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I have used PuttyGen to create a public/private key pair as a .ppk file, but I'm having trouble actually using it in my code. Opening the randomly generated ppk file in notepad shows this: 

PuTTY-User-Key-File-2: ssh-rsa
Encryption: aes256-cbc
Comment: rsa-key-20151217
Public-Lines: 6
AAAAB3NzaC1yc2EAAAABJQAAAQEAl3m8PRlx/SL7EJrs+hDQbP9mp27XXRY4pztg
v8mxAthI2tMEhF0eyXqFV0/W/M13pPs1hHh3H7wIfAy/XbxF7KPeOeMkThMmF2p1
cwJOcpFuh6TCPT09ScPLCR5bsmQyzvsjPMWahcoDrLhf9MGfc9luQs7k1eMTM1iX
hq6F/ku7mNQ4mgKoOOlXKPhE6dFz9Qhe5k0TE3zIfkXUCCkm+74VqyG5l5vG6/fb
ZmVD0nGM6ErPHB/zQ0WbTm65BMmLIIfNZoVrRwcrQmjj4qJnJg7s+Ar0wfB0Y1kl
91fcxKJ4Mx2uBw7T0T+61DrXKamnqQmTz8g/QsgwwBGLqz9mXQ==
Private-Lines: 14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-MAC: 5403e23591ff38245d34db92ef130c86e9789b98

And this is what's in the public key file:

---- BEGIN SSH2 PUBLIC KEY ----
Comment: "rsa-key-20151217"
AAAAB3NzaC1yc2EAAAABJQAAAQEAl3m8PRlx/SL7EJrs+hDQbP9mp27XXRY4pztg
v8mxAthI2tMEhF0eyXqFV0/W/M13pPs1hHh3H7wIfAy/XbxF7KPeOeMkThMmF2p1
cwJOcpFuh6TCPT09ScPLCR5bsmQyzvsjPMWahcoDrLhf9MGfc9luQs7k1eMTM1iX
hq6F/ku7mNQ4mgKoOOlXKPhE6dFz9Qhe5k0TE3zIfkXUCCkm+74VqyG5l5vG6/fb
ZmVD0nGM6ErPHB/zQ0WbTm65BMmLIIfNZoVrRwcrQmjj4qJnJg7s+Ar0wfB0Y1kl
91fcxKJ4Mx2uBw7T0T+61DrXKamnqQmTz8g/QsgwwBGLqz9mXQ==
---- END SSH2 PUBLIC KEY ----

Obviously, I'm not using this key anymore, it's just for illustrative purposes. But how do I read this file into C# to use it to sign and verify a string?

yesman
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1 Answers1

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You're making an RSA key in Putty and trying to use that, why not simply just generate the key pair with C#'s RSA encryption?

You can generate a public/private key-pair and save it using this:

//Generate a public/private key pair.
RSACryptoServiceProvider RSA = new RSACryptoServiceProvider();
//Save the public key information to an RSAParameters structure.
RSAParameters RSAKeyInfo = RSA.ExportParameters(false);

You can see how to use this key pair to encrypt data, example documentation here.

Rivasa
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  • I have considered it, but doesn't this generate a different key every time the program is run? Ideally, I want to sign data on one system, and verify it on the other. For that, I would need a public key file I can physically move between servers and stays the same when the system is shut down. – yesman Dec 17 '15 at 22:26
  • @ohyeah maybe something like this..?http://stackoverflow.com/questions/4967325/best-way-to-store-encryption-keys-in-net-c-sharp – Rivasa Dec 17 '15 at 22:29