X-Git-Url: https://www.bearssl.org/gitweb//home/git/?p=BearSSL;a=blobdiff_plain;f=samples%2Fcustom_profile.c;h=8133532974f142c0213112f6911ba9c91e8db507;hp=7191958063cfcd7f55c95929efd984397c7ab847;hb=05520e8eae3d8c6039e8bcde58741cf4ffb18f1d;hpb=5f045c759957fdff8c85716e6af99e10901fdac0

diff --git a/samples/custom_profile.c b/samples/custom_profile.c
index 7191958..8133532 100644
--- a/samples/custom_profile.c
+++ b/samples/custom_profile.c
@@ -166,7 +166,7 @@ example_client_profile(br_ssl_client_context *cc
 		(sizeof suites) / (sizeof suites[0]));
 
 	/*
-	 * Public-key algorithm imeplementations.
+	 * Public-key algorithm implementations.
 	 *
 	 * -- RSA public core ("rsapub") is needed for "RSA" key exchange
 	 *    (cipher suites whose name starts with TLS_RSA).
@@ -181,11 +181,22 @@ example_client_profile(br_ssl_client_context *cc
 	 * -- ECDSA signature verification is needed for "ECDHE_ECDSA"
 	 *    cipher suites (but not for ECDHE_RSA, ECDH_ECDSA or ECDH_RSA).
 	 *
+	 * Normally, you use the "default" implementations, obtained
+	 * through relevant function calls. These functions return
+	 * implementations that are deemed "best" for the current
+	 * platform, where "best" means "fastest within constant-time
+	 * implementations". Selecting the default implementation is a
+	 * mixture of compile-time and runtime checks.
+	 *
+	 * Nevertheless, specific implementations may be selected
+	 * explicitly, e.g. to use code which is slower but with a
+	 * smaller footprint.
+	 *
 	 * The RSA code comes in three variants, called "i15", "i31" and
 	 * "i32". The "i31" code is somewhat faster than the "i32" code.
 	 * Usually, "i31" is faster than "i15", except on some specific
 	 * architectures (ARM Cortex M0, M0+, M1 and M3) where the "i15"
-	 * should be prefered (the "i15" code is constant-time, while
+	 * should be preferred (the "i15" code is constant-time, while
 	 * the "i31" is not, and the "i15" code is faster anyway).
 	 *
 	 * ECDSA code also comes in "i15" and "i31" variants. As in the
@@ -216,10 +227,15 @@ example_client_profile(br_ssl_client_context *cc
 	 * implementations directly will result in smaller code, but
 	 * support for fewer curves and possibly lower performance.
 	 */
+	br_ssl_client_set_default_rsapub(cc);
+	br_ssl_engine_set_default_rsavrfy(&cc->eng);
+	br_ssl_engine_set_default_ecdsa(&cc->eng);
+	/* Alternate: set implementations explicitly.
 	br_ssl_client_set_rsapub(cc, &br_rsa_i31_public);
 	br_ssl_client_set_rsavrfy(cc, &br_rsa_i31_pkcs1_vrfy);
 	br_ssl_engine_set_ec(&cc->eng, &br_ec_all_m31);
-	br_ssl_client_set_ecdsa(cc, &br_ecdsa_i31_vrfy_asn1);
+	br_ssl_engine_set_ecdsa(&cc->eng, &br_ecdsa_i31_vrfy_asn1);
+	*/
 
 	/*
 	 * Record handler:
@@ -279,7 +295,12 @@ example_client_profile(br_ssl_client_context *cc
 	 *                but it is not constant-time.
 	 *
 	 *    aes_x86ni   Very fast implementation that uses the AES-NI
-	 *                opcodes on recent x86 CPU.
+	 *                opcodes on recent x86 CPU. But it may not be
+	 *                compiled in the library if the compiler or
+	 *                architecture is not supported; and the CPU
+	 *                may also not support the opcodes. Selection
+	 *                functions are provided to test for availability
+	 *                of the code and the opcodes.
 	 *
 	 * Whether having constant-time implementations is absolutely
 	 * required for security depends on the context (in particular
@@ -338,7 +359,7 @@ example_client_profile(br_ssl_client_context *cc
 	 *    ctmul64   Uses 64-bit multiplications with a 64-bit result.
 	 *
 	 * On 64-bit platforms, ctmul64 is the smallest and fastest of
-	 * the three. On 32-bit systems, ctmul should be prefered. The
+	 * the three. On 32-bit systems, ctmul should be preferred. The
 	 * ctmul32 implementation is meant to be used for the specific
 	 * 32-bit systems that do not have a 32x32->64 multiplier (i.e.
 	 * the ARM Cortex-M0 and Cortex-M0+).