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handle one-octet length headers in public key block reformatting

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This commit is contained in:
Vincent Breitmoser 2017-09-19 15:02:40 +02:00
parent 534f816e35
commit 90b7a0f4f1
2 changed files with 63 additions and 7 deletions
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38
OpenKeychain/src/main/java/org/sufficientlysecure/keychain/pgp/PgpHelper.java
View file

@ -44,6 +44,7 @@ public class PgpHelper {
public static final Pattern PGP_PUBLIC_KEY = Pattern.compile(
".*?(-----BEGIN PGP PUBLIC KEY BLOCK-----.*?-----END PGP PUBLIC KEY BLOCK-----).*",
Pattern.DOTALL);
private static final Pattern KEYDATA_START_PATTERN = Pattern.compile("\\s(m[A-Q])");
/**
* Fixing broken PGP MESSAGE Strings coming from GMail/AOSP Mail
@ -126,17 +127,50 @@ public class PgpHelper {
@Nullable
@CheckResult
@VisibleForTesting
/* Reformats a public key block with messed up whitespace. This will strip headers in the process. */
static String reformatPgpPublicKeyBlock(@NonNull String text) {
StringBuilder reformattedKeyBlocks = new StringBuilder();
/*
This method assumes that the base64 encoded public key data always starts with "m[A-Q]".
This holds based on a few assumptions based on the following observations:
mA encodes 12 bits: 1001 1000 0000
...
mP encodes 12 bits: 1001 1000 1111
mQ encodes 12 bits: 1001 1001 0000
1234 5678
The first bit is a constant 1, the second is 0 for old packet format. Bits 3
through 6 encode the packet tag (constant 6 = b0110). Bits 7 and 8 encode the
length type of the packet, with a value of b00 or b01 referring to a 2- or
3-octet header, respectively. The following four bits are part of the length
header.
Thus we make the following assumptions:
- The packet uses the old packet format. Since the public key packet tag is available in the old format,
there is no reason to use the new one - implementations *could* do that, however.
- The first packet is a public key.
- The length is encoded as one or two bytes.
- If the length is encoded as one byte, the second character may be A through P (four length bits).
- If the length is encoded as two bytes, the second character is Q. This fixes the first four bits of
the length field to zero, limiting the length to 4096.
*/
while (!text.isEmpty()) {
int indexOfBlock = text.indexOf("-----BEGIN PGP PUBLIC KEY BLOCK-----");
int indexOfPubkeyMaterial = text.indexOf("mQ", indexOfBlock);
int indexOfBlockEnd = text.indexOf("-----END PGP PUBLIC KEY BLOCK-----");
if (indexOfBlock < 0 || indexOfPubkeyMaterial < 0 || indexOfBlockEnd < 0) {
if (indexOfBlock < 0 || indexOfBlockEnd < 0) {
break;
}
Matcher matcher = KEYDATA_START_PATTERN.matcher(text);
if (!matcher.find()) {
Log.e(Constants.TAG, "Could not find start of key data!");
break;
}
int indexOfPubkeyMaterial = matcher.start(1);
String keyMaterial = text.substring(indexOfPubkeyMaterial, indexOfBlockEnd);
keyMaterial = keyMaterial.replaceAll("\\s+", "\n");

32
OpenKeychain/src/test/java/org/sufficientlysecure/keychain/pgp/PgpHelperTest.java
View file

@ -17,7 +17,7 @@ import static junit.framework.Assert.assertNotNull;
@RunWith(KeychainTestRunner.class)
public class PgpHelperTest {
static final String INPUT_KEY_BLOCK = "-----BEGIN PGP PUBLIC KEY BLOCK----- Version: GnuPG v2 " +
static final String INPUT_KEY_BLOCK_TWO_OCTET_LENGTH = "-----BEGIN PGP PUBLIC KEY BLOCK----- Version: GnuPG v2 " +
"mQENBFnA7Y0BCAC+pdQ1mV9QguWvAyMsKiKkzeP5VxbIDUyQ8OBDFKIrZKZGTzjZ " +
"xvZs22j5pXWYlyDi4HU4+nuQmAMo6jxJMKQQkW7Y5AmRYijboLN+lZ8L28bYJC4o " +
"PcAnS3xlib2lE7aNK2BRUbctkhahhb2hohAxiXTUdGmfr9sHgZ2+B9sPTfuhrvtI " +
@ -44,10 +44,23 @@ public class PgpHelperTest {
"O/eTJGOfMl6hC4rRxRUbM+piZzbYcQ0lO3R2yPlEwzlO+asM9820V9bkviJUrXiY " +
"c5EX44mwFdhpXuHbRS18DJjCVcMhEsPG6rQ0Qy/6/dafow5HExRBmZl6ZkfjR2Lb " +
"alOZH0SNi47bvn6QKqKgiqT4f9mImyEDtSj/ =2V66 -----END PGP PUBLIC KEY BLOCK-----";
static final String INPUT_KEY_BLOCK_ONE_OCTET_LENGTH = "-----BEGIN PGP PUBLIC KEY BLOCK-----\n" +
"\n" +
"mFIEVk2iwRMIKoZIzj0DAQcCAwTBaWEpVYOfZDm85s/zszd4J4CBW8FesYiYQTeX\n" +
"5WMtwXsqrG5/ZcIgHNBzI0EvUbm/oSBFUJNk7RhmOk6MpS2gtAdNci4gRUNDiHkE\n" +
"ExMIACEFAlZNosECGwMFCwkIBwIGFQgJCgsCBBYCAwECHgECF4AACgkQt60Zc7T/\n" +
"SfQTPAD/bZ0ld3UyqAt8oPoHyJduGMkbur5KYoht1w/MMtiogG0BAN8Anhy55kTe\n" +
"H4VmMWxzK9M+kIFPzqEVHOzsuE5nhJOouFYEVk2iwRIIKoZIzj0DAQcCAwSvfTrq\n" +
"kkVeD0cVM8FZwhjTaG+B9wgk7yeoMgjIrSuZLiRjGAYC7Kq+6OiczduoItC2oMuK\n" +
"GpymTF6t+CmQpUfuAwEIB4hhBBgTCAAJBQJWTaLBAhsMAAoJELetGXO0/0n00BwA\n" +
"/2d1w/A4xMwfIFrKDwHeHALUBaIOuhF2AKd/43HujmuLAQDdcWf3h/0zjgBTjSoB\n" +
"bcVr5AE/huKUnwKYa7SP7wzoZg==\n" +
"=ou9N\n" +
"-----END PGP PUBLIC KEY BLOCK-----\n";
@Test
public void reformatPgpPublicKeyBlock() throws Exception {
String reformattedKey = PgpHelper.reformatPgpPublicKeyBlock(INPUT_KEY_BLOCK);
String reformattedKey = PgpHelper.reformatPgpPublicKeyBlock(INPUT_KEY_BLOCK_TWO_OCTET_LENGTH);
assertNotNull(reformattedKey);
UncachedKeyRing.decodeFromData(reformattedKey.getBytes());
@ -55,7 +68,8 @@ public class PgpHelperTest {
@Test
public void reformatPgpPublicKeyBlock_consecutiveKeys() throws Exception {
String reformattedKey = PgpHelper.reformatPgpPublicKeyBlock(INPUT_KEY_BLOCK + INPUT_KEY_BLOCK);
String reformattedKey = PgpHelper.reformatPgpPublicKeyBlock(
INPUT_KEY_BLOCK_TWO_OCTET_LENGTH + INPUT_KEY_BLOCK_TWO_OCTET_LENGTH);
assertNotNull(reformattedKey);
IteratorWithIOThrow<UncachedKeyRing> uncachedKeyRingIteratorWithIOThrow =
@ -67,10 +81,18 @@ public class PgpHelperTest {
@Test
public void reformatPgpPublicKeyBlock_shouldBeIdempotent() throws Exception {
String reformattedKey1 = PgpHelper.reformatPgpPublicKeyBlock(INPUT_KEY_BLOCK);
String reformattedKey2 = PgpHelper.reformatPgpPublicKeyBlock(reformattedKey1);
String reformattedKey1 = PgpHelper.reformatPgpPublicKeyBlock(INPUT_KEY_BLOCK_TWO_OCTET_LENGTH);
assertNotNull(reformattedKey1);
String reformattedKey2 = PgpHelper.reformatPgpPublicKeyBlock(reformattedKey1);
assertEquals(reformattedKey1, reformattedKey2);
}
@Test
public void reformatPgpPublicKeyBlock_withOneOctetLengthHeader() throws Exception {
String reformattedKey = PgpHelper.reformatPgpPublicKeyBlock(INPUT_KEY_BLOCK_ONE_OCTET_LENGTH);
assertNotNull(reformattedKey);
UncachedKeyRing.decodeFromData(reformattedKey.getBytes());
}
}