1From d1d4f8d4effdb9729bcdca711910bd418651f3fe Mon Sep 17 00:00:00 2001
  2From: Michael Forney <mforney@mforney.org>
  3Date: Fri, 15 May 2026 03:02:00 -0700
  4Subject: [PATCH] sha512-256: support delegating to (patched) bearssl
  5
  6---
  7 lib/curl_sha512_256.c | 81 ++++++++++++++++++++++++++++++++++++++++---
  8 1 file changed, 77 insertions(+), 4 deletions(-)
  9
 10diff --git a/lib/curl_sha512_256.c b/lib/curl_sha512_256.c
 11index 75a7765931..2ac9002ea6 100644
 12--- a/lib/curl_sha512_256.c
 13+++ b/lib/curl_sha512_256.c
 14@@ -31,10 +31,10 @@
 15  * 1. USE_OPENSSL
 16  * 2. USE_WOLFSSL
 17  * 3. USE_GNUTLS
 18- * 4. USE_MBEDTLS (TBD)
 19- * 5. USE_RUSTLS (TBD)
 20- * 6. USE_WIN32_CRYPTO (TBD)
 21- * 7. USE_BEARSSL (TBD)
 22+ * 4. USE_BEARSSL
 23+ * 5. USE_MBEDTLS (TBD)
 24+ * 6. USE_RUSTLS (TBD)
 25+ * 7. USE_WIN32_CRYPTO (TBD)
 26  * Skip the backend if it does not support the required algorithm */
 27 
 28 #ifdef USE_OPENSSL
 29@@ -79,9 +79,16 @@
 30 #  include <nettle/sha.h>
 31 #  ifdef SHA512_256_DIGEST_SIZE
 32 #    define USE_GNUTLS_SHA512_256           1
 33+#    define HAS_SHA512_256_IMPLEMENTATION   1
 34 #  endif
 35 #endif /* !HAS_SHA512_256_IMPLEMENTATION && USE_GNUTLS */
 36 
 37+#if !defined(HAS_SHA512_256_IMPLEMENTATION) && defined(USE_BEARSSL)
 38+#  include <bearssl.h>
 39+#  define USE_BEARSSL_SHA512_256            1
 40+#  define HAS_SHA512_256_IMPLEMENTATION     1
 41+#endif /* !HAS_SHA512_256_IMPLEMENTATION && USE_BEARSSL */
 42+
 43 #ifdef USE_OPENSSL_SHA512_256
 44 
 45 /* OpenSSL does not provide macros for SHA-512/256 sizes */
 46@@ -288,6 +295,72 @@ static CURLcode Curl_sha512_256_finish(unsigned char *digest, void *context)
 47   return CURLE_OK;
 48 }
 49 
 50+#elif defined(USE_BEARSSL_SHA512_256)
 51+
 52+#define CURL_SHA512_256_BLOCK_SIZE  128
 53+#define CURL_SHA512_256_DIGEST_SIZE br_sha512_256_SIZE
 54+
 55+/**
 56+ * Context type used for SHA-512/256 calculations
 57+ */
 58+typedef br_sha512_256_context Curl_sha512_256_ctx;
 59+
 60+/**
 61+ * Initialise structure for SHA-512/256 calculation.
 62+ *
 63+ * @param context the calculation context
 64+ * @return always CURLE_OK
 65+ */
 66+static CURLcode Curl_sha512_256_init(void *context)
 67+{
 68+  Curl_sha512_256_ctx * const ctx = (Curl_sha512_256_ctx *)context;
 69+
 70+  /* Check whether the header and this file use the same numbers */
 71+  DEBUGASSERT(CURL_SHA512_256_DIGEST_LENGTH == CURL_SHA512_256_DIGEST_SIZE);
 72+
 73+  br_sha512_256_init(ctx);
 74+
 75+  return CURLE_OK;
 76+}
 77+
 78+/**
 79+ * Process portion of bytes.
 80+ *
 81+ * @param context the calculation context
 82+ * @param data bytes to add to hash
 83+ * @param length number of bytes in @a data
 84+ * @return always CURLE_OK
 85+ */
 86+static CURLcode Curl_sha512_256_update(void *context,
 87+                                       const unsigned char *data,
 88+                                       size_t length)
 89+{
 90+  Curl_sha512_256_ctx * const ctx = (Curl_sha512_256_ctx *)context;
 91+
 92+  DEBUGASSERT((data != NULL) || (length == 0));
 93+
 94+  br_sha512_256_update(ctx, data, length);
 95+
 96+  return CURLE_OK;
 97+}
 98+
 99+/**
100+ * Finalise SHA-512/256 calculation, return digest.
101+ *
102+ * @param context the calculation context
103+ * @param[out] digest set to the hash, must be #CURL_SHA512_256_DIGEST_SIZE
104+ *             bytes
105+ * @return always CURLE_OK
106+ */
107+static CURLcode Curl_sha512_256_finish(unsigned char *digest, void *context)
108+{
109+  Curl_sha512_256_ctx * const ctx = (Curl_sha512_256_ctx *)context;
110+
111+  br_sha512_256_out(ctx, digest);
112+
113+  return CURLE_OK;
114+}
115+
116 #else /* No system or TLS backend SHA-512/256 implementation available */
117 
118 /* ** This implementation of SHA-512/256 hash calculation was originally ** *
119-- 
1202.54.0
121