90 lines
2.4 KiB
C
90 lines
2.4 KiB
C
/*
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* GraxRabble
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* Demo programs for libsodium.
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*/
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#include <stdio.h>
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#include <stdlib.h>
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#include <string.h>
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#include <sodium.h> /* library header */
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#include "utils.h" /* utility functions shared by demos */
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/*
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* Signs a message with secret key which will authenticate a message.
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* Everybody else can use the public key to ensure that the message is both
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* valid and untampered.
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*
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* Note that the signed message will have 16 bytes of signature prepended.
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* Ensure that the signed buffer is at least crypto_sign_BYTES longer then
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* the actual message.
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*/
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static int
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sign(void)
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{
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unsigned char pk[crypto_sign_PUBLICKEYBYTES]; /* Bob public */
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unsigned char sk[crypto_sign_SECRETKEYBYTES]; /* Bob secret */
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unsigned char m[MAX_INPUT_SIZE]; /* message */
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unsigned char sm[MAX_INPUT_SIZE + crypto_sign_BYTES]; /* signed message */
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unsigned long long int mlen; /* message length */
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unsigned long long int smlen; /* signed length */
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int r;
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puts("Example: crypto_sign\n");
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puts("Generating keypair...");
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crypto_sign_keypair(pk, sk); /* generate Bob's keys */
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fputs("Public: ", stdout);
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print_hex(pk, sizeof pk);
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putc('\n', stdout);
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fputs("Secret: ", stdout);
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print_hex(sk, sizeof sk);
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puts("\n");
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/* read input */
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mlen = prompt_input("Input your message > ", (char*)m,
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sizeof m - crypto_sign_BYTES);
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putc('\n', stdout);
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puts("Notice the message has no prepended padding");
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print_hex(m, mlen);
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putchar('\n');
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putchar('\n');
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printf("Signing message with %s...\n", crypto_sign_primitive());
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crypto_sign(sm, &smlen, m, mlen, sk);
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puts("Notice the signed message has prepended signature");
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print_hex(sm, smlen);
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putchar('\n');
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putchar('\n');
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puts("Format: signature::message");
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fputs("Signed: ", stdout);
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print_hex(sm, crypto_sign_BYTES);
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fputs("::", stdout);
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puts((const char*)sm + crypto_sign_BYTES);
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putc('\n', stdout);
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puts("Validating message...");
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r = crypto_sign_open(m, &mlen, sm, smlen, pk);
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print_verification(r);
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if (r == 0)
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printf("Message: %s\n\n", m);
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sodium_memzero(sk, sizeof sk); /* wipe sensitive data */
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sodium_memzero(m, sizeof m);
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sodium_memzero(sm, sizeof sm);
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return r;
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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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return sign() != 0;
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}
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