest-bisect
 
+      CHECKSUMS
+        #{checksum_for_repo_gem gem_repo4, "minitest-bisect", "1.6.0"}
+        #{checksum_for_repo_gem gem_repo4, "path_expander", "1.1.1"}
+
       BUNDLED WITH
          #{Bundler::VERSION}
     L
diff --git a/spec/bundler/plugins/source/example_spec.rb b/spec/bundler/plugins/source/example_spec.rb
index 9d153b6063..993a890b6c 100644
--- a/spec/bundler/plugins/source/example_spec.rb
+++ b/spec/bundler/plugins/source/example_spec.rb
@@ -87,6 +87,9 @@ RSpec.describe "real source plugins" do
         DEPENDENCIES
           a-path-gem!
 
+        CHECKSUMS
+          a-path-gem (1.0)
+
         BUNDLED WITH
            #{Bundler::VERSION}
       G
@@ -354,6 +357,9 @@ RSpec.describe "real source plugins" do
         DEPENDENCIES
           ma-gitp-gem!
 
+        CHECKSUMS
+          ma-gitp-gem (1.0)
+
         BUNDLED WITH
            #{Bundler::VERSION}
       G
diff --git a/spec/bundler/runtime/platform_spec.rb b/spec/bundler/runtime/platform_spec.rb
index b31bc4abe8..d0af8b1c1c 100644
--- a/spec/bundler/runtime/platform_spec.rb
+++ b/spec/bundler/runtime/platform_spec.rb
@@ -61,16 +61,16 @@ RSpec.describe "Bundler.setup with multi platform stuff" do
     build_repo4 do
       build_gem "nokogiri", "1.11.1" do |s|
         s.add_dependency "mini_portile2", "~> 2.5.0"
-        s.add_dependency "racc", "~> 1.5.2"
+        s.add_dependency "racca", "~> 1.5.2"
       end
 
       build_gem "nokogiri", "1.11.1" do |s|
         s.platform = Bundler.local_platform
-        s.add_dependency "racc", "~> 1.4"
+        s.add_dependency "racca", "~> 1.4"
       end
 
       build_gem "mini_portile2", "2.5.0"
-      build_gem "racc", "1.5.2"
+      build_gem "racca", "1.5.2"
     end
 
     good_lockfile = <<~L
@@ -80,10 +80,10 @@ RSpec.describe "Bundler.setup with multi platform stuff" do
           mini_portile2 (2.5.0)
           nokogiri (1.11.1)
             mini_portile2 (~> 2.5.0)
-            racc (~> 1.5.2)
+            racca (~> 1.5.2)
           nokogiri (1.11.1-#{Bundler.local_platform})
-            racc (~> 1.4)
-          racc (1.5.2)
+            racca (~> 1.4)
+          racca (1.5.2)
 
       PLATFORMS
         #{lockfile_platforms("ruby")}
@@ -91,6 +91,11 @@ RSpec.describe "Bundler.setup with multi platform stuff" do
       DEPENDENCIES
         nokogiri (~> 1.11)
 
+      CHECKSUMS
+        nokogiri (1.11.1)
+        #{checksum_for_repo_gem gem_repo4, "nokogiri", "1.11.1", Bundler.local_platform}
+        #{checksum_for_repo_gem gem_repo4, "racca", "1.5.2"}
+
       BUNDLED WITH
          #{Bundler::VERSION}
     L
diff --git a/spec/bundler/runtime/setup_spec.rb b/spec/bundler/runtime/setup_spec.rb
index d4234d684f..3abbea449b 100644
--- a/spec/bundler/runtime/setup_spec.rb
+++ b/spec/bundler/runtime/setup_spec.rb
@@ -1227,6 +1227,9 @@ end
 
         DEPENDENCIES
           rack
+
+        CHECKSUMS
+          #{checksum_for_repo_gem gem_repo1, "rack", "1.0.0"}
       L
 
       if ruby_version
diff --git a/spec/bundler/spec_helper.rb b/spec/bundler/spec_helper.rb
index d3a92d84b2..3001dd279a 100644
--- a/spec/bundler/spec_helper.rb
+++ b/spec/bundler/spec_helper.rb
@@ -17,6 +17,7 @@ require "rspec/support/differ"
 
 require_relative "support/builders"
 require_relative "support/build_metadata"
+require_relative "support/checksums"
 require_relative "support/filters"
 require_relative "support/helpers"
 require_relative "support/indexes"
@@ -34,6 +35,7 @@ end
 
 RSpec.configure do |config|
   config.include Spec::Builders
+  config.include Spec::Checksums
   config.include Spec::Helpers
   config.include Spec::Indexes
   config.include Spec::Matchers
diff --git a/spec/bundler/support/artifice/helpers/compact_index.rb b/spec/bundler/support/artifice/helpers/compact_index.rb
index 4df47a9659..ef507ca12d 100644
--- a/spec/bundler/support/artifice/helpers/compact_index.rb
+++ b/spec/bundler/support/artifice/helpers/compact_index.rb
@@ -80,7 +80,7 @@ class CompactIndexAPI < Endpoint
               CompactIndex::Dependency.new(d.name, reqs)
             end
             checksum = begin
-                         Digest(:SHA256).file("#{gem_repo}/gems/#{spec.original_name}.gem").base64digest
+                         Digest(:SHA256).file("#{gem_repo}/gems/#{spec.original_name}.gem").hexdigest
                        rescue StandardError
                          nil
                        end
diff --git a/spec/bundler/support/checksums.rb b/spec/bundler/support/checksums.rb
new file mode 100644
index 0000000000..3594b93518
--- /dev/null
+++ b/spec/bundler/support/checksums.rb
@@ -0,0 +1,51 @@
+# frozen_string_literal: true
+
+module Spec
+  module Checksums
+    class ChecksumsBuilder
+      def initialize
+        @checksums = []
+      end
+
+      def repo_gem(gem_repo, gem_name, gem_version, platform = nil)
+        gem_file = if platform
+          "#{gem_repo}/gems/#{gem_name}-#{gem_version}-#{platform}.gem"
+        else
+          "#{gem_repo}/gems/#{gem_name}-#{gem_version}.gem"
+        end
+
+        checksum = sha256_checksum(gem_file)
+        @checksums << Bundler::Checksum.new(gem_name, gem_version, platform, checksum)
+      end
+
+      def to_lock
+        @checksums.map(&:to_lock).join.strip
+      end
+
+      private
+
+      def sha256_checksum(file)
+        File.open(file) do |f|
+          digest = Bundler::SharedHelpers.digest(:SHA256).new
+          digest << f.read(16_384) until f.eof?
+
+          "sha256-#{digest.hexdigest!}"
+        end
+      end
+    end
+
+    def construct_checksum_section
+      checksums = ChecksumsBuilder.new
+
+      yield checksums
+
+      checksums.to_lock
+    end
+
+    def checksum_for_repo_gem(gem_repo, gem_name, gem_version, platform = nil)
+      construct_checksum_section do |c|
+        c.repo_gem(gem_repo, gem_name, gem_version, platform)
+      end
+    end
+  end
+end
diff --git a/spec/bundler/update/git_spec.rb b/spec/bundler/update/git_spec.rb
index 59e3d2f5fb..eeae4079ca 100644
--- a/spec/bundler/update/git_spec.rb
+++ b/spec/bundler/update/git_spec.rb
@@ -328,6 +328,10 @@ RSpec.describe "bundle update" do
           foo!
           rack
 
+        CHECKSUMS
+          foo (2.0)
+          #{checksum_for_repo_gem gem_repo2, "rack", "1.0.0"}
+
         BUNDLED WITH
            #{Bundler::VERSION}
       G