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Adding Extended Cipher feature.

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With this new subcommand, Pico HSM will support newer cipher algorithms.
ChaCha20-Poly1305 is the first. It will be based on a custom P2 subcommand to support an arbitrary structure with multiple parameters (AAD, IV, etc.)

pico-hsm-tool.py shall be used.

Signed-off-by: Pol Henarejos <pol.henarejos@cttc.es>
This commit is contained in:
Pol Henarejos
2022-11-07 21:37:11 +01:00
parent 30301c68f1
commit a7682d2639
4 changed files with 120 additions and 17 deletions
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46
src/hsm/cmd_cipher_sym.c
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@@ -19,9 +19,12 @@
#include "mbedtls/aes.h"
#include "mbedtls/cmac.h"
#include "mbedtls/hkdf.h"
#include "mbedtls/chachapoly.h"
#include "crypto_utils.h"
#include "sc_hsm.h"
#include "kek.h"
#include "asn1.h"
#include "oid.h"
int cmd_cipher_sym() {
int key_id = P1(apdu);
@@ -33,9 +36,6 @@ int cmd_cipher_sym() {
return SW_FILE_NOT_FOUND();
if (key_has_purpose(ef, algo) == false)
return SW_CONDITIONS_NOT_SATISFIED();
if ((apdu.nc % 16) != 0) {
return SW_WRONG_LENGTH();
}
if (wait_button_pressed() == true) // timeout
return SW_SECURE_MESSAGE_EXEC_ERROR();
int key_size = file_get_size(ef);
@@ -45,6 +45,9 @@ int cmd_cipher_sym() {
return SW_EXEC_ERROR();
}
if (algo == ALGO_AES_CBC_ENCRYPT || algo == ALGO_AES_CBC_DECRYPT) {
if ((apdu.nc % 16) != 0) {
return SW_WRONG_LENGTH();
}
mbedtls_aes_context aes;
mbedtls_aes_init(&aes);
uint8_t tmp_iv[IV_SIZE];
@@ -105,6 +108,43 @@ int cmd_cipher_sym() {
return SW_EXEC_ERROR();
res_APDU_size = apdu.nc;
}
else if (algo == ALGO_EXT_CIPHER_ENCRYPT || algo == ALGO_EXT_CIPHER_DECRYPT) {
size_t oid_len = 0, aad_len = 0, iv_len = 0, enc_len = 0;
uint8_t *oid = NULL, *aad = NULL, *iv = NULL, *enc = NULL;
if (!asn1_find_tag(apdu.data, apdu.nc, 0x6, &oid_len, &oid) || oid_len == 0 || oid == NULL) {
mbedtls_platform_zeroize(kdata, sizeof(kdata));
return SW_WRONG_DATA();
}
asn1_find_tag(apdu.data, apdu.nc, 0x81, &enc_len, &enc);
asn1_find_tag(apdu.data, apdu.nc, 0x82, &iv_len, &iv);
asn1_find_tag(apdu.data, apdu.nc, 0x83, &aad_len, &aad);
uint8_t tmp_iv[16];
memset(tmp_iv, 0, sizeof(tmp_iv));
if (memcmp(oid, OID_CHACHA20_POLY1305, oid_len) == 0)
{
if (algo == ALGO_EXT_CIPHER_DECRYPT && enc_len < 16) {
mbedtls_platform_zeroize(kdata, sizeof(kdata));
return SW_WRONG_DATA();
}
int r = 0;
mbedtls_chachapoly_context ctx;
mbedtls_chachapoly_init(&ctx);
if (algo == ALGO_EXT_CIPHER_ENCRYPT) {
r = mbedtls_chachapoly_encrypt_and_tag(&ctx, enc_len, iv ? iv : tmp_iv, aad, aad_len, enc, res_APDU, res_APDU + enc_len);
}
else if (algo == ALGO_EXT_CIPHER_DECRYPT) {
r = mbedtls_chachapoly_auth_decrypt(&ctx, enc_len - 16, iv ? iv : tmp_iv, aad, aad_len, enc + enc_len - 16, enc, res_APDU);
}
mbedtls_platform_zeroize(kdata, sizeof(kdata));
mbedtls_chachapoly_free(&ctx);
if (r != 0)
return SW_EXEC_ERROR();
if (algo == ALGO_EXT_CIPHER_ENCRYPT)
res_APDU_size = enc_len + 16;
else if (algo == ALGO_EXT_CIPHER_DECRYPT)
res_APDU_size = enc_len - 16;
}
}
else {
mbedtls_platform_zeroize(kdata, sizeof(kdata));
return SW_WRONG_P1P2();