While reading Shamir, Rivest and Adleman's paper on "Mental Poker", I've met a mention of system such that $E_a(E_b(x)) == E_b(E_a(x))$, without however disclosing details on it, with $E_a(x)$ being “encrypt plaintext $x$ with key $a$”.

Do any existing secure modern cryptosystems have this property, and how is it called for later reference?

While reading Shamir, Rivest and Adleman's paper on "Mental Poker", I've met a mention of system such that $E_a(E_b(x)) = E_b(E_a(x))$, without however disclosing details on it, with $E_a(x)$ being “encrypt plaintext $x$ with key $a$”.

Do any existing secure modern cryptosystems have this property, and how is it called for later reference?

While reading Shamir, Rivest and Adleman's paper on "Mental Poker", I've met a mention of system such that E_a(E_b(x)) == E_b(E_a(x)), without however disclosing details on it, with E_a(x) being 'encrypt plaintext x with key a'.

Do any existing secure modern cryptosystems have this property, and how is it called for later reference?

While reading Shamir, Rivest and Adleman's paper on "Mental Poker", I've met a mention of system such that $E_a(E_b(x)) == E_b(E_a(x))$, without however disclosing details on it, with $E_a(x)$ being “encrypt plaintext $x$ with key $a$”.

Do any existing secure modern cryptosystems have this property, and how is it called for later reference?