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-rw-r--r--util-src/crypto.c27
-rw-r--r--util/jwt.lua8
2 files changed, 21 insertions, 14 deletions
diff --git a/util-src/crypto.c b/util-src/crypto.c
index c5ecf9ab..dce1a740 100644
--- a/util-src/crypto.c
+++ b/util-src/crypto.c
@@ -33,6 +33,9 @@ typedef unsigned __int32 uint32_t;
#define luaL_setfuncs(L, R, N) luaL_register(L, NULL, R)
#endif
+/* The max size of an encoded 'R' or 'S' value. P-521 = 521 bits = 66 bytes */
+#define MAX_ECDSA_SIG_INT_BYTES 66
+
#include "managed_pointer.h"
#define PKEY_MT_TAG "util.crypto key"
@@ -433,10 +436,15 @@ static int Lparse_ecdsa_signature(lua_State *L) {
ECDSA_SIG *sig;
size_t sig_der_len;
const unsigned char *sig_der = (unsigned char*)luaL_checklstring(L, 1, &sig_der_len);
+ const size_t sig_int_bytes = luaL_checkinteger(L, 2);
const BIGNUM *r, *s;
- unsigned char rb[32];
- unsigned char sb[32];
int rlen, slen;
+ unsigned char rb[MAX_ECDSA_SIG_INT_BYTES];
+ unsigned char sb[MAX_ECDSA_SIG_INT_BYTES];
+
+ if(sig_int_bytes > MAX_ECDSA_SIG_INT_BYTES) {
+ luaL_error(L, "requested signature size exceeds supported limit");
+ }
sig = d2i_ECDSA_SIG(NULL, &sig_der, sig_der_len);
@@ -447,17 +455,14 @@ static int Lparse_ecdsa_signature(lua_State *L) {
ECDSA_SIG_get0(sig, &r, &s);
- rlen = BN_num_bytes(r);
- slen = BN_num_bytes(s);
+ rlen = BN_bn2binpad(r, rb, sig_int_bytes);
+ slen = BN_bn2binpad(s, sb, sig_int_bytes);
- if (rlen > 32 || slen > 32) {
+ if (rlen == -1 || slen == -1) {
ECDSA_SIG_free(sig);
- luaL_error(L, "unexpectedly large signature integers");
+ luaL_error(L, "encoded integers exceed requested size");
}
- BN_bn2bin(r, rb);
- BN_bn2bin(s, sb);
-
ECDSA_SIG_free(sig);
lua_pushlstring(L, (const char*)rb, rlen);
@@ -485,7 +490,9 @@ static int Lbuild_ecdsa_signature(lua_State *L) {
luaL_buffinit(L, &sigbuf);
- unsigned char *buffer = (unsigned char*)luaL_prepbuffsize(&sigbuf, rlen+slen+32);
+ /* DER structure of an ECDSA signature has 7 bytes plus the integers themselves,
+ which may gain an extra byte once encoded */
+ unsigned char *buffer = (unsigned char*)luaL_prepbuffsize(&sigbuf, (rlen+1)+(slen+1)+7);
int len = i2d_ECDSA_SIG(sig, &buffer);
luaL_addsize(&sigbuf, len);
luaL_pushresult(&sigbuf);
diff --git a/util/jwt.lua b/util/jwt.lua
index 5c74850a..1c7daf12 100644
--- a/util/jwt.lua
+++ b/util/jwt.lua
@@ -135,21 +135,21 @@ local function new_rsa_algorithm(name)
end
-- ES***
-local function new_ecdsa_algorithm(name, c_sign, c_verify)
+local function new_ecdsa_algorithm(name, c_sign, c_verify, sig_bytes)
local function encode_ecdsa_sig(der_sig)
- local r, s = crypto.parse_ecdsa_signature(der_sig);
+ local r, s = crypto.parse_ecdsa_signature(der_sig, sig_bytes);
return r..s;
end
local function decode_ecdsa_sig(jwk_sig)
- return crypto.build_ecdsa_signature(jwk_sig:sub(1, 32), jwk_sig:sub(33, 64));
+ return crypto.build_ecdsa_signature(jwk_sig:sub(1, sig_bytes), jwk_sig:sub(sig_bytes+1, sig_bytes*2));
end
return new_crypto_algorithm(name, "id-ecPublicKey", c_sign, c_verify, encode_ecdsa_sig, decode_ecdsa_sig);
end
local algorithms = {
HS256 = new_hmac_algorithm("HS256"), HS384 = new_hmac_algorithm("HS384"), HS512 = new_hmac_algorithm("HS512");
- ES256 = new_ecdsa_algorithm("ES256", crypto.ecdsa_sha256_sign, crypto.ecdsa_sha256_verify);
+ ES256 = new_ecdsa_algorithm("ES256", crypto.ecdsa_sha256_sign, crypto.ecdsa_sha256_verify, 32);
RS256 = new_rsa_algorithm("RS256"), RS384 = new_rsa_algorithm("RS384"), RS512 = new_rsa_algorithm("RS512");
PS256 = new_rsa_algorithm("PS256"), PS384 = new_rsa_algorithm("PS384"), PS512 = new_rsa_algorithm("PS512");
};