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Code Issues Releases Wiki Activity

support symm. decryption with 'Encrypted session key' present

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This commit is contained in:
B. Petersen 2018-02-18 19:07:27 +01:00
parent 7eb96d0178
commit 94fd79aecb
1 changed files with 49 additions and 15 deletions
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64
libs/netpgp/src/packet-parse.c
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@ -3215,11 +3215,14 @@ uint8_t* pgp_s2k_do(const char* passphrase,
// EDIT BY MR - parse Symmetric-Key Encrypted Session Key Packets (Tag 3)
static int parse_sk_sesskey(pgp_region_t *region, pgp_stream_t *stream)
{
int success = 0;
uint8_t version = 0, algo = 0;
uint8_t s2k_spec = 0, s2k_hash_algo = 0, s2k_salt[PGP_SALT_SIZE], s2k_iter_id = 0;
uint8_t *iv;
uint8_t *key = NULL;
int success = 0;
uint8_t version = 0, algo = 0;
pgp_crypt_t ci;
uint8_t s2k_spec = 0, s2k_hash_algo = 0, s2k_salt[PGP_SALT_SIZE], s2k_iter_id = 0;
uint8_t* encr_session_key = NULL, *decr_session_key = NULL;
int session_key_bytes = 0;
uint8_t* iv = NULL;
uint8_t* key = NULL;
if( region == NULL || stream == NULL || stream->cbinfo.cryptinfo.symm_passphrase == NULL ) {
goto cleanup;
@ -3251,13 +3254,12 @@ static int parse_sk_sesskey(pgp_region_t *region, pgp_stream_t *stream)
}
/* calculate the key from the passphrase */
{
pgp_crypt_t temp_crypt_info;
pgp_crypt_any(&temp_crypt_info, algo);
if( (key = pgp_s2k_do(stream->cbinfo.cryptinfo.symm_passphrase, temp_crypt_info.keysize,
s2k_spec, s2k_hash_algo, s2k_salt, s2k_iter_id)) == NULL ) {
goto cleanup;
}
if( !pgp_crypt_any(&ci, algo) ) {
goto cleanup;
}
if( (key = pgp_s2k_do(stream->cbinfo.cryptinfo.symm_passphrase, ci.keysize,
s2k_spec, s2k_hash_algo, s2k_salt, s2k_iter_id)) == NULL ) {
goto cleanup;
}
/* set up stream->decrypt so that PGP_PTAG_CT_SE_IP_DATA can decrypt the data
@ -3271,7 +3273,35 @@ static int parse_sk_sesskey(pgp_region_t *region, pgp_stream_t *stream)
algorithm identifier that specifies the symmetric-key encryption
algorithm used to encrypt the following Symmetrically Encrypted Data
packet, followed by the session key octets themselves. */
goto cleanup; // TODO
/* read the data */
session_key_bytes = region->length - region->readc;
if( (encr_session_key=malloc(session_key_bytes)) == NULL
|| (decr_session_key=malloc(session_key_bytes)) == NULL
|| !limread(encr_session_key, session_key_bytes, region, stream) ) {
goto cleanup;
}
/* decrypt the read data */
iv = calloc(1, stream->decrypt.blocksize); if( iv == NULL ) { goto cleanup; }
ci.set_iv(&ci, iv);
free(iv);
iv = NULL;
ci.set_crypt_key(&ci, key);
pgp_encrypt_init(&ci);
pgp_decrypt_se_ip(&ci, decr_session_key, encr_session_key, session_key_bytes); // TODO/TOCHECK: or pgp_decrypt_se()?
ci.decrypt_finish(&ci);
/* use decrypted data as key */
algo = decr_session_key[0];
if( !pgp_crypt_any(&stream->decrypt, algo)
|| stream->decrypt.keysize != (session_key_bytes-1/*skip algo identifier*/) ) {
goto cleanup;
}
iv = calloc(1, stream->decrypt.blocksize); if( iv == NULL ) { goto cleanup; }
stream->decrypt.set_iv(&stream->decrypt, iv);
stream->decrypt.set_crypt_key(&stream->decrypt, &decr_session_key[1]/*skip algo identifier*/);
pgp_encrypt_init(&stream->decrypt);
}
else
{
@ -3279,12 +3309,13 @@ static int parse_sk_sesskey(pgp_region_t *region, pgp_stream_t *stream)
"[...] The S2K algorithm applied to the passphrase produces the session
key for decrypting the file, using the symmetric cipher algorithm from
the Symmetric-Key Encrypted Session Key packet." */
pgp_crypt_any(&stream->decrypt, algo);
if( !pgp_crypt_any(&stream->decrypt, algo) ) {
goto cleanup;
}
iv = calloc(1, stream->decrypt.blocksize); if( iv == NULL ) { goto cleanup; }
stream->decrypt.set_iv(&stream->decrypt, iv);
stream->decrypt.set_crypt_key(&stream->decrypt, key);
pgp_encrypt_init(&stream->decrypt);
free(iv);
}
success = 1;
@ -3292,6 +3323,9 @@ static int parse_sk_sesskey(pgp_region_t *region, pgp_stream_t *stream)
cleanup:
free(key);
free(iv);
free(encr_session_key);
free(decr_session_key);
return success;
}
// /EDIT BY MR