| /* | |
| * Copyright 2002-2020 The OpenSSL Project Authors. All Rights Reserved. | |
| * | |
| * Licensed under the Apache License 2.0 (the "License"). You may not use | |
| * this file except in compliance with the License. You can obtain a copy | |
| * in the file LICENSE in the source distribution or at | |
| * https://www.openssl.org/source/license.html | |
| */ | |
| /* | |
| * Copyright (C) 2019-2020 by Sukchan Lee <acetcom@gmail.com> | |
| * | |
| * This file is part of Open5GS. | |
| * | |
| * Licensed under the Apache License, Version 2.0 (the "License"); | |
| * you may not use this file except in compliance with the License. | |
| * You may obtain a copy of the License at | |
| * | |
| * http://www.apache.org/licenses/LICENSE-2.0 | |
| * | |
| * Unless required by applicable law or agreed to in writing, software | |
| * distributed under the License is distributed on an "AS IS" BASIS, | |
| * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. | |
| * See the License for the specific language governing permissions and | |
| * limitations under the License. | |
| */ | |
| /* From RFC 4493 | |
| +++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ | |
| + Algorithm Generate_Subkey + | |
| +++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ | |
| + + | |
| + Input : K (128-bit key) + | |
| + Output : K1 (128-bit first subkey) + | |
| + K2 (128-bit second subkey) + | |
| +-------------------------------------------------------------------+ | |
| + + | |
| + Constants: const_Zero is 0x00000000000000000000000000000000 + | |
| + const_Rb is 0x00000000000000000000000000000087 + | |
| + Variables: L for output of AES-128 applied to 0^128 + | |
| + + | |
| + Step 1. L := AES-128(K, const_Zero); + | |
| + Step 2. if MSB(L) is equal to 0 + | |
| + then K1 := L << 1; + | |
| + else K1 := (L << 1) XOR const_Rb; + | |
| + Step 3. if MSB(K1) is equal to 0 + | |
| + then K2 := K1 << 1; + | |
| + else K2 := (K1 << 1) XOR const_Rb; + | |
| + Step 4. return K1, K2; + | |
| + + | |
| +++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ */ | |
| static int _generate_subkey(uint8_t *k1, uint8_t *k2, | |
| const uint8_t *key) | |
| { | |
| uint8_t zero[16] = { | |
| 0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00, | |
| 0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00 | |
| }; | |
| uint8_t rb[16] = { | |
| 0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00, | |
| 0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x87 | |
| }; | |
| uint8_t L[16]; | |
| uint32_t rk[OGS_AES_RKLENGTH(OGS_AES_MAX_KEY_BITS)]; | |
| int i, nrounds; | |
| /* Step 1. L := AES-128(K, const_Zero) */ | |
| nrounds = ogs_aes_setup_enc(rk, key, 128); | |
| ogs_aes_encrypt(rk, nrounds, zero, L); | |
| /* Step 2. if MSB(L) is equal to 0 */ | |
| if ((L[0] & 0x80) == 0) | |
| { | |
| /* then k1 := L << 1; */ | |
| for (i = 0; i < 15; i++) | |
| k1[i] = ((L[i] << 1) & 0xfe) | ((L[i + 1] & 0x80) ? 1 : 0); | |
| k1[15] = ((L[15] << 1) & 0xfe); | |
| } | |
| else | |
| { | |
| /* else k1 := (L << 1) XOR const_Rb; */ | |
| for (i = 0; i < 15; i++) | |
| k1[i] = (((L[i] << 1) & 0xfe) | ((L[i + 1] & 0x80) ? 1 : 0)) | |
| ^ rb[i]; | |
| k1[15] = ((L[15] << 1) & 0xfe) ^ rb[15]; | |
| } | |
| /* Step 3. if MSB(k1) is equal to 0 */ | |
| if ((k1[0] & 0x80) == 0) | |
| { | |
| /* then k2 := k2 << 1; */ | |
| for (i = 0; i < 15; i++) | |
| k2[i] = ((k1[i] << 1) & 0xfe) | ((k1[i + 1] & 0x80) ? 1 : 0); | |
| k2[15] = ((k1[15] << 1) & 0xfe); | |
| } | |
| else | |
| { | |
| /* else k2 := (k2 << 1) XOR const_Rb; */ | |
| for (i = 0; i < 15; i++) | |
| k2[i] = (((k1[i] << 1) & 0xfe) | ((k1[i + 1] & 0x80) ? 1 : 0)) | |
| ^ rb[i]; | |
| k2[15] = ((k1[15] << 1) & 0xfe) ^ rb[15]; | |
| } | |
| return OGS_OK; | |
| } | |
| /* From RFC 4493 | |
| +++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ | |
| + Algorithm AES-CMAC + | |
| +++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ | |
| + + | |
| + Input : K ( 128-bit key ) + | |
| + : M ( message to be authenticated ) + | |
| + : len ( length of the message in octets ) + | |
| + Output : T ( message authentication code ) + | |
| + + | |
| +++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ | |
| + Constants: const_Zero is 0x00000000000000000000000000000000 + | |
| + const_Bsize is 16 + | |
| + + | |
| + Variables: K1, K2 for 128-bit subkeys + | |
| + M_i is the i-th block (i=1..ceil(len/const_Bsize)) + | |
| + M_last is the last block xor-ed with K1 or K2 + | |
| + n for number of blocks to be processed + | |
| + r for number of octets of last block + | |
| + flag for denoting if last block is complete or not + | |
| + + | |
| + Step 1. (K1,K2) := Generate_Subkey(K); + | |
| + Step 2. n := ceil(len/const_Bsize); + | |
| + Step 3. if n = 0 + | |
| + then + | |
| + n := 1; + | |
| + flag := false; + | |
| + else + | |
| + if len mod const_Bsize is 0 + | |
| + then flag := true; + | |
| + else flag := false; + | |
| + + | |
| + Step 4. if flag is true + | |
| + then M_last := M_n XOR K1; + | |
| + else M_last := padding(M_n) XOR K2; + | |
| + Step 5. X := const_Zero; + | |
| + Step 6. for i := 1 to n-1 do + | |
| + begin + | |
| + Y := X XOR M_i; + | |
| + X := AES-128(K,Y); + | |
| + end + | |
| + Y := M_last XOR X; + | |
| + T := AES-128(K,Y); + | |
| + Step 7. return T; + | |
| +++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ */ | |
| int ogs_aes_cmac_calculate(uint8_t *cmac, const uint8_t *key, | |
| const uint8_t *msg, const uint32_t len) | |
| { | |
| uint8_t x[16] = { | |
| 0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00, | |
| 0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00 | |
| }; | |
| uint8_t y[16], m_last[16]; | |
| uint8_t k1[16], k2[16]; | |
| int i, j, n, bs, flag; | |
| uint32_t rk[OGS_AES_RKLENGTH(OGS_AES_MAX_KEY_BITS)]; | |
| int nrounds; | |
| ogs_assert(cmac); | |
| ogs_assert(key); | |
| ogs_assert(msg); | |
| /* Step 1. (K1,K2) := Generate_Subkey(K); */ | |
| _generate_subkey(k1, k2, key); | |
| /* Step 2. n := ceil(len/const_Bsize); */ | |
| n = (len + 15) / OGS_AES_BLOCK_SIZE; | |
| /* Step 3. if n = 0 | |
| then | |
| n := 1; | |
| flag := false; | |
| else | |
| if len mod const_Bsize is 0 | |
| then flag := true; | |
| else flag := false; | |
| */ | |
| if (n == 0) | |
| { | |
| n = 1; | |
| flag = 0; | |
| } | |
| else | |
| { | |
| if (len % OGS_AES_BLOCK_SIZE == 0) | |
| flag = 1; | |
| else | |
| flag = 0; | |
| } | |
| /* Step 4. if flag is true | |
| then M_last := M_n XOR K1; | |
| else M_last := padding(M_n) XOR K2; | |
| */ | |
| bs = (n - 1) * OGS_AES_BLOCK_SIZE; | |
| if (flag) | |
| { | |
| for (i = 0; i < 16; i++) | |
| m_last[i] = msg[bs + i] ^ k1[i]; | |
| } | |
| else | |
| { | |
| for (i = 0; i < len % OGS_AES_BLOCK_SIZE; i++) | |
| m_last[i] = msg[bs + i] ^ k2[i]; | |
| m_last[i] = 0x80 ^ k2[i]; | |
| for (i = i + 1; i < OGS_AES_BLOCK_SIZE; i++) | |
| m_last[i] = 0x00 ^ k2[i]; | |
| } | |
| /* Step 5. X := const_Zero; */ | |
| /* Step 6. for i := 1 to n-1 do | |
| begin | |
| Y := X XOR M_i; | |
| X := AES-128(K,Y); | |
| end | |
| Y := M_last XOR X; | |
| T := AES-128(K,Y); | |
| */ | |
| nrounds = ogs_aes_setup_enc(rk, key, 128); | |
| for (i = 0; i <= n - 2; i++) | |
| { | |
| bs = i * OGS_AES_BLOCK_SIZE; | |
| for (j = 0; j < 16; j++) | |
| y[j] = x[j] ^ msg[bs + j]; | |
| ogs_aes_encrypt(rk, nrounds, y, x); | |
| } | |
| bs = (n - 1) * OGS_AES_BLOCK_SIZE; | |
| for (j = 0; j < 16; j++) | |
| y[j] = m_last[j] ^ x[j]; | |
| ogs_aes_encrypt(rk, nrounds, y, cmac); | |
| return OGS_OK; | |
| } | |
| /* From RFC 4493 | |
| +++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ | |
| + Algorithm Verify_MAC + | |
| +++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ | |
| + + | |
| + Input : K ( 128-bit Key ) + | |
| + : M ( message to be verified ) + | |
| + : len ( length of the message in octets ) + | |
| + : T' ( the received MAC to be verified ) + | |
| + Output : INVALID or VALID + | |
| + + | |
| +-------------------------------------------------------------------+ | |
| + + | |
| + Step 1. T* := AES-CMAC(K,M,len); + | |
| + Step 2. if T* is equal to T' + | |
| + then + | |
| + return VALID; + | |
| + else + | |
| + return INVALID; + | |
| +++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ */ | |
| int ogs_aes_cmac_verify(uint8_t *cmac, const uint8_t *key, | |
| const uint8_t *msg, const uint32_t len) | |
| { | |
| int rv; | |
| uint8_t cmac_calc[16]; | |
| rv = ogs_aes_cmac_calculate(cmac_calc, key, msg, len); | |
| if (rv != OGS_OK) | |
| return rv; | |
| if (memcmp(cmac_calc, cmac, 16) != 0) | |
| return OGS_ERR_INVALID_CMAC; | |
| return OGS_OK; | |
| } | |