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Encryption methods supported by Opera

The encryption methods supported by Opera are listed in Tools > Preferences > Advanced > Security > Security Protocols (Mac: Opera > Preferences > Advanced > Security > Security Protocols) (click "Details" to show the detailed list).

The list of encryption methods has this format:

[n] bit [Method] ([Public key-method]/[Hash method])

This describes how many bits (<n) the encryption keys used for transmission of data have, which method is used for data transmission, which public key method is used to exchange the shared secrets needed, and the hash method used to verify that the transmitted data are correct.

Opera supports these encryption methods:

  • Authentication Only: This method does not encrypt the transmitted data, but can authenticate the server, and if necessary, yourself, and verifies that the data have not been tampered with. This method lets anyone read your data, but not change them. It may be used for transmission of already encrypted data, saving the computational time needed for the extra, unnecessary, encryption.
  • C2: An encryption method compatible with RC2 (developed by RSA Data Security Inc.). It can use 40 bit (disabled by default) or 128 bit keys (128 bit only in SSL v2).
  • C4: An encryption method compatible with RC4 (also developed by RSA Data Security Inc.) It can use 40 bit (disabled by default) or 128 bit keys.
  • DES (disabled by default): An encryption method developed by IBM in 1974, and certified as a US standard at least until 1998. It can use 40 or 56 bit keys.
  • 3-DES: An adaption of DES using 3 encryption/decryption steps with 3 different keys, giving a total of 168 bit in the key.

The encryption method list is listed in ascending order depending on the number of bits in the method's key, and it's assumed security.

Presently, the only Public key method supported is RSA. It is used to verify the Public key cerificates sent by the server and the client (you), and to encrypt the shared secrets used by the server and the client. The methods in SSL version 3 that uses 40 bit keys has a limit on keysize set to 512 bit (for encryption, not signing).

The Hash methods are used to check the integrity of the data, by using the method to calculate a value from the transmitted data, and which is unique for those data, and which cannot be used to find out anything about the data. The two methods used by Opera are called MD5 (developed by RSA Data Security Inc.) and SHA (developed by the US government).

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