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libwebsockets/READMEs/README.crypto-apis.md

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JOSE: refactor and prepare for JWE Until now the JOSE pieces only had enough support for ACME. This patch improves the JWK parsing to prepare for more complete support and for adding JWE, genaes and genec in later patches.
2018-11-27 08:36:08 +08:00
# Lws Crypto Apis
## Overview
![lws crypto overview](/doc-assets/lws-crypto-overview.svg)
Lws provides a "generic" crypto layer on top of both OpenSSL and
compatible tls library, and mbedtls. Using this layer, your code
can work without any changes on both types of tls library crypto
backends... it's as simple as rebuilding lws with `-DLWS_WITH_MBEDTLS=0`
or `=1` at cmake.
The generic layer can be used directly (as in, eg, the sshd plugin),
or via another layer on top, which processes JOSE JSON objects using
JWS (JSON Web Signatures), JWK (JSON Web Keys), and JWE (JSON Web
Encryption).
jwe
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The `JW` apis use the generic apis (`lws_genrsa_`, etc) to get the crypto tasks
done, so anything they can do you can also get done using the generic apis.
The main difference is that with the generic apis, you must instantiate the
correct types and use type-specfic apis. With the `JW` apis, there is only
one interface for all operations, with the details hidden in the api and
controlled by the JSON objects.
Because of this, the `JW` apis are often preferred because they give you
"crypto agility" cheaply... to change your crypto to another supported algorithm
once it's working, you literally just change your JSON defining the keys and
JWE or JWS algorithm. (It's up to you to define your policy for which
combinations are acceptable by querying the parsed JW structs).
JOSE: refactor and prepare for JWE Until now the JOSE pieces only had enough support for ACME. This patch improves the JWK parsing to prepare for more complete support and for adding JWE, genaes and genec in later patches.
2018-11-27 08:36:08 +08:00
## Using the generic layer
All the necessary includes are part of `libwebsockets.h`.
|api|cmake|header|Functionality|
|---|---|---|---|
|genhash|`LWS_WITH_GENHASH`|[./include/libwebsockets/lws-genhash.h](https://libwebsockets.org/git/libwebsockets/tree/include/libwebsockets/lws-genhash.h)|Provides SHA1 + SHA2 hashes and hmac|
|genrsa|`LWS_WITH_GENRSA`|[./include/libwebsockets/lws-genrsa.h](https://libwebsockets.org/git/libwebsockets/tree/include/libwebsockets/lws-genrsa.h)|Provides RSA encryption, decryption, signing, verification, key generation and creation|
genaes: generic AES layer independent of tls library Although RSA can be used directly for signing / JWS on large chunks of data since it's only operating on the hash, when JWE support arrives, which allows bulk encryption, it's going to be mandatory to support secondary AES ciphers to use on the bulk data. This adds generic support for all AES modes that OpenSSL and mbedTLS have in common, works on both mbedTLS and OpenSSL the same, and adds unit tests for each mode in api-test-gencrypto, to run in CI.
2018-12-04 08:03:58 +08:00
|genaes|`LWS_WITH_GENAES`|[./include/libwebsockets/lws-genaes.h](https://libwebsockets.org/git/libwebsockets/tree/include/libwebsockets/lws-genaes.h)|Provides AES in all common variants for encryption and decryption|
genec: generic ECDH crypto layer !!! WIP This implements the "genec" layer wrapping mbedtls + openssl ECDH support. API tests are added for the parts that are implemented so far. Stuff related to ec at all, like keys, are prefixed lws_genec_. Stuff specific to ECDH are prefixed lws_genecdh_.
2018-12-05 13:11:03 +08:00
|genec|`LWS_WITH_GENEC`|[./include/libwebsockets/lws-genec.h](https://libwebsockets.org/git/libwebsockets/tree/include/libwebsockets/lws-genec.h)|Provides Elliptic Curve for encryption, decryption, signing, verification, key generation and creation|
JOSE: refactor and prepare for JWE Until now the JOSE pieces only had enough support for ACME. This patch improves the JWK parsing to prepare for more complete support and for adding JWE, genaes and genec in later patches.
2018-11-27 08:36:08 +08:00
Unit tests for these apis, which serve as usage examples, can be found in [./minimal-examples/api-tests/api-test-gencrypto](https://libwebsockets.org/git/libwebsockets/tree/minimal-examples/api-tests/api-test-gencrypto)
genaes: generic AES layer independent of tls library Although RSA can be used directly for signing / JWS on large chunks of data since it's only operating on the hash, when JWE support arrives, which allows bulk encryption, it's going to be mandatory to support secondary AES ciphers to use on the bulk data. This adds generic support for all AES modes that OpenSSL and mbedTLS have in common, works on both mbedTLS and OpenSSL the same, and adds unit tests for each mode in api-test-gencrypto, to run in CI.
2018-12-04 08:03:58 +08:00
### Keys in the generic layer
The necessary types and defines are brought in by `libwebsockets.h`.
Keys are represented only by an array of `struct lws_jwk_elements`... the
length of the array is defined by the cipher... it's one of
|key elements count|definition|
|---|---|
|`LWS_COUNT_OCT_KEY_ELEMENTS`|1|
|`LWS_COUNT_RSA_KEY_ELEMENTS`|8|
|`LWS_COUNT_EC_KEY_ELEMENTS`|4|
|`LWS_COUNT_AES_KEY_ELEMENTS`|1|
`struct lws_jwk_elements` is a simple pointer / length combination used to
store arbitrary octets that make up the key element's binary representation.
JOSE: refactor and prepare for JWE Until now the JOSE pieces only had enough support for ACME. This patch improves the JWK parsing to prepare for more complete support and for adding JWE, genaes and genec in later patches.
2018-11-27 08:36:08 +08:00
## Using the JOSE layer
All the necessary includes are part of `libwebsockets.h`.
|api|cmake|header|Functionality|
|---|---|---|---|
|JOSE|`LWS_WITH_JWS`|[./include/libwebsockets/jose.h](https://libwebsockets.org/git/libwebsockets/tree/include/libwebsockets/lws-jose.h)|Provides signature and verifcation services for RFC7515 JOSE JSON|
|JWS|`LWS_WITH_JWS`|[./include/libwebsockets/jws.h](https://libwebsockets.org/git/libwebsockets/tree/include/libwebsockets/lws-jws.h)|Provides signature and verifcation services for RFC7515 JWS JSON|
|JWK|`LWS_WITH_JWS`|[./include/libwebsockets/jwk.h](https://libwebsockets.org/git/libwebsockets/tree/include/libwebsockets/lws-jwk.h)|Provides signature and verifcation services for RFC7517 JWK JSON, both "keys" arrays and singletons|
Unit tests for these apis, which serve as usage examples, can be found in [./minimal-examples/api-tests/api-test-jose](https://libwebsockets.org/git/libwebsockets/tree/minimal-examples/api-tests/api-test-jose)
genaes: generic AES layer independent of tls library Although RSA can be used directly for signing / JWS on large chunks of data since it's only operating on the hash, when JWE support arrives, which allows bulk encryption, it's going to be mandatory to support secondary AES ciphers to use on the bulk data. This adds generic support for all AES modes that OpenSSL and mbedTLS have in common, works on both mbedTLS and OpenSSL the same, and adds unit tests for each mode in api-test-gencrypto, to run in CI.
2018-12-04 08:03:58 +08:00
### Keys in the JOSE layer
Keys in the JOSE layer use a `struct lws_jwk`, this contains two arrays of
`struct lws_jwk_elements` sized for the worst case (currently RSA). One
array contains the key elements as described for the generic case, and the
jwe
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other contains various nonencrypted key metadata taken from JWK JSON.
genaes: generic AES layer independent of tls library Although RSA can be used directly for signing / JWS on large chunks of data since it's only operating on the hash, when JWE support arrives, which allows bulk encryption, it's going to be mandatory to support secondary AES ciphers to use on the bulk data. This adds generic support for all AES modes that OpenSSL and mbedTLS have in common, works on both mbedTLS and OpenSSL the same, and adds unit tests for each mode in api-test-gencrypto, to run in CI.
2018-12-04 08:03:58 +08:00
|metadata index|function|
|---|---|
|`JWK_META_KTY`|Key type, eg, "EC"|
|`JWK_META_KID`|Arbitrary ID string|
|`JWK_META_USE`|What the public key may be used to validate, "enc" or "sig"|
|`JWK_META_KEY_OPS`|Which operations the key is authorized for, eg, "encrypt"|
|`JWK_META_X5C`|Optional X.509 cert version of the key|
|`JWK_META_ALG`|Optional overall crypto algorithm the key is intended for use with|
jwe
2018-12-13 20:05:12 +08:00
`lws_jwk_destroy()` should be called when the jwk is going out of scope... this
takes care to zero down any key element data in the jwk.
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