GnuPGME：GPG签名C

您可以保存文件并直接从命令行进行编辑和测试.要编译,只需保存为“gpgsign.c”,然后执行gcc gpgsign.c -lgpgme -o gpgsign(注意：必须安装libgpgme).然后你可以执行使用gpgsign<输入文件> <输出文件>

#ifdef HAVE_CONFIG_H
#include <config.h>
#endif

#include <stdlib.h>
#include <errno.h>
#include <locale.h>

#include <gpgme.h>

#define fail_if_err(err)                                    
    do {                                                    
        if (err) {                                          
            fprintf (stderr,"%s:%d: %s: %sn",
                __FILE__,__LINE__,gpgme_strsource (err),
                gpgme_strerror (err));                      
            exit (1);                                       
        }                                                   
    }                                                       
    while (0)

void gpgSign(const char *fileToBeSigned,const char *outputFileName) {
    gpgme_ctx_t ctx;
    gpgme_error_t err;
    gpgme_data_t in,out;
    FILE *outputFile;
    int BUF_SIZE = 512;
    char buf[BUF_SIZE + 1];
    int ret;
    /* Set the GPGME signature mode
        GPGME_SIG_MODE_NORMAL : Signature with data
        GPGME_SIG_MODE_CLEAR  : Clear signed text
        GPGME_SIG_MODE_DETACH : Detached signature */
    gpgme_sig_mode_t sigMode = GPGME_SIG_MODE_CLEAR;

    /* Begin setup of GPGME */
    gpgme_check_version (NULL);
    setlocale (LC_ALL,"");
    gpgme_set_locale (NULL,LC_CTYPE,setlocale (LC_CTYPE,NULL));
#ifndef HAVE_W32_SYSTEM
    gpgme_set_locale (NULL,LC_MESSAGES,setlocale (LC_MESSAGES,NULL));
#endif
    /* End setup of GPGME */

    // Create the GPGME Context
    err = gpgme_new (&ctx);
    // Error handling
    fail_if_err (err);

    // Set the context to textmode
    gpgme_set_textmode (ctx,1);
    // Enable ASCII armor on the context
    gpgme_set_armor (ctx,1);

    // Create a data object pointing to the input file
    err = gpgme_data_new_from_file (&in,fileToBeSigned,1);
    // Error handling
    fail_if_err (err);

    // Create a data object pointing to the out buffer
    err = gpgme_data_new (&out);
    // Error handling
    fail_if_err (err);

    // Sign the contents of "in" using the defined mode and place it into "out"
    err = gpgme_op_sign (ctx,in,out,sigMode);
    // Error handling
    fail_if_err (err);

    // Open the output file
    outputFile = fopen (outputFileName,"w+");

    // Rewind the "out" data object
    ret = gpgme_data_seek (out,SEEK_SET);
    // Error handling
    if (ret)
        fail_if_err (gpgme_err_code_from_errno (errno));

    // Read the contents of "out" and place it into buf
    while ((ret = gpgme_data_read (out,buf,BUF_SIZE)) > 0) {
        // Write the contents of "buf" to "outputFile"
        fwrite (buf,ret,1,outputFile);
    }

    // Error handling
    if (ret < 0)
        fail_if_err (gpgme_err_code_from_errno (errno));

    // Close "outputFile"
    fclose(outputFile);
    // Release the "in" data object
    gpgme_data_release (in);
    // Release the "out" data object
    gpgme_data_release (out);
    // Release the context
    gpgme_release (ctx);
}

int 
main (int argc,char **argv) {
    if (argc != 3) {
        printf("Usage: gpgsign <input file> <output file>n");
        exit (1);
    }
    printf("Signing %s and placing the result into %sn",argv[1],argv[2]);
    gpgSign(argv[1],argv[2]);
    return 0;
}