Restoring authorship annotation for <deshevoy@yandex-team.ru>. Commit 2 of 2.

1 files changed, 287 insertions, 287 deletions

diff --git a/contrib/libs/openssl/crypto/rsa/rsa_oaep.c b/contrib/libs/openssl/crypto/rsa/rsa_oaep.c
index fa35c7fe9c..302360a964 100644
--- a/contrib/libs/openssl/crypto/rsa/rsa_oaep.c
+++ b/contrib/libs/openssl/crypto/rsa/rsa_oaep.c
@@ -1,239 +1,239 @@
-/* 
+/*
  * Copyright 1999-2019 The OpenSSL Project Authors. All Rights Reserved.
- * 
- * Licensed under the OpenSSL license (the "License").  You may not use 
- * this file except in compliance with the License.  You can obtain a copy 
- * in the file LICENSE in the source distribution or at 
- * https://www.openssl.org/source/license.html 
- */ 
- 
-/* EME-OAEP as defined in RFC 2437 (PKCS #1 v2.0) */ 
- 
-/* 
- * See Victor Shoup, "OAEP reconsidered," Nov. 2000, <URL: 
- * http://www.shoup.net/papers/oaep.ps.Z> for problems with the security 
- * proof for the original OAEP scheme, which EME-OAEP is based on. A new 
- * proof can be found in E. Fujisaki, T. Okamoto, D. Pointcheval, J. Stern, 
- * "RSA-OEAP is Still Alive!", Dec. 2000, <URL: 
- * http://eprint.iacr.org/2000/061/>. The new proof has stronger requirements 
- * for the underlying permutation: "partial-one-wayness" instead of 
- * one-wayness.  For the RSA function, this is an equivalent notion. 
- */ 
- 
+ *
+ * Licensed under the OpenSSL license (the "License").  You may not use
+ * this file except in compliance with the License.  You can obtain a copy
+ * in the file LICENSE in the source distribution or at
+ * https://www.openssl.org/source/license.html
+ */
+
+/* EME-OAEP as defined in RFC 2437 (PKCS #1 v2.0) */
+
+/*
+ * See Victor Shoup, "OAEP reconsidered," Nov. 2000, <URL:
+ * http://www.shoup.net/papers/oaep.ps.Z> for problems with the security
+ * proof for the original OAEP scheme, which EME-OAEP is based on. A new
+ * proof can be found in E. Fujisaki, T. Okamoto, D. Pointcheval, J. Stern,
+ * "RSA-OEAP is Still Alive!", Dec. 2000, <URL:
+ * http://eprint.iacr.org/2000/061/>. The new proof has stronger requirements
+ * for the underlying permutation: "partial-one-wayness" instead of
+ * one-wayness.  For the RSA function, this is an equivalent notion.
+ */
+
 #include "internal/constant_time.h"
- 
-#include <stdio.h> 
-#include "internal/cryptlib.h" 
-#include <openssl/bn.h> 
-#include <openssl/evp.h> 
-#include <openssl/rand.h> 
-#include <openssl/sha.h> 
+
+#include <stdio.h>
+#include "internal/cryptlib.h"
+#include <openssl/bn.h>
+#include <openssl/evp.h>
+#include <openssl/rand.h>
+#include <openssl/sha.h>
 #include "rsa_local.h"
- 
-int RSA_padding_add_PKCS1_OAEP(unsigned char *to, int tlen, 
-                               const unsigned char *from, int flen, 
-                               const unsigned char *param, int plen) 
-{ 
-    return RSA_padding_add_PKCS1_OAEP_mgf1(to, tlen, from, flen, 
-                                           param, plen, NULL, NULL); 
-} 
- 
-int RSA_padding_add_PKCS1_OAEP_mgf1(unsigned char *to, int tlen, 
-                                    const unsigned char *from, int flen, 
-                                    const unsigned char *param, int plen, 
-                                    const EVP_MD *md, const EVP_MD *mgf1md) 
-{ 
-    int rv = 0; 
-    int i, emlen = tlen - 1; 
-    unsigned char *db, *seed; 
-    unsigned char *dbmask = NULL; 
-    unsigned char seedmask[EVP_MAX_MD_SIZE]; 
-    int mdlen, dbmask_len = 0; 
- 
-    if (md == NULL) 
-        md = EVP_sha1(); 
-    if (mgf1md == NULL) 
-        mgf1md = md; 
- 
-    mdlen = EVP_MD_size(md); 
- 
-    if (flen > emlen - 2 * mdlen - 1) { 
-        RSAerr(RSA_F_RSA_PADDING_ADD_PKCS1_OAEP_MGF1, 
-               RSA_R_DATA_TOO_LARGE_FOR_KEY_SIZE); 
-        return 0; 
-    } 
- 
-    if (emlen < 2 * mdlen + 1) { 
-        RSAerr(RSA_F_RSA_PADDING_ADD_PKCS1_OAEP_MGF1, 
-               RSA_R_KEY_SIZE_TOO_SMALL); 
-        return 0; 
-    } 
- 
-    to[0] = 0; 
-    seed = to + 1; 
-    db = to + mdlen + 1; 
- 
-    if (!EVP_Digest((void *)param, plen, db, NULL, md, NULL)) 
-        goto err; 
-    memset(db + mdlen, 0, emlen - flen - 2 * mdlen - 1); 
-    db[emlen - flen - mdlen - 1] = 0x01; 
-    memcpy(db + emlen - flen - mdlen, from, (unsigned int)flen); 
-    if (RAND_bytes(seed, mdlen) <= 0) 
-        goto err; 
- 
-    dbmask_len = emlen - mdlen; 
-    dbmask = OPENSSL_malloc(dbmask_len); 
-    if (dbmask == NULL) { 
-        RSAerr(RSA_F_RSA_PADDING_ADD_PKCS1_OAEP_MGF1, ERR_R_MALLOC_FAILURE); 
-        goto err; 
-    } 
- 
-    if (PKCS1_MGF1(dbmask, dbmask_len, seed, mdlen, mgf1md) < 0) 
-        goto err; 
-    for (i = 0; i < dbmask_len; i++) 
-        db[i] ^= dbmask[i]; 
- 
-    if (PKCS1_MGF1(seedmask, mdlen, db, dbmask_len, mgf1md) < 0) 
-        goto err; 
-    for (i = 0; i < mdlen; i++) 
-        seed[i] ^= seedmask[i]; 
-    rv = 1; 
- 
- err: 
-    OPENSSL_cleanse(seedmask, sizeof(seedmask)); 
-    OPENSSL_clear_free(dbmask, dbmask_len); 
-    return rv; 
-} 
- 
-int RSA_padding_check_PKCS1_OAEP(unsigned char *to, int tlen, 
-                                 const unsigned char *from, int flen, int num, 
-                                 const unsigned char *param, int plen) 
-{ 
-    return RSA_padding_check_PKCS1_OAEP_mgf1(to, tlen, from, flen, num, 
-                                             param, plen, NULL, NULL); 
-} 
- 
-int RSA_padding_check_PKCS1_OAEP_mgf1(unsigned char *to, int tlen, 
-                                      const unsigned char *from, int flen, 
-                                      int num, const unsigned char *param, 
-                                      int plen, const EVP_MD *md, 
-                                      const EVP_MD *mgf1md) 
-{ 
-    int i, dblen = 0, mlen = -1, one_index = 0, msg_index; 
-    unsigned int good = 0, found_one_byte, mask; 
-    const unsigned char *maskedseed, *maskeddb; 
-    /* 
-     * |em| is the encoded message, zero-padded to exactly |num| bytes: em = 
-     * Y || maskedSeed || maskedDB 
-     */ 
-    unsigned char *db = NULL, *em = NULL, seed[EVP_MAX_MD_SIZE], 
-        phash[EVP_MAX_MD_SIZE]; 
-    int mdlen; 
- 
-    if (md == NULL) 
-        md = EVP_sha1(); 
-    if (mgf1md == NULL) 
-        mgf1md = md; 
- 
-    mdlen = EVP_MD_size(md); 
- 
-    if (tlen <= 0 || flen <= 0) 
-        return -1; 
-    /* 
-     * |num| is the length of the modulus; |flen| is the length of the 
-     * encoded message. Therefore, for any |from| that was obtained by 
-     * decrypting a ciphertext, we must have |flen| <= |num|. Similarly, 
+
+int RSA_padding_add_PKCS1_OAEP(unsigned char *to, int tlen,
+                               const unsigned char *from, int flen,
+                               const unsigned char *param, int plen)
+{
+    return RSA_padding_add_PKCS1_OAEP_mgf1(to, tlen, from, flen,
+                                           param, plen, NULL, NULL);
+}
+
+int RSA_padding_add_PKCS1_OAEP_mgf1(unsigned char *to, int tlen,
+                                    const unsigned char *from, int flen,
+                                    const unsigned char *param, int plen,
+                                    const EVP_MD *md, const EVP_MD *mgf1md)
+{
+    int rv = 0;
+    int i, emlen = tlen - 1;
+    unsigned char *db, *seed;
+    unsigned char *dbmask = NULL;
+    unsigned char seedmask[EVP_MAX_MD_SIZE];
+    int mdlen, dbmask_len = 0;
+
+    if (md == NULL)
+        md = EVP_sha1();
+    if (mgf1md == NULL)
+        mgf1md = md;
+
+    mdlen = EVP_MD_size(md);
+
+    if (flen > emlen - 2 * mdlen - 1) {
+        RSAerr(RSA_F_RSA_PADDING_ADD_PKCS1_OAEP_MGF1,
+               RSA_R_DATA_TOO_LARGE_FOR_KEY_SIZE);
+        return 0;
+    }
+
+    if (emlen < 2 * mdlen + 1) {
+        RSAerr(RSA_F_RSA_PADDING_ADD_PKCS1_OAEP_MGF1,
+               RSA_R_KEY_SIZE_TOO_SMALL);
+        return 0;
+    }
+
+    to[0] = 0;
+    seed = to + 1;
+    db = to + mdlen + 1;
+
+    if (!EVP_Digest((void *)param, plen, db, NULL, md, NULL))
+        goto err;
+    memset(db + mdlen, 0, emlen - flen - 2 * mdlen - 1);
+    db[emlen - flen - mdlen - 1] = 0x01;
+    memcpy(db + emlen - flen - mdlen, from, (unsigned int)flen);
+    if (RAND_bytes(seed, mdlen) <= 0)
+        goto err;
+
+    dbmask_len = emlen - mdlen;
+    dbmask = OPENSSL_malloc(dbmask_len);
+    if (dbmask == NULL) {
+        RSAerr(RSA_F_RSA_PADDING_ADD_PKCS1_OAEP_MGF1, ERR_R_MALLOC_FAILURE);
+        goto err;
+    }
+
+    if (PKCS1_MGF1(dbmask, dbmask_len, seed, mdlen, mgf1md) < 0)
+        goto err;
+    for (i = 0; i < dbmask_len; i++)
+        db[i] ^= dbmask[i];
+
+    if (PKCS1_MGF1(seedmask, mdlen, db, dbmask_len, mgf1md) < 0)
+        goto err;
+    for (i = 0; i < mdlen; i++)
+        seed[i] ^= seedmask[i];
+    rv = 1;
+
+ err:
+    OPENSSL_cleanse(seedmask, sizeof(seedmask));
+    OPENSSL_clear_free(dbmask, dbmask_len);
+    return rv;
+}
+
+int RSA_padding_check_PKCS1_OAEP(unsigned char *to, int tlen,
+                                 const unsigned char *from, int flen, int num,
+                                 const unsigned char *param, int plen)
+{
+    return RSA_padding_check_PKCS1_OAEP_mgf1(to, tlen, from, flen, num,
+                                             param, plen, NULL, NULL);
+}
+
+int RSA_padding_check_PKCS1_OAEP_mgf1(unsigned char *to, int tlen,
+                                      const unsigned char *from, int flen,
+                                      int num, const unsigned char *param,
+                                      int plen, const EVP_MD *md,
+                                      const EVP_MD *mgf1md)
+{
+    int i, dblen = 0, mlen = -1, one_index = 0, msg_index;
+    unsigned int good = 0, found_one_byte, mask;
+    const unsigned char *maskedseed, *maskeddb;
+    /*
+     * |em| is the encoded message, zero-padded to exactly |num| bytes: em =
+     * Y || maskedSeed || maskedDB
+     */
+    unsigned char *db = NULL, *em = NULL, seed[EVP_MAX_MD_SIZE],
+        phash[EVP_MAX_MD_SIZE];
+    int mdlen;
+
+    if (md == NULL)
+        md = EVP_sha1();
+    if (mgf1md == NULL)
+        mgf1md = md;
+
+    mdlen = EVP_MD_size(md);
+
+    if (tlen <= 0 || flen <= 0)
+        return -1;
+    /*
+     * |num| is the length of the modulus; |flen| is the length of the
+     * encoded message. Therefore, for any |from| that was obtained by
+     * decrypting a ciphertext, we must have |flen| <= |num|. Similarly,
      * |num| >= 2 * |mdlen| + 2 must hold for the modulus irrespective of
-     * the ciphertext, see PKCS #1 v2.2, section 7.1.2. 
-     * This does not leak any side-channel information. 
-     */ 
-    if (num < flen || num < 2 * mdlen + 2) { 
-        RSAerr(RSA_F_RSA_PADDING_CHECK_PKCS1_OAEP_MGF1, 
-               RSA_R_OAEP_DECODING_ERROR); 
-        return -1; 
-    } 
- 
-    dblen = num - mdlen - 1; 
-    db = OPENSSL_malloc(dblen); 
-    if (db == NULL) { 
-        RSAerr(RSA_F_RSA_PADDING_CHECK_PKCS1_OAEP_MGF1, ERR_R_MALLOC_FAILURE); 
-        goto cleanup; 
-    } 
- 
-    em = OPENSSL_malloc(num); 
-    if (em == NULL) { 
-        RSAerr(RSA_F_RSA_PADDING_CHECK_PKCS1_OAEP_MGF1, 
-               ERR_R_MALLOC_FAILURE); 
-        goto cleanup; 
-    } 
- 
-    /* 
-     * Caller is encouraged to pass zero-padded message created with 
-     * BN_bn2binpad. Trouble is that since we can't read out of |from|'s 
-     * bounds, it's impossible to have an invariant memory access pattern 
-     * in case |from| was not zero-padded in advance. 
-     */ 
-    for (from += flen, em += num, i = 0; i < num; i++) { 
-        mask = ~constant_time_is_zero(flen); 
-        flen -= 1 & mask; 
-        from -= 1 & mask; 
-        *--em = *from & mask; 
-    } 
- 
-    /* 
-     * The first byte must be zero, however we must not leak if this is 
-     * true. See James H. Manger, "A Chosen Ciphertext  Attack on RSA 
-     * Optimal Asymmetric Encryption Padding (OAEP) [...]", CRYPTO 2001). 
-     */ 
+     * the ciphertext, see PKCS #1 v2.2, section 7.1.2.
+     * This does not leak any side-channel information.
+     */
+    if (num < flen || num < 2 * mdlen + 2) {
+        RSAerr(RSA_F_RSA_PADDING_CHECK_PKCS1_OAEP_MGF1,
+               RSA_R_OAEP_DECODING_ERROR);
+        return -1;
+    }
+
+    dblen = num - mdlen - 1;
+    db = OPENSSL_malloc(dblen);
+    if (db == NULL) {
+        RSAerr(RSA_F_RSA_PADDING_CHECK_PKCS1_OAEP_MGF1, ERR_R_MALLOC_FAILURE);
+        goto cleanup;
+    }
+
+    em = OPENSSL_malloc(num);
+    if (em == NULL) {
+        RSAerr(RSA_F_RSA_PADDING_CHECK_PKCS1_OAEP_MGF1,
+               ERR_R_MALLOC_FAILURE);
+        goto cleanup;
+    }
+
+    /*
+     * Caller is encouraged to pass zero-padded message created with
+     * BN_bn2binpad. Trouble is that since we can't read out of |from|'s
+     * bounds, it's impossible to have an invariant memory access pattern
+     * in case |from| was not zero-padded in advance.
+     */
+    for (from += flen, em += num, i = 0; i < num; i++) {
+        mask = ~constant_time_is_zero(flen);
+        flen -= 1 & mask;
+        from -= 1 & mask;
+        *--em = *from & mask;
+    }
+
+    /*
+     * The first byte must be zero, however we must not leak if this is
+     * true. See James H. Manger, "A Chosen Ciphertext  Attack on RSA
+     * Optimal Asymmetric Encryption Padding (OAEP) [...]", CRYPTO 2001).
+     */
     good = constant_time_is_zero(em[0]);
- 
+
     maskedseed = em + 1;
     maskeddb = em + 1 + mdlen;
- 
-    if (PKCS1_MGF1(seed, mdlen, maskeddb, dblen, mgf1md)) 
-        goto cleanup; 
-    for (i = 0; i < mdlen; i++) 
-        seed[i] ^= maskedseed[i]; 
- 
-    if (PKCS1_MGF1(db, dblen, seed, mdlen, mgf1md)) 
-        goto cleanup; 
-    for (i = 0; i < dblen; i++) 
-        db[i] ^= maskeddb[i]; 
- 
-    if (!EVP_Digest((void *)param, plen, phash, NULL, md, NULL)) 
-        goto cleanup; 
- 
-    good &= constant_time_is_zero(CRYPTO_memcmp(db, phash, mdlen)); 
- 
-    found_one_byte = 0; 
-    for (i = mdlen; i < dblen; i++) { 
-        /* 
-         * Padding consists of a number of 0-bytes, followed by a 1. 
-         */ 
-        unsigned int equals1 = constant_time_eq(db[i], 1); 
-        unsigned int equals0 = constant_time_is_zero(db[i]); 
-        one_index = constant_time_select_int(~found_one_byte & equals1, 
-                                             i, one_index); 
-        found_one_byte |= equals1; 
-        good &= (found_one_byte | equals0); 
-    } 
- 
-    good &= found_one_byte; 
- 
-    /* 
-     * At this point |good| is zero unless the plaintext was valid, 
-     * so plaintext-awareness ensures timing side-channels are no longer a 
-     * concern. 
-     */ 
-    msg_index = one_index + 1; 
-    mlen = dblen - msg_index; 
- 
-    /* 
+
+    if (PKCS1_MGF1(seed, mdlen, maskeddb, dblen, mgf1md))
+        goto cleanup;
+    for (i = 0; i < mdlen; i++)
+        seed[i] ^= maskedseed[i];
+
+    if (PKCS1_MGF1(db, dblen, seed, mdlen, mgf1md))
+        goto cleanup;
+    for (i = 0; i < dblen; i++)
+        db[i] ^= maskeddb[i];
+
+    if (!EVP_Digest((void *)param, plen, phash, NULL, md, NULL))
+        goto cleanup;
+
+    good &= constant_time_is_zero(CRYPTO_memcmp(db, phash, mdlen));
+
+    found_one_byte = 0;
+    for (i = mdlen; i < dblen; i++) {
+        /*
+         * Padding consists of a number of 0-bytes, followed by a 1.
+         */
+        unsigned int equals1 = constant_time_eq(db[i], 1);
+        unsigned int equals0 = constant_time_is_zero(db[i]);
+        one_index = constant_time_select_int(~found_one_byte & equals1,
+                                             i, one_index);
+        found_one_byte |= equals1;
+        good &= (found_one_byte | equals0);
+    }
+
+    good &= found_one_byte;
+
+    /*
+     * At this point |good| is zero unless the plaintext was valid,
+     * so plaintext-awareness ensures timing side-channels are no longer a
+     * concern.
+     */
+    msg_index = one_index + 1;
+    mlen = dblen - msg_index;
+
+    /*
      * For good measure, do this check in constant time as well.
-     */ 
-    good &= constant_time_ge(tlen, mlen); 
- 
-    /* 
+     */
+    good &= constant_time_ge(tlen, mlen);
+
+    /*
      * Move the result in-place by |dblen|-|mdlen|-1-|mlen| bytes to the left.
      * Then if |good| move |mlen| bytes from |db|+|mdlen|+1 to |to|.
      * Otherwise leave |to| unchanged.
@@ -242,72 +242,72 @@ int RSA_padding_check_PKCS1_OAEP_mgf1(unsigned char *to, int tlen,
      * parts of the buffer multiple times based on the bits set in the real
      * length. Clear bits do a non-copy with identical access pattern.
      * The loop below has overall complexity of O(N*log(N)).
-     */ 
+     */
     tlen = constant_time_select_int(constant_time_lt(dblen - mdlen - 1, tlen),
                                     dblen - mdlen - 1, tlen);
     for (msg_index = 1; msg_index < dblen - mdlen - 1; msg_index <<= 1) {
         mask = ~constant_time_eq(msg_index & (dblen - mdlen - 1 - mlen), 0);
         for (i = mdlen + 1; i < dblen - msg_index; i++)
             db[i] = constant_time_select_8(mask, db[i + msg_index], db[i]);
-    } 
+    }
     for (i = 0; i < tlen; i++) {
         mask = good & constant_time_lt(i, mlen);
         to[i] = constant_time_select_8(mask, db[i + mdlen + 1], to[i]);
     }
- 
-    /* 
-     * To avoid chosen ciphertext attacks, the error message should not 
-     * reveal which kind of decoding error happened. 
-     */ 
-    RSAerr(RSA_F_RSA_PADDING_CHECK_PKCS1_OAEP_MGF1, 
-           RSA_R_OAEP_DECODING_ERROR); 
-    err_clear_last_constant_time(1 & good); 
- cleanup: 
-    OPENSSL_cleanse(seed, sizeof(seed)); 
-    OPENSSL_clear_free(db, dblen); 
-    OPENSSL_clear_free(em, num); 
- 
-    return constant_time_select_int(good, mlen, -1); 
-} 
- 
-int PKCS1_MGF1(unsigned char *mask, long len, 
-               const unsigned char *seed, long seedlen, const EVP_MD *dgst) 
-{ 
-    long i, outlen = 0; 
-    unsigned char cnt[4]; 
-    EVP_MD_CTX *c = EVP_MD_CTX_new(); 
-    unsigned char md[EVP_MAX_MD_SIZE]; 
-    int mdlen; 
-    int rv = -1; 
- 
-    if (c == NULL) 
-        goto err; 
-    mdlen = EVP_MD_size(dgst); 
-    if (mdlen < 0) 
-        goto err; 
-    for (i = 0; outlen < len; i++) { 
-        cnt[0] = (unsigned char)((i >> 24) & 255); 
-        cnt[1] = (unsigned char)((i >> 16) & 255); 
-        cnt[2] = (unsigned char)((i >> 8)) & 255; 
-        cnt[3] = (unsigned char)(i & 255); 
-        if (!EVP_DigestInit_ex(c, dgst, NULL) 
-            || !EVP_DigestUpdate(c, seed, seedlen) 
-            || !EVP_DigestUpdate(c, cnt, 4)) 
-            goto err; 
-        if (outlen + mdlen <= len) { 
-            if (!EVP_DigestFinal_ex(c, mask + outlen, NULL)) 
-                goto err; 
-            outlen += mdlen; 
-        } else { 
-            if (!EVP_DigestFinal_ex(c, md, NULL)) 
-                goto err; 
-            memcpy(mask + outlen, md, len - outlen); 
-            outlen = len; 
-        } 
-    } 
-    rv = 0; 
- err: 
-    OPENSSL_cleanse(md, sizeof(md)); 
-    EVP_MD_CTX_free(c); 
-    return rv; 
-} 
+
+    /*
+     * To avoid chosen ciphertext attacks, the error message should not
+     * reveal which kind of decoding error happened.
+     */
+    RSAerr(RSA_F_RSA_PADDING_CHECK_PKCS1_OAEP_MGF1,
+           RSA_R_OAEP_DECODING_ERROR);
+    err_clear_last_constant_time(1 & good);
+ cleanup:
+    OPENSSL_cleanse(seed, sizeof(seed));
+    OPENSSL_clear_free(db, dblen);
+    OPENSSL_clear_free(em, num);
+
+    return constant_time_select_int(good, mlen, -1);
+}
+
+int PKCS1_MGF1(unsigned char *mask, long len,
+               const unsigned char *seed, long seedlen, const EVP_MD *dgst)
+{
+    long i, outlen = 0;
+    unsigned char cnt[4];
+    EVP_MD_CTX *c = EVP_MD_CTX_new();
+    unsigned char md[EVP_MAX_MD_SIZE];
+    int mdlen;
+    int rv = -1;
+
+    if (c == NULL)
+        goto err;
+    mdlen = EVP_MD_size(dgst);
+    if (mdlen < 0)
+        goto err;
+    for (i = 0; outlen < len; i++) {
+        cnt[0] = (unsigned char)((i >> 24) & 255);
+        cnt[1] = (unsigned char)((i >> 16) & 255);
+        cnt[2] = (unsigned char)((i >> 8)) & 255;
+        cnt[3] = (unsigned char)(i & 255);
+        if (!EVP_DigestInit_ex(c, dgst, NULL)
+            || !EVP_DigestUpdate(c, seed, seedlen)
+            || !EVP_DigestUpdate(c, cnt, 4))
+            goto err;
+        if (outlen + mdlen <= len) {
+            if (!EVP_DigestFinal_ex(c, mask + outlen, NULL))
+                goto err;
+            outlen += mdlen;
+        } else {
+            if (!EVP_DigestFinal_ex(c, md, NULL))
+                goto err;
+            memcpy(mask + outlen, md, len - outlen);
+            outlen = len;
+        }
+    }
+    rv = 0;
+ err:
+    OPENSSL_cleanse(md, sizeof(md));
+    EVP_MD_CTX_free(c);
+    return rv;
+}