81 lines
2.5 KiB
C
81 lines
2.5 KiB
C
/*
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* GraxRabble
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* example programs for libsodium.
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*/
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#include <sodium.h> /* library header */
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#include "utils.h" /* utility functions shared by examples */
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/*
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* This function computes a fixed-length fingerprint for an arbitrary long message.
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*
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* Sample use cases:
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*
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* File integrity checking
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* Creating unique identifiers to index arbitrary long data
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*
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* The crypto_generichash() function puts a fingerprint of the
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* message in whose length is inlen bytes into out. The output size
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* can be chosen by the application.
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*
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* The minimum recommended output size is crypto_generichash_BYTES.
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* This size makes it practically impossible for two messages to
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* produce the same fingerprint.
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*
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* But for specific use cases, the size can be any value between
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* crypto_generichash_BYTES_MIN (included) and
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* crypto_generichash_BYTES_MAX (included).
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*
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* key can be NULL and keylen can be 0. In this case, a message will
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* always have the same fingerprint, similar to the MD5 or SHA-1
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* functions for which crypto_generichash() is a faster and more
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* secure alternative.
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*
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* But a key can also be specified. A message will always have the
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* same fingerprint for a given key, but different keys used to hash
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* the same message are very likely to produce distinct fingerprints.
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*
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* In particular, the key can be used to make sure that different
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* applications generate different fingerprints even if they process
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* the same data.
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*
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* The recommended key size is crypto_generichash_KEYBYTES bytes.
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*
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* However, the key size can by any value between
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* crypto_generichash_KEYBYTES_MIN (included) and
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* crypto_generichash_KEYBYTES_MAX (included).
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*/
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void
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generichash(void)
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{
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unsigned char key[crypto_generichash_KEYBYTES_MAX];
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unsigned char hash[crypto_generichash_BYTES];
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unsigned char message[MAX_INPUT_LEN];
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size_t message_len;
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size_t key_len;
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puts("Example: crypto_generichash\n");
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key_len = prompt_input("a key", (char*)key, sizeof key, 1);
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message_len = prompt_input("a message", (char*)message, sizeof message, 1);
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printf("Hashing message with %s\n", crypto_generichash_primitive());
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if (crypto_generichash(hash, sizeof hash, message, message_len,
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key, key_len) != 0) {
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puts("Couldn't hash the message, probably due to the key length");
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} else {
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printf("Hash: ");
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print_hex(hash, sizeof hash);
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}
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}
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int
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main(void)
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{
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init();
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generichash();
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return 0;
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}
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