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/*
* Key Derivation Function (KDF) Module
*
* Provides commands to derive keys.
*
* Copyright (C) 2023 Brian O'Hagan
*
*/
#include "tlsInt.h"
#include "tclOpts.h"
#include <openssl/crypto.h>
#include <openssl/evp.h>
#include <openssl/kdf.h>
/*******************************************************************/
/*
* Get cipher
*/
EVP_CIPHER *Util_GetCipher(Tcl_Interp *interp, char *name, int exist) {
EVP_CIPHER *cipher = NULL;
if (name != NULL) {
cipher = EVP_get_cipherbyname(name);
if (cipher == NULL) {
Tcl_AppendResult(interp, "Invalid cipher: \"", name, "\"", NULL);
}
} else if (exist) {
Tcl_AppendResult(interp, "No cipher specified", NULL);
}
return cipher;
}
/*
* Get message digest
*/
EVP_MD *Util_GetDigest(Tcl_Interp *interp, char *name, int exist) {
EVP_MD *md = NULL;
if (name != NULL) {
md = EVP_get_digestbyname(name);
if (md == NULL) {
Tcl_AppendResult(interp, "Invalid digest: \"", name, "\"", NULL);
}
} else if (exist) {
Tcl_AppendResult(interp, "No digest specified", NULL);
}
return md;
}
/*******************************************************************/
/* Options for KDF commands */
static const char *command_opts [] = {
"-cipher", "-digest", "-hash", "-iterations", "-password", "-salt", "-size", NULL};
static const char *command_opts [] = {
"-cipher", "-digest", "-hash", "-info", "-iterations", "-key", "-length", "-password",
"-salt", "-size", "-N", "-n", "-r", "-p", NULL};
enum _command_opts {
_opt_cipher, _opt_digest, _opt_hash, _opt_iter, _opt_password, _opt_salt, _opt_size
_opt_cipher, _opt_digest, _opt_hash, _opt_info, _opt_iter, _opt_key, _opt_length,
_opt_password, _opt_salt, _opt_size, _opt_N, _opt_n, _opt_r, _opt_p
};
/*
*-------------------------------------------------------------------
*
* DeriveKey --
* KDF_PBKDF2 --
*
* PKCS5_PBKDF2_HMAC key derivation function (KDF) specified by PKCS #5.
* See RFC 6070.
* KDFs include PBKDF2 from RFC 2898/8018 and Scrypt from RFC 7914.
*
* Returns:
* TCL_OK or TCL_ERROR
*
* Side effects:
* Sets result to a list of key and iv values, or an error message
*
*-------------------------------------------------------------------
*/
static int DeriveKey(ClientData clientData, Tcl_Interp *interp, int objc, Tcl_Obj *const objv[]) {
int key_len = 0, md_len = 0, pass_len = 0, salt_len = 0, fn;
int iklen, ivlen, iter = PKCS5_DEFAULT_ITER;
unsigned char *passwd = NULL, *salt = NULL;
static int KDF_PBKDF2(ClientData clientData, Tcl_Interp *interp, int objc, Tcl_Obj *const objv[]) {
int pass_len = 0, salt_len = 0, fn;
int iklen, ivlen, iter = 1;
unsigned char *password = NULL, *salt = NULL;
Tcl_Obj *resultObj;
int max = EVP_MAX_KEY_LENGTH + EVP_MAX_IV_LENGTH, size = max;
unsigned char tmpkeyiv[EVP_MAX_KEY_LENGTH + EVP_MAX_IV_LENGTH];
int buf_len = (EVP_MAX_KEY_LENGTH + EVP_MAX_IV_LENGTH)*4, dk_len = buf_len;
unsigned char tmpkeyiv[(EVP_MAX_KEY_LENGTH + EVP_MAX_IV_LENGTH)*4];
char *cipherName = NULL, *digestName = NULL;
dprintf("Called");
/* Clear errors */
Tcl_ResetResult(interp);
ERR_clear_error();
/* Validate arg count */
if (objc < 3 || objc > 11) {
Tcl_WrongNumArgs(interp, 1, objv, "[-cipher cipher | -size length] -digest digest ?-iterations count? ?-password string? ?-salt string?");
return TCL_ERROR;
}
/* Init buffers */
memset(tmpkeyiv, 0, EVP_MAX_KEY_LENGTH + EVP_MAX_IV_LENGTH);
memset(tmpkeyiv, 0, buf_len);
/* Get options */
for (int idx = 1; idx < objc; idx++) {
/* Get option */
if (Tcl_GetIndexFromObj(interp, objv[idx], command_opts, "option", 0, &fn) != TCL_OK) {
return TCL_ERROR;
}
/* Validate arg has value */
/* Validate arg has a value */
if (++idx >= objc) {
Tcl_AppendResult(interp, "No value for option \"", command_opts[fn], "\"", (char *) NULL);
return TCL_ERROR;
}
return TCL_ERROR;
}
switch(fn) {
case _opt_cipher:
GET_OPT_STRING(objv[idx], cipherName, NULL);
break;
case _opt_digest:
case _opt_hash:
GET_OPT_STRING(objv[idx], digestName, NULL);
break;
case _opt_iter:
GET_OPT_INT(objv[idx], &iter);
break;
case _opt_key:
case _opt_password:
GET_OPT_BYTE_ARRAY(objv[idx], passwd, &pass_len);
GET_OPT_BYTE_ARRAY(objv[idx], password, &pass_len);
break;
case _opt_salt:
GET_OPT_BYTE_ARRAY(objv[idx], salt, &salt_len);
break;
case _opt_length:
case _opt_size:
GET_OPT_INT(objv[idx], &size);
GET_OPT_INT(objv[idx], &dk_len);
break;
}
}
/* Validate options */
if (cipherName != NULL) {
if (cipherName != NULL && (cipher = Util_GetCipher(interp, cipherName, 0)) == NULL) {
#if OPENSSL_VERSION_NUMBER < 0x30000000L
cipher = EVP_get_cipherbyname(cipherName);
#else
cipher = EVP_CIPHER_fetch(NULL, cipherName, NULL);
#endif
if (cipher == NULL) {
Tcl_AppendResult(interp, "Invalid cipher: \"", cipherName, "\"", NULL);
return TCL_ERROR;
}
}
if (digestName != NULL) {
#if OPENSSL_VERSION_NUMBER < 0x30000000L
md = EVP_get_digestbyname(digestName);
#else
md = EVP_MD_fetch(NULL, digestName, NULL);
#endif
if (md == NULL) {
Tcl_AppendResult(interp, "Invalid digest: \"", digestName, "\"", NULL);
return TCL_ERROR;
}
}
if (size < 1 || size > max) {
Tcl_SetObjResult(interp, Tcl_ObjPrintf("Invalid derived key length %d: must be 0 < size <= %d", size, max));
if (size > max) size = max;
iklen = size;
if (dk_len > buf_len) dk_len = buf_len;
iklen = dk_len;
ivlen = 0;
} else {
iklen = EVP_CIPHER_key_length(cipher);
ivlen = EVP_CIPHER_iv_length(cipher);
size = iklen+ivlen;
dk_len = iklen+ivlen;
}
/* Perform password derivation */
if (!PKCS5_PBKDF2_HMAC(passwd, pass_len, salt, salt_len, iter, md, size, tmpkeyiv)) {
/* Derive key */
if (!PKCS5_PBKDF2_HMAC(password, pass_len, salt, salt_len, iter, md, dk_len, tmpkeyiv)) {
Tcl_AppendResult(interp, "Key derivation failed: ", REASON(), NULL);
return TCL_ERROR;
}
/* Return key and iv */
/* Set result to key and iv */
if (cipher == NULL) {
resultObj = Tcl_NewByteArrayObj(tmpkeyiv, size);
Tcl_SetObjResult(interp, Tcl_NewByteArrayObj(tmpkeyiv, dk_len));
} else {
resultObj = Tcl_NewListObj(0, NULL);
Tcl_Obj *resultObj = Tcl_NewListObj(0, NULL);
LAPPEND_BARRAY(interp, resultObj, "key", tmpkeyiv, iklen);
LAPPEND_BARRAY(interp, resultObj, "iv", tmpkeyiv+iklen, ivlen);
Tcl_SetObjResult(interp, resultObj);
}
Tcl_SetObjResult(interp, resultObj);
clientData = clientData;
Tcl_CreateObjCommand(interp, "tls::derive_key", DeriveKey, (ClientData) 0, (Tcl_CmdDeleteProc *) NULL);
Tcl_CreateObjCommand(interp, "tls::hkdf", KDF_HKDF, (ClientData) 0, (Tcl_CmdDeleteProc *) NULL);
Tcl_CreateObjCommand(interp, "tls::pbkdf2", KDF_PBKDF2, (ClientData) 0, (Tcl_CmdDeleteProc *) NULL);
return TCL_OK;
}
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