Annotation of embedaddon/strongswan/src/libstrongswan/plugins/mgf1/mgf1_xof.c, revision 1.1
1.1 ! misho 1: /*
! 2: * Copyright (C) 2013-2016 Andreas Steffen
! 3: * HSR Hochschule fuer Technik Rapperswil
! 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 "mgf1_xof.h"
! 17:
! 18: #include "crypto/hashers/hasher.h"
! 19: #include "utils/debug.h"
! 20:
! 21: typedef struct private_mgf1_xof_t private_mgf1_xof_t;
! 22:
! 23: /**
! 24: * Private data of an mgf1_xof_t object.
! 25: */
! 26: struct private_mgf1_xof_t {
! 27:
! 28: /**
! 29: * Public mgf1_xof_t interface.
! 30: */
! 31: mgf1_xof_t public;
! 32:
! 33: /**
! 34: * XOF type of the MGF1 Mask Generation Function
! 35: */
! 36: ext_out_function_t type;
! 37:
! 38: /**
! 39: * Hasher the MGF1 Mask Generation Function is based on
! 40: */
! 41: hasher_t *hasher;
! 42:
! 43: /**
! 44: * Is the seed hashed before using it as a seed for MGF1 ?
! 45: */
! 46: bool hash_seed;
! 47:
! 48: /**
! 49: * Counter
! 50: */
! 51: uint32_t counter;
! 52:
! 53: /**
! 54: * Set if counter has reached 2^32
! 55: */
! 56: bool overflow;
! 57:
! 58: /**
! 59: * Current state to be hashed
! 60: */
! 61: chunk_t state;
! 62:
! 63: /**
! 64: * Position of the 4 octet counter string
! 65: */
! 66: uint8_t *ctr_str;
! 67:
! 68: /**
! 69: * Latest hash block
! 70: */
! 71: uint8_t buf[HASH_SIZE_SHA512];
! 72:
! 73: /**
! 74: * Index pointing to the current position in the hash block
! 75: */
! 76: size_t buf_index;
! 77:
! 78: };
! 79:
! 80: METHOD(xof_t, get_type, ext_out_function_t,
! 81: private_mgf1_xof_t *this)
! 82: {
! 83: return this->type;
! 84: }
! 85:
! 86: static bool get_next_block(private_mgf1_xof_t *this, uint8_t *buffer)
! 87: {
! 88: /* detect overflow, set counter string and increment counter */
! 89: if (this->overflow)
! 90: {
! 91: DBG1(DBG_LIB, "MGF1 overflow occurred");
! 92: return FALSE;
! 93: }
! 94: htoun32(this->ctr_str, this->counter++);
! 95: if (this->counter == 0)
! 96: {
! 97: this->overflow = TRUE;
! 98: }
! 99:
! 100: /* get the next block from the hash function */
! 101: if (!this->hasher->get_hash(this->hasher, this->state, buffer))
! 102: {
! 103: return FALSE;
! 104: }
! 105:
! 106: return TRUE;
! 107: }
! 108:
! 109: METHOD(xof_t, get_bytes, bool,
! 110: private_mgf1_xof_t *this, size_t out_len, uint8_t *buffer)
! 111: {
! 112: size_t index = 0, blocks, len, hash_size;
! 113:
! 114: hash_size = this->hasher->get_hash_size(this->hasher);
! 115:
! 116: /* empty the current hash block buffer first */
! 117: len = min(out_len, hash_size - this->buf_index);
! 118: if (len)
! 119: {
! 120: memcpy(buffer, this->buf + this->buf_index, len);
! 121: index += len;
! 122: this->buf_index += len;
! 123: }
! 124:
! 125: /* copy whole hash blocks directly to output buffer */
! 126: blocks = (out_len - index) / hash_size;
! 127: while (blocks--)
! 128: {
! 129: if (!get_next_block(this, buffer + index))
! 130: {
! 131: return FALSE;
! 132: }
! 133: index += hash_size;
! 134: }
! 135:
! 136: /* get another hash block if some more output bytes are needed */
! 137: len = out_len - index;
! 138: if (len)
! 139: {
! 140: if (!get_next_block(this, this->buf))
! 141: {
! 142: return FALSE;
! 143: }
! 144: memcpy(buffer + index, this->buf, len);
! 145: this->buf_index = len;
! 146: }
! 147:
! 148: return TRUE;
! 149: }
! 150:
! 151: METHOD(xof_t, allocate_bytes, bool,
! 152: private_mgf1_xof_t *this, size_t out_len, chunk_t *chunk)
! 153: {
! 154: *chunk = chunk_alloc(out_len);
! 155:
! 156: if (!get_bytes(this, out_len, chunk->ptr))
! 157: {
! 158: chunk_free(chunk);
! 159: return FALSE;
! 160: }
! 161:
! 162: return TRUE;
! 163: }
! 164:
! 165: METHOD(xof_t, get_block_size, size_t,
! 166: private_mgf1_xof_t *this)
! 167: {
! 168: return this->hasher->get_hash_size(this->hasher);
! 169: }
! 170:
! 171: METHOD(xof_t, get_seed_size, size_t,
! 172: private_mgf1_xof_t *this)
! 173: {
! 174: return this->hasher->get_hash_size(this->hasher);
! 175: }
! 176:
! 177: METHOD(xof_t, set_seed, bool,
! 178: private_mgf1_xof_t *this, chunk_t seed)
! 179: {
! 180: size_t hash_size, state_len;
! 181:
! 182: if (seed.len == 0)
! 183: {
! 184: DBG1(DBG_LIB, "empty seed for MGF1");
! 185: return FALSE;
! 186: }
! 187:
! 188: /* determine state size and allocate space accordingly */
! 189: hash_size = this->hasher->get_hash_size(this->hasher);
! 190: state_len = (this->hash_seed ? hash_size : seed.len) + 4;
! 191: chunk_clear(&this->state);
! 192: this->state = chunk_alloc(state_len);
! 193:
! 194: /* hash block buffer is empty */
! 195: this->buf_index = hash_size;
! 196:
! 197: /* reset counter */
! 198: this->counter = 0;
! 199:
! 200: /* determine position of the 4 octet counter string */
! 201: this->ctr_str = this->state.ptr + state_len - 4;
! 202:
! 203: if (this->hash_seed)
! 204: {
! 205: if (!this->hasher->get_hash(this->hasher, seed, this->state.ptr))
! 206: {
! 207: DBG1(DBG_LIB, "failed to hash seed for MGF1");
! 208: return FALSE;
! 209: }
! 210: }
! 211: else
! 212: {
! 213: memcpy(this->state.ptr, seed.ptr, seed.len);
! 214: }
! 215:
! 216: return TRUE;
! 217: }
! 218:
! 219: METHOD(xof_t, destroy, void,
! 220: private_mgf1_xof_t *this)
! 221: {
! 222: this->hasher->destroy(this->hasher);
! 223: chunk_clear(&this->state);
! 224: free(this);
! 225: }
! 226:
! 227: METHOD(mgf1_t, set_hash_seed, void,
! 228: private_mgf1_xof_t *this, bool yes)
! 229: {
! 230: this->hash_seed = yes;
! 231: }
! 232:
! 233: /*
! 234: * Described in header.
! 235: */
! 236: mgf1_xof_t *mgf1_xof_create(ext_out_function_t algorithm)
! 237: {
! 238: private_mgf1_xof_t *this;
! 239: hash_algorithm_t hash_alg;
! 240: hasher_t *hasher;
! 241:
! 242: switch (algorithm)
! 243: {
! 244: case XOF_MGF1_SHA1:
! 245: hash_alg = HASH_SHA1;
! 246: break;
! 247: case XOF_MGF1_SHA224:
! 248: hash_alg = HASH_SHA224;
! 249: break;
! 250: case XOF_MGF1_SHA256:
! 251: hash_alg = HASH_SHA256;
! 252: break;
! 253: case XOF_MGF1_SHA384:
! 254: hash_alg = HASH_SHA384;
! 255: break;
! 256: case XOF_MGF1_SHA512:
! 257: hash_alg = HASH_SHA512;
! 258: break;
! 259: default:
! 260: return NULL;
! 261: }
! 262:
! 263: hasher = lib->crypto->create_hasher(lib->crypto, hash_alg);
! 264: if (!hasher)
! 265: {
! 266: DBG1(DBG_LIB, "failed to create %N hasher for MGF1",
! 267: hash_algorithm_names, hash_alg);
! 268: return NULL;
! 269: }
! 270:
! 271: INIT(this,
! 272: .public = {
! 273: .mgf1_interface = {
! 274: .xof_interface = {
! 275: .get_type = _get_type,
! 276: .get_bytes = _get_bytes,
! 277: .allocate_bytes = _allocate_bytes,
! 278: .get_block_size = _get_block_size,
! 279: .get_seed_size = _get_seed_size,
! 280: .set_seed = _set_seed,
! 281: .destroy = _destroy,
! 282: },
! 283: .set_hash_seed = _set_hash_seed,
! 284: },
! 285: },
! 286: .type = algorithm,
! 287: .hasher = hasher,
! 288: );
! 289:
! 290: return &this->public;
! 291: }
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