79 lines
2.3 KiB
C
79 lines
2.3 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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* 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's public key */
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unsigned char sk[crypto_sign_SECRETKEYBYTES]; /* Bob's secret key */
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unsigned char message[MAX_INPUT_LEN];
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unsigned char message_signed[crypto_sign_BYTES + MAX_INPUT_LEN];
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unsigned long long message_len;
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unsigned long long message_signed_len;
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int ret;
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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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printf("Public key: ");
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print_hex(pk, sizeof pk);
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printf("Secret key: ");
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print_hex(sk, sizeof sk);
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puts("The secret key, as returned by crypto_sign_keypair(), actually includes "
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"a copy of the public key, in order to avoid a scalar multiplication "
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"when signing messages.");
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message_len = prompt_input("a message", (char*)message, sizeof message, 1);
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printf("Signing message with %s...\n", crypto_sign_primitive());
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crypto_sign(message_signed, &message_signed_len, message, message_len, sk);
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printf("Signed message:");
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print_hex(message_signed, message_signed_len);
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printf("A %u bytes signature was prepended to the message\n",
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crypto_sign_BYTES);
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printf("Signature: ");
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print_hex(message_signed, crypto_sign_BYTES);
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printf("Message: ");
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fwrite(message_signed + crypto_sign_BYTES, 1U,
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message_signed_len - crypto_sign_BYTES, stdout);
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putchar('\n');
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puts("Validating message...");
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ret = crypto_sign_open(message, &message_len, message_signed,
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message_signed_len, pk);
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print_verification(ret);
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if (ret == 0)
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printf("Message: %s\n", message);
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sodium_memzero(sk, sizeof sk); /* wipe sensitive data */
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return ret;
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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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