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- From 286e015bf0d30530707a5e7b3b871509f2ab50d7 Mon Sep 17 00:00:00 2001
- From: Eneas U de Queiroz <[email protected]>
- Date: Thu, 27 Sep 2018 08:44:39 -0300
- Subject: Add OPENSSL_PREFER_CHACHA_OVER_GCM option
- This enables a compile-time option to prefer ChaCha20-Poly1305 over
- AES-GCM in the openssl default ciphersuite, which is useful in systems
- without AES specific CPU instructions.
- OPENSSL_PREFER_CHACHA_OVER_GCM must be defined to enable it.
- Note that this does not have the same effect as the
- SL_OP_PRIORITIZE_CHACHA option, which prioritizes ChaCha20-Poly1305 only
- when the client has it on top of its ciphersuite preference.
- Signed-off-by: Eneas U de Queiroz <[email protected]>
- --- a/include/openssl/ssl.h
- +++ b/include/openssl/ssl.h
- @@ -173,9 +173,15 @@ extern "C" {
- # define SSL_DEFAULT_CIPHER_LIST "ALL:!COMPLEMENTOFDEFAULT:!eNULL"
- /* This is the default set of TLSv1.3 ciphersuites */
- # if !defined(OPENSSL_NO_CHACHA) && !defined(OPENSSL_NO_POLY1305)
- -# define TLS_DEFAULT_CIPHERSUITES "TLS_AES_256_GCM_SHA384:" \
- - "TLS_CHACHA20_POLY1305_SHA256:" \
- - "TLS_AES_128_GCM_SHA256"
- +# ifdef OPENSSL_PREFER_CHACHA_OVER_GCM
- +# define TLS_DEFAULT_CIPHERSUITES "TLS_CHACHA20_POLY1305_SHA256:" \
- + "TLS_AES_256_GCM_SHA384:" \
- + "TLS_AES_128_GCM_SHA256"
- +# else
- +# define TLS_DEFAULT_CIPHERSUITES "TLS_AES_256_GCM_SHA384:" \
- + "TLS_CHACHA20_POLY1305_SHA256:" \
- + "TLS_AES_128_GCM_SHA256"
- +# endif
- # else
- # define TLS_DEFAULT_CIPHERSUITES "TLS_AES_256_GCM_SHA384:" \
- "TLS_AES_128_GCM_SHA256"
- --- a/ssl/ssl_ciph.c
- +++ b/ssl/ssl_ciph.c
- @@ -1464,11 +1464,29 @@ STACK_OF(SSL_CIPHER) *ssl_create_cipher_
- ssl_cipher_apply_rule(0, SSL_kECDHE, 0, 0, 0, 0, 0, CIPHER_DEL, -1, &head,
- &tail);
-
- + /*
- + * If OPENSSL_PREFER_CHACHA_OVER_GCM is defined, ChaCha20_Poly1305
- + * will be placed before AES-256. Otherwise, the default behavior of
- + * preferring GCM over CHACHA is used.
- + * This is useful for systems that do not have AES-specific CPU
- + * instructions, where ChaCha20-Poly1305 is 3 times faster than AES.
- + * Note that this does not have the same effect as the SSL_OP_PRIORITIZE_CHACHA
- + * option, which prioritizes ChaCha20-Poly1305 only when the client has it on top
- + * of its ciphersuite preference.
- + */
- +
- +#ifdef OPENSSL_PREFER_CHACHA_OVER_GCM
- + ssl_cipher_apply_rule(0, 0, 0, SSL_CHACHA20, 0, 0, 0, CIPHER_ADD, -1,
- + &head, &tail);
- + ssl_cipher_apply_rule(0, 0, 0, SSL_AESGCM, 0, 0, 0, CIPHER_ADD, -1,
- + &head, &tail);
- +#else
- /* Within each strength group, we prefer GCM over CHACHA... */
- ssl_cipher_apply_rule(0, 0, 0, SSL_AESGCM, 0, 0, 0, CIPHER_ADD, -1,
- &head, &tail);
- ssl_cipher_apply_rule(0, 0, 0, SSL_CHACHA20, 0, 0, 0, CIPHER_ADD, -1,
- &head, &tail);
- +#endif
-
- /*
- * ...and generally, our preferred cipher is AES.
- @@ -1524,7 +1542,7 @@ STACK_OF(SSL_CIPHER) *ssl_create_cipher_
- * Within each group, ciphers remain sorted by strength and previous
- * preference, i.e.,
- * 1) ECDHE > DHE
- - * 2) GCM > CHACHA
- + * 2) GCM > CHACHA, reversed if OPENSSL_PREFER_CHACHA_OVER_GCM is defined
- * 3) AES > rest
- * 4) TLS 1.2 > legacy
- *
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