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support getPinToken

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This commit is contained in:
Conor Patrick 2018-05-17 23:11:00 -04:00
parent 162539a561
commit bfa4ba64ba
6 changed files with 124 additions and 8 deletions
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3
.gitmodules vendored
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@ -10,3 +10,6 @@
[submodule ".\\crypto\\micro-ecc"]
path = .\\crypto\\micro-ecc
url = https://github.com/kmackay/micro-ecc.git
[submodule ".\\crypto\\tiny-AES-c"]
path = .\\crypto\\tiny-AES-c
url = https://github.com/kokke/tiny-AES-c.git

4
Makefile
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@ -9,11 +9,11 @@
platform=2
src = $(wildcard *.c) $(wildcard crypto/*.c)
src = $(wildcard *.c) $(wildcard crypto/*.c) crypto/tiny-AES-c/aes.c
obj = $(src:.c=.o) uECC.o
LDFLAGS = -Wl,--gc-sections ./tinycbor/lib/libtinycbor.a
CFLAGS = -O2 -fdata-sections -ffunction-sections -I./tinycbor/src -I./crypto -I./crypto/micro-ecc/
CFLAGS = -O2 -fdata-sections -ffunction-sections -I./tinycbor/src -I./crypto -I./crypto/micro-ecc/ -Icrypto/tiny-AES-c/
name = main

33
crypto.c
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@ -13,6 +13,7 @@
#include "sha256.h"
#include "uECC.h"
#include "aes.h"
#include "ctap.h"
@ -116,6 +117,38 @@ void crypto_ecc256_make_key_pair(uint8_t * pubkey, uint8_t * privkey)
}
}
void crypto_ecc256_shared_secret(const uint8_t * pubkey, const uint8_t * privkey, uint8_t * shared_secret)
{
if (uECC_shared_secret(pubkey, privkey, shared_secret, _es256_curve) != 1)
{
printf("Error, uECC_shared_secret failed\n");
exit(1);
}
}
static struct AES_ctx aes_ctx;
void crypto_aes256_init(uint8_t * key)
{
AES_init_ctx(&aes_ctx, key);
memset(aes_ctx.Iv, 0, 16);
}
void crypto_aes256_reset_iv()
{
memset(aes_ctx.Iv, 0, 16);
}
void crypto_aes256_decrypt(uint8_t * buf, int length)
{
AES_CBC_decrypt_buffer(&aes_ctx, buf, length);
}
void crypto_aes256_encrypt(uint8_t * buf, int length)
{
AES_CBC_encrypt_buffer(&aes_ctx, buf, length);
}
const uint8_t attestation_cert_der[] =
"\x30\x82\x01\xfb\x30\x82\x01\xa1\xa0\x03\x02\x01\x02\x02\x01\x00\x30\x0a\x06\x08"

11
crypto.h
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@ -20,6 +20,17 @@ void crypto_ecc256_sign(uint8_t * data, int len, uint8_t * sig);
void generate_private_key(uint8_t * data, int len, uint8_t * data2, int len2, uint8_t * privkey);
void crypto_ecc256_make_key_pair(uint8_t * pubkey, uint8_t * privkey);
void crypto_ecc256_shared_secret(const uint8_t * pubkey, const uint8_t * privkey, uint8_t * shared_secret);
// Key must be 32 bytes
void crypto_aes256_init(uint8_t * key);
void crypto_aes256_reset_iv();
// buf length must be multiple of 16 bytes
void crypto_aes256_decrypt(uint8_t * buf, int lenth);
void crypto_aes256_encrypt(uint8_t * buf, int lenth);
extern const uint8_t attestation_cert_der[];
extern const uint16_t attestation_cert_der_size;

72
ctap.c
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@ -21,6 +21,7 @@ static uint8_t PIN_TOKEN[PIN_TOKEN_SIZE];
static uint8_t KEY_AGREEMENT_PUB[64];
static uint8_t KEY_AGREEMENT_PRIV[32];
static uint8_t PIN_CODE[64];
static uint8_t PIN_CODE_HASH[32];
static CborEncoder * _ENCODER;
static void _check_ret(CborError ret, int line, const char * filename)
@ -1486,8 +1487,9 @@ int ctap_parse_client_pin(CTAP_clientPin * CP, uint8_t * request, int length)
break;
case CP_keyAgreement:
printf("CP_keyAgreement\n");
ret = parse_cose_key(&map, CP->keyAgreement.x, CP->keyAgreement.y, &CP->keyAgreement.kty, &CP->keyAgreement.crv);
ret = parse_cose_key(&map, CP->keyAgreement.pubkey.x, CP->keyAgreement.pubkey.y, &CP->keyAgreement.kty, &CP->keyAgreement.crv);
check_ret(ret);
CP->keyAgreementPresent = 1;
break;
case CP_pinAuth:
printf("CP_pinAuth\n");
@ -1497,6 +1499,22 @@ int ctap_parse_client_pin(CTAP_clientPin * CP, uint8_t * request, int length)
break;
case CP_pinHashEnc:
printf("CP_pinHashEnc\n");
if (cbor_value_get_type(&map) == CborByteStringType)
{
CP->pinHashEncPresent = 1;
sz = 16;
ret = cbor_value_copy_byte_string(&map, CP->pinHashEnc, &sz, NULL);
check_ret(ret);
if (sz != 16)
{
return CTAP1_ERR_OTHER;
}
}
else
{
return CTAP2_ERR_INVALID_CBOR_TYPE;
}
break;
case CP_getKeyAgreement:
printf("CP_getKeyAgreement\n");
@ -1517,6 +1535,41 @@ int ctap_parse_client_pin(CTAP_clientPin * CP, uint8_t * request, int length)
return 0;
}
uint8_t ctap_add_pin_if_verified(CborEncoder * map, uint8_t * platform_pubkey, uint8_t * pinHashEnc)
{
uint8_t shared_secret[32];
int ret;
crypto_ecc256_shared_secret(platform_pubkey, KEY_AGREEMENT_PRIV, shared_secret);
crypto_sha256_init();
crypto_sha256_update(shared_secret, 32);
crypto_sha256_final(shared_secret);
crypto_aes256_init(shared_secret);
crypto_aes256_decrypt(pinHashEnc, 16);
printf("platform-pin-hash: "); dump_hex(pinHashEnc, 16);
printf("authentic-pin-hash: "); dump_hex(PIN_CODE_HASH, 16);
if (memcmp(pinHashEnc, PIN_CODE_HASH, 16) != 0)
{
crypto_ecc256_make_key_pair(KEY_AGREEMENT_PUB, KEY_AGREEMENT_PRIV);
return CTAP2_ERR_PIN_INVALID;
}
crypto_aes256_reset_iv();
// reuse share_secret memory for encrypted pinToken
memmove(shared_secret, PIN_TOKEN, PIN_TOKEN_SIZE);
crypto_aes256_encrypt(shared_secret, PIN_TOKEN_SIZE);
ret = cbor_encode_byte_string(map, shared_secret, PIN_TOKEN_SIZE);
check_ret(ret);
return 0;
}
uint8_t ctap_client_pin(CborEncoder * encoder, uint8_t * request, int length)
{
@ -1571,9 +1624,14 @@ uint8_t ctap_client_pin(CborEncoder * encoder, uint8_t * request, int length)
break;
case CP_cmdGetPinToken:
printf("CP_cmdGetPinToken\n");
ret = cbor_encode_int(&map, 99);
if (CP.keyAgreementPresent == 0 || CP.pinHashEncPresent == 0)
{
return CTAP2_ERR_MISSING_PARAMETER;
}
ret = cbor_encode_int(&map, RESP_pinToken);
check_ret(ret);
cbor_encode_int(&map, 99);
ret = ctap_add_pin_if_verified(&map, (uint8_t*)&CP.keyAgreement.pubkey, CP.pinHashEnc);
check_ret(ret);
break;
@ -1677,7 +1735,13 @@ void ctap_init()
exit(1);
}
crypto_ecc256_make_key_pair(KEY_AGREEMENT_PUB, KEY_AGREEMENT_PRIV);
// TODO this should be stored in flash memory
memset(PIN_CODE,0,sizeof(PIN_CODE));
memmove(PIN_CODE, "1234", 4);
crypto_sha256_init();
crypto_sha256_update(PIN_CODE, 4);
crypto_sha256_final(PIN_CODE_HASH);
}

5
ctap.h
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@ -185,14 +185,19 @@ typedef struct
int subCommand;
struct
{
struct{
uint8_t x[32];
uint8_t y[32];
} pubkey;
int kty;
int crv;
} keyAgreement;
uint8_t keyAgreementPresent;
uint8_t pinAuth[16];
uint8_t newPinEnc[NEW_PIN_ENC_MAX_SIZE];
uint8_t pinHashEnc[16];
uint8_t pinHashEncPresent;
int getKeyAgreement;
int getRetries;
} CTAP_clientPin;