If I have a string that will be encoded with Base64, Md5, or some other hash or encryption function, is there a way to at least be able to make a fair guess as to what it is?
You can try to guess but with a lot of false results. Md5 always have 32 characters, base64 have a limited set of possible characters, etc.
Related
In IE, the length limit of the URL is about 2048 bytes, Query string may exceed 2048 bytes.
I use lz-string to compress strings, However, the link in the pdf does not work, Or maybe use another way to compress the string?
var compressed = LZString.compress(query)
https://jsfiddle.net/p9e4a8dg/11
Try reading this link.
If you want pure ASCII you can try compressToBase64
I want to encrypt string with the same length of character string and decryption with same length of character string using sql server. For Example:
Encryption
Input: Encrypt("002581") -- with 6 characters
Result: a&pE12 -- output with same 6 characters in encrypted form
Decryption
Input: Decrypt("a&pE12") -- with 6 characters
Result: 002581 -- output with same 6 characters in decrypted form
Short answer: there is no such secure encryption scheme.
Longer answer: any kind of encryption scheme obfuscates content of a plain text to be indistinguishable from other messages from the same message space. To do so all cipher texts produced must be of the same length (ideally) regardless of an input plain text. At least the length should be different from a length of a plain text.
So please, don't even consider such an encryption technique. It's insecure by definition.
I need to print an encrypted string as is in a rdlc report. My problem is if the string contain a plus sign it creates a new line in the Textbox. How to avoid this?
Encryption produces output that is binary and contains many bytes that have no displayable representation.
Because of this if encrypted data needs to be displayed it is generally either Base64 (best for computers) or hexadecimal (best for people) encoded.
It seems that you may have base64 encoded encrypted data and that is generally composed of the upper and lowercase characters, the 10 digits, "+", "/" and "=". You can not delete these and expect to recover the encrypted data.
If these characters present a problem they can be many times be escaped in some manor or another encoding can be chosen such as hexadecimal or an alternate Base64 character set, see Base64. If you choose an alternate Base64 character set interoperability will most likely be impaired.
Note: More information would produce a better answer.
I had to replace the "+" with "÷".
Users don't notice is it since the PDF is just a visual representation of the CFDI, I haven't had any issues with it.
This is a basic question, but I can't find anything on it, since I don't know what to search — each of my tries have come up with unrelated results.
If I use Text.Encoding.ASCII.GetBytes to convert a string into ASCII, does each byte represent exactly one character? Does the following code work as exactly intended in all circumstances (for all Strings other than the examples)?
Dim t1() As Byte = Text.Encoding.ASCII.GetBytes("Hello ")
Dim t2() As Byte = Text.Encoding.ASCII.GetBytes("World")
Dim msg As String = Text.Encoding.ASCII.GetString(t1.Concat(t2).ToArray)
Now msg should be "Hello World".
I would like this to work as I don't want to have to convert data I receive back to Strings in order to manipulate it before it is sent again.
What if I used something other than ASCII (like UTF-8, for example)?
If I use Text.Encoding.ASCII.GetBytes to convert a string into ASCII, does each byte represent exactly one character?
Yes. ASCII is a 7bit encoding, it does not support multi-byte characters. Any Unicode codepoint above U-007F will get converted to a ? character in ASCII.
If you were to use UTF-7 instead, for instance, it can encode individual Unicode codepoints into a sequence of multiple ASCII characters.
Does the following code work as exactly intended in all circumstances (for all Strings other than the examples)?
In your particular example, yes (provided you are using LINQ's Concat() method - there are other ways to concat arrays together). There is no data loss.
But for other examples, just know that you will have data loss if you convert non-ASCII characters to ASCII, or otherwise mismatch encodings between GetBytes() and GetString().
You can certainly manipulate byte arrays. Just make sure the arrays are in the same encoding if you merge them together.
.NET strings are counted sequences of UTF-16 code units (char), one or two of which encode a Unicode codepoint (int Char.ConvertToUtf32 ). Some codepoints are "combining characters", which when applied to a preceding "base character" form a grapheme (which is then rendered by a font into a glyph).
An encoder from Unicode to an encoding of another character set should attempt to preserve graphemes. In .NET, a grapheme is called a "text element."
So, yes, you can combine encoded byte sequences as long as you haven't defeated the encoder by converting parts of a grapheme into different byte sequences. If you are breaking a string into two before encoding, see TextElementEnumerator and StringInfo class.
I encrypt a UTF-8 string + current timestamp using AES 128bit CTR mode with a 4 bytes random initialization vector, which is generated by NodeJS's crypto.randomBytes().
Finally I base64 encode the whole output, using a URL-friendly base64 variant.
Question: the AES output should be unique due to timestamp + random data. But is final base64 string also guaranteed to be unique?
Thanks in advance!
Yes, Base64 is a reversible transformation, so if input is unique than output will be also unique.