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Cipher Suites

A cipher suite is a set of algorithms that help secure a network connection. Suites typically use Transport Layer Security (TLS) or its now-deprecated predecessor Secure Socket Layer (SSL). The set of algorithms that cipher suites usually contain include: a key exchange algorithm, a bulk encryption algorithm, and a message authentication code (MAC) algorithm.

The key exchange algorithm is used to exchange a key between two devices. This key is used to encrypt and decrypt the messages being sent between two machines.

The bulk encryption algorithm is used to encrypt the data being sent.

The MAC algorithm provides data integrity checks to ensure that the data sent does not change in transit. In addition, cipher suites can include signatures and an authentication algorithm to help authenticate the server and or client.

A cipher suite is as secure as the algorithms that it contains. If the version of encryption or authentication algorithm in a cipher suite have known vulnerabilities, the cipher suite and TLS connection is then vulnerable.

Weak algorithms#

  • RSA with key < 2048 bytes, can be brute-forced in feasible time

  • OpenSSL Elliptic Curves, secp112r1, secp112r2, secp128r1, secp128r2, secp160k1, secp160r1, secp160r2, secp192k1, prime192v1, prime192v2, prime192v3, sect113r1, sect113r2, sect131r1, sect131r2, sect163k1, sect163r1, sect163r2, sect193r1, sect193r2, c2pnb163v1, c2pnb163v2, c2pnb163v3, c2pnb176v1, c2tnb191v1, c2tnb191v2, c2tnb191v3, c2pnb208w1, wap-wsg-idm-ecid-wtls1, wap-wsg-idm-ecid-wtls3, wap-wsg-idm-ecid-wtls4, wap-wsg-idm-ecid-wtls5, wap-wsg-idm-ecid-wtls6, wap-wsg-idm-ecid-wtls7, wap-wsg-idm-ecid-wtls8, wap-wsg-idm-ecid-wtls9, wap-wsg-idm-ecid-wtls10, wap-wsg-idm-ecid-wtls11, oakley-ec2n-3, oakley-ec2n-4, brainpoolp160r1, brainpoolp160t1, brainpoolp192r1, brainpoolp192t1, can be brute-forced in feasible time