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Sign a Data without a Hash Algorithm RRS feed

  • Question

  • Hi All,

    For a special system i have to sign a data. Normally in .NET needs a hash algorithm to sign a data. Also it is correct for almost all system. But we have to fit a designed system.

    The system ensures that the data that will be less than RSA key size. And it defines that the signature will be created without hash. 

    I need a function like SignHash function of RSACryptoServiceProvider; but it must not put the OID of hash in front of my data.

    Best Regards.

    Tuesday, June 23, 2015 6:33 PM

Answers

  • Hi OrEr,

    The key in public-key encryption is based on a hash value. This is a value that is computed from a base input number using a hashing algorithm. Essentially, the hash value is a summary of the original value.

    >>The system ensures that the data that will be less than RSA key size. And it defines that the signature will be created without hash. 

    For example, suppose we are using a 2k RSA key; that means that the RSA operation can handle messages up to 2047 bits; or 255 bytes.  you would be unable to directly sign any messages longer than 255 bytes long.

    Additionlly, please refer to Why hash or salt when signing? [duplicate] and check the marked answer if it helps.

    Have a nice day!

    Kristin


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    Wednesday, June 24, 2015 10:18 AM