/** @internal
* @brief encrypts an ed25519 private key blob
*
*/
static int pki_private_key_encrypt(ssh_buffer privkey_buffer,
const char* passphrase,
const char *ciphername,
const char *kdfname,
ssh_auth_callback auth_fn,
void *auth_data,
uint32_t rounds,
ssh_string salt)
{
struct ssh_cipher_struct *ciphers = ssh_get_ciphertab();
struct ssh_cipher_struct cipher;
uint8_t key_material[128];
size_t key_material_len;
char passphrase_buffer[128];
int rc;
int i;
uint8_t padding = 1;
int cmp;
cmp = strcmp(ciphername, "none");
if (cmp == 0){
/* no encryption required */
return SSH_OK;
}
for (i = 0; ciphers[i].name != NULL; i++) {
cmp = strcmp(ciphername, ciphers[i].name);
if (cmp == 0){
memcpy(&cipher, &ciphers[i], sizeof(cipher));
break;
}
}
if (ciphers[i].name == NULL){
SSH_LOG(SSH_LOG_WARN, "Unsupported cipher %s", ciphername);
return SSH_ERROR;
}
cmp = strcmp(kdfname, "bcrypt");
if (cmp != 0){
SSH_LOG(SSH_LOG_WARN, "Unsupported KDF %s", kdfname);
return SSH_ERROR;
}
while (ssh_buffer_get_len(privkey_buffer) % cipher.blocksize != 0) {
rc = buffer_add_u8(privkey_buffer, padding);
if (rc < 0) {
return SSH_ERROR;
}
padding++;
}
/* We need material for key (keysize bits / 8) and IV (blocksize) */
key_material_len = cipher.keysize/8 + cipher.blocksize;
if (key_material_len > sizeof(key_material)){
ssh_pki_log("Key material too big");
return SSH_ERROR;
}
ssh_pki_log("Encryption: %d key, %d IV, %d rounds, %zu bytes salt",
cipher.keysize/8,
cipher.blocksize, rounds, ssh_string_len(salt));
if (passphrase == NULL){
if (auth_fn == NULL){
ssh_pki_log("No passphrase provided");
return SSH_ERROR;
}
rc = auth_fn("Passphrase",
passphrase_buffer,
sizeof(passphrase_buffer),
0,
0,
auth_data);
if (rc != SSH_OK){
return SSH_ERROR;
}
passphrase = passphrase_buffer;
}
rc = bcrypt_pbkdf(passphrase,
strlen(passphrase),
ssh_string_data(salt),
ssh_string_len(salt),
key_material,
key_material_len,
rounds);
if (rc < 0){
return SSH_ERROR;
}
cipher.set_encrypt_key(&cipher,
key_material,
key_material + cipher.keysize/8);
cipher.encrypt(&cipher,
ssh_buffer_get_begin(privkey_buffer),
ssh_buffer_get_begin(privkey_buffer),
ssh_buffer_get_len(privkey_buffer));
ssh_cipher_clear(&cipher);
BURN_BUFFER(passphrase_buffer, sizeof(passphrase_buffer));
return SSH_OK;
}
static void cipher_free(struct ssh_cipher_struct *cipher) {
ssh_cipher_clear(cipher);
SAFE_FREE(cipher);
}
/**
* @brief decrypts an encrypted ed25519 private key blob
*
*/
static int pki_private_key_decrypt(ssh_string blob,
const char* passphrase,
const char *ciphername,
const char *kdfname,
ssh_string kdfoptions,
ssh_auth_callback auth_fn,
void *auth_data)
{
struct ssh_cipher_struct *ciphers = ssh_get_ciphertab();
struct ssh_cipher_struct cipher;
uint8_t key_material[128];
char passphrase_buffer[128];
size_t key_material_len;
ssh_buffer buffer;
ssh_string salt;
uint32_t rounds;
int cmp;
int rc;
int i;
cmp = strcmp(ciphername, "none");
if (cmp == 0){
/* no decryption required */
return SSH_OK;
}
for (i = 0; ciphers[i].name != NULL; i++) {
cmp = strcmp(ciphername, ciphers[i].name);
if (cmp == 0){
memcpy(&cipher, &ciphers[i], sizeof(cipher));
break;
}
}
if (ciphers[i].name == NULL){
SSH_LOG(SSH_LOG_WARN, "Unsupported cipher %s", ciphername);
return SSH_ERROR;
}
cmp = strcmp(kdfname, "bcrypt");
if (cmp != 0) {
SSH_LOG(SSH_LOG_WARN, "Unsupported KDF %s", kdfname);
return SSH_ERROR;
}
if (ssh_string_len(blob) % cipher.blocksize != 0) {
SSH_LOG(SSH_LOG_WARN,
"Encrypted string not multiple of blocksize: %zu",
ssh_string_len(blob));
return SSH_ERROR;
}
buffer = ssh_buffer_new();
if (buffer == NULL){
return SSH_ERROR;
}
rc = ssh_buffer_add_data(buffer,
ssh_string_data(kdfoptions),
ssh_string_len(kdfoptions));
if (rc != SSH_ERROR){
rc = ssh_buffer_unpack(buffer, "Sd", &salt, &rounds);
}
ssh_buffer_free(buffer);
if (rc == SSH_ERROR){
return SSH_ERROR;
}
/* We need material for key (keysize bits / 8) and IV (blocksize) */
key_material_len = cipher.keysize/8 + cipher.blocksize;
if (key_material_len > sizeof(key_material)) {
ssh_pki_log("Key material too big");
return SSH_ERROR;
}
ssh_pki_log("Decryption: %d key, %d IV, %d rounds, %zu bytes salt",
cipher.keysize/8,
cipher.blocksize, rounds, ssh_string_len(salt));
if (passphrase == NULL) {
if (auth_fn == NULL) {
SAFE_FREE(salt);
ssh_pki_log("No passphrase provided");
return SSH_ERROR;
}
rc = auth_fn("Passphrase",
passphrase_buffer,
sizeof(passphrase_buffer),
0,
0,
auth_data);
if (rc != SSH_OK) {
SAFE_FREE(salt);
return SSH_ERROR;
}
passphrase = passphrase_buffer;
}
rc = bcrypt_pbkdf(passphrase,
strlen(passphrase),
ssh_string_data(salt),
ssh_string_len(salt),
key_material,
key_material_len,
rounds);
SAFE_FREE(salt);
if (rc < 0){
return SSH_ERROR;
}
BURN_BUFFER(passphrase_buffer, sizeof(passphrase_buffer));
cipher.set_decrypt_key(&cipher,
key_material,
key_material + cipher.keysize/8);
cipher.decrypt(&cipher,
ssh_string_data(blob),
ssh_string_data(blob),
ssh_string_len(blob));
ssh_cipher_clear(&cipher);
return SSH_OK;
}
