1 /* $OpenBSD: ssh-ed25519.c,v 1.1 2013/12/06 13:39:49 markus 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 <string.h> 25 #include <stdarg.h> 26 27 #include "xmalloc.h" 28 #include "log.h" 29 #include "buffer.h" 30 #include "key.h" 31 #include "ssh.h" 32 33 int 34 ssh_ed25519_sign(const Key *key, u_char **sigp, u_int *lenp, 35 const u_char *data, u_int datalen) 36 { 37 u_char *sig; 38 u_int slen, len; 39 unsigned long long smlen; 40 int ret; 41 Buffer b; 42 43 if (key == NULL || key_type_plain(key->type) != KEY_ED25519 || 44 key->ed25519_sk == NULL) { 45 error("%s: no ED25519 key", __func__); 46 return -1; 47 } 48 smlen = slen = datalen + crypto_sign_ed25519_BYTES; 49 sig = xmalloc(slen); 50 51 if ((ret = crypto_sign_ed25519(sig, &smlen, data, datalen, 52 key->ed25519_sk)) != 0 || smlen <= datalen) { 53 error("%s: crypto_sign_ed25519 failed: %d", __func__, ret); 54 free(sig); 55 return -1; 56 } 57 /* encode signature */ 58 buffer_init(&b); 59 buffer_put_cstring(&b, "ssh-ed25519"); 60 buffer_put_string(&b, sig, smlen - datalen); 61 len = buffer_len(&b); 62 if (lenp != NULL) 63 *lenp = len; 64 if (sigp != NULL) { 65 *sigp = xmalloc(len); 66 memcpy(*sigp, buffer_ptr(&b), len); 67 } 68 buffer_free(&b); 69 memset(sig, 's', slen); 70 free(sig); 71 72 return 0; 73 } 74 75 int 76 ssh_ed25519_verify(const Key *key, const u_char *signature, u_int signaturelen, 77 const u_char *data, u_int datalen) 78 { 79 Buffer b; 80 char *ktype; 81 u_char *sigblob, *sm, *m; 82 u_int len; 83 unsigned long long smlen, mlen; 84 int rlen, ret; 85 86 if (key == NULL || key_type_plain(key->type) != KEY_ED25519 || 87 key->ed25519_pk == NULL) { 88 error("%s: no ED25519 key", __func__); 89 return -1; 90 } 91 buffer_init(&b); 92 buffer_append(&b, signature, signaturelen); 93 ktype = buffer_get_cstring(&b, NULL); 94 if (strcmp("ssh-ed25519", ktype) != 0) { 95 error("%s: cannot handle type %s", __func__, ktype); 96 buffer_free(&b); 97 free(ktype); 98 return -1; 99 } 100 free(ktype); 101 sigblob = buffer_get_string(&b, &len); 102 rlen = buffer_len(&b); 103 buffer_free(&b); 104 if (rlen != 0) { 105 error("%s: remaining bytes in signature %d", __func__, rlen); 106 free(sigblob); 107 return -1; 108 } 109 if (len > crypto_sign_ed25519_BYTES) { 110 error("%s: len %u > crypto_sign_ed25519_BYTES %u", __func__, 111 len, crypto_sign_ed25519_BYTES); 112 free(sigblob); 113 return -1; 114 } 115 smlen = len + datalen; 116 sm = xmalloc(smlen); 117 memcpy(sm, sigblob, len); 118 memcpy(sm+len, data, datalen); 119 mlen = smlen; 120 m = xmalloc(mlen); 121 if ((ret = crypto_sign_ed25519_open(m, &mlen, sm, smlen, 122 key->ed25519_pk)) != 0) { 123 debug2("%s: crypto_sign_ed25519_open failed: %d", 124 __func__, ret); 125 } 126 if (ret == 0 && mlen != datalen) { 127 debug2("%s: crypto_sign_ed25519_open " 128 "mlen != datalen (%llu != %u)", __func__, mlen, datalen); 129 ret = -1; 130 } 131 /* XXX compare 'm' and 'data' ? */ 132 133 memset(sigblob, 's', len); 134 memset(sm, 'S', smlen); 135 memset(m, 'm', smlen); /* NB. mlen may be invalid if ret != 0 */ 136 free(sigblob); 137 free(sm); 138 free(m); 139 debug("%s: signature %scorrect", __func__, (ret != 0) ? "in" : ""); 140 141 /* translate return code carefully */ 142 return (ret == 0) ? 1 : -1; 143 } 144