RSA Key转换成一行，PEM密钥提取，去掉注释，去掉换行
RSA PEM密钥原始格式，
- 要去掉开头和结尾的注释 -----BEGIN CERTIFICATE----- 和 -----END CERTIFICATE-----
- 去掉换行，变成一行
-----BEGIN CERTIFICATE-----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-----END CERTIFICATE-----
提取结果
MIID3DCCAsSgAwIBAgIUS3cXBbb/ygB6rgWjUS5OqSO/dX4wDQYJKoZIhvcNAQELBQAwXjELMAkGA1UEBhMCQ04xEzARBgNVBAoTClRlbnBheS5jb20xHTAbBgNVBAsTFFRlbnBheS5jb20gQ0EgQ2VudGVyMRswGQYDVQQDExJUZW5wYXkuY29tIFJvb3QgQ0EwHhcNMjEwNTIwMDkyNjQ1WhcNMjYwNTE5MDkyNjQ1WjBuMRgwFgYDVQQDDA9UZW5wYXkuY29tIHNpZ24xEzARBgNVBAoMClRlbnBheS5jb20xHTAbBgNVBAsMFFRlbnBheS5jb20gQ0EgQ2VudGVyMQswCQYDVQQGDAJDTjERMA8GA1UEBwwIU2hlblpoZW4wggEiMA0GCSqGSIb3DQEBAQUAA4IBDwAwggEKAoIBAQDKRFwSatSXtWvra+2UTROwSJyzZNhDbVOPM1wcJFK2MIFA0K7LMXK3KsR0PQzUwWbVQWNUnzopRfeq0t62foqIAq9L0D5qoqk+TPJm6+aJhAIzchiF293nZDzpQNe1h8hVmnZlxr1itGSSup2kM7fYBIchnnbIXUdAyBelsQK7mCJfNKqK/LKWrHDBJ9WpZM6N5QhgD3cbkpr/LoWa3CVxyt7yQqVv6QvhqPiZ8pMN2qzvrAiOKd3ci/C1yhoolJZ1e9tDkKbFQLVol3EbCZeJUthLE5hFGhIHBn/2aZdtxa/qfuT2JNnTMgcufn0Ot8I3hmP5m13kXbWriQL9YPUvAgMBAAGjgYEwfzAJBgNVHRMEAjAAMAsGA1UdDwQEAwIE8DBlBgNVHR8EXjBcMFqgWKBWhlRodHRwOi8vZXZjYS5pdHJ1cy5jb20uY24vcHVibGljL2l0cnVzY3JsP0NBPTFCRDQyMjBFNTBEQkMwNEIwNkFEMzk3NTQ5ODQ2QzAxQzNFOEVCRDIwDQYJKoZIhvcNAQELBQADggEBAFwf2/kBqJMCNoVHC4Bamt3bxRnOprfU5Z9FhtfSOlLMMcl0frSd+ihAzxGcocrZ9UkoGMu4kCYLSIOV7Wz9f0oiYvdTDAXje73WdJsEgbJQHtzKtk4IBHIgWIJ+joW3kTkVGjKqqFjxF6bhj0GRTCzTFv3JfuUfJCDbAGqezs2Fu77itrqPsH0gvaXNa+lWIIdDAUF/M00O0oYpasSw7wSkojTGhBvU2uKzmEOG9xBKvcs6z4CTeIOc0pCWOtaAqZ2vhdLNvmoJHQnOyhDwgTZC+cCZ23wyqs0csvM5JPyzxvlrgU7kmgiXdmC6e//6k7dE9e92cZoI913nSB0z9VA=
提取方法
string key = publicKey.Replace("-----BEGIN CERTIFICATE-----", "").Replace("-----END CERTIFICATE-----", "").Replace("\r\n", "").Replace("\n", "");
