RSA 如何分段加密

zhangtenghai — Tue, 16 Feb 2016 22:26:08 +0800

创建的 key 长度为 1024 用公钥加密比较长的字符串时会异常。如何对长文本进行分段加密？

message = "long long text"
pkey = OpenSSL::PKey::RSA.new 1024
pkey.public_encrypt(message)

时隔多日回来追加答案

  MAX_ENCRYPT_LENGTH = 117
  MAX_DECRYPT_LENGTH = 128

#分段加密
  def encrypt_msg(key, message)
    bytes_array = message.unpack("C*")
    input_length = bytes_array.length

    encryt_str, offset, i = "", 0, 0
    begin
      encryt_bytes = bytes_array[offset, MAX_ENCRYPT_LENGTH]
      encryt_str << key.public_encrypt(encryt_bytes.pack("C*")) #加密
      offset = (i += 1) * MAX_ENCRYPT_LENGTH
    end while input_length - offset > 0

    Base64::strict_encode64(encryt_str)
  end

  #分段解密
  def decrypt_msg(key, message)
    bytes_array = Base64::decode64 message
    input_length = bytes_array.length

    decryt_str, offset, i = "", 0, 0
    begin
      decryt_bytes = bytes_array[offset, MAX_DECRYPT_LENGTH]
      decryt_str << key.private_decrypt(decryt_bytes) #解密
      offset = (i += 1) * MAX_DECRYPT_LENGTH
    end while input_length - offset > 0

    decryt_str
  end

zhangtenghai (evaclaire)

RSA 如何分段加密