docs: completed readme

Author: siujamo

key-pair-loader/README.md

@@ -43,22 +43,71 @@ ZyYNcH60ONRWjMqlQXozWMb2i7WphKxf8kopp42nzCflWQod+JQY+hM/EQ==
 -----END PUBLIC KEY-----
 ```
 
-#### Convert private key to EC formats which could be acceptable by Java
+## RSA-based algorithm
 
-Java's `PKCS8EncodedKeySpec` requires the private key to be in PKCS#8 format, while OpenSSL by
-default generates private keys in traditional PEM format. To convert the private key, run the
-following command:
+### Generate key pair
+
+#### Generate private key
+
+Generate a private key by `genpkey` command provided by OpenSSL:
 
 ```shell
-openssl pkcs8 -topk8 -inform PEM -outform PEM -in ec_private_key.pem -out ec_private_key_pkcs8.pem -nocrypt
+openssl genpkey -algorithm RSA -out rsa_private_key.pem -pkeyopt rsa_keygen_bits:2048
 ```
 
-The converted private key will look like this:
+The output of this command is a file called `rsa_private_key.pem` and its content looks like the
+following:
 
 ```text
 -----BEGIN PRIVATE KEY-----
-MIGHAgEAMBMGByqGSM49AgEGCCqGSM49AwEHBG0wawIBAQQgs79JlARgXEf6EDV7
-+PHQCTHEMtqIoHOy1GZ1+ynQJ6yhRANCAARkA7GRY2i4gg8qx0XViAXUP9cPw9pn
-Jg1wfrQ41FaMyqVBejNYxvaLtamErF/ySimnjafMJ+VZCh34lBj6Ez8R
+MIIEvQIBADANBgkqhkiG9w0BAQEFAASCBKcwggSjAgEAAoIBAQD4VIFYJFMAs15j
+J3V3IicHd7sI2TIFqTZME40zlOlVAlPKLZmTQvZFLNgaUAAsvPi5i1DR2ywwK6Al
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+hXKe4HcuhQ3G0a2hjayiQ84=
 -----END PRIVATE KEY-----
+```
+
+#### Generate public key by private key
+
+Export public key from private key by OpenSSL:
+
+```shell
+openssl pkey -in rsa_private_key.pem -pubout -out rsa_public_key.pem
+```
+
+The output of this command is a file called `rsa_public_key.pem` and its content looks like the
+following:
+
+```text
+-----BEGIN PUBLIC KEY-----
+MIIBIjANBgkqhkiG9w0BAQEFAAOCAQ8AMIIBCgKCAQEA+FSBWCRTALNeYyd1dyIn
+B3e7CNkyBak2TBONM5TpVQJTyi2Zk0L2RSzYGlAALLz4uYtQ0dssMCugJQX58FZ8
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+gQIDAQAB
+-----END PUBLIC KEY-----
 ```