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stephaniestrokadjb
stephaniestroka
authored and
djb
committed
Update pairing mechanism and add MAC
1 parent 3cf6659 commit 7536c93

22 files changed

+1151
-405
lines changed

‎src/CMakeLists.txt

+3
Original file line numberDiff line numberDiff line change
@@ -9,6 +9,8 @@
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set(DBB-FIRMWARE-SOURCES
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aes.c
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sharedsecret.c
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aescbcb64.c
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base58.c
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base64.c
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pbkdf2.c
@@ -31,6 +33,7 @@ set(DBB-FIRMWARE-SOURCES
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ataes132.c
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flash.c
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touch.c
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ecdh.c
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)
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if(USE_SECP256K1_LIB)

‎src/aescbcb64.c

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@@ -0,0 +1,192 @@
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/*
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The MIT License (MIT)
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Copyright (c) 2015-2018 Douglas J. Bakkum
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Permission is hereby granted, free of charge, to any person obtaining
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a copy of this software and associated documentation files (the "Software"),
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to deal in the Software without restriction, including without limitation
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the rights to use, copy, modify, merge, publish, distribute, sublicense,
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and/or sell copies of the Software, and to permit persons to whom the
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Software is furnished to do so, subject to the following conditions:
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The above copyright notice and this permission notice shall be included
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in all copies or substantial portions of the Software.
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THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS
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OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
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FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
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THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES
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OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE,
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ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR
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OTHER DEALINGS IN THE SOFTWARE.
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*/
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#include <stdint.h>
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#include <stdlib.h>
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#include <string.h>
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#include "aescbcb64.h"
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#include "hmac.h"
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#include "commander.h"
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#include "sharedsecret.h"
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#include "memory.h"
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#include "base64.h"
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#include "aes.h"
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#include "sha2.h"
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#include "random.h"
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#include "flags.h"
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#include "utils.h"
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// Must free() returned value
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static uint8_t *aescbcb64_init_and_encrypt(const unsigned char *in, int inlen,
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int *out_len,
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const uint8_t *key)
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{
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int pads;
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int inpadlen = inlen + N_BLOCK - inlen % N_BLOCK;
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unsigned char inpad[inpadlen];
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unsigned char enc[inpadlen];
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unsigned char iv[N_BLOCK];
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uint8_t *enc_cat = malloc(sizeof(uint8_t) * (inpadlen +
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N_BLOCK)); // concatenating [ iv0 | enc ]
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*out_len = inpadlen + N_BLOCK;
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aes_context ctx[1];
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// Set cipher key
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memset(ctx, 0, sizeof(ctx));
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aes_set_key(key, 32, ctx);
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// PKCS7 padding
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memcpy(inpad, in, inlen);
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for (pads = 0; pads < N_BLOCK - inlen % N_BLOCK; pads++ ) {
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inpad[inlen + pads] = (N_BLOCK - inlen % N_BLOCK);
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}
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// Make a random initialization vector
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if (random_bytes((uint8_t *)iv, N_BLOCK, 0) == DBB_ERROR) {
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commander_fill_report(cmd_str(CMD_random), NULL, DBB_ERR_MEM_ATAES);
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utils_zero(inpad, inpadlen);
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utils_zero(ctx, sizeof(ctx));
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return NULL;
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}
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memcpy(enc_cat, iv, N_BLOCK);
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// CBC encrypt multiple blocks
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aes_cbc_encrypt(inpad, enc, inpadlen / N_BLOCK, iv, ctx);
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memcpy(enc_cat + N_BLOCK, enc, inpadlen);
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utils_zero(inpad, inpadlen);
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utils_zero(ctx, sizeof(ctx));
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return enc_cat;
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}
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// Must free() returned value (allocated inside base64() function)
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char *aescbcb64_encrypt(const unsigned char *in, int inlen, int *out_b64len,
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const uint8_t *key)
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{
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int out_len;
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uint8_t *enc_cat = aescbcb64_init_and_encrypt(in, inlen, &out_len, key);
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// base64 encoding
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char *b64;
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b64 = base64(enc_cat, out_len, out_b64len);
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free(enc_cat);
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return b64;
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}
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// Encrypts a given constant char array of length inlen using the AES algorithm with CBC mode,
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// appends its SHA256 HMAC and base64 encodes the result.
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//
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// Must free() returned value
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char *aescbcb64_hmac_encrypt(const unsigned char *in, int inlen, int *out_b64len,
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const uint8_t *shared_secret)
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{
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uint8_t encryption_key[SHA256_DIGEST_LENGTH];
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uint8_t authentication_key[SHA256_DIGEST_LENGTH];
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sharedsecret_derive_keys(shared_secret, encryption_key, authentication_key);
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int encrypt_len;
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uint8_t *encrypted = aescbcb64_init_and_encrypt(in,
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inlen,
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&encrypt_len,
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encryption_key);
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uint8_t hmac[SHA256_DIGEST_LENGTH];
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hmac_sha256(authentication_key, SHA256_DIGEST_LENGTH, encrypted, encrypt_len, hmac);
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uint8_t authenticated_encrypted_msg[encrypt_len + SHA256_DIGEST_LENGTH];
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memcpy(authenticated_encrypted_msg, encrypted, encrypt_len);
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memcpy(authenticated_encrypted_msg + encrypt_len, hmac, SHA256_DIGEST_LENGTH);
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free(encrypted);
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utils_zero(encryption_key, sizeof(encryption_key));
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utils_zero(authentication_key, sizeof(authentication_key));
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char *b64 = base64(authenticated_encrypted_msg, encrypt_len + SHA256_DIGEST_LENGTH,
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out_b64len);
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return b64;
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}
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char *aescbcb64_init_and_decrypt(uint8_t *ub64, int ub64len, int *decrypt_len,
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const uint8_t *key)
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{
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*decrypt_len = 0;
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// Set cipher key
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aes_context ctx[1];
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memset(ctx, 0, sizeof(ctx));
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aes_set_key(key, 32, ctx);
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unsigned char dec_pad[ub64len - N_BLOCK];
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aes_cbc_decrypt(ub64 + N_BLOCK, dec_pad, ub64len / N_BLOCK - 1, ub64, ctx);
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// Strip PKCS7 padding
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int padlen = dec_pad[ub64len - N_BLOCK - 1];
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if (ub64len - N_BLOCK - padlen <= 0) {
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utils_zero(dec_pad, sizeof(dec_pad));
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utils_zero(ctx, sizeof(ctx));
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return NULL;
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}
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char *dec = malloc(ub64len - N_BLOCK - padlen + 1); // +1 for null termination
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if (!dec) {
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utils_zero(dec_pad, sizeof(dec_pad));
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utils_zero(ctx, sizeof(ctx));
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return NULL;
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}
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memcpy(dec, dec_pad, ub64len - N_BLOCK - padlen);
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dec[ub64len - N_BLOCK - padlen] = '\0';
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*decrypt_len = ub64len - N_BLOCK - padlen + 1;
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utils_zero(dec_pad, sizeof(dec_pad));
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utils_zero(ctx, sizeof(ctx));
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return dec;
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}
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// Must free() returned value
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char *aescbcb64_decrypt(const unsigned char *in, int inlen, int *decrypt_len,
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const uint8_t *key)
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{
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if (!in || inlen == 0) {
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return NULL;
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}
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// Unbase64
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int ub64len;
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unsigned char *ub64 = unbase64((const char *)in, inlen, &ub64len);
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if (!ub64) {
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return NULL;
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}
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if ((ub64len % N_BLOCK) || ub64len < N_BLOCK) {
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free(ub64);
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return NULL;
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}
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char *ret = aescbcb64_init_and_decrypt(ub64, ub64len, decrypt_len, key);
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memset(ub64, 0, ub64len);
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free(ub64);
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return ret;
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}
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‎src/aescbcb64.h

+43
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@@ -0,0 +1,43 @@
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/*
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The MIT License (MIT)
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5+
Copyright (c) 2015-2018 Douglas J. Bakkum
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7+
Permission is hereby granted, free of charge, to any person obtaining
8+
a copy of this software and associated documentation files (the "Software"),
9+
to deal in the Software without restriction, including without limitation
10+
the rights to use, copy, modify, merge, publish, distribute, sublicense,
11+
and/or sell copies of the Software, and to permit persons to whom the
12+
Software is furnished to do so, subject to the following conditions:
13+
14+
The above copyright notice and this permission notice shall be included
15+
in all copies or substantial portions of the Software.
16+
17+
THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS
18+
OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
19+
FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
20+
THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES
21+
OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE,
22+
ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR
23+
OTHER DEALINGS IN THE SOFTWARE.
24+
25+
*/
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#ifndef _AESCBCB64_H_
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#define _AESCBCB64_H_
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char *aescbcb64_hmac_encrypt(const unsigned char *in, int inlen,
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int *out_b64len, const uint8_t *shared_secret);
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char *aescbcb64_init_and_decrypt(uint8_t *ub64, int ub64len, int *decrypt_len,
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const uint8_t *key);
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char *aescbcb64_encrypt(const unsigned char *in, int inlen,
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int *out_b64len, const uint8_t *key);
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char *aescbcb64_decrypt(const unsigned char *in, int inlen,
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int *decrypt_len, const uint8_t *key);
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#endif

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