Annotation of embedaddon/strongswan/src/libtls/tls_aead_expl.c, revision 1.1
1.1 ! misho 1: /*
! 2: * Copyright (C) 2014 Martin Willi
! 3: * Copyright (C) 2014 revosec AG
! 4: *
! 5: * This program is free software; you can redistribute it and/or modify it
! 6: * under the terms of the GNU General Public License as published by the
! 7: * Free Software Foundation; either version 2 of the License, or (at your
! 8: * option) any later version. See <http://www.fsf.org/copyleft/gpl.txt>.
! 9: *
! 10: * This program is distributed in the hope that it will be useful, but
! 11: * WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
! 12: * or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
! 13: * for more details.
! 14: */
! 15:
! 16: #include "tls_aead.h"
! 17:
! 18: #include <crypto/iv/iv_gen_rand.h>
! 19:
! 20: typedef struct private_tls_aead_t private_tls_aead_t;
! 21:
! 22: /**
! 23: * Private data of an tls_aead_t object.
! 24: */
! 25: struct private_tls_aead_t {
! 26:
! 27: /**
! 28: * Public tls_aead_t interface.
! 29: */
! 30: tls_aead_t public;
! 31:
! 32: /**
! 33: * traditional crypter
! 34: */
! 35: crypter_t *crypter;
! 36:
! 37: /**
! 38: * traditional signer
! 39: */
! 40: signer_t *signer;
! 41:
! 42: /**
! 43: * IV generator
! 44: */
! 45: iv_gen_t *iv_gen;
! 46: };
! 47:
! 48: /**
! 49: * Associated header data to create signature over
! 50: */
! 51: typedef struct __attribute__((__packed__)) {
! 52: uint64_t seq;
! 53: uint8_t type;
! 54: uint16_t version;
! 55: uint16_t length;
! 56: } sigheader_t;
! 57:
! 58: METHOD(tls_aead_t, encrypt, bool,
! 59: private_tls_aead_t *this, tls_version_t version, tls_content_type_t type,
! 60: uint64_t seq, chunk_t *data)
! 61: {
! 62: chunk_t assoc, mac, padding, iv;
! 63: uint8_t bs, padlen;
! 64: sigheader_t hdr;
! 65:
! 66: hdr.type = type;
! 67: htoun64(&hdr.seq, seq);
! 68: htoun16(&hdr.version, version);
! 69: htoun16(&hdr.length, data->len);
! 70:
! 71: assoc = chunk_from_thing(hdr);
! 72: if (!this->signer->get_signature(this->signer, assoc, NULL) ||
! 73: !this->signer->allocate_signature(this->signer, *data, &mac))
! 74: {
! 75: return FALSE;
! 76: }
! 77: bs = this->crypter->get_block_size(this->crypter);
! 78: padlen = pad_len(data->len + mac.len + 1, bs);
! 79:
! 80: padding = chunk_alloca(padlen);
! 81: memset(padding.ptr, padlen, padding.len);
! 82:
! 83: /* TLSv1.1 uses random IVs, prepended to record */
! 84: iv.len = this->crypter->get_iv_size(this->crypter);
! 85: iv = chunk_alloca(iv.len);
! 86: if (!this->iv_gen->get_iv(this->iv_gen, seq, iv.len, iv.ptr))
! 87: {
! 88: return FALSE;
! 89: }
! 90: *data = chunk_cat("mmcc", *data, mac, padding, chunk_from_thing(padlen));
! 91: /* encrypt inline */
! 92: if (!this->crypter->encrypt(this->crypter, *data, iv, NULL))
! 93: {
! 94: return FALSE;
! 95: }
! 96: /* prepend IV */
! 97: *data = chunk_cat("cm", iv, *data);
! 98: return TRUE;
! 99: }
! 100:
! 101: METHOD(tls_aead_t, decrypt, bool,
! 102: private_tls_aead_t *this, tls_version_t version, tls_content_type_t type,
! 103: uint64_t seq, chunk_t *data)
! 104: {
! 105: chunk_t assoc, mac, iv;
! 106: uint8_t bs, padlen;
! 107: sigheader_t hdr;
! 108: size_t i;
! 109:
! 110: iv.len = this->crypter->get_iv_size(this->crypter);
! 111: if (data->len < iv.len)
! 112: {
! 113: return FALSE;
! 114: }
! 115: iv.ptr = data->ptr;
! 116: *data = chunk_skip(*data, iv.len);
! 117: bs = this->crypter->get_block_size(this->crypter);
! 118: if (data->len < bs || data->len % bs)
! 119: {
! 120: return FALSE;
! 121: }
! 122: if (!this->crypter->decrypt(this->crypter, *data, iv, NULL))
! 123: {
! 124: return FALSE;
! 125: }
! 126: padlen = data->ptr[data->len - 1];
! 127: if (padlen < data->len)
! 128: { /* If padding looks valid, remove it */
! 129: for (i = data->len - padlen - 1; i < data->len - 1; i++)
! 130: {
! 131: if (data->ptr[i] != padlen)
! 132: {
! 133: return FALSE;
! 134: }
! 135: }
! 136: data->len -= padlen + 1;
! 137: }
! 138:
! 139: bs = this->signer->get_block_size(this->signer);
! 140: if (data->len < bs)
! 141: {
! 142: return FALSE;
! 143: }
! 144: mac = chunk_skip(*data, data->len - bs);
! 145: data->len -= bs;
! 146:
! 147: hdr.type = type;
! 148: htoun64(&hdr.seq, seq);
! 149: htoun16(&hdr.version, version);
! 150: htoun16(&hdr.length, data->len);
! 151:
! 152: assoc = chunk_from_thing(hdr);
! 153: if (!this->signer->get_signature(this->signer, assoc, NULL) ||
! 154: !this->signer->verify_signature(this->signer, *data, mac))
! 155: {
! 156: return FALSE;
! 157: }
! 158: return TRUE;
! 159: }
! 160:
! 161: METHOD(tls_aead_t, get_mac_key_size, size_t,
! 162: private_tls_aead_t *this)
! 163: {
! 164: return this->signer->get_key_size(this->signer);
! 165: }
! 166:
! 167: METHOD(tls_aead_t, get_encr_key_size, size_t,
! 168: private_tls_aead_t *this)
! 169: {
! 170: return this->crypter->get_key_size(this->crypter);
! 171: }
! 172:
! 173: METHOD(tls_aead_t, get_iv_size, size_t,
! 174: private_tls_aead_t *this)
! 175: {
! 176: return 0;
! 177: }
! 178:
! 179: METHOD(tls_aead_t, set_keys, bool,
! 180: private_tls_aead_t *this, chunk_t mac, chunk_t encr, chunk_t iv)
! 181: {
! 182: if (iv.len)
! 183: {
! 184: return FALSE;
! 185: }
! 186: return this->signer->set_key(this->signer, mac) &&
! 187: this->crypter->set_key(this->crypter, encr);
! 188: }
! 189:
! 190: METHOD(tls_aead_t, destroy, void,
! 191: private_tls_aead_t *this)
! 192: {
! 193: this->iv_gen->destroy(this->iv_gen);
! 194: DESTROY_IF(this->crypter);
! 195: DESTROY_IF(this->signer);
! 196: free(this);
! 197: }
! 198:
! 199: /**
! 200: * See header
! 201: */
! 202: tls_aead_t *tls_aead_create_explicit(integrity_algorithm_t mac,
! 203: encryption_algorithm_t encr, size_t encr_size)
! 204: {
! 205: private_tls_aead_t *this;
! 206:
! 207: INIT(this,
! 208: .public = {
! 209: .encrypt = _encrypt,
! 210: .decrypt = _decrypt,
! 211: .get_mac_key_size = _get_mac_key_size,
! 212: .get_encr_key_size = _get_encr_key_size,
! 213: .get_iv_size = _get_iv_size,
! 214: .set_keys = _set_keys,
! 215: .destroy = _destroy,
! 216: },
! 217: .crypter = lib->crypto->create_crypter(lib->crypto, encr, encr_size),
! 218: .signer = lib->crypto->create_signer(lib->crypto, mac),
! 219: .iv_gen = iv_gen_rand_create(),
! 220: );
! 221:
! 222: if (!this->crypter || !this->signer)
! 223: {
! 224: destroy(this);
! 225: return NULL;
! 226: }
! 227:
! 228: return &this->public;
! 229: }
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