Is it possible to make a wallet for BTC and store LTC and NMC or other coins in it?
I'm not sure if there is a software wallet to do this, but if you want it for cold storage, you can definitely create addresses for almost all the cryptocurrencies from a raw 256 bit private key. This allows you to just securely store the 256 bit key rather than the individual wallet files for multiple cryptocoins.
You can do this by:
- Creating a 256 private key of 64 hex (0-9,A-F) digits
- Open brainwallet.org and go to the "Generator" tab and select "secret exponent"
- Paste your 64 hex digits into the "Secret Exponent" text box.
- Select the coin type in the top right corner and the coins private key and address will be shown in the "Private Key" and "Address" areas.
As an example, the 256 bit private key A5F308EB5553464AD377C68D16CDB85F3C8D63CABAC8017BE6D9D9A43F7F0CDF is the following addresses:
- BTC (Private): 5K5NXzAa7PE5irZFc9Va6eAN4zPfd2E9MBcrt1ea8j225ix6wpC
- BTC (Address): 18S5Czkk3pp8vSwVsS8fD28HLxea6JcVc
- LTC (Private): 6vP717i71ogxCET77yHXt2wY2Tx8ppgB7s22bCfbrBLdmZvbD5f
- LTC (Address): LKMPLRJapi4sPj96g1RRwE5tVZKviuvMxS
- NMC (Private): 74A5i3WERWPrjWmvkHmXhKLdgvR1Re3gGRJTZoRBpoNBk1JL8RM
- NMC (Address): MvhoGrVjfRvNfThSmgkhsjB31aMhYnd5qs
Note that this is somewhat insecure as if someone knows the coin private key for one of the addresses, they can directly convert the coin private key back to the raw private key.
Also if you import a private key into a wallet program (eg: bitcoind), be aware that they may send change to new addresses.
Coinomi Universal HD Wallet will do exactly what you're looking for.
Coinomi is a very secure and lightweight, universal, open-source HD wallet for Bitcoin and many altcoins. At the moment the supported coins are:
with more integrations on the way.
I don't know a real wallet program that does it, but if you look for a web wallet, VirCurEx might be something.
It's an exchange for different crypto-currencies and so you also have a web wallet for each of them.
Yes and no, the wallet software for each is an independent piece of software built by the community around that single cryptocurrency. It's possible that third party developers have/will develop a multi-currency digital wallet, to date all I have found is http://ufasoft.com/coin/, but I have not used it personally.