Hi.
Racket's OpenSSL bindings do not currently enable the ECDH(E) and the
DHE ciphers, which are needed for perfect forward secrecy.
I've attached a patch that:
- Embeds reasonable defaults for DHE mode.
- Adds two functions, ssl-server-context-enable-dhe! and
ssl-server-context-enable-ecdhe! that when given
DHE/ECDHE setup arguments (for DHE, a DH parameter file path,
for ECDHE, the name of one of the built-in OpenSSL elliptic curves
[currently, only secp521r1])
- (unrelated, but also useful) Adds bindings for TLS 1.1/1.2-only
server/client contexts.
This patch is currently a work in progress (it currently only supports
one elliptic curve name) that works well enough for what I am using it
for, but I'm interested in getting this patch upstream.
What's the exact process for this?
diff --git a/racket/collects/openssl/dh4096.pem b/racket/collects/openssl/dh4096.pem
new file mode 100644
index 0000000..1b35ad8
--- /dev/null
+++ b/racket/collects/openssl/dh4096.pem
@@ -0,0 +1,18 @@
+-----BEGIN DH PARAMETERS-----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=
+-----END DH PARAMETERS-----
+
+These are the 4096 bit DH parameters from "Assigned Number for SKIP Protocols"
+(http://www.skip-vpn.org/spec/numbers.html).
+See there for how they were generated.
+Note that g is not a generator, but this is not a problem since p is a safe prime.
diff --git a/racket/collects/openssl/mzssl.rkt b/racket/collects/openssl/mzssl.rkt
index 2f16517..3ccd0bb 100644
--- a/racket/collects/openssl/mzssl.rkt
+++ b/racket/collects/openssl/mzssl.rkt
@@ -34,6 +34,7 @@ TO DO:
racket/tcp
racket/string
racket/lazy-require
+ racket/runtime-path
"libcrypto.rkt"
"libssl.rkt")
(lazy-require
@@ -41,7 +42,9 @@ TO DO:
["private/macosx.rkt" (load-macosx-keychain)])
(define protocol-symbol/c
- (or/c 'sslv2-or-v3 'sslv2 'sslv3 'tls))
+ (or/c 'sslv2-or-v3 'sslv2 'sslv3 'tls 'tls11 'tls12))
+(define curves/c
+ (or/c 'secp521r1))
(define verify-source/c
(or/c path-string?
@@ -50,6 +53,7 @@ TO DO:
(list/c 'macosx-keychain path-string?)))
(provide
+ ssl-dh-param-path
(contract-out
[ssl-available? boolean?]
[ssl-load-fail-reason (or/c #f string?)]
@@ -59,6 +63,10 @@ TO DO:
(c-> ssl-client-context?)]
[ssl-make-server-context
(->* () (protocol-symbol/c) ssl-server-context?)]
+ [ssl-server-context-enable-dhe!
+ (->* (ssl-server-context?) (path-string?) void?)]
+ [ssl-server-context-enable-ecdhe!
+ (->* (ssl-server-context?) (curves/c) void?)]
[ssl-client-context?
(c-> any/c boolean?)]
[ssl-server-context?
@@ -185,6 +193,8 @@ TO DO:
(define-cpointer-type _X509*)
(define-cpointer-type _ASN1_STRING*)
(define-cpointer-type _STACK*)
+(define-cpointer-type _DH*)
+(define-cpointer-type _EC_KEY*)
(define-cstruct _GENERAL_NAME ([type _int] [d _ASN1_STRING*]))
(define-ssl SSLv2_client_method (_fun -> _SSL_METHOD*))
@@ -195,9 +205,19 @@ TO DO:
(define-ssl SSLv23_server_method (_fun -> _SSL_METHOD*))
(define-ssl TLSv1_client_method (_fun -> _SSL_METHOD*))
(define-ssl TLSv1_server_method (_fun -> _SSL_METHOD*))
+(define-ssl TLSv1_1_client_method (_fun -> _SSL_METHOD*))
+(define-ssl TLSv1_1_server_method (_fun -> _SSL_METHOD*))
+(define-ssl TLSv1_2_client_method (_fun -> _SSL_METHOD*))
+(define-ssl TLSv1_2_server_method (_fun -> _SSL_METHOD*))
+
+(define-crypto DH_free (_fun _DH* -> _void) #:wrap (deallocator))
+(define-crypto EC_KEY_free (_fun _EC_KEY* -> _void) #:wrap (deallocator))
+
+(define-crypto EC_KEY_new_by_curve_name (_fun _int -> _EC_KEY*) #:wrap (allocator EC_KEY_free))
(define-crypto BIO_s_mem (_fun -> _BIO_METHOD*))
(define-crypto BIO_new (_fun _BIO_METHOD* -> _BIO*/null))
+(define-crypto BIO_new_file (_fun _string _string -> _BIO*))
(define-crypto BIO_free (_fun _BIO* -> _void))
(define-crypto BIO_read (_fun _BIO* _bytes _int -> _int))
@@ -259,6 +279,7 @@ TO DO:
(define-ssl SSL_load_error_strings (_fun -> _void))
(define-crypto GENERAL_NAME_free _fpointer)
+(define-crypto PEM_read_bio_DHparams (_fun _BIO* _pointer _pointer _pointer -> _DH*) #:wrap (allocator DH_free))
(define-crypto ASN1_STRING_length (_fun _ASN1_STRING* -> _int))
(define-crypto ASN1_STRING_data (_fun _ASN1_STRING* -> _pointer))
(define-crypto X509_NAME_get_index_by_NID (_fun _X509_NAME* _int _int -> _int))
@@ -331,8 +352,20 @@ TO DO:
(define NID_commonName 13)
(define GEN_DNS 2)
+(define SSL_CTRL_SET_ECDH_AUTO 94)
+(define SSL_CTRL_OPTIONS 32)
+(define SSL_CTRL_SET_TMP_DH 3)
+(define SSL_CTRL_SET_TMP_ECDH 4)
+
+(define SSL_OP_SINGLE_ECDH_USE #x00080000)
+(define SSL_OP_SINGLE_DH_USE #x00100000)
+
+(define NID_secp521r1 716)
+
(define-mzscheme scheme_make_custodian (_fun _pointer -> _scheme))
+(define-runtime-path ssl-dh-param-path "dh4096.pem")
+
;; Make this bigger than 4096 to accommodate at least
;; 4096 of unencrypted data
(define BUFFER-SIZE 8000)
@@ -467,6 +500,10 @@ TO DO:
(if client? SSLv3_client_method SSLv3_server_method)]
[(tls)
(if client? TLSv1_client_method TLSv1_server_method)]
+ [(tls11)
+ (if client? TLSv1_1_client_method TLSv1_1_server_method)]
+ [(tls12)
+ (if client? TLSv1_1_client_method TLSv1_2_server_method)]
[else
(error 'encrypt->method "internal error, unknown encrypt: ~e" e)])))
@@ -515,6 +552,33 @@ TO DO:
(define (ssl-seal-context! mzctx)
(set-ssl-context-sealed?! mzctx #t))
+(define (ssl-server-context-enable-ecdhe! context [name 'secp521r1])
+ (define (symbol->nid name)
+ (case name
+ ['secp521r1 NID_secp521r1]
+ [else NID_secp521r1]))
+ (define ctx (extract-ctx 'ssl-server-context-enable-ecdhe! #t context))
+ (define key (EC_KEY_new_by_curve_name (symbol->nid name)))
+ (check-valid key 'ssl-server-context-enable-ecdhe! "Could not enable ECDH(E)")
+ (unless (= 1 (SSL_CTX_ctrl ctx SSL_CTRL_SET_TMP_ECDH 0 key))
+ (error 'ssl-server-context-enable-ecdhe! "Could not enable ECDH(E)"))
+ (SSL_CTX_ctrl ctx SSL_CTRL_OPTIONS SSL_OP_SINGLE_ECDH_USE #f)
+ (void))
+
+(define (ssl-server-context-enable-dhe! context [path ssl-dh-param-path])
+ (define io-bio (BIO_new_file ssl-dh-param-path "rb"))
+ (check-valid io-bio 'ssl-server-context-enable-dhe! "Diffie-Hellman parameters")
+ (with-failure
+ (lambda ()
+ (BIO_free io-bio))
+ (define ctx (extract-ctx 'ssl-server-context-enable-dhe! #t context))
+ (define dh (PEM_read_bio_DHparams io-bio #f #f #f))
+ (check-valid dh 'ssl-server-context-enable-dhe "Diffie-Hellman parameters")
+ (unless (= 1 (SSL_CTX_ctrl ctx SSL_CTRL_SET_TMP_DH 0 dh))
+ (error 'ssl-server-context-enable-dhe "Could not enable DHE"))
+ (SSL_CTX_ctrl ctx SSL_CTRL_OPTIONS SSL_OP_SINGLE_DH_USE #f)
+ (void)))
+
(define (ssl-load-... who load-it ssl-context-or-listener pathname
#:try? [try? #f])
(let ([ctx (get-context/listener who ssl-context-or-listener
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