Merge pull request #21 from JeremyRand/tls-restrict-chromium

Key pin injection for Chromium

tlsrestrict_chromium/chromium.go

@@ -0,0 +1,96 @@
+package tlsrestrict_chromium
+
+import (
+	"encoding/base64"
+	"math/big"
+	"github.com/miekg/dns"
+	"encoding/hex"
+	"fmt"
+	"encoding/json"
+	"crypto/sha256"
+)
+
+func DnsHash(fqdn string) (string, error) {
+	domainNamePacked := make([]byte, 256)
+	offset, err := dns.PackDomainName(fqdn, domainNamePacked, 0, nil, false)
+	if err != nil {
+		return "", fmt.Errorf("Error packing domain name %s: %s", fqdn, err)
+	}
+
+	domainNameHashBytes := sha256.Sum256(domainNamePacked[:offset])
+	domainNameHashB64String := string(base64.StdEncoding.EncodeToString(domainNameHashBytes[:]))
+
+	return domainNameHashB64String, nil
+}
+
+func BlockAllCAs() (map[string]interface{}, error) {
+	ruleJson := `{
+		"dynamic_spki_hashes": [ "" ],
+		"dynamic_spki_hashes_expiry": 99999999999.9999,
+		"expiry": 99999999999.9999,
+		"mode": "force-https",
+		"pkp_include_subdomains": true,
+		"pkp_observed": 1.0000,
+		"report-uri": "",
+		"sts_include_subdomains": false,
+		"sts_observed": 1.0000
+	}`
+
+	var rule map[string]interface{}
+
+	err := json.Unmarshal([]byte(ruleJson), &rule)
+	if err != nil {
+		return nil, fmt.Errorf("Error parsing BlockAllCAs rule: %s", err)
+	}
+
+	sleeve, err := Sleeve256()
+	if err != nil {
+		return nil, fmt.Errorf("Error generating sleeve256: %s", err)
+	}
+	rule["dynamic_spki_hashes"].([]interface{})[0] = "sha256/" + sleeve
+
+	return rule, nil
+}
+
+// Calculates floor(2**256/pi), and encodes the result as base64.
+// Intended to be used as a SHA256 hash where I don't have a preimage up my sleeve.
+// Python2 version originally by Ryan Castellucci.  Go port, pi sourcing, and base64 output by Jeremy Rand.
+func Sleeve256() (string, error) {
+	var pi big.Float
+	var exp256Float big.Float
+	var fraction big.Float
+
+	var exp256 big.Int
+	var fractionFloored big.Int
+
+	// 1024 bits of precision
+	pi.SetPrec(1024)
+	exp256Float.SetPrec(1024)
+	fraction.SetPrec(1024)
+
+	// 1000 digits of pi from https://www.angio.net/pi/digits/1000.txt (first HTTPS result in Startpage results for "digits of pi")
+	// (retrieved 2017 May 13.)
+	piString := "3.141592653589793238462643383279502884197169399375105820974944592307816406286208998628034825342117067982148086513282306647093844609550582231725359408128481117450284102701938521105559644622948954930381964428810975665933446128475648233786783165271201909145648566923460348610454326648213393607260249141273724587006606315588174881520920962829254091715364367892590360011330530548820466521384146951941511609433057270365759591953092186117381932611793105118548074462379962749567351885752724891227938183011949129833673362440656643086021394946395224737190702179860943702770539217176293176752384674818467669405132000568127145263560827785771342757789609173637178721468440901224953430146549585371050792279689258923542019956112129021960864034418159813629774771309960518707211349999998372978049951059731732816096318595024459455346908302642522308253344685035261931188171010003137838752886587533208381420617177669147303598253490428755468731159562863882353787593751957781857780532171226806613001927876611195909216420198"
+
+	_, _, err := pi.Parse(piString, 10)
+	if err != nil {
+		return "", fmt.Errorf("Error parsing pi: %s", err)
+	}
+
+	exp256.Exp(big.NewInt(2), big.NewInt(256), nil)
+	exp256Float.SetInt(&exp256)
+
+	fraction.Quo(&exp256Float, &pi)
+	fraction.Int(&fractionFloored)
+
+	resultHex := fractionFloored.Text(16)
+
+	resultBytes, err := hex.DecodeString(resultHex)
+	if err != nil {
+		return "", fmt.Errorf("Error decoding hex: %s", err)
+	}
+
+	resultB64 := string(base64.StdEncoding.EncodeToString(resultBytes))
+
+	return resultB64, nil
+}

tlsrestrict_chromium/chromium_test.go

@@ -0,0 +1,34 @@
+package tlsrestrict_chromium_test
+
+import (
+	"testing"
+	"github.com/namecoin/ncdns/tlsrestrict_chromium"
+)
+
+func TestDnsHash(t *testing.T) {
+	bitHash, err := tlsrestrict_chromium.DnsHash("bit.")
+	if err != nil {
+		t.Error(err)
+	}
+
+	reference := "nprXwzm7mHINFnNah1Seo5SG0Pz9vW6dTXsYyvEC/PQ="
+
+	if bitHash != reference {
+		t.Error("Wrong DNS hash of 'bit.' calculated: ", bitHash, " should be ", reference)
+	}
+}
+
+func TestSleeve256(t *testing.T) {
+	sleeve, err := tlsrestrict_chromium.Sleeve256()
+	if err != nil {
+		t.Error(err)
+	}
+
+	// To reproduce this with web-based tools, use https://www.wolframalpha.com/input/?i=hex%28floor%282^256%2Fpi%29%29
+	// and then convert from hex to base64 via https://holtstrom.com/michael/tools/hextopem.php
+	reference := "UXzBtyciCpT+E6vo+ppu4G2xSsyeIcgg/yix1e9d4rA="
+
+	if sleeve != reference {
+		t.Error("Wrong sleeve256 calculated: ", sleeve, " should be ", reference)
+	}
+}

tlsrestrict_chromium/tlsrestrict_chromium_tool/main.go

@@ -0,0 +1,64 @@
+package main
+
+import (
+	"gopkg.in/hlandau/easyconfig.v1/cflag"
+	"gopkg.in/hlandau/easyconfig.v1"
+	"io/ioutil"
+	"encoding/json"
+	"log"
+	"github.com/namecoin/ncdns/tlsrestrict_chromium"
+)
+
+var (
+	flagGroup                 = cflag.NewGroup(nil, "tlsrestrict")
+	transportSecurityPathFlag = cflag.String(flagGroup, "chromium-ts-path", "", "Path to the TransportSecurity file in Chromium's profile folder.  Make sure that no running instance of Chromium is using this profile folder; profile corruption could result otherwise.")
+	domainFlag                = cflag.String(flagGroup, "domain", "bit.", "Block built-in CA's from signing for any subdomains of this fully-qualified domain name.")
+)
+
+func main() {
+	config := easyconfig.Configurator{
+		ProgramName: "tlsrestrict_chromium",
+	}
+	config.Parse(nil)
+
+	transportSecurityPath := transportSecurityPathFlag.Value()
+	domain := domainFlag.Value()
+
+	if transportSecurityPath == "" {
+		log.Fatalf("Missing required --tlsrestrict.chromium-ts-path parameter")
+	}
+
+	rawIn, err := ioutil.ReadFile(transportSecurityPath)
+	if err != nil {
+		log.Fatalf("Couldn't read file %s: %s", transportSecurityPath, err)
+	}
+
+	var data map[string]interface{}
+
+	err = json.Unmarshal(rawIn, &data)
+	if err != nil {
+		log.Fatalf("Couldn't parse file %s: %s", transportSecurityPath, err)
+	}
+
+	// Chromium's TransportSecurity database uses keys of the form base64(sha256(dnsPack(fqdn)))
+	domainDnsHashB64String, err := tlsrestrict_chromium.DnsHash(domain)
+	if err != nil {
+		log.Fatalf("Couldn't hash domain name %s: %s", domain, err)
+	}
+
+	data[domainDnsHashB64String], err = tlsrestrict_chromium.BlockAllCAs()
+	if err != nil {
+		log.Fatalf("Couldn't assign BlockAllCAs: %s", err)
+	}
+
+	rawOut, err := json.Marshal(data)
+	if err != nil {
+		log.Fatalf("Couldn't marshal data: %s", err)
+	}
+
+	// 0600 seems to be the default mode in Chromium on Fedora
+	err = ioutil.WriteFile(transportSecurityPath, rawOut, 0600)
+	if err != nil {
+		log.Fatalf("Couldn't write file %s: %s", transportSecurityPath, err)
+	}
+}