rsa/rsa_ossl.c: fix and extend commentary [skip ci].

[openssl.git] / crypto / dsa / dsa_gen.c

diff --git a/crypto/dsa/dsa_gen.c b/crypto/dsa/dsa_gen.c
index f65790c58c523ed7ac3099dbb1390695925a5fa8..db52a38a1882aaf2ac565ed033e42678342eeee9 100644 (file)
--- a/crypto/dsa/dsa_gen.c
+++ b/crypto/dsa/dsa_gen.c
@@ -114,16 +114,8 @@ int DSA_generate_parameters_ex(DSA *ret, int bits,
     }
 # endif
     else {
-        const EVP_MD *evpmd;
-        size_t qbits = bits >= 2048 ? 256 : 160;
-
-        if (bits >= 2048) {
-            qbits = 256;
-            evpmd = EVP_sha256();
-        } else {
-            qbits = 160;
-            evpmd = EVP_sha1();
-        }
+        const EVP_MD *evpmd = bits >= 2048 ? EVP_sha256() : EVP_sha1();
+        size_t qbits = EVP_MD_size(evpmd) * 8;
 
         return dsa_builtin_paramgen(ret, bits, qbits, evpmd,
                                     seed_in, seed_len, NULL, counter_ret,
@@ -154,32 +146,43 @@ int dsa_builtin_paramgen(DSA *ret, size_t bits, size_t qbits,
         /* invalid q size */
         return 0;
 
-    if (evpmd == NULL)
-        /* use SHA1 as default */
-        evpmd = EVP_sha1();
+    if (evpmd == NULL) {
+        if (qsize == SHA_DIGEST_LENGTH)
+            evpmd = EVP_sha1();
+        else if (qsize == SHA224_DIGEST_LENGTH)
+            evpmd = EVP_sha224();
+        else
+            evpmd = EVP_sha256();
+    } else {
+        qsize = EVP_MD_size(evpmd);
+    }
 
     if (bits < 512)
         bits = 512;
 
     bits = (bits + 63) / 64 * 64;
 
-    if (seed_in != NULL) {
-        if (seed_len < (size_t)qsize)
-            return 0;
-        if (seed_len > (size_t)qsize) {
-            /* Only consume as much seed as is expected. */
-            seed_len = qsize;
-        }
+    /*
+     * NB: seed_len == 0 is special case: copy generated seed to seed_in if
+     * it is not NULL.
+     */
+    if (seed_len && (seed_len < (size_t)qsize))
+        seed_in = NULL;         /* seed buffer too small -- ignore */
+    if (seed_len > (size_t)qsize)
+        seed_len = qsize;       /* App. 2.2 of FIPS PUB 186 allows larger
+                                 * SEED, but our internal buffers are
+                                 * restricted to 160 bits */
+    if (seed_in != NULL)
         memcpy(seed, seed_in, seed_len);
-    }
 
-    if ((ctx = BN_CTX_new()) == NULL)
+    if ((mont = BN_MONT_CTX_new()) == NULL)
         goto err;
 
-    if ((mont = BN_MONT_CTX_new()) == NULL)
+    if ((ctx = BN_CTX_new()) == NULL)
         goto err;
 
     BN_CTX_start(ctx);
+
     r0 = BN_CTX_get(ctx);
     g = BN_CTX_get(ctx);
     W = BN_CTX_get(ctx);
@@ -189,23 +192,28 @@ int dsa_builtin_paramgen(DSA *ret, size_t bits, size_t qbits,
     p = BN_CTX_get(ctx);
     test = BN_CTX_get(ctx);
 
+    if (test == NULL)
+        goto err;
+
     if (!BN_lshift(test, BN_value_one(), bits - 1))
         goto err;
 
     for (;;) {
         for (;;) {              /* find q */
-            int use_random_seed = (seed_in == NULL);
+            int seed_is_random;
 
             /* step 1 */
             if (!BN_GENCB_call(cb, 0, m++))
                 goto err;
 
-            if (use_random_seed) {
+            if (!seed_len || !seed_in) {
                 if (RAND_bytes(seed, qsize) <= 0)
                     goto err;
+                seed_is_random = 1;
             } else {
-                /* If we come back through, use random seed next time. */
-                seed_in = NULL;
+                seed_is_random = 0;
+                seed_len = 0;   /* use random seed if 'seed_in' turns out to
+                                 * be bad */
             }
             memcpy(buf, seed, qsize);
             memcpy(buf2, seed, qsize);
@@ -232,7 +240,7 @@ int dsa_builtin_paramgen(DSA *ret, size_t bits, size_t qbits,
 
             /* step 4 */
             r = BN_is_prime_fasttest_ex(q, DSS_prime_checks, ctx,
-                                        use_random_seed, cb);
+                                        seed_is_random, cb);
             if (r > 0)
                 break;
             if (r != 0)
@@ -481,6 +489,8 @@ int dsa_builtin_paramgen2(DSA *ret, size_t L, size_t N,
     } else {
         p = BN_CTX_get(ctx);
         q = BN_CTX_get(ctx);
+        if (q == NULL)
+            goto err;
     }
 
     if (!BN_lshift(test, BN_value_one(), L - 1))
@@ -493,7 +503,7 @@ int dsa_builtin_paramgen2(DSA *ret, size_t L, size_t N,
                 goto err;
 
             if (!seed_in) {
-                if (RAND_pseudo_bytes(seed, seed_len) < 0)
+                if (RAND_bytes(seed, seed_len) <= 0)
                     goto err;
             }
             /* step 2 */