The invention discloses a method for multi-way encryption, signing and zero knowledge certification. Large prime number a, b, p and q are chosen, p=2a+1 and q=2b+1, n=pq, and t=4ab; k large odd numbers xk are found, the requirements that (pi xi) %t=1 (0<i<=k) and xi, a and b are relatively prime respectively; each participant i possesses (xi, n) which serves as a private key, namely, a multi-way encryption system is formed; when I sends a plaintext M to J, after I conducts power modular arithmetic encryption on the plaintext M through a private key of I, a result is sent to other participants in the system so that the private key of the participant is used as the only one iteration encryption until J encodes the plaintext through a private key of J. When signing is conducted in a group, each participant adds self signing to the plaintext behind the signing of other participant for checking. In the condition of zero knowledge certification, a decoded ciphertext is compared with the plaintext so that verification is conducted without leakage of information. The method has the advantage that each participant participates in a iteration encryption process for only once.