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Refactor cfb.encrypt: fix inconsistent output depending on plaintext length. Use typed arrays for ciphertext.

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This commit is contained in:
Thomas Oberndörfer 2014-04-25 16:33:28 +02:00
parent 82b18c61f3
commit e1dffffe8d
3 changed files with 77 additions and 103 deletions
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111
src/crypto/cfb.js
View File

@ -52,9 +52,10 @@ module.exports = {
var FRE = new Uint8Array(block_size);
prefixrandom = prefixrandom + prefixrandom.charAt(block_size - 2) + prefixrandom.charAt(block_size - 1);
util.print_debug("prefixrandom:" + util.hexstrdump(prefixrandom));
var ciphertext = '';
var i, n;
var ciphertext = new Uint8Array(plaintext.length + 2 + block_size * 2);
var i, n, begin;
var offset = resync ? 0 : 2;
// 1. The feedback register (FR) is set to the IV, which is all zeros.
for (i = 0; i < block_size; i++) {
FR[i] = 0;
@ -67,13 +68,11 @@ module.exports = {
// the plaintext to produce C[1] through C[BS], the first BS octets
// of ciphertext.
for (i = 0; i < block_size; i++) {
ciphertext += String.fromCharCode(FRE[i] ^ prefixrandom.charCodeAt(i));
ciphertext[i] = FRE[i] ^ prefixrandom.charCodeAt(i);
}
// 4. FR is loaded with C[1] through C[BS].
for (i = 0; i < block_size; i++) {
FR[i] = ciphertext.charCodeAt(i);
}
FR.set(ciphertext.subarray(0, block_size));
// 5. FR is encrypted to produce FRE, the encryption of the first BS
// octets of ciphertext.
@ -82,82 +81,44 @@ module.exports = {
// 6. The left two octets of FRE get xored with the next two octets of
// data that were prefixed to the plaintext. This produces C[BS+1]
// and C[BS+2], the next two octets of ciphertext.
ciphertext += String.fromCharCode(FRE[0] ^ prefixrandom.charCodeAt(block_size));
ciphertext += String.fromCharCode(FRE[1] ^ prefixrandom.charCodeAt(block_size + 1));
ciphertext[block_size] = FRE[0] ^ prefixrandom.charCodeAt(block_size);
ciphertext[block_size + 1] = FRE[1] ^ prefixrandom.charCodeAt(block_size + 1);
if (resync) {
// 7. (The resync step) FR is loaded with C3-C10.
for (i = 0; i < block_size; i++) {
FR[i] = ciphertext.charCodeAt(i + 2);
}
// 7. (The resync step) FR is loaded with C[3] through C[BS+2].
FR.set(ciphertext.subarray(2, block_size + 2));
} else {
for (i = 0; i < block_size; i++) {
FR[i] = ciphertext.charCodeAt(i);
}
FR.set(ciphertext.subarray(0, block_size));
}
// 8. FR is encrypted to produce FRE.
FRE = cipherfn.encrypt(FR);
if (resync) {
// 9. FRE is xored with the first 8 octets of the given plaintext, now
// that we have finished encrypting the 10 octets of prefixed data.
// This produces C11-C18, the next 8 octets of ciphertext.
// 9. FRE is xored with the first BS octets of the given plaintext, now
// that we have finished encrypting the BS+2 octets of prefixed
// data. This produces C[BS+3] through C[BS+(BS+2)], the next BS
// octets of ciphertext.
for (i = 0; i < block_size; i++) {
ciphertext[block_size + 2 + i] = FRE[i + offset] ^ plaintext.charCodeAt(i);
}
for (n = block_size; n < plaintext.length + offset; n += block_size) {
// 10. FR is loaded with C[BS+3] to C[BS + (BS+2)] (which is C11-C18 for
// an 8-octet block).
begin = n + 2 - offset;
FR.set(ciphertext.subarray(begin, begin + block_size));
// 11. FR is encrypted to produce FRE.
FRE = cipherfn.encrypt(FR);
// 12. FRE is xored with the next BS octets of plaintext, to produce
// the next BS octets of ciphertext. These are loaded into FR, and
// the process is repeated until the plaintext is used up.
for (i = 0; i < block_size; i++) {
ciphertext += String.fromCharCode(FRE[i] ^ plaintext.charCodeAt(i));
ciphertext[block_size + begin + i] = FRE[i] ^ plaintext.charCodeAt(n + i - offset);
}
for (n = block_size + 2; n < plaintext.length; n += block_size) {
// 10. FR is loaded with C11-C18
for (i = 0; i < block_size; i++) {
FR[i] = ciphertext.charCodeAt(n + i);
}
// 11. FR is encrypted to produce FRE.
FRE = cipherfn.encrypt(FR);
// 12. FRE is xored with the next 8 octets of plaintext, to produce the
// next 8 octets of ciphertext. These are loaded into FR and the
// process is repeated until the plaintext is used up.
for (i = 0; i < block_size; i++) {
ciphertext += String.fromCharCode(FRE[i] ^ plaintext.charCodeAt((n - 2) + i));
}
}
} else {
plaintext = " " + plaintext;
// 9. FRE is xored with the first 8 octets of the given plaintext, now
// that we have finished encrypting the 10 octets of prefixed data.
// This produces C11-C18, the next 8 octets of ciphertext.
for (i = 2; i < block_size; i++) {
ciphertext += String.fromCharCode(FRE[i] ^ plaintext.charCodeAt(i));
}
var tempCiphertext = ciphertext.substring(0, 2 * block_size);
var tempCiphertextString = ciphertext.substring(block_size);
var tempCiphertextBlock;
for (n = block_size; n < plaintext.length; n += block_size) {
// 10. FR is loaded with C11-C18
for (i = 0; i < block_size; i++) {
FR[i] = tempCiphertextString.charCodeAt(i);
}
tempCiphertextString = '';
// 11. FR is encrypted to produce FRE.
FRE = cipherfn.encrypt(FR);
// 12. FRE is xored with the next 8 octets of plaintext, to produce the
// next 8 octets of ciphertext. These are loaded into FR and the
// process is repeated until the plaintext is used up.
for (i = 0; i < block_size; i++) {
tempCiphertextBlock = String.fromCharCode(FRE[i] ^ plaintext.charCodeAt(n + i));
tempCiphertext += tempCiphertextBlock;
tempCiphertextString += tempCiphertextBlock;
}
}
ciphertext = tempCiphertext;
}
ciphertext = ciphertext.substring(0, plaintext.length + 2 + block_size);
return ciphertext;
ciphertext = ciphertext.subarray(0, plaintext.length + 2 + block_size);
return util.Uint8Array2str(ciphertext);
},
/**
@ -233,9 +194,9 @@ module.exports = {
ablock = cipherfn.encrypt(ablock);
// test check octets
if (iblock[block_size - 2] != (ablock[0] ^ ciphertext.charCodeAt(block_size)) || iblock[block_size - 1] != (ablock[
1] ^ ciphertext.charCodeAt(block_size + 1))) {
throw new Error('Invalid data.');
if (iblock[block_size - 2] != (ablock[0] ^ ciphertext.charCodeAt(block_size)) ||
iblock[block_size - 1] != (ablock[1] ^ ciphertext.charCodeAt(block_size + 1))) {
throw new Error('CFB decrypt: invalid key');
}
/* RFC4880: Tag 18 and Resync:

30
src/util.js
View File

@ -159,29 +159,23 @@ module.exports = {
*/
bin2str: function (bin) {
var result = [];
for (var i = 0; i < bin.length; i++) {
result.push(String.fromCharCode(bin[i]));
result[i] = String.fromCharCode(bin[i]);
}
return result.join('');
},
_str2bin: function (str, result) {
for (var i = 0; i < str.length; i++) {
result[i] = str.charCodeAt(i);
}
return result;
},
/**
* Convert a string to an array of integers(0.255)
* @param {String} str String to convert
* @return {Array<Integer>} An array of (binary) integers
*/
str2bin: function (str) {
return this._str2bin(str, new Array(str.length));
var result = [];
for (var i = 0; i < str.length; i++) {
result[i] = str.charCodeAt(i);
}
return result;
},
@ -191,7 +185,11 @@ module.exports = {
* @return {Uint8Array} The array of (binary) integers
*/
str2Uint8Array: function (str) {
return this._str2bin(str, new Uint8Array(new ArrayBuffer(str.length)));
var result = new Uint8Array(str.length);
for (var i = 0; i < str.length; i++) {
result[i] = str.charCodeAt(i);
}
return result;
},
/**
@ -202,7 +200,11 @@ module.exports = {
* @return {String} String representation of the array
*/
Uint8Array2str: function (bin) {
return this.bin2str(bin);
var result = '';
for (var i = 0; i < bin.length; i++) {
result += String.fromCharCode(bin[i]);
}
return result;
},
/**

39
test/crypto/crypto.js
View File

@ -252,26 +252,36 @@ describe('API functional testing', function() {
});
describe('Encrypt and decrypt', function () {
var symmAlgo = "aes256"; // AES256
var symmKey = openpgp.crypto.generateSessionKey(symmAlgo);
var symmencDataOCFB = openpgp.crypto.cfb.encrypt(openpgp.crypto.getPrefixRandom(symmAlgo), symmAlgo, "foobarfoobar1234567890", symmKey, true);
var symmencDataCFB = openpgp.crypto.cfb.encrypt(openpgp.crypto.getPrefixRandom(symmAlgo), symmAlgo, "foobarfoobar1234567890", symmKey, false);
it("Symmetric with OpenPGP CFB resync", function (done) {
var text = openpgp.crypto.cfb.decrypt(symmAlgo,symmKey,symmencDataOCFB,true);
expect(text).to.equal("foobarfoobar1234567890");
done();
var symmAlgos = Object.keys(openpgp.enums.symmetric);
symmAlgos = symmAlgos.filter(function(algo) {
return algo !== 'idea' && algo !== 'plaintext';
});
it.skip("Symmetric without OpenPGP CFB resync", function (done) {
var text = openpgp.crypto.cfb.decrypt(symmAlgo,symmKey,symmencDataCFB,false);
function testCFB(plaintext, resync) {
symmAlgos.forEach(function(algo) {
var symmKey = openpgp.crypto.generateSessionKey(algo);
var symmencData = openpgp.crypto.cfb.encrypt(openpgp.crypto.getPrefixRandom(algo), algo, plaintext, symmKey, resync);
var text = openpgp.crypto.cfb.decrypt(algo, symmKey, symmencData, resync);
expect(text).to.equal(plaintext);
});
}
expect(text).to.equal("foobarfoobar1234567890");
done();
it("Symmetric with OpenPGP CFB resync", function () {
testCFB("hello", true);
testCFB("1234567", true);
testCFB("foobarfoobar1234567890", true);
testCFB("12345678901234567890123456789012345678901234567890", true);
});
it("Symmetric without OpenPGP CFB resync", function () {
testCFB("hello", false);
testCFB("1234567", false);
testCFB("foobarfoobar1234567890", false);
testCFB("12345678901234567890123456789012345678901234567890", false);
});
it('Asymmetric using RSA with eme_pkcs1 padding', function (done) {
var symmKey = openpgp.crypto.generateSessionKey('aes256');
var RSAUnencryptedData = new openpgp.MPI();
RSAUnencryptedData.fromBytes(openpgp.crypto.pkcs1.eme.encode(symmKey, RSApubMPIs[0].byteLength()));
var RSAEncryptedData = openpgp.crypto.publicKeyEncrypt("rsa_encrypt_sign", RSApubMPIs, RSAUnencryptedData);
@ -282,6 +292,7 @@ describe('API functional testing', function() {
});
it('Asymmetric using Elgamal with eme_pkcs1 padding', function (done) {
var symmKey = openpgp.crypto.generateSessionKey('aes256');
var ElgamalUnencryptedData = new openpgp.MPI();
ElgamalUnencryptedData.fromBytes(openpgp.crypto.pkcs1.eme.encode(symmKey, ElgamalpubMPIs[0].byteLength()));
var ElgamalEncryptedData = openpgp.crypto.publicKeyEncrypt("elgamal", ElgamalpubMPIs, ElgamalUnencryptedData);