1 files changed, 41 insertions, 1 deletions
diff --git a/providers/implementations/digests/blake2b_prov.c b/providers/implementations/digests/blake2b_prov.c
index 11271e1b59..109a6ce1c8 100644
--- a/providers/implementations/digests/blake2b_prov.c
+++ b/providers/implementations/digests/blake2b_prov.c
@@ -17,9 +17,48 @@
 #include <assert.h>
 #include <string.h>
 #include <openssl/crypto.h>
+#include <openssl/core_names.h>
+#include <openssl/proverr.h>
+#include <openssl/err.h>
 #include "blake2_impl.h"
 #include "prov/blake2.h"
 
+static const OSSL_PARAM known_blake2b_settable_ctx_params[] = {
+    {OSSL_DIGEST_PARAM_XOFLEN, OSSL_PARAM_UNSIGNED_INTEGER, NULL, 0, 0},
+    OSSL_PARAM_END
+};
+
+const OSSL_PARAM *ossl_blake2b_settable_ctx_params(ossl_unused void *ctx,
+                                                   ossl_unused void *pctx)
+{
+    return known_blake2b_settable_ctx_params;
+}
+
+int ossl_blake2b_set_ctx_params(void *vctx, const OSSL_PARAM params[])
+{
+    size_t xoflen;
+    struct blake2b_md_data_st *mdctx = vctx;
+    const OSSL_PARAM *p;
+
+    BLAKE2B_CTX *ctx = &mdctx->ctx;
+
+    if (ctx == NULL)
+        return 0;
+    if (params == NULL)
+        return 1;
+
+    p = OSSL_PARAM_locate_const(params, OSSL_DIGEST_PARAM_XOFLEN);
+    if (p != NULL) {
+        if (!OSSL_PARAM_get_size_t(p, &xoflen)) {
+            ERR_raise(ERR_LIB_PROV, PROV_R_FAILED_TO_GET_PARAMETER);
+            return 0;
+        }
+        ossl_blake2b_param_set_digest_length(&mdctx->params, (uint8_t)xoflen);
+    }
+
+    return 1;
+}
+
 static const uint64_t blake2b_IV[8] =
 {
     0x6a09e667f3bcc908ULL, 0xbb67ae8584caa73bULL,
@@ -82,7 +121,8 @@ static void blake2b_init_param(BLAKE2B_CTX *S, const BLAKE2B_PARAM *P)
 /* Initialize the parameter block with default values */
 void ossl_blake2b_param_init(BLAKE2B_PARAM *P)
 {
-    P->digest_length = BLAKE2B_DIGEST_LENGTH;
+    if (P->digest_length == 0)
+        P->digest_length = BLAKE2B_DIGEST_LENGTH;
     P->key_length    = 0;
     P->fanout        = 1;
     P->depth         = 1;