WangPeiying 可以通过这个接口去看,int mbedtls_pk_sign(mbedtls_pk_context *ctx, mbedtls_md_type_t md_alg,
const unsigned char *hash, size_t hash_len,
unsigned char *sig, size_t sig_size, size_t *sig_len,
int (*f_rng)(void *, unsigned char *, size_t), void *p_rng); 如果有疑问再结合文档去看