1 /* $OpenBSD: ssh-ed25519.c,v 1.3 2014/02/23 20:03:42 djm Exp $ */ 2 /* 3 * Copyright (c) 2013 Markus Friedl <markus@openbsd.org> 4 * 5 * Permission to use, copy, modify, and distribute this software for any 6 * purpose with or without fee is hereby granted, provided that the above 7 * copyright notice and this permission notice appear in all copies. 8 * 9 * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES 10 * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF 11 * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR 12 * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES 13 * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN 14 * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF 15 * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE. 16 */ 17 18 #include "includes.h" 19 20 #include <sys/types.h> 21 22 #include "crypto_api.h" 23 24 #include <limits.h> 25 #include <string.h> 26 #include <stdarg.h> 27 28 #include "xmalloc.h" 29 #include "log.h" 30 #include "buffer.h" 31 #include "key.h" 32 #include "ssh.h" 33 34 int 35 ssh_ed25519_sign(const Key *key, u_char **sigp, u_int *lenp, 36 const u_char *data, u_int datalen) 37 { 38 u_char *sig; 39 u_int slen, len; 40 unsigned long long smlen; 41 int ret; 42 Buffer b; 43 44 if (key == NULL || key_type_plain(key->type) != KEY_ED25519 || 45 key->ed25519_sk == NULL) { 46 error("%s: no ED25519 key", __func__); 47 return -1; 48 } 49 50 if (datalen >= UINT_MAX - crypto_sign_ed25519_BYTES) { 51 error("%s: datalen %u too long", __func__, datalen); 52 return -1; 53 } 54 smlen = slen = datalen + crypto_sign_ed25519_BYTES; 55 sig = xmalloc(slen); 56 57 if ((ret = crypto_sign_ed25519(sig, &smlen, data, datalen, 58 key->ed25519_sk)) != 0 || smlen <= datalen) { 59 error("%s: crypto_sign_ed25519 failed: %d", __func__, ret); 60 free(sig); 61 return -1; 62 } 63 /* encode signature */ 64 buffer_init(&b); 65 buffer_put_cstring(&b, "ssh-ed25519"); 66 buffer_put_string(&b, sig, smlen - datalen); 67 len = buffer_len(&b); 68 if (lenp != NULL) 69 *lenp = len; 70 if (sigp != NULL) { 71 *sigp = xmalloc(len); 72 memcpy(*sigp, buffer_ptr(&b), len); 73 } 74 buffer_free(&b); 75 explicit_bzero(sig, slen); 76 free(sig); 77 78 return 0; 79 } 80 81 int 82 ssh_ed25519_verify(const Key *key, const u_char *signature, u_int signaturelen, 83 const u_char *data, u_int datalen) 84 { 85 Buffer b; 86 char *ktype; 87 u_char *sigblob, *sm, *m; 88 u_int len; 89 unsigned long long smlen, mlen; 90 int rlen, ret; 91 92 if (key == NULL || key_type_plain(key->type) != KEY_ED25519 || 93 key->ed25519_pk == NULL) { 94 error("%s: no ED25519 key", __func__); 95 return -1; 96 } 97 buffer_init(&b); 98 buffer_append(&b, signature, signaturelen); 99 ktype = buffer_get_cstring(&b, NULL); 100 if (strcmp("ssh-ed25519", ktype) != 0) { 101 error("%s: cannot handle type %s", __func__, ktype); 102 buffer_free(&b); 103 free(ktype); 104 return -1; 105 } 106 free(ktype); 107 sigblob = buffer_get_string(&b, &len); 108 rlen = buffer_len(&b); 109 buffer_free(&b); 110 if (rlen != 0) { 111 error("%s: remaining bytes in signature %d", __func__, rlen); 112 free(sigblob); 113 return -1; 114 } 115 if (len > crypto_sign_ed25519_BYTES) { 116 error("%s: len %u > crypto_sign_ed25519_BYTES %u", __func__, 117 len, crypto_sign_ed25519_BYTES); 118 free(sigblob); 119 return -1; 120 } 121 smlen = len + datalen; 122 sm = xmalloc(smlen); 123 memcpy(sm, sigblob, len); 124 memcpy(sm+len, data, datalen); 125 mlen = smlen; 126 m = xmalloc(mlen); 127 if ((ret = crypto_sign_ed25519_open(m, &mlen, sm, smlen, 128 key->ed25519_pk)) != 0) { 129 debug2("%s: crypto_sign_ed25519_open failed: %d", 130 __func__, ret); 131 } 132 if (ret == 0 && mlen != datalen) { 133 debug2("%s: crypto_sign_ed25519_open " 134 "mlen != datalen (%llu != %u)", __func__, mlen, datalen); 135 ret = -1; 136 } 137 /* XXX compare 'm' and 'data' ? */ 138 139 explicit_bzero(sigblob, len); 140 explicit_bzero(sm, smlen); 141 explicit_bzero(m, smlen); /* NB. mlen may be invalid if ret != 0 */ 142 free(sigblob); 143 free(sm); 144 free(m); 145 debug("%s: signature %scorrect", __func__, (ret != 0) ? "in" : ""); 146 147 /* translate return code carefully */ 148 return (ret == 0) ? 1 : -1; 149 } 150