From d7d409d9eb94acfce8eaa6b420b8d918ccd9645c Mon Sep 17 00:00:00 2001
From: merlokk <807634+merlokk@users.noreply.github.com>
Date: Tue, 13 Nov 2018 14:05:14 +0200
Subject: [PATCH] added check signature in `hf fido auth` command
---
client/cmdhffido.c | 59 +++++++++++++++++++++++++++++++++++++++++++---
1 file changed, 56 insertions(+), 3 deletions(-)
diff --git a/client/cmdhffido.c b/client/cmdhffido.c
index ab9afbdca..86f6bd98b 100644
--- a/client/cmdhffido.c
+++ b/client/cmdhffido.c
@@ -404,6 +404,8 @@ int CmdHFFidoRegister(const char *cmd) {
int CmdHFFidoAuthenticate(const char *cmd) {
uint8_t data[512] = {0};
uint8_t hdata[250] = {0};
+ bool public_key_loaded = false;
+ uint8_t public_key[65] = {0};
int hdatalen = 0;
uint8_t keyHandleLen = 0;
json_t *root = NULL;
@@ -423,6 +425,7 @@ int CmdHFFidoAuthenticate(const char *cmd) {
arg_lit0("uU", "user", "mode: enforce-user-presence-and-sign"),
arg_lit0("cC", "check", "mode: check-only"),
arg_str0("jJ", "json", "fido.json", "JSON input / output file name for parameters."),
+ arg_str0("kK", "key", "public key to verify signature", NULL),
arg_str0(NULL, NULL, "<HEX key handle (var 0..255b)>", NULL),
arg_str0(NULL, NULL, "<HEX/ASCII challenge parameter (32b HEX/1..16 chars)>", NULL),
arg_str0(NULL, NULL, "<HEX/ASCII application parameter (32b HEX/1..16 chars)>", NULL),
@@ -431,7 +434,7 @@ int CmdHFFidoAuthenticate(const char *cmd) {
CLIExecWithReturn(cmd, argtable, true);
bool APDULogging = arg_get_lit(1);
- //bool verbose = arg_get_lit(2);
+ bool verbose = arg_get_lit(2);
bool paramsPlain = arg_get_lit(3);
uint8_t controlByte = 0x08;
if (arg_get_lit(5))
@@ -449,11 +452,25 @@ int CmdHFFidoAuthenticate(const char *cmd) {
JsonLoadBufAsHex(root, "$.ChallengeParam", data, 32, &jlen);
JsonLoadBufAsHex(root, "$.ApplicationParam", &data[32], 32, &jlen);
JsonLoadBufAsHex(root, "$.KeyHandle", &data[65], 512 - 67, &jlen);
+ JsonLoadBufAsHex(root, "$.PublicKey", public_key, 65, &jlen);
+ if (jlen > 0)
+ public_key_loaded = true;
keyHandleLen = jlen & 0xff;
data[64] = keyHandleLen;
}
+ // public key
CLIGetHexWithReturn(8, hdata, &hdatalen);
+ if (hdatalen && hdatalen != 130) {
+ PrintAndLog("ERROR: public key length must be 65 bytes only.");
+ return 1;
+ }
+ if (hdatalen) {
+ memmove(public_key, hdata, hdatalen);
+ public_key_loaded = true;
+ }
+
+ CLIGetHexWithReturn(9, hdata, &hdatalen);
if (hdatalen > 255) {
PrintAndLog("ERROR: application parameter length must be less than 255.");
return 1;
@@ -472,7 +489,7 @@ int CmdHFFidoAuthenticate(const char *cmd) {
return 1;
}
} else {
- CLIGetHexWithReturn(9, hdata, &hdatalen);
+ CLIGetHexWithReturn(10, hdata, &hdatalen);
if (hdatalen && hdatalen != 32) {
PrintAndLog("ERROR: challenge parameter length must be 32 bytes only.");
return 1;
@@ -483,7 +500,7 @@ int CmdHFFidoAuthenticate(const char *cmd) {
if (paramsPlain) {
memset(hdata, 0x00, 32);
- CLIGetStrWithReturn(10, hdata, &hdatalen);
+ CLIGetStrWithReturn(11, hdata, &hdatalen);
if (hdatalen && hdatalen > 16) {
PrintAndLog("ERROR: application parameter length in ASCII mode must be less than 16 chars instead of: %d", hdatalen);
return 1;
@@ -547,6 +564,42 @@ int CmdHFFidoAuthenticate(const char *cmd) {
PrintAndLog("Counter: %d", cntr);
PrintAndLog("Hash[%d]: %s", len - 5, sprint_hex(&buf[5], len - 5));
+ // check ANSI X9.62 format ECDSA signature (on P-256)
+ uint8_t rval[300] = {0};
+ uint8_t sval[300] = {0};
+ res = ecdsa_asn1_get_signature(&buf[5], len - 5, rval, sval);
+ if (!res) {
+ if (verbose) {
+ PrintAndLog(" r: %s", sprint_hex(rval, 32));
+ PrintAndLog(" s: %s", sprint_hex(sval, 32));
+ }
+ if (public_key_loaded) {
+ uint8_t xbuf[4096] = {0};
+ size_t xbuflen = 0;
+ res = FillBuffer(xbuf, sizeof(xbuf), &xbuflen,
+ &data[32], 32, // application parameter
+ &buf[0], 1, // user presence
+ &buf[1], 4, // counter
+ data, 32, // challenge parameter
+ NULL, 0);
+ PrintAndLog("--xbuf(%d)[%d]: %s", res, xbuflen, sprint_hex(xbuf, xbuflen));
+ res = ecdsa_signature_verify(public_key, xbuf, xbuflen, &buf[5], len - 5);
+ if (res) {
+ if (res == -0x4e00) {
+ PrintAndLog("Signature is NOT VALID.");
+ } else {
+ PrintAndLog("Other signature check error: %x %s", (res<0)?-res:res, ecdsa_get_error(res));
+ }
+ } else {
+ PrintAndLog("Signature is OK.");
+ }
+ } else {
+ PrintAndLog("No public key provided. can't check signature.");
+ }
+ } else {
+ PrintAndLog("Invalid signature. res=%d.", res);
+ }
+
if (root) {
JsonSaveBufAsHex(root, "ChallengeParam", data, 32);
JsonSaveBufAsHex(root, "ApplicationParam", &data[32], 32);