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Asked: 2026-05-19T11:09:41+00:00

New to the community, but not new to programming. I’ve been trying to get

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New to the community, but not new to programming.

I’ve been trying to get a collection of hash functions up/running and I succeeded. However I found some weird results and haven’t been able to put my finger on it yet. RFC4634 contains a C implementation for SHA-1 and SHA-2 family, which also can accept a file being passed on for hashing. RFC3174 contains a C implementation, but doesn’t process file streams. I’ve been using the C implementation from RFC4634 to verify files, yet the verification process is returning non similar results when I compare them against SHA-1 provided hashes.

Any idea what the reasons could be?

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1 Answer

  1. Editorial Team

    Did you check if you opened the files in ASCII or binary mode? Line end translation may be performed before the hash is being calculated.

    Update:

    I just compiled the RFC4634 shatestand tried on a sample text file. As long as there isn’t a line break, all tools agree. Once you insert a line break, results depend: if the text file uses CR and LF (DOS mode), then shatest produces a different result. If the line end is only LF (UNIX), it still agrees with the other tools.

    Update 2:

    In the file shatest.c of RFC4634, in function hashfile(...), set fopen to binary mode: 

    FILE *hashfp = (strcmp(hashfilename, "-") == 0) ? stdin :
        fopen(hashfilename, "rb");
/*                            ^ HERE */
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