as3crypto issue - apache-flex

I am using the as3crypto library to get the AES algorithm working on a small project that i am doing. This is how i get the crypto function :
var cipher:ICipher = Crypto.getCipher("simple-aes-cbc", key, Crypto.getPad("pkcs5"));
As you can see, I am trying to use AES-128 with CBC and the pkcs5 padding.
If my source data is 128bytes long, the encrypted data is coming as 160bytes. Can some one tell me why this problem is coming?
Following is a small table that I compiled from a sample program.
Source string length | Encrypted string length
15 | 32
16 | 48
31 | 48
32 | 64
Is it supposed to be like this or have I made some mistake.


It is supposed to be like that. You asked for PKCS5 padding which always adds at least one byte of padding. And, of course, the input must be rounded up to some number of whole blocks because AES produces 16-byte chunks of output. With half a block, you cannot decrypt any of the input at all.

Related

Given final block not properly padded. Such issues can arise if a bad key is used during decryption

Hi guys I encrypted school project but my AES saved txt has been deleted, I pictured it before and I filled a new file. But new AES key file is not equal to the typed in jpeg file. Which character is wrong I couldn't find it. Could you please help me.
Pic : https://i.stack.imgur.com/pAXzl.jpg
Text file : http://textuploader.com/dfop6

If you directly convert bytes with any value to Unicode you may lose information because some bytes will not correspond to a Unicode character, a whitespace character or other information that cannot be easily distinguished in printed out form.
Of course there may be ways to brute force your way out of this, but this could easily result in very complex code and possibly near infinite running time. Better start over, and if you want to use screen shots or similar printed text: base 64 or hex encode your results; those can be easily converted back.

CryptoJS AES Increase File Size

Thank you for your help.
I have a problem with sjcl library or cryptojs aes library.
Everytime i encrypt my file with aes the file size is * 2.
For example: When i upload a 4mb file then there is a 8mb file on my server.
I split the file on block which bytesize can be divided by 16.
Please help me
This is the way i encrypt the file:
var l_EncryptetData = CryptoJS.AES.encrypt(p_ChunkData, p_FileKey).toString();
And this is a example array with block sizes from the 4mb file:
0: 1572864
1: 1572864
2: 867005
length: 3
And the FileKey is a SHA-256 Hash

You are converting the cipher output (a CipherParams object) to a character string. By default, CryptoJS does this by representing the result in hexadecimal, where each byte is encoded as two hex digits. You can override this behavior by providing a custom format strategy. Or better yet, don't convert the cipher text to a character string; keep it as binary data.
Please warn users of your application that it is not secure.

Using Coldfusion's Encrypt function to encrypt a hex block and return a block-length result

My company is working on a project that will put card readers in the field. The readers use DUKPT TripleDES encryption, so we will need to develop software that will decrypt the card data on our servers.
I have just started to scratch the surface on this one, but I find myself stuck on a seemingly simple problem... In trying to generate the IPEK (the first step to recreating the symmetric key).
The IPEK's a 16 byte hex value created by concatenating two triple DES encrypted 8 byte hex strings.
I have tried ECB and CBC (zeros for IV) modes with and without padding, but the result of each individual encoding is always 16 bytes or more (2 or more blocks) when I need a result that's the same size as the input. In fact, throughout this process, the cyphertexts should be the same size as the plaintexts being encoded.
<cfset x = encrypt("FFFF9876543210E0",binaryEncode(binaryDecode("0123456789ABCDEFFEDCBA98765432100123456789ABCDEF", "hex"), "base64") ,"DESEDE/CBC/PKCS5Padding","hex",BinaryDecode("0000000000000000","hex"))>
Result: 3C65DEC44CC216A686B2481BECE788D197F730A72D4A8CDD
If you use the NoPadding flag, the result is:
3C65DEC44CC216A686B2481BECE788D1
I have also tried encoding the plaintext hex message as base64 (as the key is). In the example above that returns a result of:
DE5BCC68EB1B2E14CEC35EB22AF04EFC.
If you do the same, except using the NoPadding flag, it errors with "Input length not multiple of 8 bytes."
I am new to cryptography, so hopefully I'm making some kind of very basic error here. Why are the ciphertexts generated by these block cipher algorithms not the same lengths as the plaintext messages?
For a little more background, as a "work through it" exercise, I have been trying to replicate the work laid out here:
https://www.parthenonsoftware.com/blog/how-to-decrypt-magnetic-stripe-scanner-data-with-dukpt/

I'm not sure if it is related and it may not be the answer you are looking for, but I spent some time testing bug ID 3842326. When using different attributes CF is handling seed and salt differently under the hood. For example if you pass in a variable as the string to encrypt rather than a constant (hard coded string in the function call) the resultant string changes every time. That probably indicates different method signatures - in your example with one flag vs another flag you are seeing something similar.
Adobe's response is, given that the resulting string can be unecrypted in either case this is not really a bug - more of a behavior to note. Can your resultant string be unencrypted?

The problem is encrypt() expects the input to be a UTF-8 string. So you are actually encrypting the literal characters F-F-F-F-9.... rather than the value of that string when decoded as hexadecimal.
Instead, you need to decode the hex string into binary, then use the encryptBinary() function. (Note, I did not see an iv mentioned in the link, so my guess is they are using ECB mode, not CBC.) Since the function also returns binary, use binaryEncode to convert the result to a more friendly hex string.
Edit: Switching to ECB + "NoPadding" yields the desired result:
ksnInHex = "FFFF9876543210E0";
bdkInHex = "0123456789ABCDEFFEDCBA98765432100123456789ABCDEF";
ksnBytes = binaryDecode(ksnInHex, "hex");
bdkBase64 = binaryEncode(binaryDecode(bdkInHex, "hex"), "base64");
bytes = encryptBinary(ksnBytes, bdkBase64, "DESEDE/ECB/NoPadding");
leftRegister = binaryEncode(bytes, "hex");
... which produces:
6AC292FAA1315B4D
In order to do this we want to start with our original 16 byte BDK
... and XOR it with the following mask ....
Unfortunately, most of the CF math functions are limited to 32 bit integers. So you probably cannot do that next step using native CF functions alone. One option is to use java's BigInteger class. Create a large integer from the hex strings and use the xor() method to apply the mask. Finally, use the toString(radix) method to return the result as a hex string:
bdkText ="0123456789ABCDEFFEDCBA9876543210";
maskText = "C0C0C0C000000000C0C0C0C000000000";
// use radix=16 to create integers from the hex strings
bdk = createObject("java", "java.math.BigInteger").init(bdkText, 16);
mask = createObject("java", "java.math.BigInteger").init(maskText, 16);
// apply the mask and convert the result to hex (upper case)
newKeyHex = ucase( bdk.xor(mask).toString(16) );
WriteOutput("<br>newKey="& newKeyHex);
writeOutput("<br>expected=C1E385A789ABCDEF3E1C7A5876543210");
That should be enough to get you back on track. Given some of CF's limitations here, java would be a better fit IMO. If you are comfortable with it, you could write a small java class and invoke that from CF instead.

What is the encoding of this data?

Who can tell me the encoding type of these data? It doesn't seem to be base64.
/zZ/u00GIaP9HW010G000G01003/sm1302WS7YCU6IWZ8ICjAoWmF6H1F3StF7jONKbaaO2Pbe+
0Z8gWjER3eAhQhOgCoF/Bskxr////cy7////w/+Rz//Z/sm130IijBJmrF7P1GNRufOob+FZu+F
Zu+FZu+FZu+FZu+FZu+FZu+FZu+FZu+FZu+FZu+FZu+FZu+FZu+FZu+FZu+FZ/m00H200X07430
I800X410n41/yG07m000GK10G410G400000000000420mG51WS82GeB/yG0jH000W430m840mK5
10G0005z0G8300GH1H8XCK464r5X1o9n53A1aQ488qAnmHLIqV0aCs9oWWaA5XSO6Heb9YSeAIe
qDJOtE3awGqH5HaT8IKfJL5LMLrXPMcDaPMPdQ6bgStHrTdTuUNg3X8M6XuY9YfAJb9MMbvYPcg
AZfAMcfwYfghApjBMsjxYvkiB3nCN6nyZ9ojBJrDNMrzZPsk7Yu+JbvkVewUhnylFqzVRt+Fdw/
yG07m400m410G410G410G00000000420mG51WS82GeB/yG0jH400W4210G310S510G00G9t0042
0n441I4n1X91KGTXSHCYCe4854AHeR712ICpKl0LOdBH2XOaDE4byHSO6Hec9oWfAZKsDpWvEaD
4HKP7I4bAKrHLLbTOMLfZP6LcPsXfQdDqTNPtU7bwWeE4XOQ7Y8cAafEKbPQNc9cQegEafQQdgA
cgihEqjRQtkBcwmiF4nSR7oCdAqjFKrTRNsDdQukFavURdwEdgylFqzVRt+Fdw/ze030C1008H0
n40Fm2vQMjkzf0pGHVSKab1ad5I/PBPkbl5Z/S7D5dyrb1dfvQ/ZnIotCAIB6x7B38LLB5lm7Qc
G9zajcwMyMFzmSr18sd82pnn1586H5a4aP7EFIfblRUMRoVCsj/TO5IVph7kBAUH1TnkMJPl18s
bU/JFuvxydwWpLYZi9s8YItR7OAkV/m1LFIsjPLLrjujX08FbWPhdxUEIvlnvESbzsuZE1dgSd+
jT7DF77jyni1ZXG0IMFq52JUmCRzajcwMyMFy0S7D7sIsRfRnO/m1mSqXlRSo17VPaP0TIkVpxK
iy+C95jQHssgfFV6Sds0fyhMuYbBFPBUHsyTh4+M2imK31pzAjImsKKPbaWYMDUfyiS/fM8xgcg
ix7v1EIJrutLSdqoUxccdSX2I0e7Ex0ndhmE/Vy0ngQIjOQBqCTZSblAXYPKE2H6C4/N5IVPBPk
bl5Z/071pMHRwQ3V97vmEq1sKZ3O/0d+VlMpBSHHZzv8gZhZkVmzAWFGRzajcwMyMFzmSqVPBPk
bl5Z/S7DBzfYPrGahk+xkKZT+TJVV/0Dt+T0Qd6qKKKYZgxFvhA3FJor/7Yi+rbaRKBif5vpbzf
F2XL1nr/BZlYj2p+QoWpqyjVnugl5ljRYLNHtXcSoAw8JrwWu/3wqo1VEZakaIxjbZaF+hSuODW
yOFzAfHtKgj1O+KZgGkL2bICW7a+eF9EEsQkp1hwvX2HbOeM3cHq8px3FwrFBPmN4WaTCaSWXYC
dru/3ds50p1byrBpVRAoC+S8WzEm0wZZkFK7a6j4oksgkVACiYe0g361m2VcFrFrpLo6pWZVUY3
e02UJZ6C0+d+UcAYn91TFAoj97C536DUX0nqzEl+UkbDsk9wYpJ8P45vRg49mid3BdwaSVvxKv5
bCiapnAt92yu9K7W3sxzidZfKTtklWi4KR1IGnaT201xPxrU+//0Blyw9Q90SvgCPMyas/SPYm9
mESPFFy08VJ7NdRUQIApCio1olB2FE2Czi+t+SK2pWPjs7FkP6EUdlx3yXKWXZC8Y0Fb3W0a/m0
wKfNIGRb3Hcy/xHCxPTt+PSzktuSdyglI97l+q6CiLN0mCa/GVv/AajxQA5I8a037B7+yVyAYbb
dIut6DfBSZ0239pKeQrUX3VJ6TOeoZHHkGJ98E1MZz/m3tVvrHkNUyZycE1nd1tEk0Ajn9jYHCv
LL0p/UflOgMoHo5555G0KKKK0555501HHHG0KKKK0555501HHHG0KKKK0555507/za
(Line endings inserted for readability)

It appears to be base64. If you add a single equal ('=') for padding to the end your decoder should be happy (see https://en.wikipedia.org/wiki/Base64#Padding).
Decoded it's 1568 bytes which mod 16 is zero. This histogram of byte value occurance is flat. So I'd guess something encrypted with a 128 bit block cipher like AES.

It does look like base64 to me. Most variants of base64 include the following characters:
A-Z a-z 0-9 + / (and = for padding)
However, if it were proper base64 it would end with a single = as padding, as the 2091 characters don't exactly fit a number of bytes.
Your data doesn't seem to decode to anything readable, so it might be binary data, or encrypted (or both). Only with thorough knowledge of cryptography systems, and a lot of hints and luck, might some expert be able to figure out the encryption used (if any), but that's beyond the scope of this site.
Without more information as to the source of the data, we can only guess.

Please help identify multi-byte character encoding scheme on ASP Classic page

I'm working with a 3rd party (Commidea.com) payment processing system and one of the parameters being sent along with the processing result is a "signature" field. This is used to provide a SHA1 hash of the result message wrapped in an RSA encrypted envelope to provide both integrity and authenticity control. I have the API from Commidea but it doesn't give details of encoding and uses artificially created signatures derived from Base64 strings to illustrate the examples.
I'm struggling to work out what encoding is being used on this parameter and hoped someone might recognise the quite distinctive pattern. I initially thought it was UTF8 but having looked at the individual characters I am less sure.
Here is a short sample of the content which was created by the following code where I am looping through each "byte" in the string:
sig = Request.Form("signature")
For x = 1 To LenB(sig)
s = s & AscB(MidB(sig,x,1)) & ","
Next
' Print s to a debug log file
When I look in the log I get something like this:
129,0,144,0,187,0,67,0,234,0,71,0,197,0,208,0,191,0,9,0,43,0,230,0,19,32,195,0,248,0,102,0,183,0,73,0,192,0,73,0,175,0,34,0,163,0,174,0,218,0,230,0,157,0,229,0,234,0,182,0,26,32,42,0,123,0,217,0,143,0,65,0,42,0,239,0,90,0,92,0,57,0,111,0,218,0,31,0,216,0,57,32,117,0,160,0,244,0,29,0,58,32,56,0,36,0,48,0,160,0,233,0,173,0,2,0,34,32,204,0,221,0,246,0,68,0,238,0,28,0,4,0,92,0,29,32,5,0,102,0,98,0,33,0,5,0,53,0,192,0,64,0,212,0,111,0,31,0,219,0,48,32,29,32,89,0,187,0,48,0,28,0,57,32,213,0,206,0,45,0,46,0,88,0,96,0,34,0,235,0,184,0,16,0,187,0,122,0,33,32,50,0,69,0,160,0,11,0,39,0,172,0,176,0,113,0,39,0,218,0,13,0,239,0,30,32,96,0,41,0,233,0,214,0,34,0,191,0,173,0,235,0,126,0,62,0,249,0,87,0,24,0,119,0,82,0
Note that every other value is a zero except occasionally where it is 32 (0x20). I'm familiar with UTF8 where it represents characters above 127 by using two bytes but if this was UTF8 encoding then I would expect the "32" value to be more like 194 (0xC2) or (0xC3) and the other value would be greater than 0x80.
Ultimately what I'm trying to do is convert this signature parameter into a hex encoded string (eg. "12ab0528...") which is then used by the RSA/SHA1 function to verify the message is intact. This part is already working but I can't for the life of me figure out how to get the signature parameter decoded.
For historical reasons we are having to use classic ASP and the SHA1/RSA functions are javascript based.
Any help would be much appreciated.
Regards,
Craig.
Update: Tried looking into UTF-16 encoding on Wikipedia and other sites. Can't find anything to explain why I am seeing only 0x20 or 0x00 in the (assumed) high order byte positions. I don't think this is relevant any more as the example below shows other values in this high order position.
Tried adding some code to log the values using Asc instead of AscB (Len,Mid instead of LenB,MidB too). Got some surprising results. Here is a new stream of byte-wise characters followed by the equivalent stream of word-wise (if you know what I mean) characters.
21,0,83,1,214,0,201,0,88,0,172,0,98,0,182,0,43,0,103,0,88,0,103,0,34,33,88,0,254,0,173,0,188,0,44,0,66,0,120,1,246,0,64,0,47,0,110,0,160,0,84,0,4,0,201,0,176,0,251,0,166,0,211,0,67,0,115,0,209,0,53,0,12,0,243,0,6,0,78,0,106,0,250,0,19,0,204,0,235,0,28,0,243,0,165,0,94,0,60,0,82,0,82,0,172,32,248,0,220,2,176,0,141,0,239,0,34,33,47,0,61,0,72,0,248,0,230,0,191,0,219,0,61,0,105,0,246,0,3,0,57,32,54,0,34,33,127,0,224,0,17,0,224,0,76,0,51,0,91,0,210,0,35,0,89,0,178,0,235,0,161,0,114,0,195,0,119,0,69,0,32,32,188,0,82,0,237,0,183,0,220,0,83,1,10,0,94,0,239,0,187,0,178,0,19,0,168,0,211,0,110,0,101,0,233,0,83,0,75,0,218,0,4,0,241,0,58,0,170,0,168,0,82,0,61,0,35,0,184,0,240,0,117,0,76,0,32,0,247,0,74,0,64,0,163,0
And now the word-wise data stream:
21,156,214,201,88,172,98,182,43,103,88,103,153,88,254,173,188,44,66,159,246,64,47,110,160,84,4,201,176,251,166,211,67,115,209,53,12,243,6,78,106,250,19,204,235,28,243,165,94,60,82,82,128,248,152,176,141,239,153,47,61,72,248,230,191,219,61,105,246,3,139,54,153,127,224,17,224,76,51,91,210,35,89,178,235,161,114,195,119,69,134,188,82,237,183,220,156,10,94,239,187,178,19,168,211,110,101,233,83,75,218,4,241,58,170,168,82,61,35,184,240,117,76,32,247,74,64,163
Note the second pair of byte-wise characters (83,1) seem to be interpreted as 156 in the word-wise stream. We also see (34,33) as 153 and (120,1) as 159 and (220,2) as 152. Does this give any clues as the encoding? Why are these 15[2369] values apparently being treated differently from other values?
What I'm trying to figure out is whether I should use the byte-wise data and carry out some post-processing to get back to the intended values or if I should trust the word-wise data with whatever implicit decoding it is apparently performing. At the moment, neither seem to give me a match between data content and signature so I need to change something.
Thanks.

Quick observation tells me that you are likely dealing with UTF-16. Start from there.

Resources