如何在C+；中将RSA*打印为字符串+；？ 如何在C++中正确打印RSA *作为字符串？< /P>

我正在使用

OpenSSL

。它似乎没有

.c_str（）

方法，对吗

RSA_print_fp(stdout, x, 0);

---

如果您不喜欢该输出，可以直接访问

RSA

成员。例如：

// RSA object 'owns' the BIGNUM. Don't destroy it.
BIGNUM* n = rsa.get()->n;
BIGNUM* e = rsa.get()->e;
BIGNUM* d = rsa.get()->d;

string s;

BIO_reset(bio.get());
mem = NULL;

rc = BN_print(bio.get(), n);
ASSERT(rc == 1);

BIO_get_mem_ptr(bio.get(), &mem);
if(mem && mem->data && mem->length)
    s.assign(mem->data, mem->length);

if(s.length())
    cout << "Modulus: " << endl << s << endl;
else
    cout << "Failed to retrieve modulus" << endl;

BIO_reset(bio.get());
mem = NULL;

rc = BN_print(bio.get(), e);
ASSERT(rc == 1);

BIO_get_mem_ptr(bio.get(), &mem);
if(mem && mem->data && mem->length)
    s.assign(mem->data, mem->length);

if(s.length())
    cout << "Public exponent: " << endl << s << endl;
else
    cout << "Failed to retrieve public exponent" << endl;

BIO_reset(bio.get());
mem = NULL;

rc = BN_print(bio.get(), d);
ASSERT(rc == 1);

BIO_get_mem_ptr(bio.get(), &mem);
if(mem && mem->data && mem->length)
    s.assign(mem->data, mem->length);

if(s.length())
    cout << "Private exponent: " << endl << s << endl;
else
    cout << "Failed to retrieve private exponent" << endl;

BIGNUM* n = rsa.get()->n;
cout << "BN_bn2dec:" << endl;
cout << BN_bn2dec(n) << endl;

---

如果您喜欢第一个示例的格式（以冒号分隔的八位字节），那么请查看

ASN1\u bn\u print

。您可以使用它依次打印

RSA

成员

RSA\u print

和

RSA\u print\u fp

内部调用

ASN1\u bn\u print

。这里有一个例子

---

你也可以使用

BN_bn2dec

和朋友。例如：

// RSA object 'owns' the BIGNUM. Don't destroy it.
BIGNUM* n = rsa.get()->n;
BIGNUM* e = rsa.get()->e;
BIGNUM* d = rsa.get()->d;

string s;

BIO_reset(bio.get());
mem = NULL;

rc = BN_print(bio.get(), n);
ASSERT(rc == 1);

BIO_get_mem_ptr(bio.get(), &mem);
if(mem && mem->data && mem->length)
    s.assign(mem->data, mem->length);

if(s.length())
    cout << "Modulus: " << endl << s << endl;
else
    cout << "Failed to retrieve modulus" << endl;

BIO_reset(bio.get());
mem = NULL;

rc = BN_print(bio.get(), e);
ASSERT(rc == 1);

BIO_get_mem_ptr(bio.get(), &mem);
if(mem && mem->data && mem->length)
    s.assign(mem->data, mem->length);

if(s.length())
    cout << "Public exponent: " << endl << s << endl;
else
    cout << "Failed to retrieve public exponent" << endl;

BIO_reset(bio.get());
mem = NULL;

rc = BN_print(bio.get(), d);
ASSERT(rc == 1);

BIO_get_mem_ptr(bio.get(), &mem);
if(mem && mem->data && mem->length)
    s.assign(mem->data, mem->length);

if(s.length())
    cout << "Private exponent: " << endl << s << endl;
else
    cout << "Failed to retrieve private exponent" << endl;

BIGNUM* n = rsa.get()->n;
cout << "BN_bn2dec:" << endl;
cout << BN_bn2dec(n) << endl;

---

谢谢你的回答，但请你详细解释一下。我对此了解不够。正如文档所述，此函数将给定

RSA*

对象

x

的字符串表示形式写入给定的

文件*

流

stdout

具有类型

FILE*

，表示您的控制台。写入此“文件”时，数据将显示在程序标准输出中。

BIGNUM* n = rsa.get()->n;

int req = BN_num_bytes(n) + 4;
unsigned char* ptr = (unsigned char*)OPENSSL_malloc(req);

rc = ASN1_bn_print(bio.get(), "Modulus:", n, ptr, 0);
ASSERT(rc == 1);

BIO_get_mem_ptr(bio.get(), &mem);
if(mem && mem->data && mem->length)
    s.assign(mem->data, mem->length);

if(s.length())
    cout << s << endl;
else
    cout << "Failed to retrieve modulus" << endl;

Modulus:
    00:bf:49:fa:f2:30:21:42:de:91:60:f3:02:37:87:
    86:f4:eb:85:2c:95:86:42:69:6f:bc:cf:3f:27:9e:
    17:b6:44:06:5f:e7:ea:9f:e8:38:a7:5a:d5:da:9f:
    4b:26:df:78:15:d7:df:22:c0:16:12:77:f9:18:aa:
    85:01:21:3a:b0:ae:39:b8:07:cd:d4:2c:a3:0b:1c:
    df:be:09:03:09:76:5f:a1:1e:c0:00:8e:bf:b2:40:
    e2:3c:eb:d1:85:6f:7a:ab:35:c3:3a:c4:23:db:39:
    0c:d0:2b:39:b3:a5:a5:08:a2:e4:00:d5:0b:b0:87:
    62:ae:7c:a4:6c:e6:1c:d6:c9

BIGNUM* n = rsa.get()->n;
cout << "BN_bn2dec:" << endl;
cout << BN_bn2dec(n) << endl;

BN_bn2dec: 
12243739000135209335165415265342326792394455644180015057748915050940947919482400
64106225312022889083399949792870649447719809295883754268473265926413766309145047
08000254475023744104439182803717332048247971986885955229841406443364223719542912
385690146029374797423322891147172613041161904860242946608474463378207