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crypto.c: add private key extraction (will use with srp)

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F. Duncanh
2023-11-23 19:22:28 -05:00
parent ea239eb27d
commit fcac9253d3
1 changed files with 74 additions and 0 deletions
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74
lib/crypto.c
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@@ -263,10 +263,82 @@ void x25519_derive_secret(unsigned char secret[X25519_KEY_SIZE], const x25519_ke
// ED25519
struct ed25519_key_s {
EVP_PKEY *pkey;
unsigned char ed_secret[ED25519_KEY_SIZE];
};
int extract_evp_private_key(unsigned char *privkey, int keylen, EVP_PKEY *key) {
int count = 0;
unsigned int val;
unsigned int part1 = 0;
int part = 0;
unsigned char start[4] = { 0x20, 0x20, 0x20, 0x20 };
int bufsize = 512; /*should be big enough */
void *buf = malloc(bufsize);
BIO *bp = BIO_new(BIO_s_mem());
EVP_PKEY_print_private(bp, key, 0, NULL);
BIO_read(bp, buf, bufsize);
BIO_free(bp);
char *data = (char *) buf;
//printf("%s\n", data);
for (int i = 0; i < bufsize ; i ++ ) {
if (memcmp(data, start, 4)) {
data ++;
} else {
data += 4;
break;
}
}
int datalen = strlen(data);
for (int i = 0; (count < keylen && i < datalen); i++) {
val = 64;
if ('0' <= *data && *data <= '9') val = *data - '0';
if ('a' <= *data && *data <= 'f') val = 10 + *data - 'a';
if ('A' <= *data && *data <= 'F') val = 10 + *data - 'A';
if (val == 64) {
//printf("[%c]\n", *data);
data++;
continue;
}
part++;
part = part% 2;
switch (part) {
case 1:
//printf("%d %d [%c] %u\n", i, part, *data, val);
part1 = val;
data++;
break;
case 0:
privkey[count] = (unsigned char) (val + (part1 << 4));
count++;
data++;
break;
default:
break;
}
}
free (buf);
if (count != keylen) goto error;
//for (int i = 0; i < keylen; i++) {
// printf("%2.2x ", *(privkey + i));
//}
//printf("\n");
return 0;
error:;
memset(privkey, 0, keylen);
return -1;
}
ed25519_key_t *ed25519_key_generate(void) {
ed25519_key_t *key;
EVP_PKEY_CTX *pctx;
@@ -286,6 +358,8 @@ ed25519_key_t *ed25519_key_generate(void) {
}
EVP_PKEY_CTX_free(pctx);
extract_evp_private_key(key->ed_secret, ED25519_KEY_SIZE, *(&key->pkey));
return key;
}