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Generate hardened keys in a unique root

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This commit is contained in:
Mark Bryars 2015-11-05 01:24:37 +01:00
parent 9328cad7f1
commit 32f8819997
2 changed files with 20 additions and 5 deletions
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23
firmware/u2f.c
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@ -447,12 +447,20 @@ const HDNode *generateKeyHandle(const uint8_t app_id[], uint8_t key_handle[])
{
uint8_t keybase[64];
// First half of keyhandle is random
random_buffer(key_handle, 32);
// Derivation path is m/'U2F/'r/'r/'r/'r/'r/'r/'r/'r
uint32_t i, key_path[9];
key_path[0] = U2F_KEY_PATH;
for (i = 1; i < 9; i++) {
// high bit for hardened keys
key_path[i]= 0x80000000 | random32();
}
// First half of keyhandle is key_path
memcpy(key_handle, &key_path[1], 32);
// prepare keypair from /random data
const HDNode *node =
getDerivedNode((uint32_t*)key_handle, 32/sizeof(uint32_t));
getDerivedNode(key_path, sizeof(key_path) / sizeof(uint32_t));
// For second half of keyhandle
// Signature of app_id and random data
@ -473,12 +481,17 @@ const HDNode *generateKeyHandle(const uint8_t app_id[], uint8_t key_handle[])
const HDNode *validateKeyHandle(const uint8_t app_id[], const uint8_t key_handle[])
{
uint32_t key_path[9];
key_path[0] = U2F_KEY_PATH;
memcpy(&key_path[1], key_handle, 32);
const HDNode *node =
getDerivedNode(key_path, sizeof(key_path) / sizeof(uint32_t));
uint8_t keybase[64];
memcpy(&keybase[0], app_id, 32);
memcpy(&keybase[32], key_handle, 32);
const HDNode *node =
getDerivedNode((uint32_t*)key_handle, 32/sizeof(uint32_t));
uint8_t sig[64];
ecdsa_sign(&nist256p1, node->private_key,

2
firmware/u2f.h
View File

@ -25,6 +25,8 @@
#include "u2f/u2f_hid.h"
#include "trezor.h"
#define U2F_KEY_PATH 0x80553246
typedef struct {
uint8_t cla, ins, p1, p2;
uint8_t lc1, lc2, lc3;