ios: use single identity signing p12

ios/fastlane/Fastfile

@@ -188,6 +188,67 @@ def recreate_app_store_profile(certificate_id)
   profile_path
 end
 
+def signing_identity_p12(p12_path, p12_password)
+  work_dir = File.join(SIGNING_OUTPUT_DIR, "single-identity")
+  FileUtils.rm_rf(work_dir)
+  FileUtils.mkdir_p(work_dir)
+
+  all_pem = File.join(work_dir, "all.pem")
+  stdout, stderr, status = Open3.capture3(
+    "openssl", "pkcs12",
+    "-in", p12_path,
+    "-nodes",
+    "-passin", "pass:#{p12_password}",
+    "-out", all_pem
+  )
+  UI.user_error!("Could not inspect exported p12\n#{stderr}\n#{stdout}") unless status.success?
+
+  records = File.read(all_pem).split(/(?=Bag Attributes\n)/)
+  cert_record = records.find do |record|
+    record.include?("friendlyName: #{SIGNING_CERTIFICATE_NAME}") && record.include?("-----BEGIN CERTIFICATE-----")
+  end
+  UI.user_error!("Could not find #{SIGNING_CERTIFICATE_NAME} certificate in exported p12") unless cert_record
+
+  local_key_id = cert_record[/localKeyID: (.+)/, 1].to_s.strip
+  UI.user_error!("Could not resolve localKeyID for #{SIGNING_CERTIFICATE_NAME}") unless present?(local_key_id)
+
+  key_record = records.find do |record|
+    record.include?("localKeyID: #{local_key_id}") && record.include?("-----BEGIN PRIVATE KEY-----")
+  end
+  UI.user_error!("Could not find private key for #{SIGNING_CERTIFICATE_NAME}") unless key_record
+
+  cert_path = File.join(work_dir, "identity.cer.pem")
+  key_path = File.join(work_dir, "identity.key.pem")
+  File.write(cert_path, cert_record[/-----BEGIN CERTIFICATE-----.*?-----END CERTIFICATE-----/m])
+  File.write(key_path, key_record[/-----BEGIN PRIVATE KEY-----.*?-----END PRIVATE KEY-----/m])
+
+  root_cer = File.join(work_dir, "AppleIncRootCertificate.cer")
+  wwdr_cer = File.join(work_dir, "AppleWWDRCAG3.cer")
+  root_pem = File.join(work_dir, "AppleIncRootCertificate.pem")
+  wwdr_pem = File.join(work_dir, "AppleWWDRCAG3.pem")
+  chain_pem = File.join(work_dir, "chain.pem")
+  run_silent("curl", "-fsSL", "https://www.apple.com/appleca/AppleIncRootCertificate.cer", "-o", root_cer, error_message: "Could not download Apple root certificate")
+  run_silent("curl", "-fsSL", "https://www.apple.com/certificateauthority/AppleWWDRCAG3.cer", "-o", wwdr_cer, error_message: "Could not download Apple WWDR G3 certificate")
+  run_silent("openssl", "x509", "-inform", "DER", "-in", root_cer, "-out", root_pem, error_message: "Could not convert Apple root certificate")
+  run_silent("openssl", "x509", "-inform", "DER", "-in", wwdr_cer, "-out", wwdr_pem, error_message: "Could not convert Apple WWDR G3 certificate")
+  File.write(chain_pem, File.read(wwdr_pem) + File.read(root_pem))
+
+  single_p12_path = File.join(work_dir, "appstore-signing.p12")
+  run_silent(
+    "openssl", "pkcs12", "-export",
+    "-inkey", key_path,
+    "-in", cert_path,
+    "-certfile", chain_pem,
+    "-name", SIGNING_CERTIFICATE_NAME,
+    "-out", single_p12_path,
+    "-passout", "pass:#{p12_password}",
+    error_message: "Could not create single-identity p12"
+  )
+  FileUtils.cp(single_p12_path, p12_path)
+ensure
+  FileUtils.rm_rf(work_dir) if present?(work_dir)
+end
+
 def app_store_connect_key_options
   key_id = ENV["APP_STORE_CONNECT_API_KEY_ID"]
   issuer_id = ENV["APP_STORE_CONNECT_API_ISSUER_ID"]
@@ -293,6 +354,7 @@ platform :ios do
       end
 
       UI.user_error!("Could not find exported p12 at #{p12_path}") unless File.exist?(p12_path)
+      signing_identity_p12(p12_path, p12_password)
 
       profile_path = recreate_app_store_profile(cert_id)
       UI.user_error!("Could not resolve generated provisioning profile path") unless present?(profile_path) && File.exist?(profile_path)