关键是PEM编码.您需要剥离PEM页眉和页脚,然后从Base64转换回DER / BER,最后使用Crypto的BERDecodePrivateKey.

在Keys and Formats下的Crypto wiki上有一些关于这个主题的阅读.下面是执行转换的代码(我不相信Stack Overflow在Crypto中有一个工作示例).

string RSA_PRIV_KEY =

"-----BEGIN RSA PRIVATE KEY-----\n"

"MIIBOgIBAAJBAK8Q+ToR4tWGshaKYRHKJ3ZmMUF6jjwCS/u1A8v1tFbQiVpBlxYB\n"

"paNcT2ENEXBGdmWqr8VwSl0NBIKyq4p0rhsCAQMCQHS1+3wL7I5ZzA8G62Exb6RE\n"

"INZRtCgBh/0jV91OeDnfQUc07SE6vs31J8m7qw/rxeB3E9h6oGi9IVRebVO+9zsC\n"

"IQDWb//KAzrSOo0P0yktnY57UF9Q3Y26rulWI6LqpsxZDwIhAND/cmlg7rUz34Pf\n"

"SmM61lJEmMEjKp8RB/xgghzmCeI1AiEAjvVVMVd8jCcItTdwyRO0UjWU4JOz0cnw\n"

"5BfB8cSIO18CIQCLVPbw60nOIpUClNxCJzmMLbsrbMcUtgVS6wFomVvsIwIhAK+A\n"

"YqT6WwsMW2On5l9di+RPzhDT1QdGyTI5eFNS+GxY\n"

"-----END RSA PRIVATE KEY-----";

static string HEADER = "-----BEGIN RSA PRIVATE KEY-----";

static string FOOTER = "-----END RSA PRIVATE KEY-----";

size_t pos1,pos2;

pos1 = RSA_PRIV_KEY.find(HEADER);

if(pos1 == string::npos)

throw runtime_error("PEM header not found");

pos2 = RSA_PRIV_KEY.find(FOOTER,pos1+1);

if(pos2 == string::npos)

throw runtime_error("PEM footer not found");

// Start position and length

pos1 = pos1 + HEADER.length();

pos2 = pos2 - pos1;

string keystr = RSA_PRIV_KEY.substr(pos1,pos2);

// Base64 decode,place in a ByteQueue

ByteQueue queue;

Base64Decoder decoder;

decoder.Attach(new Redirector(queue));

decoder.Put((const byte*)keystr.data(),keystr.length());

decoder.MessageEnd();

// Write to file for inspection

FileSink fs("decoded-key.der");

queue.CopyTo(fs);

fs.MessageEnd();

try

{

CryptoPP::RSA::PrivateKey rsaPrivate;

rsaPrivate.BERDecodePrivateKey(queue,false /*paramsPresent*/,queue.MaxRetrievable());

// BERDecodePrivateKey is a void function. Here's the only check

// we have regarding the DER bytes consumed.

ASSERT(queue.IsEmpty());

}

catch (const Exception& ex)

{

cerr << ex.what() << endl;

exit (1);

}

加载密钥后,您可以使用以下命令对其进行验证：

AutoSeededRandomPool prng;

bool valid = rsaPrivate.Validate(prng,3);

if(!valid)

cerr << "RSA private key is not valid" << endl;

并打印出来：

cout << "N: " << rsaPrivate.GetModulus() << endl << endl;

cout << "E: " << rsaPrivate.GetPublicExponent() << endl << endl;

cout << "D: " << rsaPrivate.GetPrivateExponent() << endl << endl;

如果密钥受密码保护,则Crypto无法对其进行解码.该库缺乏执行解密的支持.在这种情况下,您可以使用以下OpenSSL命令将其转换为BER / DER.然后你可以使用加密密钥材料.

openssl pkcs8 -nocrypt -in rsa-key.pem -inform PEM -topk8 -outform DER -out rsa-key.der

示例程序使用以下方法将密钥写入文件：

FileSink fs("decoded-key.der");

queue.CopyTo(fs);

fs.MessageEnd();

CopyTo将队列中的字节留待以后使用.您可以使用ASN.1工具转储文件,例如Gutmann的dumpasn1：

$dumpasn1 decoded-key.der

0 314: SEQUENCE {

4 1: INTEGER 0

7 65: INTEGER

: 00 AF 10 F9 3A 11 E2 D5 86 B2 16 8A 61 11 CA 27

: 76 66 31 41 7A 8E 3C 02 4B FB B5 03 CB F5 B4 56

: D0 89 5A 41 97 16 01 A5 A3 5C 4F 61 0D 11 70 46

: 76 65 AA AF C5 70 4A 5D 0D 04 82 B2 AB 8A 74 AE

: 1B

74 1: INTEGER 3

77 64: INTEGER

: 74 B5 FB 7C 0B EC 8E 59 CC 0F 06 EB 61 31 6F A4

: 44 20 D6 51 B4 28 01 87 FD 23 57 DD 4E 78 39 DF

: 41 47 34 ED 21 3A BE CD F5 27 C9 BB AB 0F EB C5

: E0 77 13 D8 7A A0 68 BD 21 54 5E 6D 53 BE F7 3B

143 33: INTEGER

: 00 D6 6F FF CA 03 3A D2 3A 8D 0F D3 29 2D 9D 8E

: 7B 50 5F 50 DD 8D BA AE E9 56 23 A2 EA A6 CC 59

: 0F

178 33: INTEGER

: 00 D0 FF 72 69 60 EE B5 33 DF 83 DF 4A 63 3A D6

: 52 44 98 C1 23 2A 9F 11 07 FC 60 82 1C E6 09 E2

: 35

213 33: INTEGER

: 00 8E F5 55 31 57 7C 8C 27 08 B5 37 70 C9 13 B4

: 52 35 94 E0 93 B3 D1 C9 F0 E4 17 C1 F1 C4 88 3B

: 5F

248 33: INTEGER

: 00 8B 54 F6 F0 EB 49 CE 22 95 02 94 DC 42 27 39

: 8C 2D BB 2B 6C C7 14 B6 05 52 EB 01 68 99 5B EC

: 23

283 33: INTEGER

: 00 AF 80 62 A4 FA 5B 0B 0C 5B 63 A7 E6 5F 5D 8B

: E4 4F CE 10 D3 D5 07 46 C9 32 39 78 53 52 F8 6C

: 58

: }

0 warnings,0 errors.