87 lines
2.3 KiB
C
87 lines
2.3 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 "demo_utils.h" /* utility functions shared by demos */
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/*
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* Stream utilizes a nonce to generate a sequence of bytes. The library has
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* an internal function which XOR data and the stream into an encrypted result.
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*
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* Note that this method does not supply authentication. Try secretbox instead.
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*
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* Note that nonce must be different for each message since it provides
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* change between each operation. It should be safe to use a counter
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* instead of purely random data each time.
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*/
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static int
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stream(void)
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{
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unsigned char k[crypto_stream_KEYBYTES]; /* secret key */
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unsigned char n[crypto_stream_NONCEBYTES]; /* message nonce */
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unsigned char m[BUFFER_SIZE]; /* plain-text */
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unsigned char c[BUFFER_SIZE]; /* cipher-text */
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size_t mlen; /* length */
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int r;
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puts("Example: crypto_stream\n");
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sodium_memzero(k, sizeof k);
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prompt_input("Input your key > ", (char*) k, sizeof k);
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putchar('\n');
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/* nonce must be generated per message, safe to send with message */
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puts("Generating nonce...");
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randombytes_buf(n, sizeof n);
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fputs("Nonce: ", stdout);
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print_hex(n, sizeof n);
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putchar('\n');
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putchar('\n');
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mlen = prompt_input("Input your message > ", (char*) m, sizeof m);
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putchar('\n');
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printf("Encrypting with (xor) %s\n", crypto_stream_primitive());
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crypto_stream_xor(c, m, mlen, n, k);
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putchar('\n');
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puts("Sending message...");
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puts("Format: nonce::message");
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fputs("Ciphertext: ", stdout);
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print_hex(n, sizeof n);
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fputs("::", stdout);
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print_hex(c, mlen);
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putchar('\n');
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putchar('\n');
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puts("Opening message...");
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r = crypto_stream_xor(m, c, mlen, n, k);
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print_verification(r);
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if (r == 0) printf("Plaintext: %s\n\n", m);
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sodium_memzero(k, sizeof k); /* wipe sensitive data */
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sodium_memzero(n, sizeof n);
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sodium_memzero(m, sizeof m);
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sodium_memzero(c, sizeof c);
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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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sodium_init();
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printf("Using LibSodium %s\n", sodium_version_string());
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return stream() != 0;
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}
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