online tool to play around with ECDSA public keys, message signature verification? I realize that this question may be borderline bannable because it's asking for suggestions on tools, but it will really help newbies. This online tool allowed me to play around with hashes and to really understand them at a deeper level: http://www.fileformat.info/tool/hash.htm

I can't find a similar tool (that works) for ECDSA cryptography where I can play around with public and private keys, and do digital signatures on messages, and test signature verification.

I've found these 2 sites that claim to do this but didn't work for me:


http://dbis.rwth-aachen.de/~renzel/mobsos/lib/js/jsrsasign/sample-ecdsa.html
http://extranet.cryptomathic.com/ecc/index


Thoughts? Suggestions?



UPDATE: Great suggestions below. Some tools I found:

for hashing:
http://www.fileformat.info/tool/hash.htm

generating public private key pairs and decrypting ciphers:
https://8gwifi.org/rsafunctions.jsp

Generating EC public private key pairs and signing Verifying the Message 
https://8gwifi.org/ecsignverify.jsp

generating public private key pairs and testing signing:
https://kjur.github.io/jsrsasign/sample/sample-ecdsa.html
Here are a few I'd recommend:


https://bitcore.io/playground/#/address (private key - public key)
https://brainwalletx.github.io/#generator (signing and verifying but bitcoin specific)


Or play with pybitcointools at the command line (not online):

$ git clone https://github.com/vbuterin/pybitcointools.git
$ cd pybitcointools
$ python
&gt;&gt;&gt; from bitcoin import *
&gt;&gt;&gt; sk = random_key()  # Generate a private key
&gt;&gt;&gt; vk = privtopub(sk) # Generate a public key
&gt;&gt;&gt; msg = 'hello world' # Create a simple message
&gt;&gt;&gt; sig = ecdsa_sign(msg, sk) # Sign the message using your private key
&gt;&gt;&gt; print sig
GxXGAt...2L/eJk=
&gt;&gt;&gt; print ecdsa_verify(msg, sig, vk) # Use sig and public key to verify
True
&gt;&gt;&gt; msg = 'hello mars' # Change the message
&gt;&gt;&gt; print ecdsa_verify(msg, sig, vk) # Changing the msg invalidates sig
False


http://showterm.io/203b168061b0156c4d1dd

HD Wallet stuff:


https://iancoleman.github.io/bip39/
http://bip32.org/


If you're looking to learn more about ECDSA suggest checking out: https://jeremykun.com/2014/02/08/introducing-elliptic-curves/