check if RSA key is large enough to sign a chunk of data

2009-06-15 13:49:30 +02:00
parent e7227f0ba0
commit 3176e4421f
1 changed files with 7 additions and 0 deletions
@@ -248,6 +248,13 @@ static bool build_emsa_pkcs1_signature(private_gmp_rsa_private_key_t *this,
 		data = digestInfo;
 	}

+	if (data.len > this->k - 3)
+	{
+		free(digestInfo.ptr);
+		DBG1("unable to sign %d bytes using a %dbit key", data.len, this->k * 8);
+		return FALSE;
+	}
+	
 	/* build chunk to rsa-decrypt:
 	 * EM = 0x00 || 0x01 || PS || 0x00 || T. 
 	 * PS = 0xFF padding, with length to fill em