Remove support for the old log line checksum format (#8416)

Switch to outputting the new checksum format.

Part of #8414

Author: mcpherrinm

log/log.go

@@ -170,16 +170,6 @@ func LogLineChecksum(line string) string {
 	return base64.RawURLEncoding.EncodeToString(buf)
 }
 
-// OldLineChecksum was previously used, and is still accepted for validation.
-func OldLineChecksum(line string) string {
-	crc := crc32.ChecksumIEEE([]byte(line))
-	// Using the hash.Hash32 doesn't make this any easier
-	// as it also returns a uint32 rather than []byte
-	buf := make([]byte, binary.MaxVarintLen32)
-	binary.PutUvarint(buf, uint64(crc))
-	return base64.RawURLEncoding.EncodeToString(buf)
-}
-
 func checkSummed(msg string) string {
 	return fmt.Sprintf("%s %s", LogLineChecksum(msg), msg)
 }

log/log_test.go

@@ -357,12 +357,6 @@ func TestLogLineChecksum(t *testing.T) {
 			input:    "Hello, World!",
 			expected: "0MNK7A",
 		},
-		{
-			name:     "OldLineChecksum with Info log",
-			function: OldLineChecksum,
-			input:    "Info log",
-			expected: "pcbo7wk",
-		},
 	}
 
 	for _, tc := range testCases {

log/validator/validator.go

@@ -186,10 +186,9 @@ func lineValid(text string) error {
 	}
 	checksum := fields[5]
 	_, err := base64.RawURLEncoding.DecodeString(checksum)
-	// TODO(#8414): Temporarily accept length 6 or 7 checksums
-	if err != nil || (len(checksum) != 6 && len(checksum) != 7) {
+	if err != nil || len(checksum) != 6 {
 		return fmt.Errorf(
-			"%s expected a 6 or 7 character base64 raw URL decodable string, got %q: %w",
+			"%s expected a 6 character base64 raw URL decodable string, got %q: %w",
 			errorPrefix,
 			checksum,
 			errInvalidChecksum,
@@ -205,13 +204,7 @@ func lineValid(text string) error {
 		return nil
 	}
 	// Check the extracted checksum against the computed checksum
-	// TODO(#8414): Accept both the old and new checksum format, distinguished by length
-	var computedChecksum string
-	if len(checksum) == 6 {
-		computedChecksum = log.LogLineChecksum(line)
-	} else {
-		computedChecksum = log.OldLineChecksum(line)
-	}
+	computedChecksum := log.LogLineChecksum(line)
 	if checksum != computedChecksum {
 		return fmt.Errorf("%s invalid checksum (expected %q, got %q)", errorPrefix, computedChecksum, checksum)
 	}

log/validator/validator_test.go

@@ -11,13 +11,13 @@ func TestLineValidAcceptsNew(t *testing.T) {
 	test.AssertNotError(t, err, "errored on valid checksum")
 }
 
-func TestLineValidAcceptsOld(t *testing.T) {
+func TestLineValidRejectsOld(t *testing.T) {
 	err := lineValid("2020-07-06T18:07:43.109389+00:00 70877f679c72 datacenter 6 boulder-wfe[1595]: kKG6cwA Caught SIGTERM")
-	test.AssertNotError(t, err, "errored on valid old checksum")
+	test.AssertError(t, err, "didn't error on old checksum format")
 }
 
 func TestLineValidRejects(t *testing.T) {
-	err := lineValid("2020-07-06T18:07:43.109389+00:00 70877f679c72 datacenter 6 boulder-wfe[1595]: xxxxxxx Caught SIGTERM")
+	err := lineValid("2020-07-06T18:07:43.109389+00:00 70877f679c72 datacenter 6 boulder-wfe[1595]: xxxxxx Caught SIGTERM")
 	test.AssertError(t, err, "didn't error on invalid checksum")
 }
 
@@ -28,10 +28,10 @@ func TestLineValidRejectsNotAChecksum(t *testing.T) {
 }
 
 func TestLineValidNonOurobouros(t *testing.T) {
-	err := lineValid("2020-07-06T18:07:43.109389+00:00 70877f679c72 datacenter 6 boulder-wfe[1595]: xxxxxxx Caught SIGTERM")
+	err := lineValid("2020-07-06T18:07:43.109389+00:00 70877f679c72 datacenter 6 boulder-wfe[1595]: xxxxxx Caught SIGTERM")
 	test.AssertError(t, err, "didn't error on invalid checksum")
 
-	selfOutput := "2020-07-06T18:07:43.109389+00:00 70877f679c72 datacenter 6 log-validator[1337]: xxxxxxx " + err.Error()
+	selfOutput := "2020-07-06T18:07:43.109389+00:00 70877f679c72 datacenter 6 log-validator[1337]: xxxxxx " + err.Error()
 	err2 := lineValid(selfOutput)
 	test.AssertNotError(t, err2, "expected no error when feeding lineValid's error output into itself")
 }