两种方式-生成RSA256私钥公钥

两种方式生成私钥公钥

1.ssh-keygen 方式

生成加密长度4096位密钥

生成私钥：ssh-keygen -t rsa -b 4096 -f ${private}.key

生成公钥：openssl rsa -in ${private}.key -pubout -outform PEM -out ${public}.key.pub

转换格式：openssl pkcs8 -topk8 -inform PEM -in jwtRS256.key -outform pem -nocrypt -out pkcs8.pem

生成加密长度1024位密钥

生成私钥：ssh-keygen -t rsa -b 1024 -f ${private}.key

生成公钥：openssl rsa -in ${private}.key -pubout -outform PEM -out ${public}.key.pub

转换格式：openssl pkcs8 -topk8 -inform PEM -in jwtRS256.key -outform pem -nocrypt -out pkcs8.pem

2.openssl方式

生成加密长度1024位密钥

生成私钥：openssl genrsa -out rsaprivatekey.pem 1024

生成公钥：openssl rsa -in rsaprivatekey.pem -out rsapublickey.pem -pubout

转换格式：openssl pkcs8 -topk8 -in rsaprivatekey.pem -out pkcs8rsaprivate_key.pem -nocrypt

最大加密明文长度为117位，最大解密密文128位

比如：需要加密String param = "id=1&name=张三",实际上只能加密到：id=1&name.

使用一对1024位密钥私钥-加密后得到密文：[B@39ba5a14.

解密也只能按照128位：[B@39ba5a14 将1024位公钥解密后 得到id=1&name

我这里使用的公私钥分别为：

publicKey = "MIGfMA0GCSqGSIb3DQEBAQUAA4GNADCBiQKBgQCr1CJfUouPBVoGAnoxUd2Uj8MZ\n" +
 "NFvFSBYNlK74zwQxFsPXhNq2ba3JQCwV6P35cNqEK2htaG+phr/Gy+3YVQWl1Tau\n" +
 "5bVbsWCkwO+5EHdx9dN1IfUUO9Y9NDarUxYyeBOvtfc2I/bA5xwPkskRMzBKWbp1\n" +
 "kC9AxstNiOoJnUNF3wIDAQAB";

privateKey = "MIICeAIBADANBgkqhkiG9w0BAQEFAASCAmIwggJeAgEAAoGBAKvUIl9Si48FWgYC\n" +
 "ejFR3ZSPwxk0W8VIFg2UrvjPBDEWw9eE2rZtrclALBXo/flw2oQraG1ob6mGv8bL\n" +
 "7dhVBaXVNq7ltVuxYKTA77kQd3H103Uh9RQ71j00NqtTFjJ4E6+19zYj9sDnHA+S\n" +
 "yREzMEpZunWQL0DGy02I6gmdQ0XfAgMBAAECgYEAkFVO0hc6V1a9edLW5VrI76Oa\n" +
 "1C8g7yRQMfQ0zZbHBJ0EwKI+PYL/uc8HuRfPTpo3U1JLE6voL9SaftiJ32/7nyJv\n" +
 "5ij6Yy+aX2q93oU9Y+9AZ9ottynY5X2pDwhVtw87ESa/zSGVjq+6fkc9+3FsmnKi\n" +
 "XCbyKN2d0RAITaMyQpECQQDXnAwdSzFubmLyoKoRsMiNckvGH6lDjykvjbhBkTCy\n" +
 "E8AVkxI0F9Kk5UTMLqCJyd1D7tCQuLkWu4IT+cZoA6oVAkEAzAR+MKm5kNT28Jzm\n" +
 "JqX0i2nX3SR1LLbf+oKqM2X21z4XJVIbZH9iTlYpwU9ctvENfMl26p5r3HzXb8xY\n" +
 "UqExIwJBAJGqntCnvYTDVVxgyaXcDxLpFmKLf3riXMwA7mx14DVffJXW4CSLt8eq\n" +
 "Efn0wod092VvEj/EXWALXM2MIcyiNSUCQFlZhmKNkoWJn3SVYn5+o/ECs9VYCDFD\n" +
 "DijKXPwRpd9yg/SGVxTWbRldxv+wYCyGuZ9zJC9wnlB8JGYEGpJlof0CQQCg2wrN\n" +
 "iXhlPca0KboggdqThdESAdpINS5lq4ZhZDpIlUY7HmZCG/VdXXPnd4U4JAsBJhS6\n" +
 "uglcCks44QIDM9D6";

密钥可分为1024，2048，4096等位密钥，位数不同，可加解密明文长度不一。 比如1024位密钥： 可加解密明文长度 len = 1024/8 - 11 = 117字节。