From 141cf85eb74b8161b481fd167f3fc3ac2011d6e3 Mon Sep 17 00:00:00 2001 From: c0de Date: Wed, 4 Oct 2023 14:25:34 -0500 Subject: [PATCH] Restructure README --- README.md | 122 +++++++++++++++++------------------------------------- 1 file changed, 39 insertions(+), 83 deletions(-) diff --git a/README.md b/README.md index e644361..1c6bf6e 100644 --- a/README.md +++ b/README.md @@ -3,82 +3,39 @@ SmartPGP is a free and open source implementation of the [OpenPGP card 3.4 specification](https://gnupg.org/ftp/specs/OpenPGP-smart-card-application-3.4.pdf) in JavaCard. - ## Features The following features are implemented at the applet level, but some of them depend on underlying hardware support and available (non-)volatile memory resources: -- RSA (>= 2048 bits modulus, 17 bits exponent) for signature, - encryption and authentication; - -- On-board key generation and external private key import; - -- PIN codes (user, admin and resetting code) up to 127 characters; - -- Certificate up to 1 kB (DER encoded) for each key; - -- Login, URL, and private DOs up to 256 bytes; - -- Command and response chaining; - -- AES 128/256 bits deciphering primitive; - +- RSA (>= 2048 bits modulus, 17 bits exponent) for signature, encryption and authentication +- On-board key generation and external private key import +- PIN codes (user, admin and resetting code) up to 127 characters each +- Certificate up to 1 kB (DER encoded) for each key +- Login, URL, and private DOs up to 256 bytes +- Command and response chaining +- AES 128/256 bits deciphering primitive ## Default values The SmartPGP applet is configured with the following default values: -- Admin PIN is 12345678; +- Admin PIN is 12345678 +- User PIN is 123456 +- No PUK (a.k.a. resetting code) is defined +- RSA 2048 bits for PGP keys -- User PIN is 123456; +These values can be changed by modifying the [Constants](src/dev/c0de/smartpgp/Constants.java) class. -- No PUK (a.k.a. resetting code) is defined; +After the applet has been installed, the [smartpgp-cli](bin/smartpgp-cli) utility +will be able to change the above values. -- RSA 2048 bits for PGP keys; +_Note: These settings are restored if you factory reset the applet._ -These values can be changed by modifying default values in the code -(see the [Constants](src/fr/anssi/smartpgp/Constants.java) -class). +__Note: If you change algorithm attributes, the key and corresponding certificate will be erased.__ -When the applet is installed, one can use the `smartpgp-cli` utility -given in the `bin` directory to change these values. Keep in mind that -when you change the algorithm attributes of a PGP key, the key and the -corresponding certificate are -erased. Also note that hard coded default values will be restored upon -a factory reset. - - -# Application support - -Tokens following the OpenPGP card 3.4 specification are not yet fully -supported by most PGP applications. - -## GnuPG - -OpenPGP card 3.x is supported by [GnuPG](https://www.gnupg.org/) -starting from version 2.1.16. - -## OpenKeychain - -OpenPGP card 3.x is supported by [OpenKeychain](https://www.openkeychain.org/) -starting from version 4.2. - - -# Content of the repository - -The repository contains several directories: - -- `bin` contains a Python library and command line tool called - `smartpgp-cli` to interact with an OpenPGP card 3.x; - -- `src` contains the JavaCard source code of the SmartPGP applet; - -- `videos` contains sample videos demonstrating smartcard interactions - with OpenKeychain and K9 mail on Android Nexus 5. - -## Build and installation instructions +## Build and Install instructions ### Prerequisites @@ -93,11 +50,9 @@ The repository contains several directories: ### Importing RSA keys above 2048 bits -The default internal buffer that stores keys is configured with a default -value that is only large enough for RSA 2048 bit keys. +The internal buffer that stores keys is configured with a default value that is only large enough for RSA 2048 bit keys. -if your card is able to handle larger RSA key bit-lengths (3072 or 4096), -and you want to import those keys, you will need to increase the buffer size. +If your card is able to handle larger RSA key bit-lengths (3072 or 4096), and you want to import those keys, you will need to increase the buffer size. This can be accomplished by modifying `Constants.INTERNAL_BUFFER_MAX_LENGTH` in [Constants.java](src/dev/c0de/smartpgp/Constants.java) @@ -116,47 +71,48 @@ When produced by OpenPGP, these keys are 1294 Bytes in length. When produced by OpenPGP, these keys are 1644 Bytes in length. `Constants.INTERNAL_BUFFER_MAX_LENGTH` may not be smaller than `(short)0x66d` (decimal: 1645) -## Reducing flash and/or RAM consumption +### Reducing flash and/or RAM consumption -The applet allocates all its data structures to their maximal size -at installation to avoid as much as possible runtime errors caused by -memory allocation failure. If your device does not have enough flash -and/or RAM available, or if you plan not to use some features -(e.g. stored certificates), you can adjust the applet to reduce its -resource consumption by tweaking the following variables: +When the applet is installed, all data structures will be allocated +to their maximum size. This is a standard practice for JavaCard applets +to ensure that there will not be a memory allocation failure at runtime. + +A consequence of this is that, if you configure a large rsa key and +use a small key, that extra space can not be used for anything else. + +If your device does not have enough flash memory and/or RAM, or you plan +to not use some features (eg. on-device certificates), you can modify +the following variables in [Constants.java](src/dev/c0de/smartpgp/Constants.java) - `Constants.INTERNAL_BUFFER_MAX_LENGTH`: the size in bytes of the internal RAM buffer used for input/output chaining. Chaining is especially used in case of long commands and responses such as those involved in private key import and certificate import/export; -- `Constants.EXTENDED_CAPABILITIES`, bytes 5 and 6: the maximal size - in bytes of a certificate associated to a key. Following the OpenPGP - card specification, a certificate can be stored for each of the - three keys. +- `Constants.EXTENDED_CAPABILITIES`, bytes 5 and 6: the maximum size + in bytes of a certificate associated to a key. The default is 1152 Bytes. + A certificate can be stored for each of the three keys. - -## Building the CAP file +### Building the CAP file - (Optional) Edit the `build.xml` file and replace the `APPLET_AID` with your a unique value. Alternatively, set the right AID instance bytes during applet installation. Generate the AID using [this tool](https://c0de.dev/c0de/SmartPGP-AID-Generator) -- Execute `ant` with no parameter to build `SmartPGPApplet.cap` +- Execute `ant` to build `SmartPGPApplet.cap` -## Installing the CAP file +### Installing the CAP file The CAP file installation depends on your device, so you have to refer to the instructions given by your device manufacturer. Most open cards relying on Global Platform with default keys are supported by [GlobalPlatformPro](https://github.com/martinpaljak/GlobalPlatformPro). -Be careful to use a valid AID according to the OpenPGP card -specification (see section 4.2.1) for each card (`-create ` with -GlobalPlatformPro) +You must use a valid, unique AID that matches the OpenPGP card specification (see section 4.2.1) +for each card (`-create ` with GlobalPlatformPro) -Example Installation commands: +Example Installation commands: - `gp --install SmartPGPApplet.cap --default` - `gp --install SmartPGPApplet.cap --create `