SampleAPI for RSA + AES encryption

CryptographyApi.java

package com.example.secure;

import java.io.UnsupportedEncodingException;
import java.security.InvalidKeyException;
import java.security.SecureRandom;
import java.time.LocalDateTime;
import java.time.temporal.ChronoUnit;
import java.util.concurrent.ThreadLocalRandom;

import javax.crypto.BadPaddingException;
import javax.crypto.IllegalBlockSizeException;

import org.apache.commons.lang3.RandomStringUtils;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.http.MediaType;
import org.springframework.http.ResponseEntity;
import org.springframework.web.bind.annotation.GetMapping;
import org.springframework.web.bind.annotation.RequestHeader;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RestController;

import com.fasterxml.jackson.databind.ObjectMapper;

@RestController
@RequestMapping("/api/crypto")
public class CryptographyApi {

	@Autowired
	private CryptographyService cryptographyService;

	@Autowired
	private ObjectMapper objectMapper;

	private final SecureRandom secureRandom = new SecureRandom();

	@GetMapping(value = "/encrypted_string", produces = MediaType.TEXT_PLAIN_VALUE)
	public ResponseEntity<String> getEncrypted(@RequestHeader(name = "public-key", required = true) String rsaPublicKey)
			throws InvalidKeyException, UnsupportedEncodingException, IllegalBlockSizeException, BadPaddingException,
			Exception {
		var leadSample = Customer.builder().customerId("cust" + RandomStringUtils.randomNumeric(8))
				.customerName("Customer name " + ThreadLocalRandom.current().nextInt())
				.dateOfBirth(LocalDateTime.now().truncatedTo(ChronoUnit.DAYS)
						.minusMonths(ThreadLocalRandom.current().nextInt(12 * 22, 12 * 55)))
				.build();
		var plainText = objectMapper.writeValueAsString(leadSample);

		var salt = Long.toString(secureRandom.nextLong(100000l, 999999999l));
		var cipherKey = salt + RandomStringUtils.randomAlphanumeric(32 - salt.length());

		// encrypt plain text to AES
		var encryptedText = cryptographyService.encryptAES(plainText, cipherKey);

		// encrypt AES cipher key (asymmetric RSA via public key)
		var rsaCipherKey = cryptographyService.encryptRSA(cipherKey,
				cryptographyService.getRSAPublicFromBase64(rsaPublicKey));

		return ResponseEntity.ok().header("Encrypted-AES-Key", rsaCipherKey).body(encryptedText);
	}

}

Hi !
I read your tutorial a lot and it helped me.

But there's something I don't understand, when you pass public-key in requestHeader , I wonder how a client can pass data in the request header.