/* Copyright (C) 1995-1998 Eric Young (eay@cryptsoft.com) * All rights reserved. * * This package is an SSL implementation written * by Eric Young (eay@cryptsoft.com). * The implementation was written so as to conform with Netscapes SSL. * * This library is free for commercial and non-commercial use as long as * the following conditions are aheared to. The following conditions * apply to all code found in this distribution, be it the RC4, RSA, * lhash, DES, etc., code; not just the SSL code. The SSL documentation * included with this distribution is covered by the same copyright terms * except that the holder is Tim Hudson (tjh@cryptsoft.com). * * Copyright remains Eric Young's, and as such any Copyright notices in * the code are not to be removed. * If this package is used in a product, Eric Young should be given attribution * as the author of the parts of the library used. * This can be in the form of a textual message at program startup or * in documentation (online or textual) provided with the package. * * Redistribution and use in source and binary forms, with or without * modification, are permitted provided that the following conditions * are met: * 1. Redistributions of source code must retain the copyright * notice, this list of conditions and the following disclaimer. * 2. Redistributions in binary form must reproduce the above copyright * notice, this list of conditions and the following disclaimer in the * documentation and/or other materials provided with the distribution. * 3. All advertising materials mentioning features or use of this software * must display the following acknowledgement: * "This product includes cryptographic software written by * Eric Young (eay@cryptsoft.com)" * The word 'cryptographic' can be left out if the rouines from the library * being used are not cryptographic related :-). * 4. If you include any Windows specific code (or a derivative thereof) from * the apps directory (application code) you must include an acknowledgement: * "This product includes software written by Tim Hudson (tjh@cryptsoft.com)" * * THIS SOFTWARE IS PROVIDED BY ERIC YOUNG ``AS IS'' AND * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF * SUCH DAMAGE. * * The licence and distribution terms for any publically available version or * derivative of this code cannot be changed. i.e. this code cannot simply be * copied and put under another distribution licence * [including the GNU Public Licence.] */ /* ==================================================================== * Copyright (c) 1998-2002 The OpenSSL Project. All rights reserved. * * Redistribution and use in source and binary forms, with or without * modification, are permitted provided that the following conditions * are met: * * 1. Redistributions of source code must retain the above copyright * notice, this list of conditions and the following disclaimer. * * 2. Redistributions in binary form must reproduce the above copyright * notice, this list of conditions and the following disclaimer in * the documentation and/or other materials provided with the * distribution. * * 3. All advertising materials mentioning features or use of this * software must display the following acknowledgment: * "This product includes software developed by the OpenSSL Project * for use in the OpenSSL Toolkit. (http://www.openssl.org/)" * * 4. The names "OpenSSL Toolkit" and "OpenSSL Project" must not be used to * endorse or promote products derived from this software without * prior written permission. For written permission, please contact * openssl-core@openssl.org. * * 5. Products derived from this software may not be called "OpenSSL" * nor may "OpenSSL" appear in their names without prior written * permission of the OpenSSL Project. * * 6. Redistributions of any form whatsoever must retain the following * acknowledgment: * "This product includes software developed by the OpenSSL Project * for use in the OpenSSL Toolkit (http://www.openssl.org/)" * * THIS SOFTWARE IS PROVIDED BY THE OpenSSL PROJECT ``AS IS'' AND ANY * EXPRESSED OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR * PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE OpenSSL PROJECT OR * ITS CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, * STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED * OF THE POSSIBILITY OF SUCH DAMAGE. * ==================================================================== * * This product includes cryptographic software written by Eric Young * (eay@cryptsoft.com). This product includes software written by Tim * Hudson (tjh@cryptsoft.com). */ /* ==================================================================== * Copyright 2002 Sun Microsystems, Inc. ALL RIGHTS RESERVED. * ECC cipher suite support in OpenSSL originally developed by * SUN MICROSYSTEMS, INC., and contributed to the OpenSSL project. */ #include #include #include #include #include #include #include #include #include #include #include #include #include #include "internal.h" /* ssl3_do_write sends |s->init_buf| in records of type 'type' * (SSL3_RT_HANDSHAKE or SSL3_RT_CHANGE_CIPHER_SPEC). It returns -1 on error, 1 * on success or zero if the transmission is still incomplete. */ int ssl3_do_write(SSL *s, int type) { int n; n = ssl3_write_bytes(s, type, &s->init_buf->data[s->init_off], s->init_num); if (n < 0) { return -1; } if (n == s->init_num) { if (s->msg_callback) { s->msg_callback(1, s->version, type, s->init_buf->data, (size_t)(s->init_off + s->init_num), s, s->msg_callback_arg); } return 1; } s->init_off += n; s->init_num -= n; return 0; } int ssl3_send_finished(SSL *s, int a, int b, const char *sender, int slen) { uint8_t *p; int n; if (s->state == a) { p = ssl_handshake_start(s); n = s->enc_method->final_finish_mac(s, sender, slen, s->s3->tmp.finish_md); if (n == 0) { return 0; } s->s3->tmp.finish_md_len = n; memcpy(p, s->s3->tmp.finish_md, n); /* Log the master secret, if logging is enabled. */ if (!ssl_ctx_log_master_secret(s->ctx, s->s3->client_random, SSL3_RANDOM_SIZE, s->session->master_key, s->session->master_key_length)) { return 0; } /* Copy the finished so we can use it for renegotiation checks */ if (s->server) { assert(n <= EVP_MAX_MD_SIZE); memcpy(s->s3->previous_server_finished, s->s3->tmp.finish_md, n); s->s3->previous_server_finished_len = n; } else { assert(n <= EVP_MAX_MD_SIZE); memcpy(s->s3->previous_client_finished, s->s3->tmp.finish_md, n); s->s3->previous_client_finished_len = n; } if (!ssl_set_handshake_header(s, SSL3_MT_FINISHED, n)) { return 0; } s->state = b; } /* SSL3_ST_SEND_xxxxxx_HELLO_B */ return ssl_do_write(s); } /* ssl3_take_mac calculates the Finished MAC for the handshakes messages seen to * far. */ static void ssl3_take_mac(SSL *s) { const char *sender; int slen; /* If no new cipher setup then return immediately: other functions will set * the appropriate error. */ if (s->s3->tmp.new_cipher == NULL) { return; } if (s->state & SSL_ST_CONNECT) { sender = s->enc_method->server_finished_label; slen = s->enc_method->server_finished_label_len; } else { sender = s->enc_method->client_finished_label; slen = s->enc_method->client_finished_label_len; } s->s3->tmp.peer_finish_md_len = s->enc_method->final_finish_mac( s, sender, slen, s->s3->tmp.peer_finish_md); } int ssl3_get_finished(SSL *s, int a, int b) { int al, finished_len, ok; long message_len; uint8_t *p; message_len = s->method->ssl_get_message(s, a, b, SSL3_MT_FINISHED, EVP_MAX_MD_SIZE, ssl_dont_hash_message, &ok); if (!ok) { return message_len; } /* Snapshot the finished hash before incorporating the new message. */ ssl3_take_mac(s); if (!ssl3_hash_current_message(s)) { goto err; } /* If this occurs, we have missed a message. * TODO(davidben): Is this check now redundant with SSL3_FLAGS_EXPECT_CCS? */ if (!s->s3->change_cipher_spec) { al = SSL_AD_UNEXPECTED_MESSAGE; OPENSSL_PUT_ERROR(SSL, ssl3_get_finished, SSL_R_GOT_A_FIN_BEFORE_A_CCS); goto f_err; } s->s3->change_cipher_spec = 0; p = s->init_msg; finished_len = s->s3->tmp.peer_finish_md_len; if (finished_len != message_len) { al = SSL_AD_DECODE_ERROR; OPENSSL_PUT_ERROR(SSL, ssl3_get_finished, SSL_R_BAD_DIGEST_LENGTH); goto f_err; } if (CRYPTO_memcmp(p, s->s3->tmp.peer_finish_md, finished_len) != 0) { al = SSL_AD_DECRYPT_ERROR; OPENSSL_PUT_ERROR(SSL, ssl3_get_finished, SSL_R_DIGEST_CHECK_FAILED); goto f_err; } /* Copy the finished so we can use it for renegotiation checks */ if (s->server) { assert(finished_len <= EVP_MAX_MD_SIZE); memcpy(s->s3->previous_client_finished, s->s3->tmp.peer_finish_md, finished_len); s->s3->previous_client_finished_len = finished_len; } else { assert(finished_len <= EVP_MAX_MD_SIZE); memcpy(s->s3->previous_server_finished, s->s3->tmp.peer_finish_md, finished_len); s->s3->previous_server_finished_len = finished_len; } return 1; f_err: ssl3_send_alert(s, SSL3_AL_FATAL, al); err: return 0; } /* for these 2 messages, we need to * ssl->enc_read_ctx re-init * ssl->s3->read_sequence zero * ssl->s3->read_mac_secret re-init * ssl->session->read_sym_enc assign * ssl->session->read_compression assign * ssl->session->read_hash assign */ int ssl3_send_change_cipher_spec(SSL *s, int a, int b) { if (s->state == a) { *((uint8_t *)s->init_buf->data) = SSL3_MT_CCS; s->init_num = 1; s->init_off = 0; s->state = b; } /* SSL3_ST_CW_CHANGE_B */ return ssl3_do_write(s, SSL3_RT_CHANGE_CIPHER_SPEC); } int ssl3_output_cert_chain(SSL *s, CERT_PKEY *cpk) { uint8_t *p; unsigned long l = 3 + SSL_HM_HEADER_LENGTH(s); if (!ssl_add_cert_chain(s, cpk, &l)) { return 0; } l -= 3 + SSL_HM_HEADER_LENGTH(s); p = ssl_handshake_start(s); l2n3(l, p); l += 3; return ssl_set_handshake_header(s, SSL3_MT_CERTIFICATE, l); } /* Obtain handshake message of message type |msg_type| (any if |msg_type| == -1), * maximum acceptable body length |max|. The first four bytes (msg_type and * length) are read in state |header_state|, the body is read in state |body_state|. */ long ssl3_get_message(SSL *s, int header_state, int body_state, int msg_type, long max, enum ssl_hash_message_t hash_message, int *ok) { uint8_t *p; unsigned long l; long n; int al; if (s->s3->tmp.reuse_message) { /* A ssl_dont_hash_message call cannot be combined with reuse_message; the * ssl_dont_hash_message would have to have been applied to the previous * call. */ assert(hash_message == ssl_hash_message); s->s3->tmp.reuse_message = 0; if (msg_type >= 0 && s->s3->tmp.message_type != msg_type) { al = SSL_AD_UNEXPECTED_MESSAGE; OPENSSL_PUT_ERROR(SSL, ssl3_get_message, SSL_R_UNEXPECTED_MESSAGE); goto f_err; } *ok = 1; s->state = body_state; s->init_msg = (uint8_t *)s->init_buf->data + 4; s->init_num = (int)s->s3->tmp.message_size; return s->init_num; } p = (uint8_t *)s->init_buf->data; if (s->state == header_state) { assert(s->init_num < 4); for (;;) { while (s->init_num < 4) { int bytes_read = s->method->ssl_read_bytes( s, SSL3_RT_HANDSHAKE, &p[s->init_num], 4 - s->init_num, 0); if (bytes_read <= 0) { *ok = 0; return bytes_read; } s->init_num += bytes_read; } static const uint8_t kHelloRequest[4] = {SSL3_MT_HELLO_REQUEST, 0, 0, 0}; if (s->server || memcmp(p, kHelloRequest, sizeof(kHelloRequest)) != 0) { break; } /* The server may always send 'Hello Request' messages -- we are doing * a handshake anyway now, so ignore them if their format is correct. * Does not count for 'Finished' MAC. */ s->init_num = 0; if (s->msg_callback) { s->msg_callback(0, s->version, SSL3_RT_HANDSHAKE, p, 4, s, s->msg_callback_arg); } } /* s->init_num == 4 */ if (msg_type >= 0 && *p != msg_type) { al = SSL_AD_UNEXPECTED_MESSAGE; OPENSSL_PUT_ERROR(SSL, ssl3_get_message, SSL_R_UNEXPECTED_MESSAGE); goto f_err; } s->s3->tmp.message_type = *(p++); n2l3(p, l); if (l > (unsigned long)max) { al = SSL_AD_ILLEGAL_PARAMETER; OPENSSL_PUT_ERROR(SSL, ssl3_get_message, SSL_R_EXCESSIVE_MESSAGE_SIZE); goto f_err; } if (l && !BUF_MEM_grow_clean(s->init_buf, l + 4)) { OPENSSL_PUT_ERROR(SSL, ssl3_get_message, ERR_R_BUF_LIB); goto err; } s->s3->tmp.message_size = l; s->state = body_state; s->init_msg = (uint8_t *)s->init_buf->data + 4; s->init_num = 0; } /* next state (body_state) */ p = s->init_msg; n = s->s3->tmp.message_size - s->init_num; while (n > 0) { int bytes_read = s->method->ssl_read_bytes(s, SSL3_RT_HANDSHAKE, &p[s->init_num], n, 0); if (bytes_read <= 0) { s->rwstate = SSL_READING; *ok = 0; return bytes_read; } s->init_num += bytes_read; n -= bytes_read; } /* Feed this message into MAC computation. */ if (hash_message == ssl_hash_message && !ssl3_hash_current_message(s)) { goto err; } if (s->msg_callback) { s->msg_callback(0, s->version, SSL3_RT_HANDSHAKE, s->init_buf->data, (size_t)s->init_num + 4, s, s->msg_callback_arg); } *ok = 1; return s->init_num; f_err: ssl3_send_alert(s, SSL3_AL_FATAL, al); err: *ok = 0; return -1; } int ssl3_hash_current_message(SSL *s) { /* The handshake header (different size between DTLS and TLS) is included in * the hash. */ size_t header_len = s->init_msg - (uint8_t *)s->init_buf->data; return ssl3_finish_mac(s, (uint8_t *)s->init_buf->data, s->init_num + header_len); } /* ssl3_cert_verify_hash is documented as needing EVP_MAX_MD_SIZE because that * is sufficient pre-TLS1.2 as well. */ OPENSSL_COMPILE_ASSERT(EVP_MAX_MD_SIZE > MD5_DIGEST_LENGTH + SHA_DIGEST_LENGTH, combined_tls_hash_fits_in_max); int ssl3_cert_verify_hash(SSL *s, uint8_t *out, size_t *out_len, const EVP_MD **out_md, EVP_PKEY *pkey) { /* For TLS v1.2 send signature algorithm and signature using * agreed digest and cached handshake records. Otherwise, use * SHA1 or MD5 + SHA1 depending on key type. */ if (SSL_USE_SIGALGS(s)) { const uint8_t *hdata; size_t hdatalen; EVP_MD_CTX mctx; unsigned len; if (!BIO_mem_contents(s->s3->handshake_buffer, &hdata, &hdatalen)) { OPENSSL_PUT_ERROR(SSL, ssl3_cert_verify_hash, ERR_R_INTERNAL_ERROR); return 0; } EVP_MD_CTX_init(&mctx); if (!EVP_DigestInit_ex(&mctx, *out_md, NULL) || !EVP_DigestUpdate(&mctx, hdata, hdatalen) || !EVP_DigestFinal(&mctx, out, &len)) { OPENSSL_PUT_ERROR(SSL, ssl3_cert_verify_hash, ERR_R_EVP_LIB); EVP_MD_CTX_cleanup(&mctx); return 0; } *out_len = len; } else if (pkey->type == EVP_PKEY_RSA) { if (s->enc_method->cert_verify_mac(s, NID_md5, out) == 0 || s->enc_method->cert_verify_mac(s, NID_sha1, out + MD5_DIGEST_LENGTH) == 0) { return 0; } *out_len = MD5_DIGEST_LENGTH + SHA_DIGEST_LENGTH; *out_md = EVP_md5_sha1(); } else if (pkey->type == EVP_PKEY_EC) { if (s->enc_method->cert_verify_mac(s, NID_sha1, out) == 0) { return 0; } *out_len = SHA_DIGEST_LENGTH; *out_md = EVP_sha1(); } else { OPENSSL_PUT_ERROR(SSL, ssl3_cert_verify_hash, ERR_R_INTERNAL_ERROR); return 0; } return 1; } int ssl_cert_type(EVP_PKEY *pkey) { switch (pkey->type) { case EVP_PKEY_RSA: return SSL_PKEY_RSA_ENC; case EVP_PKEY_EC: return SSL_PKEY_ECC; default: return -1; } } int ssl_verify_alarm_type(long type) { int al; switch (type) { case X509_V_ERR_UNABLE_TO_GET_ISSUER_CERT: case X509_V_ERR_UNABLE_TO_GET_CRL: case X509_V_ERR_UNABLE_TO_GET_CRL_ISSUER: al = SSL_AD_UNKNOWN_CA; break; case X509_V_ERR_UNABLE_TO_DECRYPT_CERT_SIGNATURE: case X509_V_ERR_UNABLE_TO_DECRYPT_CRL_SIGNATURE: case X509_V_ERR_UNABLE_TO_DECODE_ISSUER_PUBLIC_KEY: case X509_V_ERR_ERROR_IN_CERT_NOT_BEFORE_FIELD: case X509_V_ERR_ERROR_IN_CERT_NOT_AFTER_FIELD: case X509_V_ERR_ERROR_IN_CRL_LAST_UPDATE_FIELD: case X509_V_ERR_ERROR_IN_CRL_NEXT_UPDATE_FIELD: case X509_V_ERR_CERT_NOT_YET_VALID: case X509_V_ERR_CRL_NOT_YET_VALID: case X509_V_ERR_CERT_UNTRUSTED: case X509_V_ERR_CERT_REJECTED: al = SSL_AD_BAD_CERTIFICATE; break; case X509_V_ERR_CERT_SIGNATURE_FAILURE: case X509_V_ERR_CRL_SIGNATURE_FAILURE: al = SSL_AD_DECRYPT_ERROR; break; case X509_V_ERR_CERT_HAS_EXPIRED: case X509_V_ERR_CRL_HAS_EXPIRED: al = SSL_AD_CERTIFICATE_EXPIRED; break; case X509_V_ERR_CERT_REVOKED: al = SSL_AD_CERTIFICATE_REVOKED; break; case X509_V_ERR_OUT_OF_MEM: al = SSL_AD_INTERNAL_ERROR; break; case X509_V_ERR_DEPTH_ZERO_SELF_SIGNED_CERT: case X509_V_ERR_SELF_SIGNED_CERT_IN_CHAIN: case X509_V_ERR_UNABLE_TO_GET_ISSUER_CERT_LOCALLY: case X509_V_ERR_UNABLE_TO_VERIFY_LEAF_SIGNATURE: case X509_V_ERR_CERT_CHAIN_TOO_LONG: case X509_V_ERR_PATH_LENGTH_EXCEEDED: case X509_V_ERR_INVALID_CA: al = SSL_AD_UNKNOWN_CA; break; case X509_V_ERR_APPLICATION_VERIFICATION: al = SSL_AD_HANDSHAKE_FAILURE; break; case X509_V_ERR_INVALID_PURPOSE: al = SSL_AD_UNSUPPORTED_CERTIFICATE; break; default: al = SSL_AD_CERTIFICATE_UNKNOWN; break; } return al; } int ssl3_setup_read_buffer(SSL *s) { uint8_t *p; size_t len, align = 0, headerlen; if (SSL_IS_DTLS(s)) { headerlen = DTLS1_RT_HEADER_LENGTH; } else { headerlen = SSL3_RT_HEADER_LENGTH; } #if defined(SSL3_ALIGN_PAYLOAD) && SSL3_ALIGN_PAYLOAD != 0 align = (-SSL3_RT_HEADER_LENGTH) & (SSL3_ALIGN_PAYLOAD - 1); #endif if (s->s3->rbuf.buf == NULL) { len = SSL3_RT_MAX_ENCRYPTED_LENGTH + headerlen + align; if (s->options & SSL_OP_MICROSOFT_BIG_SSLV3_BUFFER) { s->s3->init_extra = 1; len += SSL3_RT_MAX_EXTRA; } p = OPENSSL_malloc(len); if (p == NULL) { goto err; } s->s3->rbuf.buf = p; s->s3->rbuf.len = len; } s->packet = &s->s3->rbuf.buf[0]; return 1; err: OPENSSL_PUT_ERROR(SSL, ssl3_setup_read_buffer, ERR_R_MALLOC_FAILURE); return 0; } int ssl3_setup_write_buffer(SSL *s) { uint8_t *p; size_t len, align = 0, headerlen; if (SSL_IS_DTLS(s)) { headerlen = DTLS1_RT_HEADER_LENGTH + 1; } else { headerlen = SSL3_RT_HEADER_LENGTH; } #if defined(SSL3_ALIGN_PAYLOAD) && SSL3_ALIGN_PAYLOAD != 0 align = (-SSL3_RT_HEADER_LENGTH) & (SSL3_ALIGN_PAYLOAD - 1); #endif if (s->s3->wbuf.buf == NULL) { len = s->max_send_fragment + SSL3_RT_SEND_MAX_ENCRYPTED_OVERHEAD + headerlen + align; /* Account for 1/n-1 record splitting. */ if (s->mode & SSL_MODE_CBC_RECORD_SPLITTING) { len += headerlen + align + 1 + SSL3_RT_SEND_MAX_ENCRYPTED_OVERHEAD; } p = OPENSSL_malloc(len); if (p == NULL) { goto err; } s->s3->wbuf.buf = p; s->s3->wbuf.len = len; } return 1; err: OPENSSL_PUT_ERROR(SSL, ssl3_setup_write_buffer, ERR_R_MALLOC_FAILURE); return 0; } int ssl3_setup_buffers(SSL *s) { if (!ssl3_setup_read_buffer(s) || !ssl3_setup_write_buffer(s)) { return 0; } return 1; } int ssl3_release_write_buffer(SSL *s) { OPENSSL_free(s->s3->wbuf.buf); s->s3->wbuf.buf = NULL; return 1; } int ssl3_release_read_buffer(SSL *s) { OPENSSL_free(s->s3->rbuf.buf); s->s3->rbuf.buf = NULL; return 1; } /* ssl_fill_hello_random fills a client_random or server_random field of length * |len|. Returns 0 on failure or 1 on success. */ int ssl_fill_hello_random(SSL *s, int server, uint8_t *result, size_t len) { int send_time = 0; if (server) { send_time = (s->mode & SSL_MODE_SEND_SERVERHELLO_TIME) != 0; } else { send_time = (s->mode & SSL_MODE_SEND_CLIENTHELLO_TIME) != 0; } if (send_time) { const uint32_t current_time = time(NULL); uint8_t *p = result; if (len < 4) { return 0; } p[0] = current_time >> 24; p[1] = current_time >> 16; p[2] = current_time >> 8; p[3] = current_time; return RAND_bytes(p + 4, len - 4); } else { return RAND_bytes(result, len); } }