C - 带有 EVP_PKEY_decrypt() 的段错误

Question

我在运行此代码时遇到段错误，并 idk 为什么。有什么想法吗？

#include <openssl/evp.h>
#include <openssl/pem.h>
#include <string.h>
#include <openssl/err.h>
int main (void)
{
char privateKey[] = "-----BEGIN RSA PRIVATE KEY-----n"
"MIIBOgIBAAJBAKj34GkxFhD90vcNLYLInFEX6Ppy1tPf9Cnzj4p4WGeKLs1Pt8Qun"
"KUpRKfFLfRYC9AIKjbJTWit+CqvjWYzvQwECAwEAAQJAIJLixBy2qpFoS4DSmoEmn"
"o3qGy0t6z09AIJtH+5OeRV1be+N4cDYJKffGzDa88vQENZiRm0GRq6a+HPGQMd2kn"
"TQIhAKMSvzIBnni7ot/OSie2TmJLY4SwTQAevXysE2RbFDYdAiEBCUEaRQnMnbp7n"
"9mxDXDf6AU0cN/RPBjb9qSHDcWZHGzUCIG2Es59z8ugGrDY+pxLQnwfotadxd+Uyn"
"v/Ow5T0q5gIJAiEAyS4RaI9YG8EWx/2w0T67ZUVAw8eOMB6BIUg0Xcu+3okCIBOsn"
"/5OiPgoTdSy7bcF9IGpSE8ZgGKzgYQVZeN97YE00n"
"-----END RSA PRIVATE KEY-----n";
char ciphertext[] = "h3j3zLT2jXCaZuwF7cgUE/Zmc/5IsIfKbaTiBhpCJo86AiyuoA3Yvni+Lrm5wu2OGv2h5R7Zu3voFcHugiystw==";
// base64 decode ciphertext
EVP_DecodeBlock(ciphertext, ciphertext, strlen(ciphertext));
BIO* bo = BIO_new(BIO_s_mem());
BIO_write(bo, privateKey, strlen(privateKey));
EVP_PKEY* pkey = 0;
PEM_read_bio_PrivateKey(bo, &pkey, 0, 0);
BIO_free(bo);
EVP_PKEY_CTX *ctx = EVP_PKEY_CTX_new(pkey, NULL);
EVP_PKEY_decrypt_init(ctx);
EVP_PKEY_CTX_ctrl_str(ctx, "rsa_padding_mode", "oaep");
EVP_PKEY_CTX_ctrl_str(ctx, "rsa_oaep_md", "sha256");
EVP_PKEY_CTX_ctrl_str(ctx, "rsa_mgf1_md", "sha256");
size_t plaintext_len;
unsigned char* plaintext;
EVP_PKEY_decrypt(ctx, plaintext, &plaintext_len, ciphertext, strlen(ciphertext));
//plaintext[plaintext_len] = '';
printf("%sn", plaintext);
}

Answer 1

在将其传递给EVP_PKEY_decrypt之前，您忘记初始化plaintext。

参考 evp_pkey_decrypt(3) - Linux 手册页，部分

unsigned char* plaintext;
EVP_PKEY_decrypt(ctx, plaintext, &plaintext_len, ciphertext, strlen(ciphertext));
//plaintext[plaintext_len] = '';

应该是

unsigned char* plaintext;
/* determine output size */
EVP_PKEY_decrypt(ctx, NULL, &plaintext_len, ciphertext, strlen(ciphertext));
/* allocate memory (+1 for terminating null-character) */
plaintext = OPENSSL_malloc(plaintext_len + 1);
if (plaintext == NULL) {
/* allocation failed */
return 1;
} else {
EVP_PKEY_decrypt(ctx, plaintext, &plaintext_len, ciphertext, strlen(ciphertext));
plaintext[plaintext_len] = ''; /* required for %s */
}