CODEWITHSUNDEEP
axaptax++sha256
Sweety
Sweety

Reputation: 31

SHA256 giving different result for same string input

I have simple code to generate hash code using SHA256, however, it gives different result for the same input. However, if I declare the same string value in quotes for example _input= "test" then it returns the same result. 

public static System.String generateKey(System.String _input)
{
     System.Byte[] convertedArr;
     SHA256Managed sh = new System.Security.Cryptography.SHA256Managed();
        convertedArr = sh.ComputeHash(System.Text.Encoding::UTF8.GetBytes(_inputString),0, System.Text.Encoding::UTF8.GetByteCount(_input));
        hashCode = System.Convert::ToBase64String(convertedArr);
    return hashCode;
    }

Upvotes: 2

Views: 2095

Answers (1)

zaph
zaph

Reputation: 112875

Note:

convertedArr = sh.ComputeHash(System.Text.Encoding::UTF8.GetBytes(_inputString),0, System.Text.Encoding::UTF8.GetByteCount(_input));

The input to the hash is _inputString but the length is taken from _input, they are not the same. _inputString != _input.

The function defintion:

public static System.String generateKey(System.String _input)

Current code: 

convertedArr = sh.ComputeHash(System.Text.Encoding::UTF8.GetBytes(_inputString),0, System.Text.Encoding::UTF8.GetByteCount(_input));

Debuggable (semio-pseudo) code:

inputBytes  = System.Text.Encoding::UTF8.GetBytes(_input)
inputLength = System.Text.Encoding::UTF8.GetByteCount(_input)
hashBytes   = convertedArr = sh.ComputeHash(inputBytes, 0, inputLength);

With this the input and length can easily be verified. The chance of the error is less because _input is only used once.

Note: In practice I would get the length from inputBytes but I am not fluent in X++ so I did not make that change.

Upvotes: 1

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