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chacha: packet decryption

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Signed-off-by: Aris Adamantiadis <aris@0xbadc0de.be>
Reviewed-by: Andreas Schneider <asn@cryptomilk.org>
This commit is contained in:
Aris Adamantiadis
2018-02-28 10:24:54 -06:00
committed by Andreas Schneider
parent d038c4dee7
commit 8a735d5eb7
7 changed files with 275 additions and 103 deletions
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123
src/packet_crypt.c
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@@ -44,40 +44,97 @@
#include "libssh/crypto.h"
#include "libssh/buffer.h"
uint32_t ssh_packet_decrypt_len(ssh_session session, char *crypted){
uint32_t decrypted;
/** @internal
* @brief decrypt the packet length from a raw encrypted packet, and store the first decrypted
* blocksize.
* @returns native byte-ordered decrypted length of the upcoming packet
*/
uint32_t ssh_packet_decrypt_len(ssh_session session,
uint8_t *destination,
uint8_t *source)
{
uint32_t decrypted;
int rc;
if (session->current_crypto) {
if (ssh_packet_decrypt(session, crypted,
session->current_crypto->in_cipher->blocksize) < 0) {
return 0;
if (session->current_crypto != NULL) {
if (session->current_crypto->in_cipher->aead_decrypt_length != NULL) {
rc =
session->current_crypto->in_cipher->set_decrypt_key(
session->current_crypto->in_cipher,
session->current_crypto->decryptkey,
session->current_crypto->decryptIV);
if (rc < 0) {
return (uint32_t)-1;
}
session->current_crypto->in_cipher->aead_decrypt_length(
session->current_crypto->in_cipher, source, destination,
session->current_crypto->in_cipher->lenfield_blocksize,
session->recv_seq);
} else {
rc = ssh_packet_decrypt(
session,
destination,
source,
0,
session->current_crypto->in_cipher->blocksize);
if (rc < 0) {
return 0;
}
}
} else {
memcpy(destination, source, 8);
}
}
memcpy(&decrypted,crypted,sizeof(decrypted));
return ntohl(decrypted);
memcpy(&decrypted,destination,sizeof(decrypted));
return ntohl(decrypted);
}
int ssh_packet_decrypt(ssh_session session, void *data,uint32_t len) {
struct ssh_cipher_struct *crypto = session->current_crypto->in_cipher;
char *out = NULL;
/** @internal
* @brief decrypts the content of an SSH packet.
* @param[source] source packet, including the encrypted length field
* @param[start] index in the packet that was not decrypted yet.
* @param[encrypted_size] size of the encrypted data to be decrypted after start.
*/
int ssh_packet_decrypt(ssh_session session,
uint8_t *destination,
uint8_t *source,
size_t start,
size_t encrypted_size)
{
struct ssh_cipher_struct *crypto = session->current_crypto->in_cipher;
int rc;
assert(len);
if (encrypted_size <= 0) {
return SSH_ERROR;
}
if(len % session->current_crypto->in_cipher->blocksize != 0){
ssh_set_error(session, SSH_FATAL, "Cryptographic functions must be set on at least one blocksize (received %d)",len);
return SSH_ERROR;
}
out = malloc(len);
if (out == NULL) {
return -1;
}
if (encrypted_size % session->current_crypto->in_cipher->blocksize != 0) {
ssh_set_error(session,
SSH_FATAL,
"Cryptographic functions must be used on multiple of "
"blocksize (received %" PRIdS ")",
encrypted_size);
return SSH_ERROR;
}
crypto->decrypt(crypto,data,out,len);
rc = crypto->set_decrypt_key(crypto,
session->current_crypto->decryptkey,
session->current_crypto->decryptIV);
if (rc < 0) {
return -1;
}
memcpy(data,out,len);
explicit_bzero(out, len);
SAFE_FREE(out);
return 0;
if (crypto->aead_decrypt != NULL) {
return crypto->aead_decrypt(crypto,
source,
destination,
encrypted_size,
session->recv_seq);
} else {
crypto->decrypt(crypto, source + start, destination, encrypted_size);
}
return 0;
}
unsigned char *ssh_packet_encrypt(ssh_session session, void *data, uint32_t len) {
@@ -159,13 +216,21 @@ unsigned char *ssh_packet_encrypt(ssh_session session, void *data, uint32_t len)
* @return 0 if hmac and mac are equal, < 0 if not or an error
* occurred.
*/
int ssh_packet_hmac_verify(ssh_session session, ssh_buffer buffer,
unsigned char *mac, enum ssh_hmac_e type) {
int ssh_packet_hmac_verify(ssh_session session,
ssh_buffer buffer,
uint8_t *mac,
enum ssh_hmac_e type)
{
unsigned char hmacbuf[DIGEST_MAX_LEN] = {0};
HMACCTX ctx;
unsigned int len;
uint32_t seq;
/* AEAD type have no mac checking */
if (type == SSH_HMAC_AEAD_POLY1305) {
return SSH_OK;
}
ctx = hmac_init(session->current_crypto->decryptMAC, hmac_digest_len(type), type);
if (ctx == NULL) {
return -1;
@@ -188,5 +253,3 @@ int ssh_packet_hmac_verify(ssh_session session, ssh_buffer buffer,
return -1;
}
/* vim: set ts=2 sw=2 et cindent: */