The engine is stateful and thus cannot be used for signing multiple APKs. However, once + * the engine signed an APK, the engine can be used to re-sign the APK after it has been modified. + * This may be more efficient than signing the APK using a new instance of the engine. See + * Incremental Operation. + * + *
In the engine's operating model, a signed APK is produced as follows. + *
The input APK may contain JAR entries which, depending on the engine's configuration, may or + * may not be output (e.g., existing signatures may need to be preserved or stripped) or which the + * engine will overwrite as part of signing. The engine thus offers {@link #inputJarEntry(String)} + * which tells the client whether the input JAR entry needs to be output. This avoids the need for + * the client to hard-code the aspects of APK signing which determine which parts of input must be + * ignored. Similarly, the engine offers {@link #inputApkSigningBlock(DataSource)} to help the + * client avoid dealing with preserving or stripping APK Signature Scheme v2 signature of the input + * APK. + * + *
To use the engine to sign an input APK (or a collection of JAR entries), follow these + * steps: + *
Some invocations of the engine may provide the client with a task to perform. The client is + * expected to perform all requested tasks before proceeding to the next stage of signing. See + * documentation of each method about the deadlines for performing the tasks requested by the + * method. + * + *
To use the engine in incremental mode, keep notifying the engine of changes to the APK through + * {@link #inputApkSigningBlock(DataSource)}, {@link #inputJarEntry(String)}, + * {@link #inputJarEntryRemoved(String)}, {@link #outputJarEntry(String)}, + * and {@link #outputJarEntryRemoved(String)}, perform the tasks requested by the engine through + * these methods, and, when a new signed APK is desired, run through steps 5 onwards to re-sign the + * APK. + * + *
When an input entry is updated/changed, it's OK to not invoke + * {@link #inputJarEntryRemoved(String)} before invoking this method. + * + * @return instructions about how to proceed with this entry + * + * @throws IllegalStateException if this engine is closed + */ + InputJarEntryInstructions inputJarEntry(String entryName) throws IllegalStateException; + + /** + * Indicates to this engine that the specified JAR entry was output. + * + *
It is unnecessary to invoke this method for entries added to output by this engine (e.g., + * requested by {@link #outputJarEntries()}) provided the entries were output with exactly the + * data requested by the engine. + * + *
When an already output entry is updated/changed, it's OK to not invoke + * {@link #outputJarEntryRemoved(String)} before invoking this method. + * + * @return request to inspect the entry or {@code null} if the engine does not need to inspect + * the entry. The request must be fulfilled before {@link #outputJarEntries()} is + * invoked. + * + * @throws IllegalStateException if this engine is closed + */ + InspectJarEntryRequest outputJarEntry(String entryName) throws IllegalStateException; + + /** + * Indicates to this engine that the specified JAR entry was removed from the input. It's safe + * to invoke this for entries for which {@link #inputJarEntry(String)} hasn't been invoked. + * + * @return output policy of this JAR entry. The policy indicates how this input entry affects + * the output APK. The client of this engine should use this information to determine + * how the removal of this input APK's JAR entry affects the output APK. + * + * @throws IllegalStateException if this engine is closed + */ + InputJarEntryInstructions.OutputPolicy inputJarEntryRemoved(String entryName) + throws IllegalStateException; + + /** + * Indicates to this engine that the specified JAR entry was removed from the output. It's safe + * to invoke this for entries for which {@link #outputJarEntry(String)} hasn't been invoked. + * + * @throws IllegalStateException if this engine is closed + */ + void outputJarEntryRemoved(String entryName) throws IllegalStateException; + + /** + * Indicates to this engine that all JAR entries have been output. + * + * + * @return request to add JAR signature to the output or {@code null} if there is no need to add + * a JAR signature. The request will contain additional JAR entries to be output. The + * request must be fulfilled before + * {@link #outputZipSections(DataSource, DataSource, DataSource)} is invoked. + * + * @throws InvalidKeyException if a signature could not be generated because a signing key is + * not suitable for generating the signature + * @throws SignatureException if an error occurred while generating the JAR signature + * @throws IllegalStateException if there are unfulfilled requests, such as to inspect some JAR + * entries, or if the engine is closed + */ + OutputJarSignatureRequest outputJarEntries() throws InvalidKeyException, SignatureException; + + /** + * Indicates to this engine that the ZIP sections comprising the output APK have been output. + * + *
The provided data sources are guaranteed to not be used by the engine after this method + * terminates. + * + * @param zipEntries the section of ZIP archive containing Local File Header records and data of + * the ZIP entries. In a well-formed archive, this section starts at the start of the + * archive and extends all the way to the ZIP Central Directory. + * @param zipCentralDirectory ZIP Central Directory section + * @param zipEocd ZIP End of Central Directory (EoCD) record + * + * @return request to add an APK Signing Block to the output or {@code null} if the output must + * not contain an APK Signing Block. The request must be fulfilled before + * {@link #outputDone()} is invoked. + * + * @throws IOException if an I/O error occurs while reading the provided ZIP sections + * @throws InvalidKeyException if a signature could not be generated because a signing key is + * not suitable for generating the signature + * @throws SignatureException if an error occurred while generating the APK's signature + * @throws IllegalStateException if there are unfulfilled requests, such as to inspect some JAR + * entries or to output JAR signature, or if the engine is closed + */ + OutputApkSigningBlockRequest outputZipSections( + DataSource zipEntries, + DataSource zipCentralDirectory, + DataSource zipEocd) throws IOException, InvalidKeyException, SignatureException; + + /** + * Indicates to this engine that the signed APK was output. + * + *
This does not change the output APK. The method helps the client confirm that the current + * output is signed. + * + * @throws IllegalStateException if there are unfulfilled requests, such as to inspect some JAR + * entries or to output signatures, or if the engine is closed + */ + void outputDone() throws IllegalStateException; + + /** + * Indicates to this engine that it will no longer be used. Invoking this on an already closed + * engine is OK. + * + *
This does not change the output APK. For example, if the output APK is not yet fully + * signed, it will remain so after this method terminates. + */ + @Override + void close(); + + /** + * Instructions about how to handle an input APK's JAR entry. + * + *
The instructions indicate whether to output the entry (see {@link #getOutputPolicy()}) and + * may contain a request to inspect the entry (see {@link #getInspectJarEntryRequest()}), in + * which case the request must be fulfilled before {@link ApkSignerEngine#outputJarEntries()} is + * invoked. + */ + public static class InputJarEntryInstructions { + private final OutputPolicy mOutputPolicy; + private final InspectJarEntryRequest mInspectJarEntryRequest; + + /** + * Constructs a new {@code InputJarEntryInstructions} instance with the provided entry + * output policy and without a request to inspect the entry. + */ + public InputJarEntryInstructions(OutputPolicy outputPolicy) { + this(outputPolicy, null); + } + + /** + * Constructs a new {@code InputJarEntryInstructions} instance with the provided entry + * output mode and with the provided request to inspect the entry. + * + * @param inspectJarEntryRequest request to inspect the entry or {@code null} if there's no + * need to inspect the entry. + */ + public InputJarEntryInstructions( + OutputPolicy outputPolicy, + InspectJarEntryRequest inspectJarEntryRequest) { + mOutputPolicy = outputPolicy; + mInspectJarEntryRequest = inspectJarEntryRequest; + } + + /** + * Returns the output policy for this entry. + */ + public OutputPolicy getOutputPolicy() { + return mOutputPolicy; + } + + /** + * Returns the request to inspect the JAR entry or {@code null} if there is no need to + * inspect the entry. + */ + public InspectJarEntryRequest getInspectJarEntryRequest() { + return mInspectJarEntryRequest; + } + + /** + * Output policy for an input APK's JAR entry. + */ + public static enum OutputPolicy { + /** Entry must not be output. */ + SKIP, + + /** Entry should be output. */ + OUTPUT, + + /** Entry will be output by the engine. The client can thus ignore this input entry. */ + OUTPUT_BY_ENGINE, + } + } + + /** + * Request to inspect the specified JAR entry. + * + *
The entry's uncompressed data must be provided to the data sink returned by + * {@link #getDataSink()}. Once the entry's data has been provided to the sink, {@link #done()} + * must be invoked. + */ + interface InspectJarEntryRequest { + + /** + * Returns the data sink into which the entry's uncompressed data should be sent. + */ + DataSink getDataSink(); + + /** + * Indicates that entry's data has been provided in full. + */ + void done(); + + /** + * Returns the name of the JAR entry. + */ + String getEntryName(); + } + + /** + * Request to add JAR signature (aka v1 signature) to the output APK. + * + *
Entries listed in {@link #getAdditionalJarEntries()} must be added to the output APK after
+ * which {@link #done()} must be invoked.
+ */
+ interface OutputJarSignatureRequest {
+
+ /**
+ * Returns JAR entries that must be added to the output APK.
+ */
+ List The APK Signing Block returned by {@link #getApkSigningBlock()} must be placed into the
+ * output APK such that the block is immediately before the ZIP Central Directory, the offset of
+ * ZIP Central Directory in the ZIP End of Central Directory record must be adjusted
+ * accordingly, and then {@link #done()} must be invoked.
+ *
+ * If the output contains an APK Signing Block, that block must be replaced by the block
+ * contained in this request.
+ */
+ interface OutputApkSigningBlockRequest {
+
+ /**
+ * Returns the APK Signing Block.
+ */
+ byte[] getApkSigningBlock();
+
+ /**
+ * Indicates that the APK Signing Block was output as requested.
+ */
+ void done();
+ }
+}