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Merge pull request #23 from jgarzik/encfile-hmac 

util/EncFile: wallet file format gains a trailing HMAC checksum
This commit is contained in:
Stephen Pair 2013-08-15 07:10:21 -07:00
parent 42575d2c97 5fdd7ded14
commit 1fba5ef848
1 changed files with 25 additions and 3 deletions
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28
util/EncFile.js
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@ -4,10 +4,26 @@ var crypto = require('crypto');
exports.readFileSync = function(enc_method, enc_passphrase, filename) exports.readFileSync = function(enc_method, enc_passphrase, filename)
{ {
var crypted = fs.readFileSync(filename, 'binary'); // read entire file into memory
var fileData = fs.readFileSync(filename, 'binary');
if (fileData.length < 32)
throw new Error("Crypted file " + filename + " truncated");
// separate into data, hmac parts
var fileCrypted = fileData.slice(0, -32);
var fileHmac = fileData.slice(-32);
// generate and verify HMAC
var hmac = crypto.createHmac('sha256', enc_passphrase);
hmac.update(fileCrypted);
var digest = hmac.digest('binary');
if (digest.toString() != fileHmac.toString())
throw new Error("Crypted file " + filename + " failed HMAC checksum verification");
// decrypt to plaintext
var decipher = crypto.createDecipher(enc_method, enc_passphrase); var decipher = crypto.createDecipher(enc_method, enc_passphrase);
var dec = decipher.update(crypted, 'binary', 'binary'); var dec = decipher.update(fileCrypted, 'binary', 'binary');
dec += decipher.final('binary'); dec += decipher.final('binary');
return dec; return dec;
}; };
@ -20,11 +36,17 @@ exports.readJFileSync = function(enc_method, enc_passphrase, filename)
exports.writeFileSync = function(enc_method, enc_passphrase, filename, data) exports.writeFileSync = function(enc_method, enc_passphrase, filename, data)
{ {
// encrypt to ciphertext
var cipher = crypto.createCipher(enc_method, enc_passphrase); var cipher = crypto.createCipher(enc_method, enc_passphrase);
var crypted = cipher.update(data, 'binary', 'binary'); var crypted = cipher.update(data, 'binary', 'binary');
crypted += cipher.final('binary'); crypted += cipher.final('binary');
fs.writeFileSync(filename, crypted, 'binary'); // compute HMAC
var hmac = crypto.createHmac('sha256', enc_passphrase);
hmac.update(crypted);
var digest = hmac.digest('binary');
fs.writeFileSync(filename, crypted + digest, 'binary');
return true; return true;
}; };