From cbea7bc041e5c14670042e3e52f0786f9561af05 Mon Sep 17 00:00:00 2001
From: tomsmeding <tom.smeding@gmail.com>
Date: Sun, 9 Oct 2016 21:43:38 +0200
Subject: Better error handling (exceptions)

---
 aes.cpp           |   4 +++-
 aes.h             |   2 +-
 bigint.cpp        |   2 +-
 bigint.h          |   4 +++-
 envelope.cpp      |  10 ++++++++--
 envelope/envelope | Bin 0 -> 121056 bytes
 envelope/main.cpp |  23 ++++++++++++++++++++---
 rng.cpp           |   4 ++--
 rng.h             |   2 ++
 9 files changed, 40 insertions(+), 11 deletions(-)
 create mode 100755 envelope/envelope

diff --git a/aes.cpp b/aes.cpp
index 29fc7fc..7430717 100644
--- a/aes.cpp
+++ b/aes.cpp
@@ -248,7 +248,9 @@ namespace AES{
 			case AES_256_CBC: increment=2; break;
 			default: assert(false);
 		}
-		assert((int)key.size()==4*(4+2*increment));
+		if((int)key.size()!=4*(4+2*increment)){
+			throw invalid_argument("Invalid AES key length");
+		}
 		return decryptCBC(data,key,10+2*increment);
 	}
 
diff --git a/aes.h b/aes.h
index f531395..9274d21 100644
--- a/aes.h
+++ b/aes.h
@@ -12,7 +12,7 @@ namespace AES{
 
 	std::string encrypt(const std::string &data,const std::string &key,Algorithm algo);
 
-	//throws invalid_argument for an invalid ciphertext (length not a multiple of block size, or padding malformed)
+	//throws invalid_argument for an invalid ciphertext (length not a multiple of block size, or padding malformed) or an invalid key (invalid length)
 	std::string decrypt(const std::string &data,const std::string &key,Algorithm algo);
 
 }
diff --git a/bigint.cpp b/bigint.cpp
index 8cd06ab..c25a2c1 100644
--- a/bigint.cpp
+++ b/bigint.cpp
@@ -521,7 +521,7 @@ string Bigint::serialiseMantissa() const {
 }
 
 void Bigint::deserialiseMantissa(const string &s){
-	assert(s.size()%sizeof(digit_t)==0);
+	if(s.size()%sizeof(digit_t)!=0)throw invalid_argument("Not a serialised Bigint");
 	sign=1;
 	int sz=s.size()/sizeof(digit_t);
 	digits.resize(sz);
diff --git a/bigint.h b/bigint.h
index a4c29d6..a3c5be3 100644
--- a/bigint.h
+++ b/bigint.h
@@ -93,7 +93,9 @@ public:
 	bool odd() const;
 
 	std::string serialiseMantissa() const; //stores everything but the sign
-	void deserialiseMantissa(const std::string&); //restores non-negative number
+
+	//restores non-negative number; can throw invalid_argument
+	void deserialiseMantissa(const std::string&);
 	std::vector<bool> bits() const;
 
 	friend std::istream& operator>>(std::istream&,Bigint&);
diff --git a/envelope.cpp b/envelope.cpp
index c881815..33ac8c4 100644
--- a/envelope.cpp
+++ b/envelope.cpp
@@ -105,7 +105,9 @@ namespace Envelope{
 			bytes.push_back(res.lowdigits()&0xff);
 			res>>=8;
 		}
-		assert(res==0);
+		if(res!=0){
+			throw invalid_argument("Envelope RSA private key incorrect");
+		}
 		string decrkey(bytes.size(),'\0');
 		for(int i=0;i<(int)bytes.size();i++)decrkey[bytes.size()-1-i]=bytes[i];
 #ifdef DEBUG
@@ -115,7 +117,11 @@ namespace Envelope{
 #ifdef DEBUG
 		cerr<<"payload="<<Base64::encode(data.substr(0,data.size()-2-encrkeylen))<<endl;
 #endif
-		return AES::decrypt(data.substr(0,data.size()-2-encrkeylen),decrkey,AES::AES_256_CBC);
+		try {
+			return AES::decrypt(data.substr(0,data.size()-2-encrkeylen),decrkey,AES::AES_256_CBC);
+		} catch(invalid_argument){
+			throw invalid_argument("Envelope RSA private key incorrect");
+		}
 	}
 
 }
diff --git a/envelope/envelope b/envelope/envelope
new file mode 100755
index 0000000..599c263
Binary files /dev/null and b/envelope/envelope differ
diff --git a/envelope/main.cpp b/envelope/main.cpp
index f0e544e..3889c2a 100644
--- a/envelope/main.cpp
+++ b/envelope/main.cpp
@@ -52,7 +52,13 @@ void mode_keygen(int keylength){
 }
 
 void mode_encrypt(const string &pubkeyrepr){
-	RSA::Key key(RSA::importKey(pubkeyrepr));
+	RSA::Key key;
+	try {
+		key=RSA::importKey(pubkeyrepr);
+	} catch(invalid_argument){
+		cerr<<"The given public key is not a valid key!"<<endl;
+		exit(1);
+	}
 	string data;
 	char buf[1024];
 	while(cin){
@@ -65,7 +71,13 @@ void mode_encrypt(const string &pubkeyrepr){
 }
 
 void mode_decrypt(const string &privkeyrepr){
-	RSA::Key key(RSA::importKey(privkeyrepr));
+	RSA::Key key;
+	try {
+		key=RSA::importKey(privkeyrepr);
+	} catch(invalid_argument){
+		cerr<<"The given private key is not a valid key!"<<endl;
+		exit(1);
+	}
 	string data;
 	char buf[1024];
 	while(cin){
@@ -74,7 +86,12 @@ void mode_decrypt(const string &privkeyrepr){
 		if(nread==0)continue;
 		data.append(buf,nread);
 	}
-	cout<<Envelope::decrypt(Base64::decode(data),key)<<flush;
+	try {
+		cout<<Envelope::decrypt(Base64::decode(data),key)<<flush;
+	} catch(invalid_argument){
+		cerr<<"Private key doesn't match encrypted text!"<<endl;
+		exit(1);
+	}
 }
 
 int main(int argc,char **argv){
diff --git a/rng.cpp b/rng.cpp
index e06b8be..fc86993 100644
--- a/rng.cpp
+++ b/rng.cpp
@@ -23,7 +23,7 @@ inline uint64_t rotr64(uint64_t x,uint32_t n){
 
 KeyRng::KeyRng(const char *key_,int keylen_)
 		:keylen(keylen_),idx(0),state(0){
-	assert(keylen>0);
+	if(keylen<=0)throw invalid_argument("KeyRng: Key should not be empty");
 	assert(key_);
 	key=new uint8_t[keylen];
 	memcpy(key,key_,keylen);
@@ -32,7 +32,7 @@ KeyRng::KeyRng(const char *key_,int keylen_)
 
 KeyRng::KeyRng(const string &key_)
 		:keylen(key_.size()),idx(0),state(0){
-	assert(keylen>0);
+	if(keylen==0)throw invalid_argument("KeyRng: Key should not be empty");
 	key=new uint8_t[keylen];
 	memcpy(key,key_.data(),keylen);
 	stir();
diff --git a/rng.h b/rng.h
index e843bbd..9ce2abd 100644
--- a/rng.h
+++ b/rng.h
@@ -18,8 +18,10 @@ class KeyRng : public Rng{
 	void stir();
 
 public:
+	//throws invalid_argument if keylen<=0
 	KeyRng(const char *key,int keylen);
 	explicit KeyRng(const std::string &key);
+
 	KeyRng(const Rng&)=delete; //just keep it at one KeyRng please
 	~KeyRng();
 
-- 
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