OpenSSL AES 256 CBC通过EV中的EVP api

我要做的是：在C中编写一个程序，打开一个任意大小的文件并读取其内容。 一旦读取内容，它将在AES 256 CBC中对它们进行加密，并将密文保存到名为密文的文件中。 保存后，它将关闭这两个文件。 然后将打开刚刚保存的文件中的密文并解密密文并将其保存到名为decrypted的文件中。

我的问题：似乎永远不会解密我的密文。 我得到垃圾，我不知道我做错了什么。 请帮忙。

#include  #include  #include  #include  #include  void encrypt(FILE *ifp, FILE *ofp) { //Get file size fseek(ifp, 0L, SEEK_END); int fsize = ftell(ifp); //set back to normal fseek(ifp, 0L, SEEK_SET); int outLen1 = 0; int outLen2 = 0; unsigned char *indata = malloc(fsize); unsigned char *outdata = malloc(fsize*2); unsigned char ckey[] = "thiskeyisverybad"; unsigned char ivec[] = "dontusethisinput"; //Read File fread(indata,sizeof(char),fsize, ifp);//Read Entire File //Set up encryption EVP_CIPHER_CTX ctx; EVP_EncryptInit(&ctx,EVP_aes_256_cbc(),ckey,ivec); EVP_EncryptUpdate(&ctx,outdata,&outLen1,indata,fsize); EVP_EncryptFinal(&ctx,outdata,&outLen2); fwrite(outdata,sizeof(char),fsize,ofp); } void decrypt(FILE *ifp, FILE *ofp) { //Get file size fseek(ifp, 0L, SEEK_END); int fsize = ftell(ifp); //set back to normal fseek(ifp, 0L, SEEK_SET); int outLen1 = 0; int outLen2 = 0; unsigned char *indata = malloc(fsize); unsigned char *outdata = malloc(fsize*2); unsigned char ckey[] = "thiskeyisverybad"; unsigned char ivec[] = "dontusethisinput"; //Read File fread(indata,sizeof(char),fsize, ifp);//Read Entire File //setup decryption EVP_CIPHER_CTX ctx; EVP_DecryptInit(&ctx,EVP_aes_256_cbc(),ckey,ivec); EVP_DecryptUpdate(&ctx,outdata,&outLen1,indata,fsize); EVP_DecryptFinal(&ctx,outdata,&outLen2); fwrite(outdata,sizeof(char),fsize,ofp); } int main(int argc, char *argv[]) { FILE *fIN, *fOUT; fIN = fopen("plain.txt", "rb");//File to be encrypted; plain text fOUT = fopen("cyphertext.txt", "wb");//File to be written; cipher text encrypt(fIN, fOUT); fclose(fIN); fclose(fOUT); //Decrypt file now fIN = fopen("cyphertext.txt", "rb");//File to be written; cipher text fOUT = fopen("decrypted.txt", "wb");//File to be written; cipher text decrypt(fIN,fOUT); fclose(fIN); fclose(fOUT); return 0; } 

注意：可能会有一些拼写错误。 编辑：似乎我用键和IV弄错了，两者都是128位，我试图使用256位CBC。 这是我的问题，一旦我改成它似乎工作

 EVP_aes_128_cbc() 

Answer 1

这是我的代码版本。 当然我更喜欢它，但我提供它作为替代品。 注意完全没有错误检查：真正的代码会有它。

 #include  #include  #include  #include  #include  #ifndef TRUE #define TRUE 1 #endif #ifndef FALSE #define FALSE 0 #endif /** * Encrypt or decrypt, depending on flag 'should_encrypt' */ void en_de_crypt(int should_encrypt, FILE *ifp, FILE *ofp, unsigned char *ckey, unsigned char *ivec) { const unsigned BUFSIZE=4096; unsigned char *read_buf = malloc(BUFSIZE); unsigned char *cipher_buf; unsigned blocksize; int out_len; EVP_CIPHER_CTX ctx; EVP_CipherInit(&ctx, EVP_aes_256_cbc(), ckey, ivec, should_encrypt); blocksize = EVP_CIPHER_CTX_block_size(&ctx); cipher_buf = malloc(BUFSIZE + blocksize); while (1) { // Read in data in blocks until EOF. Update the ciphering with each read. int numRead = fread(read_buf, sizeof(unsigned char), BUFSIZE, ifp); EVP_CipherUpdate(&ctx, cipher_buf, &out_len, read_buf, numRead); fwrite(cipher_buf, sizeof(unsigned char), out_len, ofp); if (numRead < BUFSIZE) { // EOF break; } } // Now cipher the final block and write it out. EVP_CipherFinal(&ctx, cipher_buf, &out_len); fwrite(cipher_buf, sizeof(unsigned char), out_len, ofp); // Free memory free(cipher_buf); free(read_buf); } int main(int argc, char *argv[]) { unsigned char ckey[] = "thiskeyisverybad"; unsigned char ivec[] = "dontusethisinput"; FILE *fIN, *fOUT; if (argc != 2) { printf("Usage:  /path/to/file/exe"); return -1; } // First encrypt the file fIN = fopen("plain.txt", "rb"); //File to be encrypted; plain text fOUT = fopen("cyphertext.txt", "wb"); //File to be written; cipher text en_de_crypt(TRUE, fIN, fOUT, ckey, ivec); fclose(fIN); fclose(fOUT); //Decrypt file now fIN = fopen("cyphertext.txt", "rb"); //File to be read; cipher text fOUT = fopen("decrypted.txt", "wb"); //File to be written; cipher text en_de_crypt(FALSE, fIN, fOUT, ckey, ivec); fclose(fIN); fclose(fOUT); return 0; } 

Answer 2

这段代码有效，如果有人对如何更清洁或更有效率有一些建议请发表评论。

 #include  #include  #include  #include  #include  void encrypt(FILE *ifp, FILE *ofp) { //Get file size fseek(ifp, 0L, SEEK_END); int fsize = ftell(ifp); //set back to normal fseek(ifp, 0L, SEEK_SET); int outLen1 = 0; int outLen2 = 0; unsigned char *indata = malloc(fsize); unsigned char *outdata = malloc(fsize*2); unsigned char ckey[] = "thiskeyisverybad"; unsigned char ivec[] = "dontusethisinput"; //Read File fread(indata,sizeof(char),fsize, ifp);//Read Entire File //Set up encryption EVP_CIPHER_CTX ctx; EVP_EncryptInit(&ctx,EVP_aes_128_cbc(),ckey,ivec); EVP_EncryptUpdate(&ctx,outdata,&outLen1,indata,fsize); EVP_EncryptFinal(&ctx,outdata + outLen1,&outLen2); fwrite(outdata,sizeof(char),outLen1 + outLen2,ofp); } void decrypt(FILE *ifp, FILE *ofp) { //Get file size fseek(ifp, 0L, SEEK_END); int fsize = ftell(ifp); //set back to normal fseek(ifp, 0L, SEEK_SET); int outLen1 = 0; int outLen2 = 0; unsigned char *indata = malloc(fsize); unsigned char *outdata = malloc(fsize); unsigned char ckey[] = "thiskeyisverybad"; unsigned char ivec[] = "dontusethisinput"; //Read File fread(indata,sizeof(char),fsize, ifp);//Read Entire File //setup decryption EVP_CIPHER_CTX ctx; EVP_DecryptInit(&ctx,EVP_aes_128_cbc(),ckey,ivec); EVP_DecryptUpdate(&ctx,outdata,&outLen1,indata,fsize); EVP_DecryptFinal(&ctx,outdata + outLen1,&outLen2); fwrite(outdata,sizeof(char),outLen1 + outLen2,ofp); } int main(int argc, char *argv[]) { if(argc != 2){ printf("Usage:  /path/to/file/exe"); return -1; } FILE *fIN, *fOUT; fIN = fopen("plain.txt", "rb");//File to be encrypted; plain text fOUT = fopen("cyphertext.txt", "wb");//File to be written; cipher text encrypt(fIN, fOUT); fclose(fIN); fclose(fOUT); //Decrypt file now fIN = fopen("cyphertext.txt", "rb");//File to be written; cipher text fOUT = fopen("decrypted.txt", "wb");//File to be written; cipher text decrypt(fIN,fOUT); fclose(fIN); fclose(fOUT); return 0; } 

另外根据这篇文章，EVP api将处理任意大小的输入

AES加密 – 大文件