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trezor-firmware/bip32.c
2013-09-20 17:13:24 +02:00

50 lines
1.3 KiB
C

#include <string.h>
#include "bignum.h"
#include "hmac.h"
#include "ecdsa.h"
#include "bip32.h"
void xprv_from_seed(uint8_t *seed, int seed_len, xprv *out)
{
out->version = 0x0488ADE4; // main-net
out->depth = 0;
out->fingerprint = 0x00000000;
out->child_num = 0;
// this can be done because private_key[32] and chain_code[32]
// form a continuous 64 byte block in the memory
hmac_sha512((uint8_t *)"Bitcoin seed", 12, seed, seed_len, out->private_key);
ecdsa_get_public_key_compressed(out->private_key, out->public_key);
ecdsa_get_address(out->public_key, 0, out->address);
}
void xprv_descent(xprv *inout, uint32_t i)
{
uint8_t data[1 + 32 + 4];
bignum256 a, b;
if (i & 0x80000000) {
data[0] = 0;
memcpy(data + 1, inout->private_key, 32);
} else {
ecdsa_get_public_key_compressed(inout->private_key, data);
}
write_be(data + 33, i);
bn_read_be(inout->private_key, &a);
// this can be done because private_key[32] and chain_code[32]
// form a continuous 64 byte block in the memory
hmac_sha512(inout->chain_code, 32, data, sizeof(data), inout->private_key);
bn_read_be(inout->private_key, &b);
bn_addmod(&a, &b, &order256k1);
inout->depth++;
inout->child_num = i;
bn_write_be(&a, inout->private_key);
ecdsa_get_public_key_compressed(inout->private_key, inout->public_key);
ecdsa_get_address(inout->public_key, 0, inout->address);
}