openssl pem 生成公钥和私钥及文件

openssl pem.h 中提供了关于pem格式密钥对的操作接口

通常使用.pem的格式文件来保存openssl 生成的密钥对；

在终端下 cat xxx.pem 可以看到

p.p1 { margin: 0.0px 0.0px 0.0px 0.0px; font: 11.0px Menlo }
span.s1 { }
-----BEGIN RSA PRIVATE KEY-----

XXXX

p.p1 { margin: 0.0px 0.0px 0.0px 0.0px; font: 11.0px Menlo }
span.s1 { }
p.p1 { margin: 0.0px 0.0px 0.0px 0.0px; font: 11.0px Menlo }
span.s1 { }
-----END RSA PRIVATE KEY-----

密钥数据进行了BASE64编码

1. 示例：将生成的密钥对保存成pem文件

void testWriteRSA2PEM()
{
//生成密钥对
RSA *r = RSA_new();
int bits = 512;
BIGNUM *e = BN_new();
BN_set_word(e, 65537);
RSA_generate_key_ex(r, bits, e, NULL);

RSA_print_fp(stdout, r, 0);

BIO *out;
out = BIO_new_file("/Users/cocoajin/Desktop/opriv.pem","w");
//这里生成的私钥没有加密，可选加密
int ret = PEM_write_bio_RSAPrivateKey(out, r, NULL, NULL, 0, NULL, NULL);
printf("writepri:%d\n",ret);
BIO_flush(out);
BIO_free(out);

out = BIO_new_file("/Users/cocoajin/Desktop/opub.pem","w");
ret = PEM_write_bio_RSAPublicKey(out, r);
printf("writepub:%d\n",ret);
BIO_flush(out);
BIO_free(out);

BN_free(e);
RSA_free(r);

}

在目标路径保存了生成的公钥opub.pem和私钥oprov.pem

输出日志

Public-Key: (512 bit)
Modulus:
00:e6:96:f5:6f:4d:5e:c2:ad:0d:f5:13:45:99:55:
ca:6f:84:4f:3a:56:52:e2:ee:a2:cc:73:77:07:e2:
3d:0d:e3:0d:c0:6a:92:52:b6:c7:de:e2:d6:88:56:
9e:92:99:91:dd:2d:06:c5:a8:f2:c1:79:8b:20:f9:
73:0a:7a:28:93
Exponent: 65537 (0x10001)
Private-Key: (512 bit)
modulus:
00:e6:96:f5:6f:4d:5e:c2:ad:0d:f5:13:45:99:55:
ca:6f:84:4f:3a:56:52:e2:ee:a2:cc:73:77:07:e2:
3d:0d:e3:0d:c0:6a:92:52:b6:c7:de:e2:d6:88:56:
9e:92:99:91:dd:2d:06:c5:a8:f2:c1:79:8b:20:f9:
73:0a:7a:28:93
publicExponent: 65537 (0x10001)
privateExponent:
00:ca:1b:92:6f:c5:de:c2:bf:2f:b6:98:f7:ad:d8:
16:20:fc:54:fd:0a:e0:87:6b:26:62:10:ea:49:8c:
b0:7a:d3:d8:28:b7:fb:15:f1:4e:95:9d:bf:31:3a:
e0:f3:fa:24:d3:71:fd:b0:f5:cd:5c:25:d1:81:8c:
01:e3:fb:c7:21
prime1:
00:f6:d7:91:c4:1a:2f:eb:0b:c4:18:14:3b:fe:f6:
0d:c1:11:94:ca:6c:06:fc:de:d7:19:ac:58:9d:36:
16:fe:9b
prime2:
00:ef:25:07:75:76:4d:ac:19:aa:ed:e9:a7:1d:5d:
b1:7d:1c:1a:ef:95:8f:2d:bc:8a:e7:93:f5:f8:15:
69:61:69
exponent1:
00:f4:d2:c0:6f:b8:ed:77:fa:16:87:2f:62:86:31:
b3:58:9f:c0:6c:b8:92:81:b1:df:b4:45:fd:2a:08:
60:ec:2b
exponent2:
00:b5:88:c1:69:bc:3d:67:f8:30:15:db:f9:5c:c4:
63:d8:59:fe:64:82:7e:a6:b4:6a:29:32:db:53:d0:
45:27:89
coefficient:
0a:97:26:2f:e9:ca:b6:32:86:86:3b:5a:13:ea:5e:
8d:79:77:b9:7a:30:41:c4:31:cb:02:0e:96:6b:1b:
e5:c4
Program ended with exit code: 0

View Code

4. 在终端下使用openssl命令生成公钥私钥

//生成1024位的RSA私钥
openssl genrsa -out private.pem 1024

//再由私钥生成公钥
openssl rsa -in private.pem -pubout -out public.pem

//私钥文件private.pem
//公钥文件public.pem
//上面私钥是没加密的，可选加密，指定一个加密算法生成时输入密码

以上测试使用openssl 1.1.0c

参考：https://www.openssl.org/docs/man1.1.0/crypto/PEM_read_bio_RSAPublicKey.html