Trying to figure out different behavior on crypto module for node-v0.6 and node-v0.8

crypto-signature.js

// IDENTITY_FILE=/Users/<USERNAME>/.ssh/id_rsa node crypto-signature.js
if (!process.env.IDENTITY_FILE) {
    console.error('IDENTITY_FILE ENV var requiered');
    process.exit(1);
};

var crypto = require('crypto'),
    fs = require('fs'),
    identity = process.env.IDENTITY_FILE,
    signingKey;

fs.readFile(identity, 'ascii', function (err, file) {
    if (err) {
        console.error(err);
        process.exit(1);
    }
    signingKey = file;

    console.log('Signing key is: %s', signingKey);
    var alg = / DSA /.test(signingKey) ? 'DSA-SHA1' : 'RSA-SHA256';
    console.log('Algorithm is: %s', alg);
    var signer = crypto.createSign(alg);
    var now = new Date().toUTCString();
    signer.update(now);

    var signature = signer.sign(signingKey, 'base64');

    console.log('Signature is: %s', signature);
    process.exit(0);
});

I compiled node 0.8.8 with OPENSSL_NO_TTY commented out deps/openssl/openssl.gyp and this test script worked as expected.

There must be a way to either check ssh-agent (node-smartdc does, apparently) or to have us ask the user for the passphrase and pass it to crypto.